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AP Biology > Chapter 5 > Flashcards

Chapter 5 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

fluid mosaic model

A

proteins float in the phospholipid bilayer membrane

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2
Q

Where are most of the proteins in relation to the membrane?

A

noncovalently embedded in the phospholipid bilayer

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3
Q

What are the functions of membrane proteins?

A

~move materials through the membrane
~intercellular recognition and adhesion
~receive chemical signals from the cell’s external environment

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4
Q

Where are the membrane carbohydrates found?

A

attached to lipids or protein molecules

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5
Q

What are the functions of membrane carbohydrates?

A

recognising specific molecules, such as those on the surface of adjacent cells

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6
Q

phospholipids

A

the lipids in biological membranes with both hydrophilic and hydrophobic regoins

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7
Q

hydrophilic regions in phospholipids

A

the phosphorus-containing “head” of a phospholipid is electrically charged and therefore associates with polar water molecules

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8
Q

hydrophobic regions in phospholipids

A

the long, nonpolar fatty acid “tails” of a phospholipid associate with other nonpolar materials, but they do not dissolve in water or associate with hydrophilic substances

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9
Q

How do phospholipids coexist with water?

A

They form a bilayer, where the fatty acid “tails” interact with each other and the polar “heads” face the outside, aqueous environment

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10
Q

most common fatty acids in membranes

A

chains with 16-18 carbon atoms and 0-2 double bonds

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11
Q

saturated fatty acid chains

A

no double bonds, allow for close packing

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12
Q

unsaturated fatty acid chains

A

double bonds, “kinks” make for a less dense, more fluid packing

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13
Q

steroid

A

a family of carbon compounds that have multiple linked rings

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14
Q

cholesterol

A

a steroid that plays an important role in modulating membrane fluidity

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15
Q

What are the factors that affect membrane fluidity?

A

lipid composition and temperature (among others)

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16
Q

How does lipid composition affect membrane fluidity?

A

Saturated fatty acids pack tightly together while unsaturated fatty acids or those with shorter chains increase membrane fluidity. Anaesthetics inserted into cell membranes reduce the fluidity of nerve cell membranes and thereby decrease nerve activity.

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17
Q

How does temperature affect membrane fluidity?

A

Membrane fluidity declines under cold conditions because molecules move more slowly at lower temperatures. Some organisms change lipid composition of their membranes when it gets cold.

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18
Q

What is the typical ratio between proteins and phospholipids in cell membranes?

A

1 protein molecule for every 25 phospholipid molecules

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19
Q

What determines how a membrane protein will be positioned relative to the bilayer?

A

The arrangement of the amino acids in the membrane protein

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20
Q

What are the two general types of membrane proteins?

A

peripheral and integral

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21
Q

peripheral membrane proteins

A

lack exposed hydrophobic groups and are not embedded in the bilayer

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22
Q

integral membrane proteins

A

at least partly embedded in the phospholipid bilayer, and have both hydrophilic and hydrophobic regions

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23
Q

anchored membrane proteins

A

membrane proteins that have fatty acids or other lipid groups covalently attached to them

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24
Q

transmembrane protein

A

an integral membrane protein that extends all the way through the phospholipid bilayer and protrudes on both sides

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25
Q

What happens when two cells fuse?

A

a single continuous membrane forms around both cells, and some proteins from each cell distribute themselves uniformly around this membrane

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26
Q

glycolipid

A

consists of a carbohydrate covalently bonded to a lipid

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27
Q

glycoprotein

A

consists of one or more short carbohydrate chains covalently bonded to a protein

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28
Q

proteoglycan

A

a protein with even more carbohydrate molecules attached to it, and the carbohydrate chains are often longer than in glycoproteins

29
Q

selective permeability

A

when some substances can pass through the biological membranes but not others

30
Q

passive transport

A

occurs when a substance moves from the side of the membrane where its concentration is higher to the side where its concentration is lower (down the gradient)

31
Q

active trasnport

A

requires the input of metabolic energy because it involves the movement of substances against the their concentration gradient

32
Q

diffusion

A

the process of random movement toward a state of equilibrium. It is a net movement from regions of greater concentration to regions of lesser concentration.

33
Q

What does the rate of diffusion depend on?

