CP 4 Cell Membranes and Signalling

Question 1

describe the fluid mosaic model

Answer 1

○ Plasma memb is fluid mosaic of lipids and proteins
○ Fluid lipid bilayer, proteins float freely

Question 2

What are peripheral proteins

Answer 2

○ Only interact with polar head groups of bilayer
○ Don’t go all the way thru like the other proteins

Question 3

TF lipids are not good insulators

Answer 3

F Lipids r very good insulators

Question 4

What is the Protein-Lipid composition in: nerve insulation

Answer 4

More lipids less proteins

Question 5

What is the Protein-Lipid composition in: The plasma membrane

Answer 5

pretty much 1;1

Question 6

What is the Protein-Lipid composition in: Electron transport

Answer 6

More proteins less lipids

Question 7

TF phosplolipids are amphipathic (hydrophilic end and hydrophobic end)

Answer 7

T

Question 8

What is the phospholipid structure

Answer 8

1 phosphorus and 3 fatty acids

Question 9

TF the bilayer structure depends on the lipid concentration

Answer 9

T

Question 10

TF the membrane monolayers have different composition

Answer 10

T,
External: Glycolipids, carbs, receptor proteins
Internal: Cytoskeleton

Question 11

what happens to a cell if the cell fluidity is low

Answer 11

membrane turns gel-like, could die

Question 12

What happens to a cell if the membrane fluidity is too high

Answer 12

Allows potentially dangerous molecules to get thru

Question 13

TF unsaturated hydrocarbon tails are Viscous

Answer 13

F, they r fluid

Question 14

TF saturated hydrocarbon tails r fluid

Answer 14

F, they r viscous

Question 15

TF the longer the fatty acid tail the more viscous the membrane

Answer 15

T

Question 16

What is the name of the enzyme that takes H+ from unsaturated fatty acid to make a double C bond

Answer 16

Desaturase

Question 17

What is desaturase used for

Answer 17

to increase membrane fluidity

Question 18

A higher temperature ______ membrane fluidity

Answer 18

increases

Question 19

What are the 3 Major factors to membrane fluidity

Answer 19

1) structure of phospholipid tails
2) Temperature
3) Cholesterol levels

Question 20

How is cholesterol arranged

Answer 20

• Arranged the same way as phospholipids
  ○ Head outwards and tail inside
  
  • Hydrophilic head and hydrophobic tail

Question 21

What is a function of cholesterol

Answer 21

Act as a buffer

Question 22

In higher temps, cholesterol will ______ fluidity and ______ movement of lipids

Answer 22

Reduce
Restrain

Question 23

In lower temps, cholesterol will ______ fluidity and ______ lipids from gelling

Answer 23

Increase
Prevent

Question 24

what is the difference between integral anf peripheral membrane protiens

Answer 24

Integral membrane proteins
- Contains hydrophobic domains that cross the bilayer
- Transmembrane domain
○ Has stretches of non-polar amino acids

Peripheral proteins
- Sits on the surface and form noncovalent bonds with lipids and membrane proteins
- Has no interaction with hydrophobic core

Question 25

what r 4 diff types of proteins we see in the membrane

Answer 25

transporters enzymes signal transduction attachment

Question 26

what do transporter protiens do

Answer 26

Provides channel for movement of molecules

Question 27

how does an enzyme work in the membrane

Answer 27

Substrate binds to active site on enzyme

Question 28

What are the steps to Signal Transduction

Answer 28

Reception --> Transduction --> Response

Question 29

What is the function of attachment protiens

Answer 29

Cytoskeleton and cell to cell recognition

Question 30

What are the different types of transport

Answer 30

Active Passive

Question 31

What are the characteristics of passive transport

Answer 31

- Requires no energy - Moves from high to low concentration

Question 32

what is facilitated diffusion

Answer 32

- type of passive transport ○ Large, uncharged polar molecs need carrier proteins to get thru ○ Channel proteins are corridors in memb. To allow a specific molec to pass (some gated or volt)

Question 33

What are the characteristics of Active Transport

Answer 33

- Dragged across concent. gradient so it req ATP ○ Moves Na out and K in (both against their concent gradient) ○ Proton pump, Keeps pH low, Generates membrane potential

Question 34

What is secondary active transport

Answer 34

○ Use ion gradients created by primary active transport ○ Coupled with primary pump

Question 35

What is Cotransport

Answer 35

2 solutes moving together

Question 36

what is antiport

Answer 36

Transported solute moves in the direction opposite from the gradient driving ion

Question 37

why is active transport needed

Answer 37

- Uptake of essential nutrients at lower extracellular concentration - Removal of secretory waste at higher extracellular concent. - Maintain constant intercellular concentrations of Na, H, K, Ca - Maintain membrane potential (voltage difference across plasma memb.)

Question 38

what is osmosis

Answer 38

- Type of passive diffusion that applies to water molecules - Moves from high to low concent across a selectively permeable membrane

Question 39

what is the plant versions of: isotonic hypotonic hypertonic

Answer 39

Flaccid Plasmolysis Turgid

Question 40

what is Tonicity

Answer 40

he cells ability to gain and lose water