Cells Variation and Function of Cells
Cell Theory states that: 1. All living things are made of cells 2. Cells are the basic unit of structure and function in living things 3. New cells are produced from existing cells Two major types of Cells Prokaryotic cells are very small and have no membrane bound organelles or a nucleus. All Bacteria are prokaryotes and have circular DNA. Eukaryotic Cells are more organized and complex than prokaryotes, they have membrane bound organelles, linear chromosomes and tend to be very large in comparison. P169-173
Comparison: Prokaryotes and Eukaryotes Prokaryotic cells are limited in their structure. They have ribosomes, circular DNA, rely on the exterior membrane to complete any membrane related function and rely on diffusion for transport. Prokaryotic Kingdoms/Domains 1. Eubacteria-are very diverse often have a cell wall that contains peptidoglycan 2. Archaebacteria- lack peptidoglycan in cell walls, have different membrane lipids, and have some genes that are more similar to eukaryotes than eubacteria.
Eukaryotes are complex in comparison to prokaryotes with several unique organelles that maximize their efficiency : they do or can 1. Grow much larger as they developed organization and distribution abilities 2. Compartmentalize delicate and destructive processes within separate microenvironments. 3. Specialize function of individual cells to work with other cells (multi-cellular) Plasma Membrane= the skin of a cell, it protects, nourishes, and communicates with other cells. Organelle membranes do the same
Fig. 6-9a ENDOPLASMIC RETICULUM (ER) Rough ER Smooth ER Flagellum Nuclear envelope Nucleolus Chromatin NUCLEUS Centrosome Plasma membrane CYTOSKELETON: Microfilaments Intermediate filaments Microtubules Ribosomes Microvilli Peroxisome Golgi apparatus Mitochondrion Lysosome
Fig. 6-9b NUCLEUS Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Smooth endoplasmic reticulum Ribosomes Golgi apparatus Central vacuole Microfilaments Intermediate filaments Microtubules CYTO- SKELETON Mitochondrion Peroxisome Plasma membrane Chloroplast Cell wall Wall of adjacent cell Plasmodesmata
Fig. 6-30a Collagen EXTRACELLULAR FLUID Proteoglycan complex Fibronectin Integrins Plasma membrane Microfilaments CYTOPLASM
Fig. 6-7 Outside of cell (a) TEM of a plasma membrane Inside of cell 0.1 µm Carbohydrate side chain Hydrophilic region Hydrophobic region Hydrophilic region Phospholipid Proteins (b) Structure of the plasma membrane
Fig. 7-6 RESULTS Membrane proteins Mouse cell Human cell Hybrid cell Mixed proteins after 1 hour
Fig. 7-7 Fibers of extracellular matrix (ECM) Glycoprotein Carbohydrate Glycolipid EXTRACELLULAR SIDE OF MEMBRANE Cholesterol Microfilaments of cytoskeleton Peripheral proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE
Fig. 6-30 Collagen EXTRACELLULAR FLUID Proteoglycan complex Polysaccharide molecule Carbohydrates Fibronectin Core protein Integrins Plasma membrane Proteoglycan molecule Proteoglycan complex Microfilaments CYTOPLASM
Fig. 7-8 N-terminus EXTRACELLULAR SIDE C-terminus α Helix CYTOPLASMIC SIDE
Fig. 7-15 EXTRACELLULAR FLUID Channel protein (a) A channel protein Solute CYTOPLASM Carrier protein Solute (b) A carrier protein
Fig. 7-16-7 EXTRACELLULAR FLUID [Na + ] high [K + ] low Na + Na + Na + Na + Na + Na + Na + Na + CYTOPLASM 1 Na + [Na + ] low [K + ] high 2 P ADP ATP 3 P 6 5 4 P P
Fig. 7-19 ATP + + H + H + H + Proton pump H + + H + Sucrose-H + cotransporter + H + H + Diffusion of H + H + Sucrose + + Sucrose
Fig. 6-14a Nucleus 1 µm Lysosome Lysosome Digestive enzymes Plasma membrane Digestion Food vacuole (a) Phagocytosis
Fig. 6-14b Vesicle containing two damaged organelles 1 µm Mitochondrion fragment Peroxisome fragment Peroxisome Lysosome Vesicle Mitochondrion Digestion (b) Autophagy
Fig. 7-13 Hypotonic solution Isotonic solution Hypertonic solution H 2 O H 2 O H 2 O H 2 O (a) Animal cell Lysed Normal Shriveled H 2 O H 2 O H 2 O H 2 O (b) Plant cell Turgid (normal) Flaccid Plasmolyzed
All Eukaryotes have the following organelles and structures. Nucleus Nuclear envelope- a membrane that contains the DNA and the proteins necessary to organize and maintain the DNA Chromatin-DNA and Protein that is found unwound in a cell between divisions. Chromosomes-condensed form of chromatin these are linear and found during mitosis. Nucleolus- area of the nucleus thought to be used to assemble ribosomes. Cytosol Ribosomes- RNA and protein complex that work together to read mrna and build a protein from its code.
