Membranes: organize the chemical activities of cells by organizing different metabolic processes Control the flow of substances into or out of the cell The plasma membrane of the cell is selectively permeable Outside of cell TEM 00,000! Cytoplasm Membranes: organize the chemical activities of cells by organizing different metabolic processes control the flow of substances into or out of the cell the plasma membrane of the cell is selectively permeable consists of phospholipids and proteins phospholipids form a bilayer Hydrophilic heads Water Hydrophobic tails Water
Membranes: phospholipid bilayer had the heads of the phospholipids facing outward and the tails facing inward Hydrophilic heads Water Hydrophobic tails Water Membranes: phospholipid bilayer had the heads of the phospholipids facing outward and the tails facing inward hospholipids Have a hydrophilic head two hydrophobic tails Hydrophilic head CH 3 N + CH CH 3 CH hosphate 3 O group O O O C H O O C O C O CH CH Symbol CH CH CH CH CH 3 CH 3 Hydrophobic tails
Membranes: phospholipid bilayer had the heads of the phospholipids facing outward and the tails facing inward hospholipids Hydrophilic heads Hydrophobic tails Have a hydrophilic head two hydrophobic tails Water Water Hydrophilic head CH 3 N + CH CH 3 CH hosphate 3 O group O O O C H O O C O C O CH CH Symbol CH CH CH CH CH 3 CH 3 Hydrophobic tails Membranes: phospholipid bilayer had the heads of the phospholipids facing outward and the tails facing inward hospholipids Have a hydrophilic head two hydrophobic tails The membrane is a fluid mosaic of phospholipids and proteins Fibers of the extracellular matrix Carbohydrate (of glycoprotein) Glycoprotein lasma membrane Glycolipid Microfilaments of cytoskeleton hospholipid Cholesterol roteins Cytoplasm
Membrane proteins: Function as enzymes Function as receptors for chemical messages from other cells function in transport Messenger molecule Receptor Activated molecule AT assive transport is diffusion across a membrane In passive transport, substances diffuse through membranes without work by the cell Molecules of dye Membrane Equilibrium Equilibrium
assive transport is diffusion across a membrane In passive transport, substances diffuse through membranes without work by the cell Small nonpolar molecules such as O and CO diffuse easily across the phospholipid bilayer of a membrane Hydrophilic heads Water Hydrophobic tails Water assive transport is diffusion across a membrane In passive transport, substances diffuse through membranes without work by the cell Small nonpolar molecules such as O and CO diffuse easily across the phospholipid bilayer of a membrane Many other kinds of molecules do not diffuse freely across membranes Hydrophilic heads Water Hydrophobic tails Water
assive transport is diffusion across a membrane In passive transport, substances diffuse through membranes without work by the cell Small nonpolar molecules such as O and CO diffuse easily across the phospholipid bilayer of a membrane Many other kinds of molecules do not diffuse freely across membranes transport proteins provide passage across membranes through a process called facilitated diffusion Solute molecule Transport protein Cells expend energy for active transport Individual transport proteins can move solutes against a concentration gradient which requires AT Transport protein Solute AT AD rotein changes shape hosphate detaches
Cells expend energy for active transport Individual transport proteins can move solutes against a concentration gradient which requires AT To move large numbers of molecules or molecules or particle of large size through a membrane Exocytosis and endocytosis Exocytosis Fluid outside cell Vesicle rotein Cytoplasm Cells expend energy for active transport Individual transport proteins can move solutes against a concentration gradient which requires AT To move large numbers of molecules or molecules or particle of large size through a membrane Exocytosis and endocytosis Endocytosis Vesicle forming
