Brainscape's Knowledge GenomeTM

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


See full index

Bio > Transport across cell membranes > Flashcards

Transport across cell membranes Flashcards

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

What does the cell membrane consist of?

A
  • mainly phospholipid bilayer + protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does fluid-mosaic model mean?

A
  • phospholipid molecules constantly moving = fluid
  • different protein molecules unevenly distributed = mosaic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is the phospholipid bilayer related to the partial permeability of the cell membrane?

A
  • hydrophilic heads orientated inwards towards cytoplasm or outwards towards watery extra-cellular fluid
  • hydrophobic tails orientated towards each other
  • enables lipid soluble molecules to pass quickly through but restricts passage of water soluble ions / polar molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are small molecules passed through the membrane?

A
  • e.g. carbon dioxide + oxygen diffuse through gaps between phospholipids
  • water passes through water protein channels by osmosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the functions of the bilayer?

A
  • allows non-polar substances through
  • forms barrier to water/soluble + charged substances/large molecules
  • fluidity allows it to form vesicles or fuse with other membranes (phagocytosis)
  • maintains different environments on each side
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do carrier / channel proteins do?

A

Aid passage of water soluble ions + polar molecules across membrane

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

What are channel proteins?

A

Acts as channels to allow specific ions/molecules through

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

What are carrier proteins?

A

Act as carriers (can mould / change shape) + transport larger substances in and out

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

What are intrinsic proteins?

A

Span entire membrane (can be channel or carrier proteins)

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

What are extrinsic proteins?

A

Span either one phospholipid layer or are on surface of membrane

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

What are glycoproteins?

A

Carbohydrate proteins

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

What is the role of enzymes in membranes?

A

In membranes of epithelial cells in small intestine

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

What is the role of channel proteins?

A

Have specific tertiary structure, which together with its charge + size determines which molecules can be transported by facilitated diffusion

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

What is the role of carrier proteins?

A

Possess specific tertiary structure complementary to polar molecules - aids transport by facilitated diffusion + active transport

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

What is the role of receptors for hormones in membranes?

A

Have specific tertiary structure allowing specific hormone with complementary shape to attach to its binding site

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

How do glycolipids have a role in cell membranes?

A
  • act as receptors (for specific hormones)
  • act as antigens (cell recognition)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does cholesterol play a role in the cell membrane?

A
  • type of lipid
  • molecules bind to fatty acid tails causing them to pack more closely together
  • restricts movement of phospholipids = membrane less fluid / more rigid
  • helps maintain shape of animal cells
18
Q

What is diffusion?

A

The net movement of molecules from a high conc to a low conc until equally distributed

19
Q

Is diffusion an active or passive process?

A
  • passive
  • does not require energy from respiration
20
Q

What is the rate of diffusion proportional to?

A

Surface area x conc gradient / diffusion distance

21
Q

What is rate of diffusion increased by?

A
  • higher conc gradient
  • large surface area (e.g. microvilli)
  • short diffusion distance (e.g. single cell layer)
22
Q

What is facilitated diffusion?

A
  • involves use of channel + carrier proteins
  • allows transport of polar molecules (e.g. glucose + amino acids) across membranes down a conc gradient through a membrane
  • gaseous exchange occurs via diffusion
23
Q

Is facilitated diffusion a passive or active process?

A
  • passive
  • does not require energy from respiration
  • not inhibited by respiratory inhibitors (e.g. cyanide)
24
Q

What is active transport?

A
  • Movement of molecules/ions through a partially permeable membrane
  • uses carrier proteins
  • against conc gradient
25
Q

How does active transport work?

A
  • molecule attaches to carrier protein (has specific tertiary structure complementary to polar molecule being transported)
  • causes protein to change shape + transport molecule across membrane
26
Q

Is active transport an active or passive process?

A
  • active
  • requires energy from hydrolysis of ATP produced during respiration
27
Q

What kind of cells are involved in active transport?

A

Cells that possess a large number of mitochondria to provide ATP required via respiration

28
Q

What factors decrease rate of active transport?

A

(anything decreasing rate of respiration)
- lowering of temp
- lack of oxygen
- metabolic + respiratory inhibitors (e.g. cyanide)

29
Q

How may cells be adapted for rapid transport across their internal or external membranes?

A

By an increase in number of protein channels and carrier molecules in their membranes

30
Q

What is osmosis?

A

Net movement of water molecules from a solution with a high water potential (dilute) to one with lower water potential (concentrated) across a partially permeable membrane

31
Q

Passive transport

A
  • does not require energy (ATP)
  • movement along conc gradient
  • simple diffusion, facilitated diffusion, osmosis
32
Q

Active transport

A
  • use of energy (ATP)
  • movement against conc gradient
  • active transport
33
Q

What is water potential?

A
  • Potential of water molecules to leave a solution by osmosis
  • in osmosis, water moves from higher (less negative) wp to lower (more negative) wp
34
Q

What is the water potential of pure water?

A
  • zero
  • highest water potential
35
Q

What decreases water potential?

A
  • increase in solute conc
36
Q

What is cell turgor?

A
  • water movement occurs down wp gradient
  • presence of ions in cell = lower wp = water can enter via osmosis
  • as water enters, cell vacuole enlarges & vacuole, cytoplasm, cell membrane extert outward turgor pressure on cell wall
  • provides support in plants
37
Q

What happens if a red blood cell is placed in an isotonic solution?

A
  • no osmosis, no net movement of water
38
Q

What happens if a red blood cell is placed in a solution with low solute conc?

A
  • osmosis occurs
  • water moves in down wp gradient
  • cell swells as volume increases, may burst (pressure increases to extent that cell surface membrane ruptures)
39
Q

What happens if a red blood cell is placed in a solution with high solute conc?

A
  • osmosis occurs
  • water moves out of cell down wp gradient
  • cell shrinks as volume decreases
40
Q

Is the basic structure of ALL cell membranes the same?

A

yes

Bio (10 decks)

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