Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIO HL > B2.1 Membranes > Flashcards

B2.1 Membranes Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

what are cell membranes made of

A

phospholipids in a bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the structure of phospholipids and how do they react to water

A

they have a hydrophilic head that points outwards, and a hydrophobic tail( made of fatty acids) which move away from water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why is the plasma membrane fluid

A

because the phospholipids dont have bonds and are held together through attraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the function of the phospholipid bilayer

A

they create a strong, stable barrier between aqueous solutions that allow substances to leave or enter the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is diffusion

A

the passive movement of particles from a higher to lower concentration, down a concentration gradient, using kinetic energy of the molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

when does diffusion across the cell membrane occur

A

the plasma membrane is fully permeable to the solute.
The lipid bilayer is permeable to non polar substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are peripheral proteins

A

proteins attached to the outer surface of the bilayer or the inner surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

functions of peripheral proteins

A

shuttles between integral proteins
scaffold proteins that hold shape
receptors for extra cellular signals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are integral proteins

A

proteins embedded in one or both layers of the membrane.
They can act as channels, receptors or antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is osmosis

A

the diffusion of water molecules across a membrane that is permeable to water(partially permeable) down a concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what happens to dissolved substances in water

A

they attract a group of polar water molecules around it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what happens when the solution is more concentrated( in terms of water potential)

A

the greater the number of water molecules that are held almost stationary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are aquaporins

A

a water channel pore in a membrane that allow water to diffuse through the plasma membrane
is a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is facilitated diffusion

A

particles of a substance that cannot diffuse across the plasma membrane are helped across the membrane by integral proteins that span the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

is facilitated diffusion passive or active

A

passive diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what do channel proteins transport

A

through facilitated diffusion, they provide hydrophilic channels for polar and charged molecules to pass through,
only specific charged particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is active transport

A

movement of particles from lower to higher concentration, using energy from ATP that has been created during respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is active transport facilitated

A

through carrier proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are pump proteins

A

used for active transport across membranes that is used selectively to move one or two specific substances across

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

characteristic features of active transport

A

occurs against a concentration gradient
active uptake is highly selective
involves pump molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is permeability determined in the case of simple diffusion

A

not selective and depends only on the size and hydrophilic or hydrophobic properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what creates selective permeability in membranes

A

facilitated diffusion and active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what cannot pass through the hydrophobic interior of membranes

A

Large polar molecules or charged molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are glycoproteins and glycolipids

A

carbohydrates that are on the surface of the plasma membrane which are attached to proteins or lipids

25
Q

what is the glycocalyx

A

glycoproteins and glycolipids together

26
Q

what do carbohydrates do in membranes

A

help with cell recognition and cell adhesion
highly hydrophilic and attracts large amounts of watedr

27
Q

Explain fluid mosaic model of membrane structure

A

described as fluid because the components are on the move
mosaic because the proteins are scattered about in patterns

28
Q

what is the effect of unsaturated fatty acids on the phospholipid bilayer

A

because unsaturated fatty acids have lower melting points, an excess makes the membrane more fluid

29
Q

what do saturated fatty acids do to the phospholipid bilayer

A

they make the membrane stronger at higher temperatures

30
Q

why must membranes be sufficiently fluid

A

they must be fluid for proteins to move around and function

31
Q

what does a decrease in temperature lead to in the membrane

A

temperature falling leads to less fluidity and the membrane can even solidify

32
Q

what is homeo-viscous adaptation

A

adaptation that allows some organisms to vary the balance between saturated and unsaturated fatty acids in response to ambient temperatures

33
Q

what is the structure of cholesterol

A

a steroid, made of hydrophilic hydroxyl and hydrophobic hydrocarbon on either side of a carbon ring

34
Q

what is the role of cholesterol in the phospholipid bilayer

A

stabilises the membrane at higher temperatures and prevents stiffening at lower temperatures
has the effect of disturbing the packing of the phospholipids, increasing the flexibility of the membrane

35
Q

what does cholesterol do to the bilayer in low temperatures

A

maintains the fluidity of the membrane by forcing apart the phospholipids and maintaining distance between them

36
Q

what does cholesterol do to the bilayer in high temperatures

A

bonds between the cholesterol and phospholipids maintain the structural integrity of the membrane and prevent them from becoming too fluid

37
Q

what is uptake into a cell called

A

endocytosis

38
Q

what is export out of a cell called

A

exocytosis

39
Q

How is endocytosis done

A

through the formation of vesicles as the plasma membrane pinches inwards, taking material into cell

40
Q

how is exocytosis done

A

vesicles fuse with the membrane and material is exported

41
Q

what is phagocytosis

A

bulk transport of solid matter being taken in

42
Q

what is pinocytosis

A

the bulk transport of fluids

43
Q

how are nerve impulses transmitted along the axon of a nerve cell

A

through momentary reversal in electric potential difference in the membrane , brought by rapid movements of sodium and potassium ions

44
Q

what are voltage gated channels/gated ion channels

A

channel proteins that are exclusively permeable for one type of ion

45
Q

what is a neurotransmitter gated ion channel

A

opens temporarily when a specific neurotransmitter bonds with it

46
Q

steps of a voltage gated channel

A

When theres a stimulus, sodium channels open and let sodium in
The interior of axon depolarises, nerve pulse initiated
more positive charge leads to more potassium channels open, sodium channels close
potassium ions exit down the axon down an electrochemical gradient
interior becomes less positive, so potassium channels close through ‘ball and chain’ protein
when there is more positive charge outside, the channel returns to fully closed

47
Q

what are exchange transporters

A

used in active transport of sodium and potassium ions
used to help generate membrane potentials

48
Q

what are the steps in exchange transporters

A

3 sodium ions loaded into binding sities
ATP reactions cause pump proteins to close to the interior and open to the exterior
3 sodium ions released and 2 potassium ions loaded
reversal of shape of pump protein and potassium ions are released

49
Q

what is indirect active transport

A

cotransporters move sodium in one direction and move glucose as well

50
Q

example of indirect active transport( glucose and sodium)

A

2 sodium ions moved for each glucose

51
Q

what is movement of sodium in terms of cotransporter protein

A

build up of concentration gradient allowing sodium to enter cotransporter protein down its concentration gradient

52
Q

what is the result of indirect active transport in terms of glucose

A

allows glucose to be transferred against it concentration gradient

53
Q

what are Cell Adhesion molecules and where are they located

A

they help maintain tissue structure/function, and help glue cells together
located on the cell surface

54
Q

What is the Extra-Cellular Matrix

A

a network of proteins and molecules that surround, support and give structure to cells and tissues

55
Q

How are CAM’s related to ECM

A

some are used to bind cells to the ECM, forming a cohesive unit

56
Q

what proteins are used for cell-cell junction

A

cadherin proteins

57
Q

what proteins are used for cell-ECM junctions

A

done through integrin proteins

58
Q

what are the 4 types of cell junctions

A

anchoring junctions( strengthens contact)
tight junctions (seal gaps between cells)
gap junctions (links cytoplasm)
signal relaying junctions ( synapses)

BIO HL (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions