Chapter 5. The Working Cell. Lecture by Richard L. Myers Translated by: Nabih A. Baeshen

Transcription

1 Chapter 5 The Working Cell PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Richard L. Myers Translated by: Nabih A. Baeshen

2 MEMBRANE STRUCTURE AND FUNCTION

3 5.1 Membranes are a fluid mosaic of phospholipids and proteins Membranes are composed of phospholipids and proteins Many phospholipids are made from unsaturated fatty acids that have kinks in their tails Membranes are commonly described as a fluid mosaic This means that the surface appears mosaic because of the proteins embedded in the phospholipids and fluid because the proteins can drift about in the phospholipids This is aided by cholesterol wedged into the bilayer to help stabilize the membrane at warm and also at lower temperature. keep it liquid

4 Kink ا Hydrophilic head ماء WATER Phospholi pid Bilayer WATER Hydrophobic tail ماء Hydrophobic regions of protein Hydrophilic regions of protein Phospholipid bilayer (cross section) The fluid mosaic model for membranes

5 5.1 Membranes are a fluid mosaic of phospholipids and proteins Many membrane proteins function as enzymes, others in signal transduction, while others are important in transport Because membranes allow some substances to cross or be transported more easily than others, they exhibit selectively permeability Nonpolar molecules (carbon dioxide and oxygen) cross easily Polar molecules (glucose and other sugars) do not cross easily

6 Messenger molecule إEnzymes Receptor Activated Molecule Enzyme activity Signal transduction

7 from a region of higher to lower concentration Concentration gradient High Concentration ماء Water Actice transport ماء Water Low Concentration Diagram of a section of a membrane sac Transport

8 5.3 Passive transport is diffusion across a membrane with no energy investment Diffusion is a process in which particles spread out evenly in an available space Particles move from an area of more concentrated particles to an area where they are less concentrated This means that particles diffuse down their concentration gradient Eventually, the particles reach equilibrium where the concentration of particles is the same throughout

9 5.3 Passive transport is diffusion across a membrane with no energy investment Diffusion across a cell membrane does not require energy, so it is called passive transport The concentration gradient itself represents potential energy for diffusion

10 Molecules of dye إEquilibrium Membrane Passive transport of one type of molecule

11 Two different Substances ن Membrane Equilibrium Passive transport of two types of molecules

12 5.4 Osmosis is the diffusion of water across a membrane It is crucial for cells that water moves across their membrane Water moves across membranes in response to solute concentration inside and outside of the cell by a process called osmosis Osmosis will move water across a membrane down its concentration gradient until the concentration of solute is equal on both sides of the membrane

13 Osmosis, the diffusion of water across اmembrane a Lower concentration of solute Higher concentration of solute Equal concentration of solute Solute molecule H 2 O Selectively permeable membrane Water Molecule Net flow of water Solute molecule with cluster of water molecules زيئات المذاب مع تجمعات من جزيئات الماء

14 5.5 Water balance between cells and their surroundings is crucial to organisms Tonicity is a term that describes the ability of a solution to cause a cell to gain or lose water Tonicity is dependent on the concentration of a nonpenetrating solute on both sides of the membrane Isotonic indicates that the concentration of a solute is the same on both sides Hypertonic indicates that the concentration of solute is higher outside the cell Hypotonic indicates a higher concentration of solute inside the cell

15 5.5 Water balance between cells and their surroundings is crucial to organisms Many organisms are able to maintain water balance within their cells by a process called osmoregulation This process prevents excessive uptake or excessive loss of water Plant, prokaryotic, and fungal cells have different issues with osmoregulation because of their cell walls

16 Many organisms are able to maintain water balance within their cells by a process called osmoregulation Isotonic solution Hypotonic solution Hypertonic solution Animal cell (A) Normal (B) Lysed (C) Shriveled Plasma Membrane Plant cell (D) Flaccid (E) Turgid (F) Shriveled (plasmolyzed ) How animal and plant cells behave in different solutions

17 5.6 Transport proteins may facilitate diffusion across membranes Many substances that are necessary for viability of the cell do not freely diffuse across the membrane because of their polarity. They require the help of specific transport proteins These proteins assist in facilitated diffusion, ( type of passive transport that does not require energy) including sugar,amino acids and ions. water transported through specific transport protein called aquaporin

18 5.6 Transport proteins may facilitate diffusion across membranes Some proteins function by becoming a hydrophilic tunnel for passage Other proteins bind their passenger, change shape, and release their passenger on the other side In both of these situations, the protein is specific for the substrate,

19 These proteins assist in facilitated diffusion, a type of passive transport that does not require energy Solute molecule Transport protein Transport protein providing a channel for the diffusion of a specific solute across a membrane

20 5.8 Cells expend energy in the active transport of a solute against its concentration gradient Cells have a mechanism for moving a solute against its concentration gradient It requires the expenditure of energy in the form of ATP The mechanism alters the shape of the membrane protein through phosphorylation using ATP

21 5.8 Cells expend energy in the active transport of a solute against its concentration gradient Transport Protein Solute Protein changes shape Phosphate Detaches 1 Solute binding ا 2 Phosphorylation 3 Transport 4 Protein reversion Active transport of a solute across a membrane

22 5.9 Exocytosis and endocytosis transport large molecules across membranes A cell uses two mechanisms for moving large molecules across membranes Exocytosis is used to export bulky molecules, such as proteins or polysaccharides Endocytosis is used to import substances useful to the livelihood of the cell In both cases, material to be transported is packaged within a vesicle that fuses with the membrane

23 ENERGY AND THE CELL

24 5.10 Cells transform energy as they perform work Cells are small units, a chemical factory, housing thousands of chemical reactions The result of reactions is maintenance of the cell, manufacture of cellular parts, and replication

25 5.10 Cells transform energy as they perform work Energy is the capacity to do work and cause change Work is accomplished when an object is moved against an opposing force, such as friction There are two kinds of energy Kinetic energy is the energy of motion Potential energy is energy that an object possesses as a result of its location

26 Kinetic energy, the energy of motion Potential energy, stored energy as a result of location or structure Potential energy being converted to kinetic energy

27 5.12 Chemical reactions either release or store energy A living organism produces thousands of endergonic and exergonic chemical reactions All of these combined is called metabolism A metabolic pathway is a series of chemical reactions that either break down a complex molecule or build up a complex molecule

28 5.12 Chemical reactions either release or store energy A cell does three main types of cellular work Chemical work driving endergonic reactions Transport work pumping substances across membranes Mechanical work beating of cilia To accomplish work, a cell must manage its energy resources, and it does so by energy coupling the use of exergonic processes to drive an endergonic one

29 A cell does three main types of cellular work

30 5.13 ATP shuttles chemical energy and drives cellular work ATP, adenosine triphosphate, is the energy currency of cells. ATP is the immediate source of energy that powers most forms of cellular work. It is composed of adenine (a nitrogenous base), ribose (a five-carbon sugar), and three phosphate groups.