Endocytosis: hagocytosis inocytosis Receptor-mediated endocytosis seudopodium of amoeba Food being ingested lasma membrane Material bound to receptor proteins LM 30! IT Cytoplasm hagocytosis inocytosis Receptor-mediated endocytosis TEM 54,000! TEM 96,500! Cellular energy
Cellular energy: Exergonic reactions Release energy and yield products that contain less potential energy Reactants otential energy of molecules Energy released roducts Amount of energy released Cellular energy: Exergonic reactions Release energy and yield products that contain less potential energy Endergonic reactions Absorb energy and yield products rich in potential energy Reactants roducts otential energy of molecules Energy released roducts Amount of energy released otential energy of molecules Reactants Energy required Amount of energy required
Where and how is AT produced from food and O? Energy capture and AT synthesis requires a combination of: Enzymes Membranes Osmosis Difusion ECOSYSTEM CO Glucose + + H O Sunlight energy hotosynthesis in chloroplasts Cellular respiration in mitochondria O AT (for cellular work) Heat energy Cellular energy: Exothermic reactions Release energy and yield products that contain less potential energy Reactants otential energy of molecules Energy released roducts Amount of energy released
Cellular energy: Exothermic reactions Release energy and yield products that contain less potential energy Endothermic reactions Absorb energy and yield products rich in potential energy Reactants roducts otential energy of molecules Energy released roducts Amount of energy released otential energy of molecules Reactants Energy required Amount of energy required Cellular energy: Exothermic reactions Release energy and yield products that contain less potential energy Endothermic reactions Absorb energy and yield products rich in potential energy Reactants roducts otential energy of molecules? Energy released roducts Amount of energy released + otential energy of molecules Reactants? Energy required Amount of energy required AT shuttles chemical energy and drives cellular work
hosphorylation Hydrolysis Cellular energy: Exothermic reactions Release energy and yield products that contain less potential energy Endothermic reactions Absorb energy and yield products rich in potential energy Reactants roducts otential energy of molecules AT Energy released roducts Amount of energy released + otential energy of molecules Reactants AT Energy required Amount of energy required AT shuttles chemical energy and drives cellular work Cellular energy: AT shuttles chemical energy and drives cellular work AT Energy from exergonic reactions Energy for endergonic reactions AD +
AT The energy in an AT molecule lies in the bonds between its phosphate groups Adenosine Triphosphate Adenosine diphosphate hosphate groups H O Adenine Hydrolysis + + Energy Ribose AT AD AT The energy in an AT molecule lies in the bonds between its phosphate groups Adenosine Triphosphate Adenosine diphosphate hosphate groups H O Adenine Hydrolysis + + Energy Ribose AT O + FOOD AD
AT AT drives endergonic reactions by phosphorylation AT Chemical work Mechanical work Transport work Membrane protein Solute + Motor protein Reactants roduct Molecule formed rotein moved Solute transported AD + Enzymes speed up the cell s chemical reactions by lowering energy barriers E A barrier Enzyme Reactants roducts 1
Specific enzymes carryout each task and are not used up 1 Enzyme available with empty active site Active site Substrate (sucrose) Substrate binds to enzyme with induced fit Glucose Enzyme (sucrase) Fructose H O 4 roducts are released 3 Substrate is converted to products Enzyme activities are regulated: A competitive inhibitor Takes the place of a substrate in the active site A noncompetitive inhibitor Alters an enzyme s function by changing its shape Substrate Active site Enzyme Normal binding of substrate Competitive inhibitor Noncompetitive inhibitor Enzyme inhibition
