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 – 1000x 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: Cell (Plasma) Membrane Cytosol Chromosomes Ribosomes

A. Prokaryotic Cells NO NUCLEUS! NO MEMBRANE BOUND ORGANELLES! 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

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

4c. 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

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

4e. Vacuoles MEMBRANE BOUND Food Vacuole- stores food

b. Contractile Vacuole Found in Protists that live in fresh water 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

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

8a. 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 only 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 cross-linked proteins called dyneins

8b. 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

8c. 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) 9a. Tight Junctions Plasma membrane tightly pressed against each other Prevent leakage of extracellular fluid across epithelial cells (like skin)

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

Intercellular Junctions (animals) 9c. 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