Chapter 5 Membrane Structures, Synthesis And Transport

Question 1

Phospholipid bilayer

Answer 1

The framework of the two membrane
Consists of two layers of phospholipids
Are amphipathic

Question 2

Lipid raft

Answer 2

A group of lipids that float together as a unit within a larger sea of lipids

Question 3

Passive Transport

Answer 3

The transport of a substance across a membrane that does not require an import energy.

Question 4

Active Transport

Answer 4

Move a substance from an area of low concentration to one of high concentration with the aid of a transport protein. active transport requires an input of energy from a source such as ATP

Question 5

What can go through artificial bilayer

Answer 5

Gases, very small, uncharged molecules, ethanol, water and urea

Question 6

Simple diffusion

Answer 6

Occurs when a substance moves from region of high concentration to a region of lower concentration

Question 7

Facilitated diffusion

Answer 7

A transport protein provides a passageway for a substance to diffuse across a membrane

Question 8

Fluid-mosaic model

Answer 8

Plasma membrane is a semi fluid phospholipid by layer with a mosaic of proteins

Question 9

Leaflet

Answer 9

Half of a phospholipid bilayer

Question 10

Lipid transfer: Scramblases

Answer 10

From protein channel between leaflets for lipids to transfer down a concentration gradient no ATP

Question 11

Flippase

Answer 11

Move lipids from the outer to inner leaflet using ATP

Question 12

Floppase

Answer 12

Move lipids from the inner to outer leaflet using ATP

Question 13

Bilayer fluidity

Answer 13

Optimal level of bilayer fluidity is essential for normal cell function, growth, and division
Membranes are less fluid at low temperatures
Organisms can alter lipid composition to ensure optimal fluidity

Question 14

Transmembrane proteins

Answer 14

Spans from one side of the membrane, through the hydrophobic interior, to the other side of the bilayer

Question 15

Lipid anchored protein

Answer 15

Covalent attachment of a lipid to an amino acid side chain within the protein anchors the protein to the membrane by inserting into the bilayer

Question 16

Estimated percentage of membrane proteins is substantial

Answer 16

29%-30% of all genes may encode membrane proteins

Question 17

Membrane are important medically as

Answer 17

Approximately 70% of medications exert effects by binding to the membrane proteins
Example anti-histamine, which bind to histamine receptors in cell membrane

Question 18

Glycosylation

Answer 18

Process of covalently attaching a carbohydrate to a protein or lipid

Question 19

Isotonic

Answer 19

equal water and solute concentrations on both sides of the membrane

Question 20

Ligand-grated channels

Answer 20

Open in response to binding of an extra cellular ligand

Question 21

Voltage gated channels

Answer 21

Open and close in response to electrical gradients

Question 22

Mechanosensitive channels

Answer 22

Are sensitive to changes in membrane tension

Question 23

Aquaporin

Answer 23

CHIP28
Hypothesized that this protein may function as a water channel
Allows facilitated diffusion of water across the membrane

Question 24

Transporters

Answer 24

Slower than channels

For transport to occur, salute Binds in a hydrophilic pocket exposed to one side of the membrane

Question 25

Uniporter

Answer 25

Bind a single molecule or ion and transported across the membrane

Question 26

Symporters

Answer 26

Bind two or more different types of ions or molecules and transport them in the same direction

Question 27

Anti porters

Answer 27

Binds two or more different types of ions or molecules and transport them in opposite directions

Question 28

ATP driven pumps

Answer 28

Hydrolyze ATP to actively transport solutes against a gradient

Question 29

Plasma membrane

Answer 29

Bromembrane that separates the internal contents of a cell from its external environment

Question 30

Function of cellular membranes

Answer 30

Protein sorting Cell signalling Anchoring Cell division

Question 31

Carbohydrates attached to the cell surface serve two main functions

Answer 31

Cell protection and identification

Question 32

How glycogen attaches to carbohydrates

Answer 32

Covalently

Question 33

Hypertonic

Answer 33

Solution higher solute concentration outside the cell

Question 34

Hypotonic

Answer 34

Lower solute concentration outside the cell

Question 35

Turgor pressure

Answer 35

The internal water pressure generated in plant cells as cell membrane presses on the cell wall

Question 36

Channels

Answer 36

Transmembrane proteins that form a passageway fir the facilitated diffusion of ions or molecules across the membrane Most channels are gated