Chapter 7

Question 1

Amphipathic

Answer 1

Has both hydrophilic and hydrophobic regions

Question 2

The membrane is held together by mainly ———- interactions?

Answer 2

Hydrophobic. Which are weaker than covalent bonds

Question 3

What is a fluidity buffer in animal cells?

Answer 3

Cholesterol

Question 4

Integral proteins

Answer 4

Penetrate the hydrophobic interior of lipid bilayer

Question 5

Transmembrane proteins

Answer 5

Span the membrane

Type of Integral protein

Question 6

Peripheral proteins

Answer 6

Not embedded into the lipids bilayer at all but loosely bound to surface of membrane

Question 7

What are some functions of membrane proteins?

Answer 7

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

Question 8

What is cell-cell recognition?

Answer 8

Cells ability to distinguish one type of neighboring cell from another

Question 9

Glycolipids

Answer 9

Carbs covalently bonded to lipids

Question 10

Glycoprotein

Answer 10

Carbs covalently bonded to proteins

Question 11

Selective permeability

Answer 11

Allows some substances to cross more easily than others

Question 12

Transport proteins

Answer 12

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

Question 13

Aquaporins

Answer 13

Channel proteins

Consists of 4 identical polypeptide subunits, each polypeptide forms a channel that water molecules pass through single file. Altering entry of up to 3 billion water molecules per second

Question 14

Carrier proteins

Answer 14

Hold on to their passengers and change shape in a way that shuttles them across membrane

Question 15

Diffusion

Answer 15

The movement of particles of any substance so that they spread out into the available space

Question 16

Concentration gradient

Answer 16

The region along with the density of a chemical substance increases or decreases.

Question 17

What is a simple file of diffusion?

Answer 17

In the absence of any other forces a substance will diffuse from where it is more concentrated to where it is less concentrated

Question 18

Passive transport

Answer 18

The diffusion of a substance across a biological membrane.

Requires no energy

Question 19

Osmosis

Answer 19

The diffusion of free water across a selectively permeable membrane weather artificial or cellular

Question 20

Tonicity

Answer 20

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

Question 21

Hypertonic

Answer 21

“More” non penetrating solutes

Causes cell to lose water, shrivel and die

Question 22

Hypotonic

Answer 22

“Less” non penetrating solutes messing more water the bell can swell and burst

Question 23

Osmoregulation

Answer 23

The control of solute concentration and water balance

Question 24

Isotonic

Answer 24

“Same” Water diffuses across the membrane at the same rate in both directions

Question 25

Turgid

Answer 25

Very firm. Healthy state for most plant cells

Question 26

Flaccid

Answer 26

Limp Planets wilt

Question 27

Plasmolysis

Answer 27

As a plant cell shrivels its plasma membrane pulls away from the cell wall at multiple places This causes a plant to wilt and can lead to plant death

Question 28

Facilitated diffusion

Answer 28

Transport proteins that span the membrane and helpful or molecules and ions diffuse passively

Question 29

Ion channels

Answer 29

Channel proteins that transport ions

Question 30

Gated channels

Answer 30

Many ion channels function as gated channels which open or close in response to stimulus

Question 31

Active transport

Answer 31

The cell expands energy to pump a solute across a membrane against its gradient All done by carrier proteins

Question 32

Sodium potassium pump

Answer 32

Exchanges Na + for K+ across the membrane of animal cells

Question 33

Membrane potential

Answer 33

The voltage across a membrane

Question 34

Electrochemical gradient

Answer 34

Combination of chemical force and electrical force acting on an ion

Question 35

Electrogenic pump

Answer 35

A transport protein that generates voltage across a membrane

Question 36

Proton pump

Answer 36

The main electrogenic pump of plants fungi and bacteria Actively transports protons (H+) out of cell

Question 37

Cotransport

Answer 37

A transport protein can couple the downhill diffusion of the solute to the uphill transport if a second substance against its own concentration gradient

Question 38

Exocytosis

Answer 38

The cell secretes certain molecules by the fusion of vesicles with the plasma membrane

Question 39

Endocytosis

Answer 39

The cell takes in molecules and particular matter by forming new vesicles from plasma membrane