A

~diameter of molecules or ions
~temperature of the solution
~concentration gradient in the system

34
Q

simple diffusion

A

small molecules pass through the phospholipid bilayer of the membrane

35
Q

osmosis

A

a diffusion process in which water molecules pass through specialised channels in membranes

36
Q

osmotic pressure

A

the pressure that needs to be applied to a solution to prevent the flow of water across a membrane by osmosis

37
Q

What is the equation for osmotic pressure due to water?

A 
Π = cRT
Π is osmotic pressure
c is total solute concentration
R is the gas constant
T is the absolute temperature
38
Q

hypertonic solution

A

has a higher solute concentration than the other solution

39
Q

isotonic solutions

A

have equal solute concentrations

40
Q

hypotonic solution

A

has a lower solute concentration than the other solution

41
Q

turgor pressure

A

the pressure in within a plant cell which prevents further water from entering

42
Q

channel proteins

A

integral membrane proteins that form channels across the membrane through which certain substances can pass

43
Q

carrier proteins

A

speed up the diffusion of bound substances through the phospholipid bilayer, transporting polar molecules such as sugars and amino acids

44
Q

facilitated diffusion

A

diffusion is made easier by channel or carrier prpoteins

45
Q

ion channels

A

protein channels that are each for a particular ion, consisting of the same basic structure of a hydrophilic pore

46
Q

gated channel

A

opens when a stimulus causes a change in the 3D shape of the channel

47
Q

ligand

A

the binding of a chemical signal that can act as a stimuli for a gated channel

48
Q

aquaporins

A

specific channels that allow large amounts of water to move down its concentration gradient

49
Q

active transport

A

Directional, moves a substance either into or out of a cell organelle. The energy source usually comes from ATP.

50
Q

primary active transport

A

involves the direct hydrolysis of ATP, which provides the energy required for transport

51
Q

secondary active transport

A

does not use ATP directly, energy is supplied by an ion concentration gradient or an electrical gradient, established by primary active transport

52
Q

Where is the higher concentration of potassium ions?

A

inside the cell

53
Q

Where is the higher concentration of calcium ions?

A

outside the cell

54
Q

sodium-potassium pump

A

an integral membrane glycoprotein that breaks down an ATP molecule into ADP and a phosphate ion, and uses the released energy to bring two K+ ions into the cell and export three Ca+ ions

55
Q

How does secondary active transport help?

A

aids in the uptake of amino acids and sugars, which are essential raw materials for cell maintenance and growth

56
Q

secrete

A

release to the external environment

57
Q

How can cells take up or secrete intact large molecules?

A

via vesicles in processes called exocytosis and endocytosis

58
Q

exocytosis

A

the process by which materials packaged in vesicles are secreted with the cell

59
Q

How does exocytosis occur?

A

vesicle membrane fuses with the cell membrane, making an opening to the outside, and then releases the contents to the outside

60
Q

endocytosis

A

a general term for a group of processes that bring small molecules, macromolecules, large particles, and even small cells into eukaryotic cells

61
Q

How does endocytosis occur?

A

cell membrane invaginates, forming a small pocket around materials from the environment, eventually forming a vesicle which then breaks off and migrates into the cell

62
Q

receptors

A

proteins that bind to specific molecules and then set off specific cellular responses

63
Q

What are the receptors for endocytosis?

A

integral membrane proteins located on the extracellular surface of the cell membrane

64
Q

What are the types of endocytosis?

A

phagocytosis, pinocytosis, and receptor endocytosis

65
Q

phagocytosis

A

“cellular eating”

receptors in the cell membrane recognise a specific ligand on the surface of a large particle or even an entire cell, and then the phagocytic cell engulfs the particle or other cell

66
Q

pinocytosis

A

“cellular drinking”

vesicles bring fluids and dissolved substances, including proteins, into the cell

67
Q

receptor endocytosis

A

mechanism for bringing specific large molecules, recognised by specific receptors, into the cell

68
Q

endosome

A

a membrane-enclosed compartment with which the vesicle fuses; here the contents of the vesicle are separated and sorted

69
Q

low-density lipoproteins

A

where cholesterol is packaged

AP Biology (19 decks)

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