31 5.13 ATP shuttles chemical energy and drives cellular work الطاقة الكيميائية الالزمة للخلية للقيام بمهماتهاATPينقل ال Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule The transfer is called phosphorylation In the process, ATP energizes molecules

32 Adenosine أ Triphosphate (ATP) ) Phosphate group The structure and hydrolysis of ATP. The reaction of ATP and water yields ADP, a phosphate group, and energy Adenine ريبوز Ribose Hydrolysis + طاقة Adenosine Diphosphate (ADP)

33 Energy from exergonic reactions Energy for endergonic reactions The ATP cycle

34 HOW ENZYMES FUNCTION

35 5.14 Enzymes speed up the cell s chemical reactions by lowering energy barriers The cell uses catalysis to drive (speed up) biological reactions Catalysis is accomplished by enzymes, which are proteins that function as biological catalysts Each enzyme has a particular target molecule called the substrate

36 5.15 A specific enzyme catalyzes each cellular reaction Enzymes have unique three-dimensional shapes The shape is critical to their role as biological catalysts As a result of its shape, the enzyme has an active site where the enzyme interacts with the enzyme s substrate Consequently, the substrate s chemistry is altered to form the product of the enzyme reaction

37 1 Enzyme available with empty active site Active site Substrate (sucrose) 2 Substrate binds to enzyme with induced fit Enzyme (sucrase) Glucose Fructose The catalytic cycle of an enzyme 4 Products are released 3 Substrate is converted to products

38 5.15 A specific enzyme catalyzes each cellular reaction For optimum activity, enzymes require certain environmental conditions 1- Temperature is very important, and optimally, human enzymes function best at 37ºC, close to normal body temperature - High temperature will denature human enzymes 2- Enzymes also require optimal PH near neutrality for best results

39 5.15 A specific enzyme catalyzes each cellular reaction Some enzymes require nonprotein helpers Cofactors are inorganic, such as zinc, iron, or copper Coenzymes are organic molecules and are often vitamins

40 5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell Inhibitors are chemicals that inhibit an enzyme s activity One group inhibits because they compete for the enzyme s active site and thus block substrates from entering the active site These are called competitive inhibitors

41 5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell Other inhibitors do not act directly with the active site These bind somewhere else and change the shape of the enzyme so that the substrate will no longer fit the active site These are called noncompetitive inhibitors

42 Substrate Active site Enzyme Normal binding of substrate How inhibitors interfere with substrate binding Competitive Noncompetitive Inhibitor Inhibitor Enzyme inhibition

43 5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell Enzyme inhibitors are important in regulating cell metabolism Often the product of a metabolic pathway can serve as an inhibitor of one enzyme in the pathway, a mechanism called feedback inhibition The more product formed, the greater the inhibition, and in this way, regulation of the pathway is accomplished

44 Requires no energy Passive transport Requires energy Active transport Diffusion Facilitated diffusion Higher solute concentration Osmosis Higher water concentration Higher solute concentration Solute Lower solute concentration Water Lower water concentration Lower solute concentration

45 Chapter 22 Gas Exchange PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Richard L. Myers Translated by Nabih A. Baeshen

46 MECHANISMS OF GAS EXCHANGE

47 22.1 Overview: Gas exchange in an animal with lungs involves breathing, transport of gases, and exchange of gases with tissue cells Three phases of gas exchange 1-Breathing: exchange of CO 2 produced during cellular respiration with atmospheric O 2 2-Transport of oxygen and carbon dioxide in blood by circulatory system. 3- Body cells take up oxygen from the blood and release carbon dioxide to the blood. Cellular respiration requires a continuous supply of oxygen and the disposal of carbon dioxide

48 22.2 Animals exchange O 2 and CO 2 across moist body surfaces Respiratory surfaces must be thin and moist for diffusion of O 2 and CO 2 Earthworms and other animals use their skin for gas exchange Most animals have specialized body parts that promote gas exchange Gills in fish and amphibians Tracheal systems in arthropods Lungs in tetrapods that live on land Amphibians Reptiles Birds Mammals

49 22.3 Gills are adapted for gas exchange in aquatic environments Gills Are extensions of the body Increase surface to volume ratio Increase surface area for gas exchange Oxygen absorbed Carbon dioxide released In a fish, gas exchange is enhanced by Ventilation of the gills (moving water past the gills) Countercurrent flow of water and blood

50 Gill Arch Oxygen-poor blood Direction of water flow Gill Arch Oxygen-rich blood Blood vessels Lamella Operculum (gill cover) Water flow between lamellae Blood flow through capillaries in lamella Countercurrent exchange Gill filaments The structure of fish gills Diffusion of O 2 from water to blood Water flow, showing % O Blood flow in simplified capillary, showing % O 2

51 22.4 The tracheal system of insects provides direct exchange between the air and body cells Compared to water, using air to breathe has two big advantages Air contains higher concentrations of O2 Air is lighter and easier to move Air-breathing animals lose water through their respiratory surfaces

52 22.5 EVOLUTION CONNECTION: The evolution of lungs facilitated the movement of tetrapods onto land Tetrapods seem to have evolved in shallow water The first tetrapods on land diverged into three major lineages Amphibians use small lungs and their body surfaces Nonbird reptiles have lower metabolic rates and simpler lungs Birds and mammals have higher metabolic rates and more complex lungs

53 22.6 In the human respiratory system, branching tubes convey air to lungs located in the chest cavity In mammals, air is inhaled through the nostrils into the nasal cavity Air is filtered by hairs and mucus surfaces Air is warmed and moisturized Air is sampled for odors

54 22.6 In the human respiratory system, branching tubes convey air to lungs located in the chest cavity From the nasal cavity, air next passes To the pharynx Then larynx, past the vocal cords Into the trachea, held open by cartilage rings Into the paired bronchi Into bronchioles And finally to the alveoli, grapelike clusters of air sacs, where gas exchange occurs

55 Pharynx (Esophagus) Larynx Trachea Nasal cavity Left lung Oxygen-rich blood Bronchiole Oxygen-poor blood Alveoli Right lung Bronchus Bronchiole Blood Capillaries Diaphragm (Heart) The anatomy of the human respiratory system (left) and details of the structure of alveoli (right)

56 22.6 In the human respiratory system, branching tubes convey air to lungs located in the chest cavity Alveoli are well adapted for gas exchange High surface area of capillaries High surface area of alveoli In alveoli O 2 diffuses into the blood CO 2 diffuses out of the blood

57 22.7 CONNECTION: Smoking is a serious assault on the respiratory system Mucus and cilia in the respiratory passages Protect the lungs Can be damaged by smoking Without healthy cilia, smokers must cough to clear dirty mucus from the trachea

58 22.7 CONNECTION: Smoking is a serious assault on the respiratory system Smoking can cause Lung cancer Heart disease Emphysema Smoking also Increases the risk of heart attacks and strokes Raises blood pressure Increases harmful types of cholesterol Every year in USA, smoking kills about 440,000 people, which is more than all deaths from accidents, alcohol, drug abuse, HIV, and murders combined

59 Lung Heart Healthy lungs cancerous lungs

60 22.8 Negative pressure breathing ventilates our lungs Breathing is the alternate inhalation and exhalation of air (ventilation) Inhalation occurs when The rib cage expands The diaphragm moves downward The pressure around lungs decreases And air is drawn into the respiratory tract

61 22.8 Negative pressure breathing ventilates our lungs Exhalation occurs when The rib cage contracts The diaphragm moves upward The pressure around the lungs increases And air is forced out of the respiratory tract

62 Rib cage expands as rib muscles contract Air inhaled Rib cage gets smaller as rib muscles relax Air exhaled Lung Diaphragm Diaphragm contracts (moves down) Inhalation Diaphragm relaxes (moves up) Exhalation Negative pressure breathing draws air into the lungs.

