Structure/Function of Plasma Membranes

Question 1

Basic function of the plasma membrane

Answer 1

Define the borders of the cell and keep it functional

Question 2

What is selective permeability?

Answer 2

The membrane allows some materials to enter freely and leave the cell, while other materials cannot move freely, but require the use of a specialized structure

Question 3

Three functions of a cell’s plasma membrane

Answer 3

defines the cell, outlines its borders, determines the nature of its interactions with the environment

Question 4

The plasma membrane must be very

Answer 4

flexible

Question 5

complex, integral proteins

Answer 5

receptors

Question 6

example of a receptor being hijacked by a viral offender

Answer 6

HIV, human immunodeficiency virus

Question 7

components of plasma structure

Answer 7

phospholipids, proteins, cholesterol and

carbohydrates

Question 8

a phospholipid is a molecule consisting of

Answer 8

glycerol, two fatty-acids, and a phosphate-linked head group

Question 9

in a typical human cell, protein accounts for

Answer 9

50% of the composition by mass, lipids 40%, and carbs about 10%

Question 10

These extend from the outward-facing portion of the plasma membrane

Answer 10

Carbohydrates attached to lipids and proteins

Question 11

The concentration of lipids and proteins

Answer 11

Varies among different cell membranes

Question 12

Myelin is ____________

Answer 12

an outgrowth of the membrane of specialized cells that

insulates the axons of peripheral nerves

Question 13

Myelin contains only

Answer 13

18 percent proteins and 76 percent lipid

Question 14

Glycolipids vs glycoproteins

Answer 14

Carbohydrates are only on the exterior surface of the plasma membrane and are attached to proteins; are attached to lipids

Question 15

Hydrophilic; hydrophobic; amphiphilic

Answer 15

Water-loving; water-hating; dual-loving

Question 16

Hydrophobic molecules tend to be; tend to form a

Answer 16

non-polar; ball or cluster when placed in water

Question 17

Phospholipids form an excellent

Answer 17

two-layer cell membrane that separates the internal components from the external

Question 18

The head of a phosphate group has a

Answer 18

polar character or negative charge

Question 19

What is an amphiphilic molecule

Answer 19

the head can form hydrogen bonds, but the tail cannot; positively or negatively charged area and an uncharged(non-polar)area

Question 20

In an aqueous solution, phospholipids tend to arrange themselves in

Answer 20

polar heads facing outward and hydrophobic tails facing inward

Question 21

Second major component of plasma membranes

Answer 21

Proteins

Question 22

Third major component of plasma membranes

Answer 22

Carbohydrates

Question 23

Briefly summarize the role of carbohydrate molecules within the plasma membrane

Answer 23

Always found on the exterior, attaching to proteins or lipids. Consist of 2-60 monosaccharide units and can be either straight or branched. Form specialized sites on the cell surface that allow it to be recognized by other cells. Gives the cell a recognition function important to the immune system, allowing it to differentiate between foreign and home(“self”)cells.

Question 24

Carbohydrate components of glycoproteins and glycolipids are referred to as, which is ______

Answer 24

Glycocalyx; highly hydrophilic

Question 25

The glycocalyx is important for

Answer 25

cell differentiation; embryonic development; self/non-self determination; cell-cell attachments to form tissues

Question 26

Peripheral proteins are found on

Answer 26

exterior and interior surfaces of membranes, attached to integral proteins or phospholipids

Question 27

The hepatitis virus attacks

Answer 27

liver cells

Question 28

This gives viruses an opportunity for infection

Answer 28

Glycoprotein and glycolipid patterns on the surfaces of cells

Question 29

HIV penetrates

Answer 29

subtype of lymphocytes called T-helper cells, some monocytes and central nervous system cells

Question 30

HIV binds to which receptor

Answer 30

CD-4