Biology Chapter 5

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Phospholipid bi-layer with cholesterol and proteins

Ce

Cell Membrane

Hydrophobic tail

Hydrophilic head

*controls what goes in/out

*maintains homeostasis

Membrane Proteins

Transportation

Enzymatic Activity

Signal Transduction

Cell-Cell Recognition

Intercellular Joining

Attach to Cytoskeleton & ECM

Protein pumps> active transport

Ex) aquaporins: water goes through (selective permeability)

May be an enzyme with an active site

Hook together in cell junctions, long-lasting binding

Identification tags

Signal goes off if something is wrong

glycoproteins/glycolipids

Keeps things in tact

Signal to receptor

Chemical messenger (hormone)

TYPES OF PROTEINS

Integral Proteins

Inside of membrane; made of nonpolar amino acids in alpha helixes

Channel Proteins

Peripheral Proteins

loosely bounded to surface

exposed to integral proteins

SYNTHESIS OF MEMBRANES

-Membrane proteins and lipids made in ER

-In golgi, glycolipids/proteins get carbohydrate modification

-glycolipids/proteins transported to plasma membrane

-exocytosis; puts glyc./prot. outside of membrane

PASSIVE TRANSPORT

ACTIVE TRANSPORT

diffusion- molecules moves through membrane (through available space)

MORE -------> LESS concentrated

OSMOSIS

Diffusion of water across a selectively permeable membrane

Tonicity- a solution's ability to lose/gain water

water potential= solute potential + pressure potential

Facilitated Diffusion

Moving a substance against (up) concentration gradient

Entropy

Endocytosis- bulk movement of stuff into the cell

Na+ and K+ pump

Wa

Water Potential

Hypertonic:

-high water potential outside of cell

-high concentration outside of cell

Isotonic:

- = concentration in/out

-water still moves in/out of cell

CELL SIGNALING

1) paracrine signaling (local) synaptic signaling (local) 2) endocrine signaling (long distance)

Reception

Transduction

Response

How

How do we terminate the response?

Membrane Transport

Cell Signaling

Membrane Proteins

Passive/ Active Transport