63 22.9 Breathing is automatically controlled Breathing is usually under automatic control Breathing control centers in the brain sense and respond to CO 2 levels in the blood A rise in CO2 leading to drop in blood ph increases the rate and depth of breathing

64 Brain Cerebrospinal fluid Pons 1 Nerve signals trigger contraction of muscles Medulla 2 3 Breathing control centers respond to ph of blood Nerve signals indicating CO 2 and O 2 levels CO 2 and O 2 sensors in aorta Diaphragm Rib muscles Control centers that regulate breathing

65 TRANSPORT OF GASES IN THE HUMAN BODY

66 22.10 Blood transports respiratory gases The heart pumps blood to two regions The right side pumps oxygen-poor blood to the lungs The left side pumps oxygen-rich blood to the body In the lungs, blood picks up O 2 and drops off CO 2 In the body tissues, blood drops off O 2 and picks up CO 2

67 22.10 Blood transports respiratory gases Gases move from areas of higher concentration to areas of lower concentration Gases in the alveoli have more O 2 and less CO 2 than gases the blood O 2 moves from the alveoli of the lungs into the blood CO 2 moves from the blood into the alveoli of the lungs The tissues have more CO2 and less O2 than in the blood CO2 moves from the tissues into the blood O2 moves from the blood into the tissues

68 Exhaled air Inhaled air Alveolar epithelial cells Air spaces CO 2 O 2 Gas transport and exchange in the body. CO 2 -rich, O 2 -poor blood Alveolar capillaries O 2 -rich, CO 2 -poor blood Tissue capillaries Heart Tissue cells throughout body CO 2 O 2 Interstitial fluid

69 22.11 Hemoglobin carries O 2, helps transport CO 2, and buffers the blood Most animals transport O 2 bound to proteins called respiratory pigments Copper-containing pigment in Mollusca Arthropods Iron-containing hemoglobin Is used by almost all vertebrates and many invertebrates Transports oxygen, buffers blood, and transports CO 2

70 Iron atom O 2 loaded in lungs O 2 O 2 unloaded in tissues O 2 Polypeptide chain Heme group Hemoglobin loading and unloading of O2.

71 22.11 Hemoglobin carries O 2, helps transport CO 2, and buffers the blood Most CO 2 in the blood is transported as bicarbonate ions in the plasma CO + H O H CO H + HCO Carbon Water Carbonic Hydrogen Bicarbonate Dioxide Acid Ions

72 تبادل الغازات Gas Exchange رؼز ف ا صط خ آ بد رجبدي ا غبساد زاد رجبدي ا غبساد ا ز فض ل االوظج و ثب اوظذ ا ىزثى ف ا ذ ا زصبص ا ظجخ ا جظ ألوظج و ا زخ ض ثب اوظذ ا ىزثى ا ز فض ا خ ىي رشو ذ ظز ز ثبألوظج وا زخ ض ثب اوظذ ا ىزثى جغ ظطىح ا ز فظ خ ا رىى رل مخ ورغجخ ال زشبر االوظج وثب اوظ ذ ا ىزثى ػجزهب د ذا االرض ر ز ه ؼظ ا ذ ىا بد اجشاء زخصصخ ثب جظ رمى ثؼ خ رجبدي ا غبساد خ بش اجهشح ا مصجبد ا هىائ خ ف فص بد االرج رثبػ بد االرج ا صط خ Mechanisms Of Gas Exchange Three Phases Of Gas Exchange Breathing Transport Of Oxygen And Carbon Dioxide In Blood Body Tissues Take Up Oxygen And Release Carbon Dioxide Cellular Respiration Requires A Continuous Supply Of Oxygen And The Disposal Of Carbon Dioxide Respiratory Surfaces Must Be Thin And Moist For Diffusion Of O 2 And CO 2 Earthworms Most Animals Have Specialized Body Parts That Promote Gas Exchange Gills Tracheal Systems In Arthropods Tetrapods

73 تبادل الغازات Gas Exchange ا صط خ Amphibians Reptiles Mammals Extensions Of The Body Increase Surface To Volume Ratio Gas Exchange Ventilation Countercurrent Flow Advantages Higher Concentrations Respiratory Surfaces Insect Tracheal Systems Tiny Branching Tubes Air Is Piped Directly To Cells Evolved In Shallow Water Diverged Three Major Lineages Nonbird Reptiles Lower Metabolic Rates رؼز ف ا صط خ ا جز بئ بد ا شوادف ا ثذ بد ر ذداد ظطخ ا جظ رش ذ ظجخ ا ظطخ ا ى ا ذج رجبدي ا غبساد رهى خ ا ز بر ا ؼبوض فىائذ رزو شاد اوجز ططىح اجظب هب ا ز فظ خ االجهشح ا مصج خ ذشزاد ا بث ت دل مخ زفزػخ عخ ا هىاء جبشزح ا ى ا خال ب ثذأد د برهب ف ا ب ا عذ خ رفزػذ ثالثخ افزع رئ ظ خ ا شوادف غ ز ا طبئزح ا ع خ خفعخ

74 تبادل الغازات Gas Exchange رؼز ف ا صط خ ا صط خ Inhaled Through Nasal Cavity Filtered By Hairs And Mucus Surfaces Air Is Warmed And Moisturized Air Is Sampled For Odors Nasal Cavity Pharynx Then Larynx, Past The Vocal Cords Trachea Cartilage Rings Paired Bronchi Bronchioles Alveoli, Grapelike Clusters Of Air Sacs High Surface Area Of Capillaries High Surface Area Of Alveoli O 2 Diffuses Into The Blood CO 2 Diffuses Out Of The Blood االططخ و, ظز شك ا هىاء ا زجى ف اال ف زشخ ا هىاء ) ا ؼىا ك( ػ غز ك ا شؼز ا خبغ خ ر رذفئخ ورزغ ت ا هىاء ز فزس ا هىاء اج ر ش ا زوائخ ا زجى ف اال ف ا ج ؼى ا ذ جزح بر ثبال دجبي ا صىر خ ا ى ا مصجبد ا هىائ خ فزىدخ ثذ مبد غعزوف خ ا شؼت ا هىائ خ ا شؼ جبد ا هىائ خ ا ذى صالد ا هىائ خ ػ مىد االو بص ا هىائ خ ظبدخ ا ظطخ ا ؼب خ شؼ زاد ا ذ ى خ ظبدخ ا ظطخ ا ؼب خ ذى صالد ا هىائ خ زشز االوظج ا ى ا ذ طزد ثب اوظ ذ ا ىزثى خبرج ا ذ

