Transcript Fig. 4.3
Cytol ogy: The Study of Cells Outline • • • • Prokaryotes vs eukaryotes Structure of eukaryotic cells Cell surfaces Levels of cellular organization Fig. 5.1; Size ranges AHSGE • Describe similarities and differences of cell organelles, using diagrams and tables. – Identify: cell membrane, cell wall, nucleus, ribosome, smooth ER, rough ER, Golgi, vacuole, chloroplast and mitochondria – Classify organisms as prokaryotic or eukaryotic Tools For Studying Cells • #1 tool – microscope • 2 Types – – Light – uses light and lenses – Electron – uses electrons and magnets Microscopes • Light: – Uses light and lenses – Magnifies 1500 x – Live cells – Use stains • Electron: – Uses electrons and magnets – Magnifies 1 000 000 000 x – Dead cells – No colors Cell Theory • 1665: Robert Hooke: looked at cork • Called little spaces ‘cells’ Anton Van Leeuwenhoek, 1678; Looked at pond water, teeth scum Saw one-celled ‘animicules’ (bacteria) Spirochete • Schleiden – botanist – ‘plants are made of cells’ • Schwann – zoologist/physician – ‘animals are made of cells’ • Virchow – physician – ‘cells come from other cells’ – ‘cells cause disease’ Cell Theory • All organisms are made of one or more cells • The cell is the basic unit of organization of life • All cells come from pre-existing cells Types of Cells • Prokaryotes: – Nucleoid – No organelles – Unicellular – Bacteria – Cell wall – Capsule/slime layer – Pili – Flagella • Eukaryotes: – Nucleus – Organelles – Uni or multicellular – Plants, animals – Cell wall (plants) – No capsule/slime – No pili (sex) – Flagella Differences In Plant and Animal Cells • Plant: – Cell walls – Chloroplasts – Large water vacuole • Animal: – No cell wall – No chloroplasts – Small vacuoles – May have cilia/flagella Eukaryotic Cells • Three MAIN parts: – Cell membrane – Nucleus – Cytoplasm and organelles Nucleus • Nuclear membrane (envelope) • Chromatin = strand of DNA wrapped around protein – Chromatin coils up to form chromosomes Nucleus • Genes = sections of the DNA (chromatin) that are the code for making specific proteins • Nucleolus = produces ribosomes; dark colored body in the nucleus Cytoplasm and Organelles Ribosomes • Assemble amino acids into proteins – Look like small dots – May be scattered around the cytoplasm or attached to ER – Cells that need proteins (muscle, pancreas) DNA is made into RNA RNA leaves the nucleus. (with the protein code) and goes to the ribosomes. Ribosomes assemble amino acids into proteins Endomembrane System • • • • Endo = inside Membrane = thin sheet (lipids) Prokaryotes do not have Membrane inside the cell divides it into compartments • Why do you need compartments? Endoplasmic Reticulum • Membrane twists and folds forming tubes and pockets – Creates compartments for various chemical reactions (dehydration synthesis) • 2 types: rough and smooth Endoplasmic Reticulum • Smooth = no ribosomes attached – Manufactures lipids (steroids) – Detoxifies drugs; amphetamines, barbiturates, antibiotics – Poisons, alcohol – Lots of smooth ER in liver cells Endoplasmic Reticulum • Rough – has ribosomes attached; – Manufactures proteins – Some proteins are exported, some stay – Cells that export proteins have a lot of rough ER (salivary glands, pancreas) Transport Vesicles • Membranous spheres that ‘bud’ off of ER – Transport unfinished proteins Golgi • Refinery, warehouse, shipping, packaging • Transport vesicles move unfinished ER products to Golgi to be processed (refined), stored Golgi • Some proteins (from the ER) are shipped out – Cells that secrete have a lot of Golgi (pancreas, ovaries, testes) • Some proteins are redistributed to other parts of the cell Lysosomes • Lyse – ‘split’ • Soma – ‘body’ • Intracellular digestive organelles • Macrophages have a lot Vacuoles • Membranous sacs that ‘bud’ from the endomembrane system (ER) • Temporary storage • Food, water, poisons • Central vacuole (plants) Endomembrane system; ER Golgi Lysosomes Vesicles Vacuoles Energy Converting Organelles • Chloroplasts • Mitochondria Chloroplasts • Plant cells • Chlorophyll = green pigment • Photosynthesis: 6CO2 + 6H2O C6H12O6 + 6O2 Mitochondria • Cellular respiration C6H12O6 + 6O2 6CO2 + 6H2O • Produces energy in the form of ATP • Muscles, nerve cells have a lot of mitochondria • Why? 1 2 3 11 4 5 6 10 7 8 9 Cytoskeleton • Movement and shape Movement • Plant cells don’t move – Cell wall • Cilia and flagella Cilia • • • • Short, hair like Work like oars Movement of a protist Movement of something in a tube – Egg in Fallopian tube – Mucus in lung Paramecium Stentor Flagella • Long, whip like ‘tail’ • One or only a few • Movement of: – Some protists (Euglena) – Sperm cells Euglena Dinoflagellate Cell Surfaces Protection, Support, Cell-to-Cell Communication Plant Cell Walls and Junctions • Cell wall = protects cell, provides strength, keeps the cell from ‘popping’ – Made of CELLULOSE (polysaccharide); very strong Plant Cell Walls and Junctions • Plasmodesmata - openings between plant cells – Allows water, sugars, etc. to pass between cells – Coordinates activities of the tissue Animal Cell Junctions • Extracellular matrix = sticky ‘coat’ • Cell junctions: – Tight junctions = bind cells tightly together – Anchoring junctions = attach cells together, allow nutrient to pass – Communicating junctions (gap junctions) = allow material to move between adjacent cells (plasmodesmata in plants) Fig. 4.21 Levels of Cellular Organization Biosphere Biomes Ecosystems Communities Populations Organisms Organ systems Organs Tissues Cells Organelles Macromolecules Molecules Atoms Cellular Organization Organism Organ systems Organs Tissues Cells Organism Tissue Organ Cell Organ System