lecture 3

Question 1

what is a membrane

Answer 1

fluid and flexible barrier of phospholipids
not stabalized by covalent bond

Question 2

how do membranes associate?

Answer 2

hydrophobic interactions

Question 3

what kind of barrier do membranes have?

Answer 3

semipermeable

Question 4

what are membranes permeable too?

Answer 4

O2, H2O, CO2, small non-polar molecules (cholesterol, glycerol)

Question 5

what are membranes impermeable too?

Answer 5

large molecules, ions, charged molecules (polar)

Question 6

how do permeable molecules move?

Answer 6

passive diffusion

Question 7

how do impermeable molecules

Answer 7

can move via. facillitated diffusion or active transport

Question 8

how does passive transport work?

Answer 8

permeable substances move down the gradient and across the barrier

Question 9

what is hypotonic (passive transport)?

Answer 9

explode
water rushes into the cell
high solute inside, low solute outside

Question 10

what is hypertonic (passive transport)?

Answer 10

shrink
water rushes out
low solute inside, high outside

Question 11

what is facilitated diffusion?

Answer 11

transport down a concentration gradient that uses protien transmitter

Question 12

what is active transport?

Answer 12

transport of molecules up the concentration gradient using energy

Question 13

active transport 1° example?

Answer 13

sodium potassium pump

Question 14

how does sodium potassium pump work?

Answer 14

first site, 3 Na+ out for every 2 K+ in
powered by atp, attaches phosphate on causing change in shape
second site, Na+ and glucose brought in

Question 15

what are the two sections of 2° active transport?

Answer 15

cotransport - transport of 2 molecules/protiens
coupled transport - one gradient is used as an energy source to power another

Question 16

what are the two types of cotransport

Answer 16

symport: 2 molecules same direction
anytiport: 2 molecules opposite direction

Question 17

bulk transport

Answer 17

molecule must enter/exit but is too large

Question 18

bulk transport example

Answer 18

cargo moves through golgi via cisternal maturation
vesicle recyling to keep cisternae unique, move in anterograde fashion
vesicle moves along tubules using kinesin
hormones and secreted in plasma membrane

Question 19

phagocytosis

Answer 19

cell eating of a specific ligin

Question 20

phagocytosis steps

Answer 20

ligin is brought in
receptor mediated endocytosis attaches to plasma membrane
clarithin brings receptors together
ligin moves to vesicle
ligin moves to lysosome