75 تبادل الغازات Gas Exchange ا صط خ Mucus And Cilia Protect The Lungs Damaged By Smoking Lung Cancer Heart Disease Emphysema Risk Of Heart Attacks And Strokes Raises Blood Pressure Increases Harmful Types Of Cholesterol Accidents, Alcohol, Drug Abuse, HIV, And Murders Combined Breathing Alternate Inhalation And Exhalation Of Air (Ventilation) Inhalation Rib Cage Expands Diaphragm Moves Downward Pressure Around Lungs Decreases رؼز ف ا صط خ ا خبغ واألهذاة رذ ا زئز ا رز ف ثب زذخ طزغب ا زئخ ا زاض ا م ت ظ ك ا ز فض ش ذ ىثبد ا م ت وا ج طبد يرفع من ضغط الدم يزيد من التعرض ألنواع الكلسترول الضارةالكلسترول الضارة فىق ا ىد ا ذىادس, رؼبغ ا ىذىي واإلد ب ػ ى ا خذراد و اال ذس و االغز بالد ا ز فض رؼبلت شه ك وسف ز ا هىاء )ا زهى خ( ا شه ك ز ذد ) زظغ( ا مفض ا صذري خفط ا ذجبة ا ذبجش خفط ا عغػ دىي ا زئخ

76 تبادل الغازات Gas Exchange رؼز ف ا صط خ ا صط خ Air Is Drawn Into The Respiratory Tract Exhalation Rib Cage Contracts Diaphragm Moves Upward Pressure Around The Lungs Increases Air Is Forced Out Of The Respiratory Tract Automatic Control Breathing Control Centers Respond To CO 2 Levels Drop In Blood Ph Increases Rate And Depth Of Breathing Transport Of Gases In The Human Body Heart Pumps Blood To Two Regions Right Side Pumps Oxygen-Poor Blood To The Lungs Left Side Pumps Oxygen-Rich Blood To The Body ظذت ا هىاء ا ى ا زاد ا ز فظ خ ا شف ز مجط ) ع ك ) ا مفض ا صذري زرفغ ا ذجبة ا ذبجش ا ى اػ ى شداد ا عغػ دىي ا زئز و طزد ا هىاء خبرج ا زاد ا ز فظ خ ا زذى االورى بر ى زاوش ا زذى ثب ز فض رظزشؼز ظزى بد ثب اوظ ذ ا ىزثى ف ا ذ ورظزج ت هب انخفاض االس الهيدروجيني في الدم يزيد ؼذي وػ ك ا ز فض م ا غبساد ف جظ اال ظب عخ ا م ت ا ذ ا ى طمز عخ ا جب ت اال ا ذ ا فم ز ا ى االوظج ا ى ا زئز ظخ ا جب ت اال ظز ا ذ ا غ ثبألوظج ا ى ثم خ اجشاء ا جظ

77 تبادل الغازات Gas Exchange رؼز ف ا صط خ ا صط خ In The Lungs, Blood Picks Up O 2 And Drops Off CO 2 In The Body Tissues, Blood Drops Off O 2 And Picks Up CO 2 O 2 Moves From The Alveoli Of The Lungs Into The Blood CO 2 Moves From The Blood Into The Alveoli Of The Lungs Tissues Have More CO2 And Less O2 Than In The Blood CO2 Moves From The Tissues Into The Blood O2 Moves From The Blood Into The Tissues ف ا زئز أخذ ا ذ االوظج و طزد ثب اوظ ذ ا ىزثى ف ا ظجخ ا جظ, ززن ا ذ االوظج و أخذ ثب اوظ ذ ا ىزثى زذزن االوظج ا ذى صالد ا هىائ خ زئز ا ى ا ذ زذزن ثب اوظ ذ ا ىزثى ا ذ ا ى ا ذى صالد ا هىائ خ زئز ثهب ثب اوظ ذ ا ىزثى اوثز وأوظج ال ب هى ف ا ذ زذزن ثب اوظ ذ ا ىزثى اال ظجخ ا ى ا ذ زذزن االوظج ا ذ ا ى اال ظجخ

78 تبادل الغازات Gas Exchange ا صط خ Animals Transport O 2 Bound To Proteins Respiratory Pigments Copper-Containing Pigment Mollusca Iron-Containing Hemoglobin Vertebrates Invertebrates Buffers Blood Heme Group CO 2 In The Blood Is Transported As Bicarbonate Ions In The Plasma رؼز ف ا صط خ ؼظ ا ذ ىا بد ر م االوظج ا زرجػ ثجزور بد ا صجغبد ا ز فظ خ ا صجغبد ا ذزى خ ػ ى ا ذبص زخى بد ا ه ىج ىث ا ذزىي ػ ى ا ذذ ذ ؼظ ا فمبر بد ا الفمبر بد و ؼبدي ا ذ ج ىػخ ا ه م ؼظ ثب اوظ ذ ا ىزثى ف ا ذ ه ئخ ا ى بد ا ج ىزثى بد ف ا جالس ب

79 Chapter 6 How Cells Harvest Chemical Energy PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Richard L. Myers

80 6.1 Photosynthesis and cellular respiration provide energy for life Energy is necessary for life processes These include growth, transport, manufacture, movement, reproduction, and others Energy that supports life on Earth is captured from sun rays reaching Earth through plant, algae, protest, and bacterial photosynthesis

81 6.1 Photosynthesis and cellular respiration provide energy for life Energy in sunlight is used in photosynthesis to make glucose from CO 2 and H 2 O with release of O 2 Other organisms use the O 2 and energy in sugar and release CO 2 and H 2 O Together, these two processes are responsible for the majority of life on Earth

82 Sunlight energy ECOSYSTEM The connection between photosynthesis and cellular respiration Photosynthesis in chloroplasts CO 2 Glucose + + H 2 O Cellular respiration in mitochondria O 2 ATP (لwork (for cellular Heat energy

83 6.2 Breathing supplies oxygen to our cells for use in cellular respiration and removes carbon dioxide Breathing and cellular respiration are closely related Breathing is necessary for exchange of CO 2 produced during cellular respiration for atmospheric O 2 Cellular respiration uses O 2 to help harvest energy from glucose and produces CO 2 in the process

84 O 2 Breathing CO 2 Lungs Bloodstream CO 2 O 2 Muscle cells carrying out Cellular Respiration The connection between breathing and cellular respiration Glucose + O 2 CO 2 + H 2 O + ATP

85 INTRODUCTION TO CELLULAR RESPIRATION

86 6.3 Cellular respiration banks energy in ATP molecules Cellular respiration is an exergonic process that transfers energy from the bonds in glucose to ATP Cellular respiration produces 38 ATP molecules from each glucose molecule Other foods (organic molecules) can be used as a source of energy as well

87 Summary equation for cellular respiration C 6 H 12 O O 2 6 CO H 2 O + ATPs Glucose Oxygen Carbon dioxide Water Energy

88 6.4 CONNECTION: The human body uses energy from ATP for all its activities The average adult human needs about 2,200 kcal of energy per day A kilocalorie (kcal) is the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1 o C This energy is used for body maintenance and for voluntary activities

89 Energy Consumed by Various Activities (in kcal).

90 6.5 Cells tap energy from electrons falling from organic fuels to oxygen The energy necessary for life is contained in the arrangement of electrons in chemical bonds in organic molecules An important question is how do cells extract this energy? When the carbon-hydrogen bonds of glucose are broken, electrons are transferred to oxygen and hydrogen oxygen bonds of water formed. Oxygen has a strong tendency to attract electrons

91 6.5 Cells tap energy from electrons falling from organic fuels to oxygen A cellular respiration equation is helpful to show the changes in hydrogen atom distribution Glucose loses its hydrogen atoms and is ultimately converted to CO 2 At the same time, O 2 gains hydrogen atoms and is converted to H 2 O Loss of electrons is called oxidation Gain of electrons is called reduction

