Nucleic acids Nucleic acids are information-rich polymers of nucleotides DNA and RNA Serve as the blueprints for proteins and thus control the life of a cell RNA and DNA are made up of very similar nucleotides. OH O P O O! Phosphate group N H N CH 2 O H H H H OH H Sugar DNA H N H N N H Nitrogenous base (A) OH O P O O! Phosphate group N H N CH 2 O H H H H OH OH Sugar RNA H N H N N H Nitrogenous base (A) 1
The sugar and phosphate form the backbone for the nucleic acid or polynucleotide A Nucleotide T C G T Sugar-phosphate backbone DNA consists of two polynucleotides twisted around each other in a double helix. C C G A G C T C Base pair TA T A A G A A A T T GC T T 2
RNA, by contrast is a single-stranded polynucleotide. C C G A G C T C Base pair TA T A A G A A A T T GC T T RNA consists of one polynucleotides twisted around itself. 3
DNA and RNA have different functions: DNA encodes information in the form of genes. RNAs are both is both the messenger of information RNAs also can have enzyme activity. C C G A G C T T A C G A T T Base A pair G C A T A T T A RNA as the progenitor of life? 4
Early scientists who observed cells made detailed sketches of what they saw. Early scientists who observed cells made detailed sketches of what they saw. CORK 5
Early scientists who observed cells made detailed sketches of what they saw. CORK These early sketches revealed an important relationship between art and biology, the most visual of the sciences 6
Microscopes provide windows to the world of the cell The light microscope (LM) enables us to see the overall shape and structure of a cell Eyepiece Ocular lens Objective lens Specimen Condenser lens Light source Light microscopes Magnify cells, living and preserved, up to 1,000 times 7
Light microscopes Magnify cells, living and preserved, up to 1,000 times The electron microscope Allows greater magnification and reveals cellular details 8
Different types of light microscopes Use different techniques to enhance contrast and selectively highlight cellular components Different types of light microscopes Use different techniques to enhance contrast and selectively highlight cellular components Figure 4.1E Figure 4.1F 220" 1,000" 9
Most cells are microscopic and vary in size and shape 10 m 1 m 100 mm (10 cm) 10 mm (1 cm) 1 mm Human height Length of some nerve and muscle cells Chicken egg Frog egg Unaided eye 100 µm 10 µm 1 µm Most plant and animal cells Nucleus Most bacteria Mitochondrion Light microscope 100 nm 10 nm 1 nm Mycoplasmas (smallest bacteria) Viruses Ribosome Proteins Lipids Small molecules Electron microscope 0.1 nm Atoms A small cell has a greater ratio of surface area to volume than a large cell of the same shape. 30 µm 10 µm 30 µm 10 µm Surface area of one large cube = 5,400 µm 2 Total surface area of 27 small cubes = 16,200 µm 2 10
There are two kinds of cells Prokaryotic and Eukaryotic. Prokaryotic cells Are small relatively simple cells 11
Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative 12
Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall 13
Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have and outer membrane (Gram-negative) Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) 14
Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) May have a flagellum (motility) Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) May have a flagellum (motility) Have pili or fimbrae (adhesins) 15
Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) May have a flagellum (motility) Have pili or fimbrae (adhesins) May have a circular plasmid Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) May have a flagellum (motility) Have pili or fimbrae (adhesins) May have a circular plasmid Are haploid with no nuclear membrane 16
Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) May have a flagellum (motility) Have pili or fimbrae (adhesins) May have a circular plasmid Are haploid with no nuclear membrane Have inclusion bodies Prokaryotic cells Are small relatively simple cells Do not have membrane bound organelles Two main classes: Gram-positive and Gram-negative May have a capsule May have a rigid cell wall May have an outer membrane (Gram-negative) May have a periplasmic space (Gram-negative) May have a flagellum (motility) Have pili or fimbrae (adhesins) May have a circular plasmid Are haploid with no nuclear membrane Have inclusion bodies Have different ribosomes 17
Eukaryotic cells are partitioned into functional compartments. Membranes form the boundaries of many eukaryotic cells. membranes 18
These membranes form compartments in the interior of the cell and enable a variety of metabolic activities membranes One such compartment is the nucleus. A true nucleus distinguishes a Eukaryotic cell from a Prokaryotic cell. Nucleus 19
A typical animal cell contains a variety of membranous organelles. Smooth endoplasmic Rough reticulum endoplasmic reticulum Nucleus Not in most plant cells Cytoskeleton Flagellum Lysosome Centriole Peroxisome Microtubule Intermediate filament Microfilament Ribosomes Golgi apparatus Mitochondrion Plasma membrane A typical plant cell has some structures that an animal cell lacks such as: chloroplasts a rigid cell wall Not in animal cells Nucleus Golgi apparatus Central vacuole Chloroplast Cell wall Rough endoplasmic reticulum Ribosomes Smooth endoplasmic reticulum Microtubule Intermediate filament Microfilament Cytoskeleton Mitochondrion Peroxisome Plasma membrane 20
The nucleus The nucleus is the cell s genetic control center Nucleus The nucleus The nucleus is the cell s genetic control center It is separated from the cytoplasm by the nuclear membrane Nucleus Two membranes of nuclear envelope 21
The nucleus The nucleus is the cell s genetic control center It is separated from the cytoplasm by the nuclear membrane It contains the cell s DNA and ultimately directs the activities of the cell. Nucleus Two membranes of nuclear envelope Many cell organelles are connected through the endomembrane system that manufactures and distributes cell products Smooth endoplasmic Rough reticulum endoplasmic reticulum Nucleus Ribosomes Golgi apparatus 22
Smooth endoplasmic reticulum has a variety of functions: Synthesizes lipids Processes toxins and drugs in liver cells Stores and releases calcium ions in muscle cells Smooth ER Rough ER Nuclear envelope Smooth ER Ribosomes Rough ER TEM 45,000" Rough endoplasmic reticulum: Manufactures membranes Makes proteins Smooth ER Rough ER Nuclear envelope Smooth ER Ribosomes Rough ER TEM 45,000" 23
Rough endoplasmic reticulum: Ribosomes on the surface of the rough ER produce proteins that are secreted, inserted into membranes, or transported to other organelles Transport vesicle buds off 4 Ribosome 1 3 Secretory (glyco-) protein inside transport vesicle Sugar chain Polypeptide 2 Glycoprotein Rough ER The Golgi apparatus: finishes, sorts, and ships cell products Receiving side of Golgi apparatus Golgi apparatus Golgi apparatus Transport vesicle from ER New vesicle forming Shipping side of Golgi apparatus Transport vesicle from the Golgi TEM 130,000" 24
Lysosomes are digestive compartments within a cell Rough ER Plasma membrane Transport vesicle (containing inactive hydrolytic enzymes) Golgi apparatus Food Engulfment of particle Lysosomes Lysosome engulfing damaged organelle Food vacuole Digestion Lysosomes are digestive compartments within a cell destroy bacteria that have been ingested Rough ER Plasma membrane Transport vesicle (containing inactive hydrolytic enzymes) Golgi apparatus Food Engulfment of particle Lysosomes Lysosome engulfing damaged organelle Food vacuole Digestion 25
Lysosomes are digestive compartments within a cell destroy bacteria that have been ingested Recycle damaged organelles Rough ER Plasma membrane Transport vesicle (containing inactive hydrolytic enzymes) Golgi apparatus Food Engulfment of particle Lysosomes Lysosome engulfing damaged organelle Food vacuole Digestion Lysosomes are digestive compartments within a cell destroy bacteria that have been ingested Recycle damaged organelles Abnormal lysozymes cause fatal diseases Rough ER Plasma membrane Transport vesicle (containing inactive hydrolytic enzymes) Golgi apparatus Cystinosis Food Engulfment of particle Lysosome engulfing damaged organelle Lysosomes Food vacuole Digestion 26
Vacuoles function in the general maintenance of the cell: Plant cells contain a large central vacuole with lysosomal and storage functions Protists have contractile vacuoles that pump out excess water Nucleus Contractile vacuoles LM 650" A review of the endomembrane system Rough ER Transport vesicle from ER to Golgi Transport vesicle from Golgi to plasma membrane Plasma membrane Nucleus Vacuole Lysosome Smooth ER Nuclear envelope Golgi apparatus 27
Chloroplasts: convert solar energy to chemical energy found in plants and some protists Convert solar energy to chemical energy in sugars Chloroplast Stroma Inner and outer membranes Granum TEM 9,750" Intermembrane space Mitochondria: harvest chemical energy from food: carry out cellular respiration uses the chemical energy in food to make ATP for cellular work Mitochondrial disease Mitochondrion Intermembrane space Outer membrane Inner membrane Cristae Matrix TEM 44,880" 28
The cytoskeleton: helps organize its structure and activities A network of protein fibers Make up the cytoskeleton. Microfilaments of actin (Enable cells to change shape and move) Actin subunit 7 nm Fibrous subunits 10 nm Tubulin subunit 25 nm Microfilament Intermediate filament Microtubule The cytoskeleton: helps organize its structure and activities A network of protein fibers Make up the cytoskeleton. Microfilaments of actin (Enable cells to change shape and move) Intermediate filaments (Reinforce the cell and anchor certain organelles) Actin subunit 7 nm Fibrous subunits 10 nm Tubulin subunit 25 nm Microfilament Intermediate filament Microtubule 29
The cytoskeleton: helps organize its structure and activities A network of protein fibers Make up the cytoskeleton. Microfilaments of actin (Enable cells to change shape and move) Intermediate filaments (Reinforce the cell and anchor certain organelles) Microtubules give the cell rigidity, provide anchors for organelles, act as tracks for organelle movement, divide the chromosomes, and power cilia and flagella Actin subunit 7 nm Fibrous subunits 10 nm Tubulin subunit 25 nm Microfilament Intermediate filament Microtubule The cytoskeleton: helps organize its structure and activities A network of protein fibers Make up the cytoskeleton. Microfilaments of actin (Enable cells to change shape and move) Intermediate filaments (Reinforce the cell and anchor certain organelles) Microtubules give the cell rigidity, provide anchors for organelles, act as tracks for organelle movement, divide the chromosomes, and power cilia and flagella Figure 4.17A Figure 4.17B Colorized SEM 4,100" LM 600" 30
