Cell Bio Exam Ii Ch-7 Membrane Structure

Front 1

Who first hypothesized that lipids were an component of the cell membrane?

Back 1

Overton

Front 2

Who discovered that the cell was composed of a lipid bilayer?

Back 2

Gorter and Grendel

Front 3

Who proposed that the lipid bilayer was covered by protein sheets?

Back 3

Davson & Danielli

Front 4

Who first proposed the fluid mosaic model of cell membranes?

Back 4

Singer & Nicolson

Front 5

What are some membrane functions?

Back 5

1. Boundary and Permeable barrier
2. Organization and localization
3. Transport
4. Signal Detection
5. Cell to Cell communication
as well as
6. Reaction site for many enzymes
7. Cell-to-cell adhesion
8. Cell-to-Extracellular matrix adhesion

Front 6

The fluid mosaic model of cell membranes was supported using what microscopy technique?

Back 6

Freeze-Fracture electron microscopy

Front 7

True or False, both the lipids and proteins of a membrane are mobile?

Back 7

True

Front 8

What components of a membrane can vary between different types of cells?

Back 8

lipids
proteins
carbohydrates in the form of glycoproteins or glycolipids

Front 9

Describe membrane asymmetry.

Back 9

Differences between the two layers in both the kind of lipids present and the degree of unsaturation of the fatty acids in the phospholipid molecules.

Front 10

What does amphipathic mean?

Back 10

A molecule having spatially separated hydrophilic and hydrophobic regions

Front 11

What are the three different types of lipids present in the membrane?

Back 11

phospholipids
glycolipids
sterols

Front 12

Both phospholipids and glycolipids can have what two substances connecting their hydrophilic and hydrophobic regions

Back 12

glycerol
sphingosine

Front 13

What is one of the functions of sterols, like cholesterol in the cell membrane?

Back 13

To stabilize the membrane at high and low temperatures.

Front 14

Blood groups are based on what type of membrane lipid?

Back 14

glycosphingolipids

Front 15

What two proteins use energy to move particular lipids from one monolayer to the other against a concentration gradient?

Back 15

Flippase and floppase

Front 16

The asymmetrical arrangement of lipids is established by what two membrane proteins?

Back 16

Flippase and floppase

Front 17

What membrane protein can move a variety of lipids down their concentration gradient without using energy?

Back 17

Scramblase

Front 18

During apoptosis what protein is activated triggering phosphatidylserine movement to the outer monolayer of the plasma membrane signaling surrounding cells to destroy it?

Back 18

Scramblase

Front 19

Why is it important for the membrane to remain fluid?

Back 19

To allow components (particularly proteins) to move about
Membrane fusion
To prevent leakage

Front 20

What factors can influence membrane fluidity?

Back 20

fatty acid chain length
degree of unsaturation of fatty acids
amount of sterols which help stabilize the membrane at both high and low temperatures

Front 21

How does a membrane with short unsaturated fatty acids handle temperature extremes?

Back 21

short unsaturated fatty acids will keep the membrane fluid in colds temperatures
in warm temperatures the membrane will become too fluid and leak

Front 22

How does a membrane with long more saturated fatty acids handle temperature extremes?

Back 22

Long saturated fatty acids keep the membrane fluid in warm temperatures
in cold temperatures the membrane can become too rigid and crack

Front 23

How many of the genes in the human genome code for membrane proteins?

Back 23

Nearly 30%

Front 24

What are the three types of proteins associated with the membrane?

Back 24

integral
peripheral
lipid anchored or lipid linked

Front 25

Which membrane proteins are at least partially embedded in the hydrophobic region of the membrane?

Back 25

integral

Front 26

Which membrane proteins are only bound to the outer surface of the membrane through weak electrostatic forces and hydrogen bonding with the hydrophilic ends of integral proteins or membrane lipids?

Back 26

peripheral

Front 27

Which membrane proteins are located on the surface of the lipid bilayer, but covalently bound to lipid molecules embedded within the bilayer?

Back 27

lipid anchored or lipid linked

Front 28

What does SDS stand for?

Back 28

sodium dodecyl sulfate

Front 29

What is the glycocalyx?

Back 29

the carbohydrate groups of plasma membrane glycoproteins and glycolipids which protrude from the cell surface and form a sugar coat

Front 30

How do cells maintain a shape that isn't spherical?

Back 30

Through the cytoskeleton and its connections to membrane proteins

Front 31

What is a membrane domain?

Back 31

an area of the cell that can maintain a specific protein composition that is distinct from the rest of the membrane

Front 32

How are membrane domains established?

Back 32

When specific proteins aggregate together
When some membrane proteins form barriers to others
When cells form "tight junctions" that prevent the movement of membrane proteins
When membrane proteins are anchored either to the cytoskeleton or the extracellular matrix

Front 33

How does an intestinal cell demonstrate membrane domains?

Back 33

these cells have membrane proteins that transport substances out of the intestine and into the body, and these proteins are restricted to the the side of the cell where the transport is taking place