92 Rearrangement of hydrogen atoms (with their electrons) in the redox reactions of cellular respiration Loss of hydrogen atoms C 6 H 12 O O 2 Glucose Gain of hydrogen atoms 6 CO H 2 O + Energy (ATP) A cellular respiration equation

93 6.5 Cells tap energy from electrons falling from organic fuels to oxygen Enzymes are necessary to oxidize glucose and other foods The enzyme that removes hydrogen from an organic molecule is called dehydrogenase Dehydrogenase requires a coenzyme called NAD + (nicotinamide adenine dinucleotide) to shuttle electrons NAD + can become reduced when it accepts electrons and oxidized when it gives them up

94 pair of redox reactions, occurring simultaneously Oxidation Dehydrogenase adenine dinucleotide اختزال Reduction NAD H NADH + H + 2 H e (carries 2 electrons)

95 6.5 Cells tap energy from electrons falling from organic fuels to oxygen The transfer of electrons to NAD + results in the formation of NADH, the reduced form of NAD + In this situation, NAD + is called an electron acceptor, but it eventually becomes oxidized (loses an electron) and is then called an electron donor

96 6.5 Cells tap energy from electrons falling from organic fuels to oxygen There are other electron carrier molecules that function like NAD +.called FAD They form a staircase where the electrons pass from one to the next down the staircase These electron carriers collectively are called the electron transport chain, and as electrons are transported down the chain, ATP is generated

97 NAD + + H + NADH 2e ATP Controlled release of energy for synthesis of ATP In cellular respiration, electrons fall down an energy staircase and finally reduce O2 H + 2e H 2 O 1 2 O 2

98 STAGES OF CELLULAR RESPIRATION AND FERMENTATION

99 6.6 Overview: Cellular respiration occurs in three main stages Stage 1: Glycolysis Stage 2: The citric acid cycle Stage 3: Oxidative phosphorylation

100 6.6 Overview: Cellular respiration occurs in three main stages Stage 1: Glycolysis Glycolysis begins respiration by breaking glucose, a sixcarbon molecule, into two molecules of a three-carbon compound called pyruvate Glucose C-C-C-C-C-C Glycolysis In Cytoplasm C-C-C C-C-C Pyruvate Pyruvate

101 6.7 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate Glucose In glycolysis, a single molecule of glucose is enzymatically cut in half through a series of steps to produce two molecules of pyruvate In the process, two molecules of NAD + are reduced to two molecules of NADH At the same time, two molecules of ATP are produced by substrate-level phosphorylation 2 ADP 2 + P NAD + NADH ATP Pyruvate H + An overview of glycolysis

102 6.6 Overview: Cellular respiration occurs in three main stages Stage 2: The citric acid cycle - The citric acid cycle completes the oxidation of organic molecules supplies the third stage with electrons generating many NADH and FADH2 -It breaks down pyruvate into carbon dioxide -This stage occurs in the mitochondria.- CO 2 Pyruvate Citric Acid Cycle Electrons

103 6.6 Overview: Cellular respiration occurs in three main stages Stage 3: Oxidative phosphorylation At this stage, electrons are shuttled through the electron transport chain As a result, ATP is generated through oxidative phosphorylation associated with chemiosmosis This stage occurs in the inner mitochondrion membrane CO 2 O 2 Electron Transport Chain Pyruvate Citric Acid Cycle Electrons H 2 O Oxidative Phosphorylation Chemiosmosis ATP Mitochondria

104 An overview of cellular respiration NADH High-energy electrons carried by NADH NADH FADH 2 and Mitochondrion Glucose GLYCOLYSIS Pyruvate CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) Cytoplasm Inner mitochondrial Membrane ATP Substrate-level phosphorylation CO 2 CO 2 ATP Substrate-level phosphorylation ATP Oxidative phosphorylation

105 6.13 Fermentation enables cells to produce ATP without oxygen Fermentation is an anaerobic (without oxygen) energygenerating process It takes advantage of glycolysis, producing two ATP molecules and reducing NAD + to NADH The trick is to oxidize the NADH without passing its electrons through the electron transport chain to oxygen

106 6.13 Fermentation enables cells to produce ATP without oxygen جعل التخمر الخال ا قادرة على انتاج ATP دون الحاجة الى األوكسج ن Your muscle cells and certain bacteria can oxidize NADH through lactic acid fermentation NADH is oxidized to NAD + when pyruvate is reduced to lactate In a sense, pyruvate is serving as an electron sink, a place to dispose of the electrons generated by oxidation reactions in glycolysis

107 تحلل جلوكوزي GLYCOLYSIS جلوكوز Glucose 2 ADP + 2 P 2 NAD + 2 ATP 2 NADH Lactic acid fermentation تخمر الحامض اللبن 2 با روف ت 2 Pyruvate 2 NADH 2 NAD + 2 الكت ت 2 Lactate

108 6.13 Fermentation enables cells to produce ATP without oxygen The baking and winemaking industry have used alcohol fermentation for thousands of years Yeasts are single-celled fungi that not only can use respiration for energy but can ferment under anaerobic conditions They convert pyruvate to CO 2 and ethanol while oxidizing NADH back to NAD +

109 GLYCOLYSIS Glucose 2 ADP + 2 P 2 NAD + 2 ATP 2 NADH 2 Pyruvate Alcohol fermentation 2 CO 2 Released 2 NADH 2 NAD + 2 Ethanol

110 INTERCONNECTIONS BETWEEN MOLECULAR BREAKDOWN AND SYNTHESIS

111 6.15 Cells use many kinds of organic molecules as fuel for cellular respiration تستخدم الخال ا العد د من المركبات العضو ة كوقود للتنفس الهوائ Although glucose is considered to be the primary source of sugar for respiration and fermentation, there are actually three sources of molecules for generation of ATP Carbohydrates (disaccharides) Proteins (after conversion to amino acids) Fats

112 Food, such as peanuts Carbohydrates Fats Proteins Sugars Glycerol Fatty acids أحماض ام ن ة Amino acids Amino groups Glucose Pyruvate G3P GLYCOLYSIS Acetyl CoA CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) ATP Pathways that break down various food molecules

113 Chapter 7 Photosynthesis: Using Light to Make Food PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Richard L. Myers Translated by Nabih A. Baeshen

114 Introduction: Plant Power Plants use water and atmospheric carbon dioxide to produce a simple sugar and liberate oxygen Earth s plants produce 160 billion metric tons of sugar each year through photosynthesis, a process that converts solar energy to chemical energy Sugar is food for humans and for animals that we consume 6 CO H C 6 H 12 O O O الطاقة Light الضوئية energy + 6 Photosynthesis البناء الضوئي Carbon dioxide ثاني اكسيد الكربون Water Glucose جلوكوز Oxygen gas غاز االكسجين

115 AN OVERVIEW OF PHOTOSYNTHESIS

116 7.1 Autotrophs are the producers of the biosphere Autotrophs are living things that are able to make their own food without using organic molecules derived from any other living thing Autotrophs that use the energy of light to produce organic molecules are called photoautotrophs Most plants, algae and other protists, and some prokaryotes are photoautotrophs الكيلب طحلب كبير Kelp, a large algae

