STUPENDOUS CELLS Microscopes Light Microscope LM use visible

STUPENDOUS CELLS

Microscopes • Light Microscope (LM) – use visible light passed through specimens and then through glass lenses • Magnification – ratio of image’s size to real size • For light microscope – 1000 x • Resolution – how clear the image is • For light microscope – resolution is. 2μm (bacteria size)

Microscopes • Electron microscope – shoots beam of electrons through specimen • Good for studying organelles – but can’t use for living cells • Scanning electron microscope (SEM) – good for studying surface of a specimen • Transmission electron microscope (TEM) –studies internal structure of cells

• The Basic Unit of Structure and Function of all living things • All cells have: JCell (Plasma) Membrane JCytosol JChromosomes JRibosomes

A. Prokaryotic Cells • NO NUCLEUS! • DNA in a “nucleoid” region • NO MEMBRANE BOUND ORGANELLES! • (i. e. no mitochondria, lysosomes, golgi, vacuoles) • Smaller than Eukaryotic cells

B. Eukaryotic Cells

• Boundary of EVERY cell • Phospholipid bilayer with proteins • SELECTIVELY PERMEABLE

1. Plasma membrane • Ratio of surface area to volume for cells must be large • This allows nutrients to travel to nucleus and waste products to travel out of cells more efficiently

2. Nucleus • Control Center – carries the code that determines the primary structure of proteins • Contains chromosomes (genetic info) • Nucleolus (makes ribosome subunits) • Surrounded by Nuclear envelope (double membrane)

3. Ribosomes • • Makes Proteins No Membrane Found in ALL cells Can be free (in cytosol) or bound (on ER)

• Carries out the following tasks • • • Synthesis of proteins Transport of proteins into membranes and organelles Transport of proteins out of the cell Metabolism Movement of lipids Detoxification of poisons • Includes the following: Nuclear envelope, ER, Golgi, lysosomes, vacuoles, Plasma membrane

• No Ribosomes • Makes lipids, makes and breaks down carbs • Detoxifies drugs (add hydroxyl to them) and proteins • Lots of ENZYMES! • Stores calcium

4 b. Rough Endoplasmic Reticulum • Has Ribosomes • Make proteins and transport them using transport vesicles • Membrane factory--grows in place by adding phospholipids and proteins

4 c. Golgi Apparatus • Manufactures, stores, sorts and ships products made in the ER • Cis face receives the vesicles from ER • Trans face tags the products giving them a “target” for other parts of the cell • Also manufactures macromolecules • Has a membrane

4 d. Lysosomes • MEMBRANE BOUND! • Enzymes for breaking down macromolecules! • Lower p. H (which means? ) • Aid in cell destruction

4 e. Vacuoles • MEMBRANE BOUND • Food Vacuole- stores food

b. Contractile Vacuole v. Found in Protists that live in fresh water v. Pumps out excess water

Central Vacuole (PLANTS) • Large Vacuole in Plants – store lots of water • Surrounded by membrane called TONOPLAST! • Stores lots of stuff like potassium, chloride dangerous substances, color pigments (flowers)

5. Mitochondria • • POWERHOUSE! Burns sugar to make ATP - Respiration Has a double membrane Contain small amount of DNA

6. Chloroplasts • • PHOTOSYNTHESIS! Not found in animal cells Contains 2 or more membranes Have flattened scs called thylakoids – stacked in Grana

7. Peroxisomes • Single membrane • Breaks things down by transferring H to Oxygen making peroxide • Also has an enzyme to break the TOXIC peroxide into water! • Can be used to break fatty acids or detoxify

8. Cytoskeleton • Can be dismantled and reassembled to change the shape of the cell • Involved in Cell Motility (movement) • Made of microtubules, microfilaments, and intermediate fibers • Function – support and shape to cell (wonderbra), anchors organelles and some enzymes

8 a. Microtubules • • Shape and Support Tracks for motor molecules Cause movement of cilia and flagella Chromosome movement in cell division

8 a. Microtubules • Centrosomes – found in animal cells – near nucleus • Organize microtubules • Contain centrioles that replicate before cell division

• Contain microtubules in special arrangements • Can be used to propel organisms (like unicellular eukaryotes), sperm • Cilia also line many organs like windpipe and oviducts to help things move • Flagella – usually one or a few – undulate to move • Cilia – many – found on cell surface – move like oars

Cilia and Flagella • Occur in a 9+2 pattern – 9 microtubules doublets in a ring surrounding 2 single microtubules • Connected by crosslinked proteins called dyneins

8 b. Microfilaments (actin) • Bears Tension (handles pulling forces) • Helps in muscle contraction (works with myosin) • Moves pseudopodia of amoeba • Helps flow of cytoplasm in plant cells • Helps form cleavage furrow during cell division

8 c. Intermediate Filaments • Made of proteins in the keratin family • Maintains cell shape (don’t disassemble like microtubules/microfilaments) • Anchors nucleus and some organelles

Extracellular Matrix (ECM) • • Seen in Animal cells Mainly made of Glycoproteins Collagen – main glycoprotein Fibronectin – bind to cell surface receptors called integrins – allow for signal transmission

9. Intercellular Junctions (animals) • 9 a. Tight Junctions • Plasma membrane tightly pressed against each other • Prevent leakage of extracellular fluid across epithelial cells (like skin)

Intercellular Junctions (animals) • 9 b. Desmosomes • Anchor junctions • Fasten cells together into strong sheets • Attach muscle cells together

Intercellular Junctions (animals) • 9 c. Gap Junctions • Make channels to connect cytoplasm of cells to adjacent cells • Allow communication between cells in many types of tissue • Can open and close based on ATP

10. Cell Wall (plants) • Used for protection, maintaining shape and preventing uptake of too much water • Made of Cellulose

Plant Cell Wall • Primary Wall • thin and flexible • seen in young plants • Middle Lamella – between walls – sticky – to glue cells together • Secondary Wall • between plasma membrane and primary wall • Strong and durable for cell protection and support (wood)

Cell Wall

11. Intercellular Junction (plants) • Plasmodesmata • Channels in plant cells • Connect cytoplasm of one cell to the next making it continuous • Allows water and small solutes to pass freely

Prokaryotic vs Eukaryotic Cell

Animal vs Plant cell