Cell surfaces: protect, support, and join cells interact via their surfaces Plasma membrane Plant cells Are supported by rigid cell walls made largely of cellulose Connect by plasmodesmata, which are connecting channels Vacuole Walls of two adjacent plant cells Plasmodesmata Layers of one plant cell wall Cytoplasm Plasma membrane 31
Animal cells are embedded in an extracellular matrix Which binds cells together in tissues Tight junctions can bind cells together into leak-proof sheets Anchoring junctions link animal cells into strong tissues Gap junctions allow substances to flow from cell to cell Tight junctions Anchoring junction Gap junctions Plasma membranes of adjacent cells Extracellular matrix Space between cells A typical animal cell contains a variety of membranous organelles. Smooth endoplasmic Rough reticulum endoplasmic reticulum Nucleus Not in most plant cells Cytoskeleton Flagellum Lysosome Centriole Peroxisome Microtubule Intermediate filament Microfilament Ribosomes Golgi apparatus Mitochondrion Plasma membrane 32
A typical plant cell has some structures that an animal cell lacks such as: chloroplasts a rigid cell wall Nucleus Rough endoplasmic reticulum Ribosomes Smooth endoplasmic reticulum Golgi apparatus Microtubule Not in animal cells Central vacuole Chloroplast Cell wall Intermediate filament Microfilament Cytoskeleton Mitochondrion Peroxisome Plasma membrane Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Energy processing Support, movement, and communication between cells 33
Review Eukaryotic organelles comprise four functional categories Manufacturing Nucleus» DNA and RNA synthesis, assembly of ribosomes Ribosomes» Protein synthesis Rough ER» Synthesis of membrane proteins, secretory proteins, hydrolytic enzymes, formation of transport vesicles Smooth ER» Lipid synthesis, carbohydrate metabolism, detoxification, and calcium ion storage Golgi» Macromolecule modification, temporary storage, transport, and lysosome formation Breakdown Energy processing Support, movement, and communication between cells Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Lysosomes» Digestion / recycling Vacuoles» Digestion / recycling, storage of chemicals, and water balance Energy processing Support, movement, and communication between cells 34
Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Energy processing Chloroplasts» Conversion of light energy to chemical energy (sugars) Mitochondria» Conversion of chemical energy of sugars, fats, proteins to the universal energy source, ATP Support, movement, and communication between cells Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Energy processing Support, movement, and communication between cells Plasma membrane and associated proteins» Cell barrier, communication, transport Cell wall» Cell shape, protection, connection to other cells Cytoskeleton» Cell shape, anchorage and movement of organelles, cell movement, signaling, transport of molecules Extracellular matrix» Connection of cells, regulation of cell function Cell junctions» Communication, connection of cells 35
Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Energy processing Support, movement, and communication between cells Review Eukaryotic organelles comprise four functional categories Manufacturing Nucleus» DNA and RNA synthesis, assembly of ribosomes Ribosomes» Protein synthesis Rough ER» Synthesis of membrane proteins, secretory proteins, hydrolytic enzymes, formation of transport vesicles Smooth ER» Lipid synthesis, carbohydrate metabolism, detoxification, and calcium ion storage Golgi» Macromolecule modification, temporary storage, transport, and lysosome formation Breakdown Energy processing Support, movement, and communication between cells 36
Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Lysosomes» Digestion / recycling Vacuoles» Digestion / recycling, storage of chemicals, and water balance Energy processing Support, movement, and communication between cells Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Energy processing Chloroplasts» Conversion of light energy to chemical energy (sugars) Mitochondria» Conversion of chemical energy of sugars, fats, proteins to the universal energy source, ATP Support, movement, and communication between cells 37
Review Eukaryotic organelles comprise four functional categories Manufacturing Breakdown Energy processing Support, movement, and communication between cells Plasma membrane and associated proteins» Cell barrier, communication, transport Cell wall» Cell shape, protection, connection to other cells Cytoskeleton» Cell shape, anchorage and movement of organelles, cell movement, signaling, transport of molecules Extracellular matrix» Connection of cells, regulation of cell function Cell junctions» Communication, connection of cells 38