117 7.1 Autotrophs are the producers of the biosphere The ability to photosynthesize is directly related to the structure of chloroplasts Chloroplasts are organelles consisting of photosynthetic pigments, enzymes, and other molecules grouped together in membranes Micrograph of cyanobacteria (photosynthetic bacteria) )

118 7.2 Photosynthesis occurs in chloroplasts in plant cells Chloroplasts are the major sites of photosynthesis in green plants Chlorophyll, an important light absorbing pigment in chloroplasts, is responsible for the green color of plants Chlorophyll plays a central role in converting solar energy to chemical energy

119 7.2 Photosynthesis occurs in chloroplasts in plant cells Leaf Cross Section Mesophyll Vein CO 2 O 2 Stoma Mesophyll Cell The location and structure of chloroplasts Chloroplast

120 7.2 Photosynthesis occurs in chloroplasts in plant cells Chloroplasts are concentrated in the cells of the mesophyll, the green tissue in the interior of the leaf Stomata are tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit Veins in the leaf deliver water absorbed by roots

121 Chloroplast Outer and inner membranes Stroma Thylakoid Intermembrane space Granum Thylakoid Space

122 7.2 Photosynthesis occurs in chloroplasts in plant cells An envelope of two membranes encloses the stroma, the dense fluid within the chloroplast A system of interconnected membranous sacs called thylakoids segregates the stroma from another compartment, the thylakoid space Thylakoids are concentrated in stacks called granam

123 7.3 Plants produce O 2 gas by splitting water Scientists have known for a long time that plants produce O 2, but early on they assumed it was extracted from CO 2 taken into the plant Using a heavy isotope of oxygen, 18 O, they showed with tracer experiments that O 2 actually comes from H 2 O Oxygen bubbles on the leaves of an aquatic plant

124 Experiment 1 6 CO H 2 O C 6 H 12 O H 2 O + 6 O 2 Not labeled Experiment 2 6 CO H 2 O C 6 H 12 O H 2 O + 6 O 2 Labeled Experiments tracking the oxygen atoms in photosynthesis

125 Fates of all the atoms in photosynthesis Reactants: 6 CO 2 12 H 2 O Products: C 6 H 12 O 6 6 H 2 O 6 O 2

126 7.4 Photosynthesis is a redox process, as is cellular respiration Photosynthesis, like respiration, is a redox (oxidation-reduction) process Water molecules are split apart by oxidation, which means that they lose electrons along with hydrogen ions (H + ) Then CO 2 is reduced to sugar as electrons and hydrogen ions are added to it

127 Photosynthesis (uses light energy) Reduction 6 CO H 2 O C 6 H 12 O O 2 Oxidation Cellular respiration (releases chemical energy) Oxidation C 6 H 12 O O 2 6 CO H 2 O + E Reduction

128 7.4 Photosynthesis is a redox process, as is cellular respiration Recall that cellular respiration uses redox reactions to harvest the chemical energy stored in a glucose molecule This is accomplished by oxidizing the sugar and reducing O 2 to H 2 O The electrons lose potential as they travel down an energy hill, the electron transport system In contrast, the food-producing redox reactions of photosynthesis reverse the flow and involve an uphill climb

129 Light H 2 O Chloroplast LIGHT REACTIONS (in thylakoids) NADP + ADP P An overview of the two stages of photosynthesis that take place in a chloroplast

130 Light ضوء H 2 O بالستيدة خضراء Chloroplast NADP + ADP P LIGHT REACTIONS (in thylakoids) ATP NADPH O 2 An overview of the two stages of photosynthesis that take place in a chloroplast نظرة شاملة لمرحلتي البناء الضوئي التي تتم في البالستيدة الخضراء

131 7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH Actually, photosynthesis occurs in two metabolic stages First stage One stage involves the light reactions In the light reactions, light energy is converted in the thylakoid membranes to chemical energy and O 2 Water is split to provide the O 2 as well as electrons

132 7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH H + ions reduce NADP + to NADPH, which is an electron carrier similar to NADH NADPH is temporarily stored and then shuttled into the Calvin cycle where it is used to make sugar Finally, the light reactions generate ATP

133 7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH Second stage The second stage is the Calvin cycle, which occurs in the stroma of the chloroplast It is a cyclic series of reactions that builds sugar molecules from CO 2 and the products of the light reactions During the Calvin cycle, CO 2 is incorporated into organic compounds, a process called carbon fixation

134 7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH نظرة شاملة : ترتبط مرحلتي البناء الضوئي ب ATP و NADH NADPH produced by the light reactions provides the electrons for reducing carbon in the Calvin cycle ATP from the light reactions provides chemical energy for the Calvin cycle The Calvin cycle is often called the dark (or light-independent) reactions

135 Light ضوء H 2 O بالستيدة خضراء Chloroplast NADP + CO 2 LIGHT REACTIONS تفاعالت الضوء (in thylakoids) )في القريصات ) ADP P ATP CALVIN CYCLE دورة كالفين (in stroma) )في الحشوة ) NADPH O 2 An overview of the two stages of photosynthesis that take place in a chloroplast نظرة شاملة لمرحلتي البناء الضوئي التي تتم في البالستيدة الخضراء Sugar سكر

136 PHOTOSYNTHESIS REVIEWED AND EXTENDED

137 7.11 Review: Photosynthesis uses light energy, CO 2, and H 2 O to make food molecules The chloroplast, which integrates the two stages of photosynthesis, makes sugar from CO 2 All but a few microscopic organisms depend on the food-making machinery of photosynthesis Plants make more food than they actually need and stockpile it as starch in roots, tubers, and fruits

138 Light H 2 O Chloroplast CO 2 Summary of the chemical processes of photosynthesis NADP + Thylakoid Membranes Photosystem II Electron transport chains Photosystem I ADP + P ATP RuBP CALVIN CYCLE (in stroma) 3-PGA Stroma NADPH G3P Cellular respiration O 2 LIGHT REACTIONS Sugars CALVIN CYCLE Cellulose Starch Other organic compounds

139 PHOTOSYNTHESIS, SOLAR RADIATION, AND EARTH S ATMOSPHERE

140 7.13 CONNECTION: Photosynthesis moderates global warming The greenhouse effect results from solar energy warming our planet Gases in the atmosphere (often called greenhouse gases), including CO 2, reflect heat back to Earth, keeping the planet warm and supporting life However, as we increase the level of greenhouse gases, Earth s temperature rises above normal, initiating problems

141 7.13 CONNECTION: Photosynthesis moderates global warming Increasing concentrations of greenhouse gases lead to global warming, a slow but steady rise in Earth s surface temperature The extraordinary rise in CO 2 is mostly due to the combustion of carbon-based fossil fuels The consequences of continued rise will be melting of polar ice, changing weather patterns, and spread of tropical disease

142 7.13 CONNECTION: Photosynthesis moderates global warming Perhaps photosynthesis can mitigate the increase in atmospheric CO 2 However, there is increasing widespread deforestation, which aggravates the global warming problem

143 Plants growing in a greenhouse

144 Sunlight Some heat energy escapes into space Atmosphere Radiant heat trapped by CO 2 and other gases CO2 in the atmosphere and global warming

