Chapter 4

Question 1

Cell membranes act as _________ barriers

Answer 1

selective

Question 2

All cell membranes prevent molecules on one side from ______ with the other side

Answer 2

freely mixing

Question 3

Plasma membrane functions

Answer 3

cell communication, import
and export of molecules, and cell growth and
motility.

Question 4

Membrane assembly begins in the_____

Answer 4

ER

Question 5

Membrane lipids are all ______

Answer 5

amphipatic

Question 6

fat molecules like triacylglycerol’s are entirely

Answer 6

hydrophobic

Question 7

how do phospholipids form sealed compartments

Answer 7

they spontaneously form sealed compartments and separate hydrophobic and hydrophilic ends

Question 8

Length of hydrocarbon tails

Answer 8

14-24
*18-20 most common

Question 9

shorter hydrocarbon tail means…

Answer 9

reduced interaction and increased fluidity

Question 10

Vegetable oils example

Answer 10

liquid at room temp due to unsaturated double bonds

Question 11

cholesterol effects on membranes

Answer 11

stiffens membranes, stabilizing factor

Question 12

Newly synthesized phospholipids are added to the _____ of the ER

Answer 12

cytosolic side

Question 13

Biosynthetic enzymes produce new phospholipids from ____

Answer 13

free fatty acids

Question 14

Scramblases

Answer 14

Randomly transfer phospholipids molecules from one monolayer to another in ER

Question 15

Flippases

Answer 15

move specific phospholipids in the golgi apparatus for specific functions

Question 16

Flippases move

Answer 16

PhosphatidylSERINE and phosphatidylETHANOLAMINE from noncytosolic monolayer to cytosolic side

This leaves phosphatidylcholine and sphingomyelin in non cytosolic side

Question 17

The asymmetric addition and distribution of membrane lipids can help…

Answer 17

curve and bend a bilayer

Question 18

Glycoproteins remain in the same _____ , with their sugars facing the ______ side

Answer 18

Orientation

Extracellular

Question 19

what is found on the cytosolic side

Answer 19

phosphatidylserine
phosphatidylethanolamine

Question 20

Glycolipids are added exclusively in the ________ monolayer

Answer 20

nonctyosolic

Question 21

Transporters

Answer 21

Na+ pump, pumps Na+ out and K+ in

Question 22

ion channels

Answer 22

allows ions to diffuse
(passive)

Question 23

Proteins despite being outnumbered 50x by lipids, make up ___ of the plasma membrane

Answer 23

50 %

Question 24

transmembrane proteins extend across bilayer as

Answer 24

single alpha helix, multiple alpha helixes, or barrel sheet

Question 25

some membranes are anchored to the cytosolic half of lipids bilayer by...

Answer 25

amphipathic Alpha helix

Question 26

Most single pass transmembrane proteins

Answer 26

are receptors for signals

Question 27

most multi-pass are

Answer 27

channels or pores

Question 28

A transmembrane polypeptide chain usually crosses bilayer as an...

Answer 28

alpha helix hydrogen bonding on the inside, hydrophobic parts contact inner membrane

Question 29

Porin

Answer 29

16 stranded - beta sheet formed into a barrel found in ecoli

Question 30

Detergents

Answer 30

cone shaped micelles with one hydrophobic tails Membrane proteins can be solubilized in detergents

Question 31

SDS

Answer 31

strong ionic detergent

Question 32

Triton X-100

Answer 32

mild nonionic detergent

Question 33

Bacteriorhodpsin

Answer 33

proton pump with 7 alpha helices, retinal detects light attached to the protein for proton pump

Question 34

Plasma membrane is supported by...

Answer 34

underlying cell cortex

Question 35

Cell wall

Answer 35

fibrous layer in plants/bacteria that encase plasma membrane

Question 36

Cell cortex

Answer 36

Stabilized by filamentous proteins in animal cells

Question 37

What gives red blood cells its shape

Answer 37

a cortex made of spectrin dimers link to form tetramers

Question 38

Formation of mouse-human hybrid cells show what...

Answer 38

Membrane proteins can move laterally in membane

Question 39

The lateral mobility can be restricted in several ways

Answer 39

1) tethered to cortex in cell or extracellular matrix outside of cell 2) proteins on another cell 3) diffusion barriers

Question 40

Tight junctions

Answer 40

separate transport proteins from other proteins

Question 41

FRAB

Answer 41

measures rate of lateral diffusion using bleaching techniques with a laser beam to measure how long it takes to diffuse evenly

Question 42

Single-particle tracking

Answer 42

shows patterns of diffusion of a protein

Question 43

lipids and proteins have covalently attached...

Answer 43

sugars, glycolipids and glycoproteins

Question 44

Glycocalyx

Answer 44

carbohydrate layer formed b glycoproteins and glycolipids *attracts water *protect cell *adhesive and helps w/ recognition

Question 45

Lectins

Answer 45

bind particular oligosaccharide side chains helps guide neutrophil (white blood cells) find their way to sites of infection

Question 46

Lipid bilayers are impermeable to ___ and ____

Answer 46

ions and most uncharged polar molecules

Question 47

Both ____ and ____ influence passive transport on charged soltutes

Answer 47

concentration gradient and membrane potential

Question 48

What molecules diffuse fastest (size and polarity)

Answer 48

smaller and hydrophobic

Question 49

channels

Answer 49

allows ions of appropriate size to passively diffused

Question 50

Transporters

Answer 50

allows passive diffusion of specific molecules

Question 51

Passive transporters move a solute along its...

Answer 51

electrochemical gradient

Question 52

Pumps

Answer 52

Actively Transport a Solute Against Its Electrochemical Gradient

Question 53

K and Na concentrations

Answer 53

Na+ high outside cell K+ high inside cell *Creates dams of energy

Question 54

Na+ pump

Answer 54

uses ATP to couple Na+ expulsion and K+ into cell

Question 55

Ca 2+ pump

Answer 55

Pumps Ca out to keep cytosolic Ca conc. low

Question 56

Symport Antiport

Answer 56

symport - transported molecules in same direction Antiport - energy provided molecule and transported molecule in opposite directions`

Question 57

Two types of Na ports in epithelial cells

Answer 57

Symport to take Na and glucose in Antiport to take K+ in and Na out

Question 58

Plants lack Na+ pumps and rely on

Answer 58

H+ pumps instead