Intro to the cell

I. Cells Smallest unit of matter that can carry on all processes of life 1665 – Robert Hooke – (Published Micrographia) Coined term “cell” Leeuwenhoek - single-celled organisms Improved microscope

II. Cell Theory Schleiden, Schwann, and Virchow All organisms are made of cells. All existing cells are produced by other living cells. The cell is the most basic unit of life.

Prokaryotes Eukaryotes Unicellular Mostly multicellular; sometimes unicellular Small cells Larger Cells No nucleus or membrane-bound organelles Nucleus with membrane-bound organelles DNA in cytoplasm DNA found in Nucleus Circular DNA Linear DNA Reproduce Asexually Reproduce asexually and sexually Cell division by binary fission Cell division by mitosis and meiosis EX: Bacteria, blue-green algae EX: Protists, Plants, Animals, Fungi

III. Basic info Organelles: cell component that performs specific functions Prokaryote: unicellular organisms lacking a membrane-bound nucleus; circular DNA Eukaryote: membrane-bound nucleus with chromosomes containing genetic info

Cell Parts

I. Cell Membrane A. Surrounds the cell and controls what comes in & out (selectively permeable) B. A bilayer of phospholipids with imbedded proteins. Polar “head” with two nonpolar “tails”

Cell Membrane cont.. C. All materials that enter and leave the cell must pass through the membrane. 1. food 2. wastes

II. Size limitations on cells A. The greater the distance from the middle of the cell, the longer it takes to transport stuff. B. As a cell grows, the volume grows faster than the surface area. C. Cells must maintain a large surface area to volume ratio to feed itself fast enough.

III. Cytoplasm A. Between cell membrane and nucleus B. Cytosol (liquid) + organelles

IV. Nucleus A. Nuclear membrane – double membrane that separates DNA from the cytoplasm. B. Nucleolus- Dark patch in the nucleus- involved in the production of ribosomes. C. Chromatin- Form that DNA takes when the cell is not dividing. D. Nuclear pores- allow materials to pass.

V. Mitochondria A. Site of cell respiration B. Folded inner membrane called cristae increase surface area to increase the the amount of ATP produced. C. Has its own bacteria-like DNA and ribosomes and is about the size of aerobic bacteria.

VI. Ribosomes A. Site of protein synthesis. B. Eukaryotic ribos are larger than Prokaryotic ribos. C. Some are “free” and floating in the cytoplasm. D. Others are “bound” to the ER.

VII. Endoplasmic Reticulum A. Rough- Series of tubes that transport proteins that are to be shipped out of the cell. B. Smooth- Series of tubes that produce streroids and helps detoxify some poisons and wastes.

VIII. Golgi Bodies A. Recieves vesicles from Rough ER with proteins. B. Finishes the packaging and/ or construction of cell products and then sends them on toward the cell membrane.

IX. Lysosome A. Bubble like vesicle with hydrolytic enzymes. B. Breaks down food, old cell parts etc…

X. Vacuoles A. In animals, small storage vesicles for food, wastes, etc.. B. In Plants, one large vacuole fills with water in the middle of the cell. 1. the pressure from this water pushes the cytoplasm against the cell walls. This gives the cell added strength.

XI. Plastids A. Cloroplasts: contains chlorophyll, photosynthesis occurs here 1. Like the Mitochondria, they have their own DNA, Ribos. Similar in size and shape to cyanobacteria. B. Amyloplasts - store starch C. Chromoplasts- Hold pigments- yellow to red.

XI. Cell Wall A. Surrounds and supports plant cells only! B. Made of cellulose C. Bacterial cells have cell walls made of different sugars. PRESSURE vessel: prevent overextension when water enters

Cytoskeleton A. Runs through cells, helps animal cells maintain shape. B. Involved with movement inside and outside the cell. Microtubules (large) involved in cell division. Microfilaments (small) cytoplasmic streaming and movement of muscles.

XIV. Cilia and flagella A. Movement of cells or material around cells. B. Cilia – small & numerous: paramecia, cells of the respiratory tract. C. Flagella- large & few: sperm, euglena

XV. Centrioles A. Made of microtubles, associated with mitosis in animals. B. Not found in plants.