145 The Working Cell Diffusion: is a process in which particles spread out evenly in an available space Selectively permeability: allow some substances to cross or be transported more easily than others Concentration gradient: from high concentration to low concentration Passive transport: is the Diffusion across a cell membrane without energy Active transport: a mechanism for moving a solute against its concentration gradient it requires the expenditure of energy in the form of ATP. Osmosis: the Water movement across membranes in response to solute concentration inside and outside of the cell down the concentration gradient. Tonicity: is a term that describes the ability of a solution to cause a cell to gain or lose water الخلية العاملة تعشيف ان صطهح اال تشاس ػ ي خ ش ع اىدض ئبد ثبىزسب ف فشاؽ زبذ خاصيت ان فار انتفاضهيت رىل ثس بز ب ثس ىخ ش س قو ثؼض اى اد فضال ػ غ ش ب يذسج انتشكيض بطق اىزشم ض اىؼبى إى بطق اىزشم ض اى خفض اال تقال انسهبي اإل زشبس خاله غشبء اىخي خ ثذ اىسبخخ إى طبقخ ان قم ان شط اىخال ب آى خ ىزسش ل اى زاة ػنس اردب ذسج اىزشم ض سزبج رىل ىجزه اىطبقخ ػي ئخ اى.ATP األس ىصيت زسشك اى بء ػجش األغش خ اسزدبثخ ىزشم ض اى زاة داخو خبسج اىخي خ ردب اسفو ذسج اىزشم ض انتىتش صطير صف قذسح اى سي ه ػي إمسبة أ فقذ اىخي خ ىي بء ان صطهح

146 الخلية العاملة The Working Cell تعشيف ان صطهح ان صطهح Osmoregulation: is the ablilty of organisms to maintain water balance within their cells facilitated diffusion: a type of passive transport that does not require energy Exocytosis: is used to export bulky moleculesout of the cell Endocytosis: is used to import substances useful to the livelihood of the cell Phagocytosis: engulfment of a particle by wrapping cell membrane around it, forming a vacuole Pinocytosis: the same as phagocytosis except that fluids are taken into small vesicles Cells: small units, a chemical factory, housing thousands of chemical reactions Energy: is the capacity to do work and cause change انت ظيى األس ىصي خبص خ ىذ ثؼض اىس ا بد اىسفبظ ػي إرضا ب اى بئ داخو خال ب ب اال تشاس ان ذ عى ع اى قو اىسيج اىز ال سزبج طقخ انطشد انخهىي آى خ ىزصذ ش اىدض ئبد اىضخ خ خبسج اىخي خ االبتالع انخهىي آى خ ىز س ذ اد بفؼخ ى ؼ شخ اىخي خ إى داخو اىخي خ انبهع ت أو اإلنتهاو انخهىي اثزالع اىدض ئبد ثزغي ف ب ثغشبء اىخي خ ن خ فد ح انششب انخهىي ػجبسح ػ فس اىجيؼ خ إال أ اىس ائو اىز رؤخز ف ز صالد صغ شح انخاليا زذاد صغ شح ث ثبثخ صب غ م بئ خ رسزض آالف اىزفبػالد اىن بئ خ انطاقت اىقذسح ػي ػ و شغو إلزذاس رغ ش

147 الخلية العاملة The Working Cell تعشيف ان صطهح ان ساس األيضي ػجبسح ػ سيسيخ اىزفبػالد اىن بئ خ اىز إ ب ر ذ أ رج خض ء ؼقذ إقشا انطاقت اسزخذا اىزفبػالد اى سشسح ىيطبقخ إل ذاد اىزفبػالد اى سزقجي ىيطبقخ ث ب رسزبخ اىطبقخ ثالثي فىسفاث األدي ىسي ( (ATP ػ يخ اىطبقخ ف اىخي خ ATP صذس اىطبقخ اىف س اىز ض د ؼظ أشنبه اىشغو اىخي ثبىطبقخ ان صطهح A metabolic pathway: is a series of chemical reactions that either break down a complex molecule or build up a complex molecule Energy coupling: it is the use of exergonic processes to drive an endergonic one ATP( adenosine triphosphate): the energy currency of cells and it is the immediate source of energy that powers most forms of cellular work Active site: where the enzyme interacts with the enzyme s substrate Cofactors: inorganic enzymes helpers Coenzymes: organic enzymes helpers Competitive inhibitors: inhibits enzymes because they compete for the enzyme s active site and thus block substrates from entering the active site ي طقت شطت ز ش زفبػو اإل ض غ ػب و اإل ض اىخبص ث انعىايم ان شافقت اد غ ش ػض خ سبػذح ىإل ض بد يشافقاث اإل ضي اث خض ئبد ػض خ سبػذح ىإل ض بد ان ثبطاث انت افسيت رق ثبىزثج ظ أل ب رسزجق س اى قغ اى شظ ف اإل ض ثبىزبى رسدت ػب ي دخ ه رىل اى قغ

148 الخلية العاملة The Working Cell تعشيف ان صطهح ان صطهح Non competitive inhibitors: bind somewhere else and change the shape of the enzyme so that the substrate will no longer fit the active site Feedback inhibition: a mechanism where the product of a metabolic pathway can serve as an inhibitor of one enzyme in the pathway Cellular respiration: an exergonic process that transfers energy from the bonds in glucose to ATP A kilocalorie (kcal): the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1 o C Dehydrogenase: the enzyme that removes hydrogen from an organic molecule NAD + (nicotinamide adenine dinucleotide): a shuttle for electrons Glycolysis The citric acid cycle ان ثبطاث غيش انت افسيت رشرجظ ز اى ثجطبد ث نب آخش اال ض غ ش شني فال صجر اى قغ اى شظ بسجب ىؼب و اال ض بانتثبيط انشجعي اآلنيت ز ش ؼ و أزذ ارح سبس آ ض م ثجظ ألزذ اإل ض بد ف رىل اى سبس انت فس انخهىي ػ ي خ رفبػو سشس ىيطبقخ اىز رسشس اىطبقخ اى خزض خ ف س اثظ خض ء اىدي م ص رخض ب ف ATP انسعشة انحشاسيت )كيهى كانىسي( م خ اىسشاسح اى طي ثخ ىشفغ دسخخ زشاسح 1 م ي خشا اى بء دسخخ ئ خ ازذح )ا ( انذيهايذسوجي يض )ا ضيى ضع انهيذسوجي )اإل ض اىز ض و اى ذس خ اىدض ء اىؼض NAD+ ) يىكهيتيذة األد ي يكىتي أييذ انث ائيت(: بقو ىالىنزش بد تحهم انجهىكىص دوسة حايض انستشيك

