Membrane Structure And Function

Question 1

Amphipathic

Answer 1

Having both a hydrophilic region and hydrophobic region

Question 2

How is membrane held together ?

Answer 2

Hydrophobic interactions

Question 3

What is the most abundant lipid in the plasma membrane

Answer 3

Phospholipids

Question 4

Phospholipids

Answer 4

Are amphipathic molecules, containing hydrophobic and hydrophilic regions

Question 5

Peripheral proteins

Answer 5

Are bound to the surface of the membrane

Question 6

Integral proteins

Answer 6

Penetrate the hydrophobic core

Question 7

Trans membrane proteins

Answer 7

Integral protein that span the membrane

Question 8

Major functions of membrane proteins

Answer 8

Transport
Enzymatic activity
Signal transduction
Cell cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracellular matrix

Question 9

Diffusion

Answer 9

Is the tendency for molecules to spread out evenly into the available space

Question 10

Where do substances diffuse down their

Answer 10

Concentration gradient

Question 11

Dynamic equilibrium

Answer 11

As many molecules cross the membrane in one direction as in the other

Question 12

Passive transport

Answer 12

Is the diffusion of a substance across a membrane with no energy investment

Question 13

What do membrane structures result in

Answer 13

Selective Permeability

• plasma membranes are selectively permeable, regulating the cell’s molecular traffic

Question 14

What is the process controlled by the plasma membrane

Answer 14

A cell must exchange materials with its surroundings

Question 15

Facilitated diffusion

Answer 15

The movement of glucose across the plasma membrane requires the use of a carrier protein.

Question 16

Transport proteins

Answer 16

Transports proteins speed the passive movement of molecules across the plasma membrane
Allows passage of hydrophilic substances across the membrane
Channel and carrier proteins

Question 17

Channel proteins

Answer 17

Provide corridors that allow a specific molecule or ion to cross the membrane . Aquaporins are channel proteins because they facilitate the diffusion of water

Question 18

Carrier proteins

Answer 18

Undergo a subtle change in shape that translocates the solute binding site across the membrane

Question 19

Ion channels

Answer 19

Facilitates the diffusion of ions

Question 20

Gated channels

Answer 20

Open or close in response to a stimulus

Question 21

Active transport

Answer 21

Uses energy to move solutes against their gradients
- allows cells to maintain concentration gradients that differ ,from their surroundings
- exp. sodium potassium pump ( the major electrogenic pump of animal cells)

Question 22

How many different proteins are there

Answer 22

20

Question 23

Membrane potential

Answer 23

It is the voltage difference across a membrane

Question 24

How is voltage created

Answer 24

It is created by differences in the distribution of positive and negative ions across a membrane

Question 25

Electrochemical gradient

Answer 25

Deives the diffusion of ions across a membrane

Question 26

Electro genetic pump

Answer 26

It is a transport protein that generates voltage across a membrane
- helps stores energy that can be used for cellular work

Question 27

Proton pump

Answer 27

The main electrogenic pump of plants, fungi, and bacteria.
They are the heart of the electron transport process. They produce the transmembrane electrochemical gradient that enables ATP Synthase to synthesize ATP

Question 28

Aquaporins

Answer 28

Transport Protein that facilitates the movement of water across the cell membrane

Question 29

Osmosis

Answer 29

Is the diffusion of water across a selectively permeable membrane
- water diffuses a membrane from the region of lower solute concentration to the region of higher solute concentration is equal on both sides

Question 30

Tonicity

Answer 30

Is the ability of a surrounding solution to cause a cell to gain or lose water

Question 31

Isotonic solution

Answer 31

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

Question 32

Hypertonic solution

Answer 32

Solute concentration is greater than that inside the cell; cell loses water

Question 33

Hypotonic solution

Answer 33

Solute concentration is less than that inside the cell; cell gains water

Question 34

Bulk transport

Answer 34

Bulk transport across the plasma membrane occurs by exocytosis and endocytosis
- it requires energy
- large molecules, such as polysaccharides and proteins, cross the membrane in bulk via vesicles

Question 35

Exocytosis

Answer 35

Transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell

Question 36

Endocytosis

Answer 36

The cell takes in macromolecules by forming vesicles from the plasma membrane
- Phagocytosis ( cellular eating ) macrophages, used phagocytosis to engulf pathogenic bacteria
- Pinocytosis ( cellular drinking )
- receptor-mediated endocytosis

Question 37

Co-receptors

Answer 37

Proteins expressed on the surface of immune cells are required for recognition by he HIV virus