Osmosis: is the diffusion of water across a membrane water travels from a solution of lower solute concentration to one of higher solute concentration Lower Higher concentration concentration of solute of solute Equal concentration of solute Solute molecule H O Selectively permeable membrane Water molecule Net flow of water Solute molecule with cluster of water molecules Osmosis: is the diffusion of water across a membrane water travels from a solution of lower solute concentration to one of higher solute concentration causes cells to shrink in hypertonic solutions swell in hypotonic solutions isotonic H O H O H O } osmoregulation Isotonic solution Hypotonic solution Hypertonic solution H O Animal cell H O (1) Normal () Lysed (3) Shriveled H O H O lasma membrane H O lant cell (4) Flaccid (5) Turgid (6) Shriveled (plasmolyzed)
hosphorylation hosphorylation Hydrolysis Hydrolysis Cellular energy: AT shuttles chemical energy and drives cellular work AT Energy for exothermic reactions AD + Energy for endothermic reactions Cellular energy: AT shuttles chemical energy and drives cellular work CO and H O AT Cellular respiration (aerobic) Glucose and O AD + Energy for endothermic reactions
hosphorylation Hydrolysis Cellular energy: AT shuttles chemical energy and drives cellular work Lactic acid AT Anaerobic glycolysis Energy for endothermic reactions Glucose AD + Breathing supplies oxygen to our cells and removes carbon dioxide O CO Breathing Lungs CO Bloodstream O Muscle cells carrying out Cellular Respiration Glucose + O CO + H O + AT
198g glucose = 66 kcal 1637g glucose = 00 kcal Cellular energy: AT shuttles chemical energy and drives cellular work C 6 H 1 O 6 + 6 O 6 CO + 6 H O + 38 ATs Glucose Oxygen gas Carbon dioxide Water Energy 38 AD 38
Cells tap energy from electrons falling from organic fuels to oxygen Electrons lose potential energy during their transfer from organic compounds to oxygen Cells tap energy from electrons falling from organic fuels to oxygen Electrons lose potential energy during their transfer from organic compounds to oxygen When glucose is converted to carbon dioxide it loses hydrogen atoms, which are added to oxygen, producing water Loss of hydrogen atoms (oxidation) C 6 H 1 O 6 + 6 O 6 CO + 6 H O + Energy Glucose Gain of hydrogen atoms (reduction) (AT)
Cells tap energy from electrons falling from organic fuels to oxygen Electrons lose potential energy during their transfer from organic compounds to oxygen When glucose is converted to carbon dioxide it loses hydrogen atoms, which are added to oxygen, producing water Dehydrogenase removes electrons (in hydrogen atoms) from fuel molecules (oxidation) and transfers them to NAD + (reduction) Oxidation H O H O + H Dehydrogenase NAD + + H Reduction NADH + H + H + + e " (carries electrons) Cells tap energy from electrons falling from organic fuels to oxygen NADH passes electrons to an electron transport chain As electrons fall from carrier to carrier and finally to O energy is released in small quantities NADH NAD + + H + e " Electron transport chain AT Controlled release of energy for synthesis of AT e " H + 1 O H O
Cellular respiration: NADH High-energy electrons carried by NADH NADH FADH and GLYCOLYSIS Glucose yruvate CITRIC ACID CYCLE OXIDATIVE HOSHORYLATION (Electron Transport and Chemiosmosis) Cytoplasm Mitochondrion AT Substrate-level phosphorylation CO CO AT Substrate-level phosphorylation AT Oxidative phosphorylation Glycolysis harvests chemical energy by oxidizing glucose to pyruvate In glycolysis, AT is used to prime a glucose molecule which is split into two molecules of pyruvate NAD + NADH + H + Glucose AD + AT yruvate
