Ch. 7

Question 1

What are the main macromolecules in membranes?

Answer 1

Lipids and proteins

Question 2

What does amphipathic mean?

Answer 2

The molecule has both hydrophobic and hydrophilic regions

Question 3

What factor influences membrane fluidity and how does it impact the membrane?

Answer 3

Temperature.

As temperatures cool, membranes switch from a fluid stare to a solid state as the phospholipids pack more closely

Question 4

What feature of the plasma membrane allows some substances to cross more easily than others?

Answer 4

Selective permeability

Question 5

Are membranes more fluid with more unsaturated fatty acids or saturated fatty acids?

Answer 5

Unsaturated fatty acids because the kinks in the tails prevent tight packing

Question 6

What steroid acts as a fluidity buffer?

Answer 6

Cholesterol

Question 7

What determines most of the membrane’s specific functions?

Answer 7

Proteins

Question 8

What two type of proteins are part of the plasma membrane and where are each of them located?

Answer 8

Integral- penetrate the hydrophobic interior

Peripheral- loosely bound to the surface of the membrane

Question 9

Where are membrane lipids and proteins synthesized?

Answer 9

The ER

Question 10

Can nonpolar molecules cross the membrane easily or do they have trouble? Why?

Answer 10

They can cross easily because they are hydrophobic and can dissolve in the lipid bilayer

Question 11

Do polar molecules and ions cross the plasma membrane with ease or difficulty? Why?

Answer 11

They have difficulty crossing and do it slowly because they are hydrophilic

Question 12

What channel proteins assist the passage of water through the membrane?

Answer 12

Aquaporins

Question 13

Transport proteins called_________ bind to molecules and change shape to shuttle then across the membrane

Answer 13

Carrier proteins

Question 14

Is work or energy required to move substances down the concentration gradient?

Answer 14

No

Question 15

The diffusion of a substance across a biological membrane

Answer 15

Passive transport

Question 16

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

Answer 16

Tonicity

Question 17

When the cell is submersed in a solution and loses water to its environment resulting in the shrinking of the cell, what is this called?

Answer 17

Hypertonic

Question 18

When water enters the cell faster than it leaves and the cell swells and bursts, what environment was it placed in?

Answer 18

Hypotonic

Question 19

What environment will result in no net movement of water across the plasma membrane?

Answer 19

Isotonic

Question 20

The control of water balance

Answer 20

Osmoregulation

Question 21

If a plant cell and its surroundings becomes isotonic what happens?

Answer 21

There is no movement of water into the cell and it becomes flaccid (limp) and the plant may wilt

Question 22

The passive movement of molecules down their concentration gradient with the help of transport proteins is called…

Answer 22

Facilitated diffusion

Question 23

What kind of transport proteins can move solutes against a concentration gradient through active transport?

Answer 23

Carrier proteins

Question 24

What is the energy supply for most active transport?

Answer 24

ATP

Question 25

What drives the diffusion of ions across a membrane?

Answer 25

Electrochemical gradient

Question 26

What is the major electrogenic pump?

Answer 26

Proton pump

Question 27

Bulk transport across the plasma membrane occurs by what processes?

Answer 27

Endocytosis and exocytosis

Question 28

What are the three types of endocytosis?

Answer 28

Phagocytosis, Pinocytosis, receptor-mediated endocytosis

Question 29

In what direction do proteins and lipids move on the plasma membrane?

Answer 29

They laterally drift

Question 30

In addition to:
Attachment to the cytoskeleton and ECM 
Transport.       And....
Enzymatic activity, 
What are the other 3 functions of membrane proteins?

Answer 30

Cell-cell recognition
Signal transduction
Intercellular joining

Question 31

Does H2O need a transport protein to pass through the membrane?

Answer 31

Yes