biology (cell membrane part1)

Question 1

The general structure of membranes is known as the

Answer 1

fluid mosaic model

Question 2

Phospholipids

Answer 2

group of polar lipids that consist of two fatty acids, a glycerol unit and a phosphate group.
hydrophilic head
hydrophobic tail binds together forming bilayer

Question 3

Membrane’s lipid composition can vary

Answer 3

• fatty acid chain length
• degree of unsaturation (double bonds)
• polar groups

Question 4

the Fluidity in the membrane depends on…

Answer 4

temperature and lipid composition.

Question 5

more fluid membrane have…

Answer 5

shorter chain of fatty acid + unsaturated

less cholestrol + high temperature

Question 6

what can happen for the fluidity of a membrane with low temperature ?

Answer 6

molecules move more slowly, and fluidity drops – decline in membrane functions

Question 7

what is the structure of the membrane

Answer 7

phospholipids moment + membrane fluidity more in unsaturated + cholesterol between the hydrophobic

Question 8

are phospholipids in membrane amphipathic?

Answer 8

yes, they have polar and non polar (soluble / non soluble) (hydrophlic/ hydrophobic)

Question 9

2 kinds of protein membrane:

Answer 9

1. peripheral (outside)

2. integral ( inside)

Question 10

Peripheral membrane proteins

Answer 10

• lack of hydrophobic groups

- don’t pentrite the bilayer

Question 11

integral membrane protien

Answer 11

• have hydrophobic and hydrophilic regions
• extend through membrane
• Can be:
  1. partially: some of the bilayer
  2. Transmembrane: cover all the bilayer.

Question 12

The proteins and lipids in the membrane are independent and only interact noncovalently.

Question 13

What is used as a cell recognition in a membrane?

Answer 13

carbohydrates, serve as recognition(identify) sites for other cells and molecules.

Question 14

types of carbohydrates in membrane

Answer 14

Glycolipids—carbohydrate + lipid

Glycoproteins—carbohydrate + protein

Question 15

cells arrange themselves in groups by:

Answer 15

cell recognition and cell adhesion

Question 16

cell recognition is

Answer 16

– one cell specifically binds to another cell of a certain type (identify)

Question 17

Molecules involved in cell recognition and binding (cell - cell recognition)

Answer 17

are glycoproteins

Question 18

cell adhesion –

Answer 18

in which the connection between the two cells is strengthened(colser)

Question 19

cell junctions a type of cell adhesion

Answer 19

are specialized structures that hold cells together;

Question 20

types of cell junctions

Answer 20

• Tight junctions
• Desmosomes
• Gap junctions

Question 21

structure of membrane contain

Answer 21

phospholipids + protein + cholesterol +carbohydrates

Question 22

tight junction

Answer 22

• prevent substance moving between space through the cell

* help unsure directional movement of materials

Question 23

desmosome

Answer 23

Connect adjacent plasma membranes but permit intercellular movement of materials.
*Allow passege of some molecules

Question 24

gap junction

Answer 24

*Made up of specialized channel proteins – connexins
Span plasma membrane of adjacent cells and intercellular space in between
Water, dissolved ions can pass from cell to cell