Fig. 6-10 1 µm Nuclear envelope: Inner membrane Outer membrane Nucleolus Chromatin Nucleus Nuclear pore Pore complex Surface of nuclear envelope 0.25 µm Ribosome Rough ER 1 µm Close-up of nuclear envelope Pore complexes (TEM) Nuclear lamina (TEM)
Organelles are membrane bound, specially designed and tasked parts of cells Endoplasmic Reticulum- network of membrane found in the cell along side the nucleus, makes lipid and protein components of the membrane and materials for export from the cell. Rough ER looks grainy because it has ribosomes embedded in its membrane. Produces membrane bound proteins and proteins for export. Smooth ER is the side of the ER away from the nucleus this is the ER responsible for lipid synthesis and detoxification often refines or modifies products from rough ER
Fig. 6-12 Smooth ER Rough ER Nuclear envelope ER lumen Cisternae Ribosomes Transport vesicle Smooth ER Rough ER Transitional ER 200 nm
Golgi Apparatus- Acts as a processing center for products from the ER. May modify some chemicals, while just sorting and packaging others for storage or release. Lysosomes are membrane bags of hydrolytic enzymes. Lysosomes keep these dangerous chemicals separate from the rest of the cell s chemicals and concentrated. They bind with food vacuoles to start the digestions of materials that have been consumed. Vacuoles-mean membrane bag and is used to refer to contractile vacuoles that pump out extra water, food vacuoles, and central vacuoles.
Fig. 6-13 cis face ( receiving side of Golgi apparatus) Cisternae 0.1 µm trans face ( shipping side of Golgi apparatus) TEM of Golgi apparatus
Mitochondria-the power house of the cell. This is the organelle that takes glucose or other chemical energy sources and converts them into ATP. Mitochondria have their own circular DNA, a lot of membrane folds, and their own ribosomes. Chloroplasts are the organelles that house chlorophyll allowing them to capture sunlight and convert the energy it carries into the chemical energy (glucose). These also have their own circular DNA, large amounts of internal membrane, and their own ribosomes.
Fig. 6-17 Intermembrane space Outer membrane Free ribosomes in the mitochondrial matrix Inner membrane Cristae Matrix 0.1 µm
Fig. 9-19 Glucose CYTOSOL Glycolysis No O 2 present: Fermentation Pyruvate O 2 present: Aerobic cellular respiration Ethanol or lactate Acetyl CoA MITOCHONDRION Citric acid cycle
Fig. 9-2 Light energy ECOSYSTEM CO 2 + H 2 O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic molecules + O 2 ATP ATP powers most cellular work Heat energy
Fig. 10-3b Chloroplast Stroma Granum Thylakoid Thylakoid space Inner membrane Outer membrane Intermembrane space 1 µm
Fig. 10-7 Light Reflected light Chloroplast Absorbed light Granum Transmitted light
Structure unique to Plants Cell Wall- in plants these are made up of Cellulose and lignin creating a rigid outer shell that is made stronger when the plant has a hypotonic environment Plastids- several different membrane sacs that hold various pigments, metabolites, etc. Chloroplast- the light converting plastid (membrane sac) it absorbs light energy and converts it to chemical energy. Central Vacuole- a huge vacuole found in the center of the cell that tends to hold water and keeps the organelles nearer the edge of the cell
Fig. 6-9b NUCLEUS Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Smooth endoplasmic reticulum Ribosomes Golgi apparatus Central vacuole Microfilaments Intermediate filaments Microtubules CYTO- SKELETON Mitochondrion Peroxisome Plasma membrane Chloroplast Cell wall Wall of adjacent cell Plasmodesmata
Cytoskeleton is the structural framework found inside of cells. Microfilaments are the smallest form of cytoskeleton fibers and are made of actin These resist tension very well. These are the fibers that are pulled on in muscles to create a contraction. Microtubules are the largest form of cytoskeleton fibers made of tubulin and they resist compression very well. These provide support to a cell against being crushed and act as a rail along which vacuoles and lysosomes can be transported. They are also the basis for the movement of cilia and flagella
Fig. 6-20 Microtubule 0.25 µm Microfilaments
Table 6-1b 10 µm Actin subunit 7 nm
Table 6-1a 10 µm Column of tubulin dimers 25 nm α β Tubulin dimer
Fig. 6-21 ATP Vesicle Receptor for motor protein (a) Motor protein (ATP powered) Microtubule of cytoskeleton Microtubule Vesicles 0.25 µm (b)