CELLS

THE DISCOVERY OF THE CELL Anton van Leeuwenhoek First person to see tiny living things in water. Robert Hooke – English physicist Looked at thin slices of plant tissue – cork Found “little chambers” in the cork Called these “chambers” cells. Anton Van Leeuwenhoek Robert Hooke

Cell Theory All living things are made of cells. Cells are the basic units of life All cells come from pre-existing cells. Fig. 7-1, pg. 169 Developed by 3 scientists Matthias Schleiden Theodor Schwann Rudolf Virchow Matthias Schleiden Theodor Schwann Rudolf Virchow

PROKARYOTES AND EUKARYOTES Prokaryotes Do not have a true nucleus – not membrane bound Single celled organisms Bacteria – Escherichia coli (E. coli) & Staphylococcus aureus – causes “Staph” infections Eukaryotes Have a true membrane bound nucleus Membrane bound organelles Can be single celled or multicellular Prokaryote Eukaryote

COMMON CELLS STRUCTURES Cell membrane – all cells – barrier around the cell Cytoplasm – liquid substance inside a cell. DNA – genetic material See Fig. 7.3, pg. 172

EUKARYOTIC CELL STRUCTURE PLANT VS. ANIMAL CELLS Plant cells: Have a cell wall Provides protection Makes the plant rigid Have a large central vacuole Animal cells No cell wall Small vacuole Contain centrioles necessary for cell division Both types of cells have organelles – tiny structures inside a cell “little organs” Fig. 7-5, pg. 174

CELL PARTS - NUCLEUS Controls all of the cell’s functions Contains DNA Contain the genetic information Nucleolus – small spot within the nucleus Where ribosomes are made Nuclear envelope (membrane) – Double layer – surrounds nucleus Nuclear membrane

CELL PARTS – RIBOSOMES Where proteins are assembled

CELL PARTS - MITOCHONDRIA Powerhouse of the cell Supply the cell with energy through cell respiration Breakdown glucose to get energy Many in muscle cells which require large amounts of energy Have their own DNA. May have evolved from bacteria. Fig. 7-12, pg. 181

CELL PARTS – CHLOROPLAST Plant cells only Gives plants their green color due to the pigment Site of photosynthesis Fig. 7-11, pg. 180 Have their own DNA. Also may have evolved from bacteria.

CELL PARTS – CELL MEMBRANE Regulates what enters and leaves the cell Provides protection and support. Selectively permeable – lets some substances in and not others and lets some substances out and not others. Lipid Bilayer – double layer membrane that surrounds all cells. Made of lipids, proteins and carbohydrates.