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Transcript
Cytoplasm (cytosol): a cell's inner space Plasma membrane Biology 11 A. Allen Cytoskeleton cytosol Cytosol: large fluid-filled space (mostly water + proteins that control most of the cell metabolisms): glycolysis, transcription factors, intracellular receptors etc. Nucleus: a cell's center Organelles Function of the nucleus: • Stores the chromosomes (genetic material) Note: Two kinds of genetic material: Reminder! Membrane-bound organelles are only found in eukaryotes. • • • • Nucleus Protein production machine: the ribosomes Mitochondria and Chloroplasts Endoplasmic Reticulum and the Golgi apparatus • Lysosomes and Peroxisomes • Adapted and/or specialized for carrying out one or more vital functions ...Nucleus: a cell's center • Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells • DNA replication and synthesis of messenger RNA (mRNA) – deoxyribonucleic acid (DNA) – ribonucleic acid (RNA) • Keeps the DNA molecules of separated from metabolic machinery of cytoplasm. Nucleolus • Dense mass of material in nucleus • Cluster of DNA and proteins • Subunits must pass through nuclear pores to reach cytoplasm • production of ribosomes in nucleolus 1 Nuclear Membrane (Envelope) Chromatin • Two outer membranes (lipid bilayers) • Cell’s collection of DNA and associated proteins • A chromosome is one DNA molecule and its associated proteins • Appearance changes as cell divides • Pores span bilayer and controls what enters/leaves nucleus. Ribosomes Endoplasmic Reticulum (ER) FUNCTION: • assembles proteins • small spherical, black dots • some are free in cytoplasm (cytoplasmic ribosomes), others are attached to the ER (ER ribosomes) …Endoplasmic Reticulum (ER) STRUCTURE • ER is a continuation of the outer nuclear membrane. • Two types: Smooth and Rough. (Rough ER has ribosomes on it) • Network of membrane that connects nuclear envelope to the cell membrane …Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER) FUNCTION: • Smooth ER (no ribrosomes): responsible for lipid and membrane protein modifications) • Rough ER (has ribosomes on it) responsible for the synthesis of other proteins). The ribosomes assemble the proteins within the rough ER. Once assembled, the proteins pinch off the ER and are released in a vesicle. 2 Golgi Body (Golgi Apparatus) …Golgi Body (Golgi Apparatus) FUNCTION: • processes, packages, and, secretes cell products (lipids & proteins) • Put finishing touches on proteins and lipids that arrive from ER • Package finished material for shipment to final destinations. (Exocytosis) • Material arrives and leaves in vesicles Mitochondria …Mitochondria STRUCTURE • Double membrane. Inner membrane is folded for greater surface area. Folds are called cristae. • Interior is called the matrix. • Contain their own genome (distinct from nuclear genome) • Self-replicating The “powerhouse” of the cell FUNCTION • ‘burns’ food, i.e. glucose to release energy. Energy is used to make ATP. ATP is a high-energy molecule that can be directly used by the cell. Lysosomes STRUCTURE • Formed by Golgi bodies • Bound by a single membrane Peroxisomes • • • • Made by Golgi Surrounded by a single membrane Get rid of toxic substances Many in the liver/ brain FUNCTIONS • Digests the food particles inside the cell with help of enzymes. These enzymes work at low pH. • Involved in autolysis (suicide of cell) • Digest foreign bacteria that invade a cell • Recycling of membrane components • Repair damage to plasma membrane lysosome 3 Cell Wall …Cell Wall FUNCTION: • maintains the shape of a plant cell • found in plants, some fungi, some protists • In plants, cell walls are made of a polysaccharide called cellulose. • Structural component that wraps around the plasma membrane Chloroplasts Vacuole • A large membrane bound sac FUNCTION: • Photosynthesis: converts sunlight, carbon dioxide, and water into sugar (makes food for plants) Cytoskeleton: a cell's scaffold • very complex and dynamic cell component! • organizes and maintains the cell's shape (e.g. epithelial cells of the gut) • anchors the organelles in place • helps during the uptake of external material (endocytosis) • involvement in cell movement • growth FUNCTION: • storage area for proteins and water • Maintain structure in plant cells by means of turgor pressure ...Cytoskeleton intermediate microtubules microfilaments filaments tubulin actin keratin family All help maintain cell shape Cilia, flagella Cytoplasmic streaming Chromosome movement Pseudopodia Organelle movement Cell division Nuclear lamina Anchorage of nucleus and some other organelles 4 ...Cytoskeleton ...Cytoskeleton ...Cytoskeleton ...Cytoskeleton Molecular motors Macrophage attacks bacteria Microfilaments (actin) allow formation of pseudopods ...Cytoskeleton ...Cytoskeleton Centrosome: Made up of centriole pairs Striated Muscle 5 Bibliography • http://users.ipfw.edu/mustafaa/PQ_B10 0-02-ppt-Chapter4Cell%20Structures%20and%20Functio ns.ppt • http://images.google.ca/imgres?imgurl =http://biology.dbs.umt.edu/biol101/la bs/lab_6_images/sect05and02/cheek% 2520cell%25201000x.jpg&imgrefurl= http://biology dbs umt edu/biol101/labs 6