149 الخلية العاملة The Working Cell تعشيف ان صطهح ان صطهح Oxidative phosphorylation انفسفشة ان ؤكس ذة Fermentation: an anaerobic (without oxygen) energy-generating process انتخ ش ػ ي خ ر ى ذ اىطبقخ ال ائ ب )د اىسبخخ أل مسد ( lactic acid fermentation: oxidizing of رؤمسذ اىخال ب اىؼضي خ ثؼض تخ ش انحايض انهب ي NADH by muscle cells and bacteria أ اع اىجنز ش ب شمت اى NADH Yeasts: single-celled fungi that not only can use respiration for energy but can ferment under anaerobic conditions انخ ائش فطش بد ز ذح اىخي خ اى خب ت ا ب رسزط غ اىق ب ثبىز فس اىخي ) ائ ب( إل زبج اىطبقخ ف قبدسح ػي اىق ب ثؼ ي خ اىزخ ش رسذ اىظش ف اىال ائ خ Autotrophs: living things that are able to make their own food without using organic molecules derived from any other living انكائ اث راتيت انتغزيت مبئ بد ز خ قبدسح ػي رص غ غزائ ب د اسزخذا خض ئبد ػض خ سز ذح أ مبئ ز آخش thing Photoautotrophs: the use of energy of light اسزخذ طبقخ اىض ء إل زبج خض ئبد انتغزيت انضىئيت to produce organic molecules by Autotrophs ػض خ ثبىنبئ بد رار خ Chloroplasts: organelles consisting of photosynthetic pigments, enzymes, and other molecules grouped together in membranes انبالستيذاث انخضشاء ػض بد رزن صجغبد ن خ ىيض ء إ ض بد شمجبد أخش د ػخ غ ثؼض ب اىجؼض ف أغش خ Chlorophyll: an important light absorbing pigment in chloroplasts, is responsible for انكهىسوفيم صجغخ ب خ ال زصبص اىض ء ف اىجالسز ذاد اىخضشاء اى سئ ىخ ػ اىي االخضش ف اى جبد ا the green color of plants

150 Chapter 21 Nutrition and Digestion PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Richard L. Myers Translated by Nabih A. Baeshen

151 OBTAINING AND PROCESSING FOOD

152 21.1 Animals ingest their food in a variety of ways Most animals have one of three kinds of diets Herbivores, plant-eaters cattle, snails, sea urchins Carnivores, meat-eaters lions, hawks, spiders Omnivores, eating both plants and other animals humans, roaches, raccoons, crows

153 21.1 Animals ingest their food in a variety of ways Animals obtain and ingest their food in different ways Suspension feeding Substrate feeding Fluid feeding Bulk feeding A substrate feeder: a caterpillar eating its way through the soft green tissues inside an oak leaf. Feces A suspension feeder: a tube worm filtering food from the surrounding water through its tentacles. Caterpillar :

154 A fluid feeder: a mosquito sucking blood. A bulk feeder: a grey heron preparing to swallow a fish head first and the rest next.

155 21.2 Overview: Food processing occurs in four stages نظرة شاملة: يتم التعامل مع الطعام ومعالجته في اربعة مراحل Food is processed in four stages Ingestion Digestion Absorption Elimination

156 Macromolecule Components Mechanical digestion breaks food down into smaller pieces Protein Polysaccharide Proteindigesting enzymes Carbohydratedigesting enzymes Amino acids Chemical digestion breaks down large organic molecules into their components Disaccharide Nucleic aciddigesting enzymes Monosaccharides Nucleic acid Nucleotides Fat Fat-digesting enzymes Glycerol Fatty acids

157 21.3 Digestion occurs in specialized compartments Sponges digest food in vacuoles Cnidarians and flatworms have a gastrovascular cavity with a single opening, the mouth Most animals have an alimentary canal with Mouth Anus Specialized regions

158 HUMAN DIGESTIVE SYSTEM

159 21.4 The human digestive system consists of an alimentary canal and accessory glands Alternating waves of contraction and relaxation by smooth muscle in the walls of the canal move food along in a process called peristalsis Sphincters control the movement of food into and out of the stomach. 1-pyloric sphincter(at the base of the stomach) Regulates the passage of food from the stomach to the small intestine 2- The cardiac sphincter (lower esophageal sphincter ) Limits the upward movement of acids into the esophagus

160 Oral cavity Tongue Mouth Salivary glands Mouth Salivary glands Pharynx Esophagus Esophagus Liver Gallbladder Stomach Esophagus Sphincter Liver Pancreas Small intestine Large intestine Rectum Anus A schematic diagram of the human digestive system Gall bladder Pancreas Small intestine Large intestine Rectum Anus Stomach Sphincter Small intestine The human digestive system

161 21.5 Digestion begins in the oral cavity Teeth break up food,and functions of saliva 1-moistens food 2- Salivary enzymes begin the hydrolysis of starch 3-Buffers neutralize acids 4-Antibacterial agents kills some bacteria ingested with food The tongue tastes, shapes the bolus of food, and moves it toward the pharynx

162 The human oral cavity Teeth Incisors Canine Premolars Molars Tongue Wisdom Tooth Salivary glands Opening of a salivary gland duct

163 21.6 After swallowing, peristalsis moves food through the esophagus to the stomach The trachea conducts air to the lungs The esophagus conducts food from the pharynx to the stomach Pharynx is the common passage for food and air Bolus of Food Muscles relax, allowing passageway to open Stomach Esophageal sphincter (contracted) Bolus of Food Muscles contract, constricting passageway and pushing bolus down Peristalsis moving a food bolus down the esophagus

164 21.8 The stomach stores food and breaks it down with acid and enzymes Acid ph 2 Parietal cells secrete hydrogen and chloride ions, which combine to make HCl Acid kills bacteria and breaks apart cells in food Pepsinogen and HCl produce pepsin Pepsin production activates more pepsinogen production positive feedback Pepsin begins the chemical digestion of proteins Acidic gastric juices mix with food to produce acid chyme

165 21.8 The stomach stores food and breaks it down with acid and enzymes What prevents the gastric juices from digesting the walls of the stomach? Mucus helps protect against HCl and pepsin New cells lining the stomach are produced about every 3 days

166 21.10 The small intestine is the major organ of chemical digestion and nutrient absorption Small intestine is named for its smaller diameter it is about 6 meters long Alkaline pancreatic juice neutralizes acid chyme and pancreatic enzymes digest food Bile, made in the liver and stored in the gall bladder, emulsifies fat for attack by pancreatic enzymes Enzymes from cells of the intestine continue digestion

167 Liver Bile Gall- Bladder Intestinal enzymes Duodenum of small intestine Acid chyme Pancreatic juice Stomach Pancreas The small intestine and related digestive organs

168

169 21.10 The small intestine is the major organ of chemical digestion and nutrient absorption Surface area for absorption is increased by Folds of the intestinal lining Fingerlike villi Nutrients pass across the epithelium and into blood Blood flows to the liver where nutrients are processed and stored

170 21.11 One of the liver s many functions is processing nutrient-laden blood from the intestines Blood from the digestive tract drains to the liver The liver performs many functions 1-Glucose in blood is converted to glycogen and stored in the liver 2-Liver synthesizes many proteins including blood clotting proteins and lipoproteins that transport fats and cholesterol 3-Liver changes toxins to less toxic forms 4-Liver produces bile

171 The hepatic portal system. Heart Liver Kidneys Hepatic portal Vein Intestines

172 21.12 The large intestine reclaims water and compacts the feces Diarrhea occurs when too little water is reclaimed Constipation occurs when too much water is reclaimed Feces are stored in the rectum Colon bacteria produce vitamins biotin, vitamin K, B vitamins Appendix Located near the junction of the small intestine and colon Makes a minor contribution to immunity

173 Large intestine (colon) Sphincter End of small intestine Rectum Anus Small intestine Cecum Appendix Unabsorbed food material The relationship of the small and large intestine.