Glycolysis harvests chemical energy by oxidizing glucose to pyruvate In the first phase of glycolysis, AT is used to energize a glucose molecule, which is then split in two Steps 1 3 A fuel molecule is energized, using AT. AT AD Step 1 Glucose REARATORY HASE (energy investment) AT AD 3 Step 4 A six-carbon intermediate splits into two three-carbon intermediates. 4 age 95 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate In the second phase of glycolysis AT, NADH, and pyruvate are formed Step 5 A redox reaction 6 9 generates NADH. Steps 6 9 AT and pyruvate are produced. NAD + 5 NAD + 5 NADH 6 NADH 6 +H + +H + AD AD AT 6 7 6 AT 7 ENERGY AYOFF HASE 7 7 8 8 H O 8 H O 8 AT AD 9 AD 9 9 9 AT yruvate age 95
Glycolysis harvests chemical energy by oxidizing glucose to pyruvate In the second phase of glycolysis AT, NADH, and pyruvate are formed Enzymes process pyruvate, releasing CO and producing NADH and acetyl CoA NAD + NADH + H + yruvate CoA Acetyl CoA (acetyl coenzyme A) CO Coenzyme A age 95 The citric acid cycle completes the oxidation of organic fuel, generating many NADH and FADH molecules For each turn of the cycle Two CO molecules are released The energy yield is one AT, three NADH, and one FADH CoA Acetyl CoA CoA carbons enter cycle Oxaloacetate NADH+ H + NAD + CITRIC ACID CYCLE Citrate CO leaves cycle NAD + Malate NADH+ H + FADH FAD AT + AD Alpha-ketoglutarate Succinate NADH + H+ NAD + CO leaves cycle
Most AT production occurs by oxidative phosphorylation Electrons from NADH and FADH travel down the electron transport chain to oxygen, which picks up H + to form water Energy released by the redox reactions is used to pump H + into the space between the mitochondrial membranes H + H + H + H + Intermembrane space. rotein complex H + H + H + Electron H + H + carrier AT synthase Inner mitochondrial membrane Electron flow NADH NAD + FADH FAD H + 1 O + H + Mitochondrial matrix H + H + H O + AD H + AT Electron Transport Chain Chemiosmosis OXIDATIVE HOSHORYLATION Figure 6.10 Review: Each molecule of glucose yields up to 38 molecules of AT Electron shuttle across membrane Mitochondrion Cytoplasm NADH NADH (or FADH ) NADH 6 NADH FADH GLYCOLYSIS Glucose yruvate Acetyl CoA CITRIC ACID CYCLE OXIDATIVE HOSHORYLATION (Electron Transport and Chemiosmosis) + AT + AT + about 34 AT by substrate-level phosphorylation by substrate-level phosphorylation by oxidative phosphorylation Maximum per glucose: About 38 AT
Fermentation is an anaerobic alternative to cellular respiration Under anaerobic conditions, many kinds of cells can use glycolysis alone to produce small amounts of AT NAD + NADH NADH NAD + GLYCOLYSIS Glucose AD + AT yruvate Lactate Fermentation is an anaerobic alternative to cellular respiration Under anaerobic conditions, many kinds of cells can use glycolysis alone to produce small amounts of AT alcohol fermentation NADH is oxidized to NAD + while converting pyruvate to CO and ethanol NAD + NADH NADH NAD + GLYCOLYSIS AD + AT CO released Glucose yruvate Ethanol Figure 6.13B
Cells use many kinds of organic molecules as fuel for cellular respiration Food, such as peanuts Carbohydrates Fats roteins Sugars Glycerol Fatty acids Amino acids Amino groups Glucose G3 yruvate Acetyl GLYCOLYSIS CoA CITRIC ACID CYCLE OXIDATIVE HOSHORYLATION (Electron Transport and Chemiosmosis) AT Food molecules provide raw materials for biosynthesis Cells use some food molecules and intermediates from glycolysis and the citric acid cycle as raw materials This process of biosynthesis consumes AT AT needed to drive biosynthesis AT CITRIC ACID CYCLE GLUCOSE SYNTHESIS Acetyl CoA yruvate G3 Glucose Amino groups Amino acids Fatty acids Glycerol Sugars roteins Fats Carbohydrates Cells, tissues, organisms
Cellular respiration occurs in three main stages: Stage 1: Glycolysis Occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of AT Stage : The citric acid cycle Takes place in the mitochondria Completes the breakdown of glucose, producing a small amount of AT Supplies the third stage of cellular respiration with electrons Stage 3: Oxidative phosphorylation Occurs in the mitochondria Uses the energy released by falling electrons to pump H + across a membrane Harnesses the energy of the H + gradient through chemiosmosis, producing AT