Chapter 4

Question 1

Plasma membrane

Answer 1

the outer boundary of a cell that separates it for external environment. It is 5-10 mm thick

Question 2

The basic characteristic of a biomembrane

Answer 2

they contain lipids, proteins and carbohydrates arranged in a bilayer. It is stabilized by van der waal interactions

Question 3

Ratio lipid-protein assemblies in mitochondrial membranes

Answer 3

high proteins:low fats as protein carriers are needed for electron transport chain.

Question 4

Ratio lipid-protein assemblies in myelin sheath

Answer 4

low protein: high lipids used as electrical insulation for nerve impulses

Question 5

3 basic type of lipids in cell membranes

Answer 5

• phosphoglycerides
• sphingolipids
• cholesterol

Question 6

sphingolipid/ceramide

Answer 6

a type of sphingosine that is linked to a fatty acid by its amino group

Question 7

Phosphoglyceride

Answer 7

lipids with a phosphate group (phospholipid) and built on a glycerol backbone

Question 8

characteristic of a phospholipid

Answer 8

• net negative charge
• amphipathic
• usually one saturated and unsaturated chain

Question 9

difference between a phosphoglyceride and sphingolipid

Answer 9

The backbone of a phosphoglyceride is a glycerol but the backbone of a sphingolipid is a spingosine

Question 10

sphingosine

Answer 10

an amino alcohol that contains a long hydrocarbon chain

Question 11

cerebroside glycolipid

Answer 11

sphingolipid linked to 1 sugar

Question 12

ganglioside glycolipid

Answer 12

sphingolipid linked to multiple sugars

Question 13

sphingomyelin

Answer 13

a phosphorlcholine added to a ceramide (a sphingolipid and a phospholipid together)

Question 14

synthesis of membrane phospholipids

Answer 14

• they are produced in the ER
• acyl transferase successfully adds 2 fatty acids to glycerol phosphate producing phosphatidic acid

Question 15

the orientation of glycolipids and glycoproteins

Answer 15

they are exoplasmic because the lumen will become the exoplasmic face

Question 16

3 groups of membrane proteins

Answer 16

• integral proteins
• peripheral
• lipid anchored

Question 17

integral proteins

Answer 17

amphipathic as they go through the bilayer and is usually the target for drugs

Question 18

peripheral

Answer 18

on the outsides (extracellular or cytoplasmic side) of the bilayer held by non covalent bonds

Question 19

lipid anchored membrane protiens

Answer 19

covalently bound to the extracellular or cytoplasmic side and distingue by the type of lipid

Question 20

3 types of lipid anchored protiens

Answer 20

• GPI: glycosylphopatidylinositol
• acylation
• prenylation

Question 21

what is a hydropathy plot used for?

Answer 21

It measures the hydrophobicity of amino acids
- negative: hydrophilic
- positive: hydrophobic

Question 22

what contributes to membrane fluidity?

Answer 22

• temperature
• sterol content
• length and saturation or fatty acyl chains
• phospholipid content

Question 23

what is a lipid raft and what is it used for?

Answer 23

When cholesterol and sphingolipids pack together to make highly ordered microdomains when the environment is disorder or more fluid.

Question 24

what is a FRAP and what is it used for?

Answer 24

fluorescence recovery after photobelaching is used to measure the rate of diffusion for membrane proteins

Question 25

what determines lipid permeability?

Answer 25

- molecular size - polarity - partition coefficient (solubility in a non polar solvent vs water)

Question 26

4 ways to move across a membrane

Answer 26

-simple diffusion - simple diffusion by ion channels - facilitated diffusion - active transport

Question 27

facilitated diffusion

Answer 27

no energy but a protein changes conformation allow solute to go through the lipid bilayer

Question 28

simple diffusion

Answer 28

no energy, does down the gradient through the lipid bi layer

Question 29

simple diffusion by ion channel (protein mediated)

Answer 29

no energy, ions go down the gradient through a channel - voltage gated - ligand gated - mechanically- gated

Question 30

active transport

Answer 30

energy required to allow transport up the gradient

Question 31

primary active transport

Answer 31

directly uses energy to pump against the gradient

Question 32

secondary active transport

Answer 32

indirectly uses energy by using a gradient made by active pump

Question 33

Km value of glucose transporters and why

Answer 33

they are there to maintain a concentration of glucose in the body

Question 34

symporter

Answer 34

simultaneously pumping in the same directions

Question 35

antiporter

Answer 35

simultaneously pumping in opposite directions

Question 36

function of the Na- glucose symporter

Answer 36

help move glucose out of the gut lumen

Question 37

why is the Na-Glucose symporter considered a secondary active transport

Answer 37

it uses the gradient set up by the Na/K pump to transport the glucose

Question 38

how does glucose get out the gut lumen and into circulation

Answer 38

it gets cotransported with sodium. every 2 sodium ion brings one glucose ion. once inside the membrane, it a GLUT 2 transporter facilitates diffusion into the blood

Question 39

Lipid- anchor membrane: acylation

Answer 39

A palmitoyl or myristal group connected to a cytosololic protein

Question 40

prenylation protein

Answer 40

A lipid-anchored membrane protein connected to a prenyl group bulit from 5 carbons

Question 41

GPI: glycosylphospatidylinositol

Answer 41

Attaches to the carboxyl terminus of sugars exoplasmically used as receptor and enzymes