Download Membrane Review Topics

HONORS BIO CH. 5 CELL MEMBRANE AND HOMEOSTASIS
REVIEW TOPICS
These are topics and vocabulary terms included in this chapter which may appear on the chapter test. See
Power point, chapter guide, warm-ups, quick reviews, and text chapter 5
5.1 Energy and the Cell
a. Energy coupling - endergonic and exergonic reactions; oxidation and reduction
b. ATP - molecule 3 parts , Phosphorylation transfers energy
a. ATP-ADP cycle: ADP + P  ATP  cell use  ADP + P
For: cell movement, synthesis, transport, any work using energy
Enzymes –What are they? – protein catalysts
Why important? – speed reactions in cells fast enough to sustain life
 Activation energy – to start a reaction, enzymes make it lower
 Active site and substrate – what are they?
 Modes of enzyme action – lock-and-key, induced fit
 Conditions that affect enzyme action
o Temperature – warm increases rate; hot denatures protein
o pH – narrow range for best pH, excess H+ or OH- break 3-D bonds
o concentration of enzyme or of substrate – either acts like a limiting reagent
o inhibitors – slow enzyme action: competitive – on active site;
 noncompetitive – somewhere else on enzyme
 feedback – a product of the reaction acts as inhibitor
5.10 Membrane Structure and Function
 Function – maintain homeostasis, control movement across membrane
o Lipid bilayer, Fluid Mosaic Model
o Phospholipid: hydrophobic and hydrophilic parts
o Membrane proteins – function of each; cholesterol, carbohydrate tags
5.14 Passive transport – uses no cell energy/ DOWN a concentration gradient
 Diffusion – between membrane molecules
 Small and nonpolar (O2, CO2. H2O)
b. Facilitated diffusion – through a membrane transport protein
 Pores or channels – open passage through protein
 Carriers – receive on one side of membrane, release on other
 Small and polar or charged (glucose, amino acids, ions)
c. Osmosis – water diffuses across a membrane
Osmotic pressure – tendency of water to move in one direction
Osmotic equilibrium – no net movement of water
o Isotonic – same solute concentration on both sides of membrane
 Water moves equally in both directions
 Natural state for animal cells; flaccid for plant cells
o Hypotonic – lower solute concentration on one side (higher water)
 Water goes FROM hypotonic TO hypertonic
 If cell environment hypotonic, water  water goes into cells
o Animal cells swell, may burst (lyse); Plant cells turgid
o Hypertonic – higher solute concentration on one side (lower water)
 Water goes TO hypertonic FROM hypotonic
 If cell environment hypertonic to cell, water  water out of cells
o cytoplasm shrinks - Animal cells shrink, shrivel
o Plant cells – cytoplasm shrinks, but wall stays- plasmolysis
5.18 Active Transport – uses cell energy ATP
a. Across membranes – AGAINST the gradient
o Protein “pumps” push particles to side where they are already more
concentrated
o In intestine – absorb as many nutrients as possible
o In kidneys – remove as many wastes as possible
o Sodium-potassium pumps – keep ion concentrations on nerve cells
b. Bulk Transport – large particles or cells, in vacuoles or vesicles
 Endocytosis – bring INTO cell
i. Phagocytosis – ‘cell eating’ – engulf food and enclose in vacuole
– Amoeba (pseudopods), white blood cells
ii. Pinocytosis – ‘cell drinking’ – small folds in cell membrane
enclose drops of liquid - Intestine lining
 Receptor-mediated endocytosis
o Coated pits enclose molecule – ex. LDL cholesterol
o Hypercholesterolemia – very high levels in blood
Exocytosis – send OUT of cell
 vesicle filled with substance merges with cell membrane
 opens outside of cell to release substance
o glands that make hormones or enzymes; contractile vacuoles