Chapter 7- Membrane structure and Function

Question 1

Selective permeability

Answer 1

Allows some substances to cross it more easily than others

Question 2

Amphipathic molecule

Answer 2

Both a hydrophilic and hydrophobic region

Question 3

Fluid mosaic model

Answer 3

Membranes are composed of a phospholipid bilayer with various protein molecules floating around within it

Question 4

Integral proteins

Answer 4

Penetrate the hydrophobic core if the lipid bilayer

Question 5

Peripheral proteins

Answer 5

Not embedded in the lipid bilayer of all they are appendages loosely bound to the surface of the membrane

Question 6

Cell-cell recognition

Answer 6

A cells ability to distinguish one type of neighboring cell from another it’s crucial to the functioning of an organism
Basis of rejection of foreign cells

Question 7

Hydrophilic substances can avoid contact with lipid bilayer by passing through…..

Answer 7

Transport proteins

Question 8

Channel proteins

Answer 8

Function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel though the membrane

Question 9

Carrier proteins

Answer 9

Hold onto their passengers and change shape in a way that shuttles them across the membrane

Question 10

Diffusion

Answer 10

The tendency for molecules of any substance to spread out evenly into the available space

Question 11

Concentration gradient

Answer 11

An increase or decrease in the density of a chemical substance in an areas cells maintain concentration gradients of ions across their membranes
Represents potential energy and drives diffusion

Question 12

Passive transport

Answer 12

Diffusion of a substance across a biological membrane

Question 13

Osmosis

Answer 13

Diffusion of water across a selectively permeable membrane
Movement of water across cell membranes and the balance of water between the cell and its environment are crucial to organisms

Question 14

Tonicity

Answer 14

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

Question 15

Isotonic

Answer 15

Equal solute concentration

Question 16

Hypertonic

Answer 16

Lower concentration of solute

Question 17

Hypotonic

Answer 17

Higher concentration of solute

Question 18

Turgid

Answer 18

The elastic wall expanding only so much before it exerts back pressure on the cell that opposes forther water uptake

Question 19

Plastmolysis

Answer 19

If a cell is in a hypertonic environment it will lose water to its surroundings and shrink as it shrinks the plasma membrane pulls away from the wall

Question 20

Facilitated diffusion

Answer 20

Many polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane

Question 21

Ion channels

Answer 21

A group of channels manu of which function as gated channels (a stimulus causes them to open or close)

Question 22

Active transport

Answer 22

To pump a molecule across a membrane against is gradient requires work (cell must expend energy)

Question 23

Electrochemical gradient

Answer 23

Combo of forces acting on an ion

Question 24

Electrogenic pump

Answer 24

Transport protein that generates voltage across a membrane

Question 25

Proton pump

Answer 25

Main electrogenic pump of plants, fungi and bacteria. It actively transport hydrogen ions

Question 26

Cotransport

Answer 26

A single ATP powered pump that transport a specific solute can indirectly drive the active transport of several solutes

Question 27

Exocytosis

Answer 27

Cell secretes macromolecules by the fusion of vesicles with the plasma membrane

Question 28

Endocytosis

Answer 28

The cell takes in macromolecules and particulate matter by forming new vesicles from the plasma membrane

Question 29

Ligands

Answer 29

Any molecule that binds specifically to a receptor site of another molecule