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Biology A-Level OCR > Membranes > Flashcards

Membranes Flashcards

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1
Q

What is compartmentalisation?

A

Separation of organelles and areas of cells via membranes

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2
Q

What is the plasma membrane?

A

A basic structure that separates the cell from its external environment

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3
Q

What is the phospholipid bilayer?

A

Hydrophilic phosphate group heads and hydrophobic fatty acid tails that form the plasma membrane

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4
Q

What is the fluid mosaic model?

A

A model presented of plasma membranes that shows proteins incorporated intrinsically and extrinsically

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5
Q

What are membrane proteins?

A

Proteins in the plasma membrane that are either intrinsic and extrinsic

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6
Q

What are intrinsic proteins?

A

Proteins that are embedded through both layers of the plasma membrane and come in two types; carrier and channel

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7
Q

What are channel proteins?

A

Proteins that have a hydrophilic channel and allow passive movement for polar molecules and ions

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8
Q

What are carrier proteins?

A

Proteins that have a role in passive and active transport and often changes the shape of the protein

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9
Q

What are glycoproteins?

A

Intrinsic proteins embedded with carbohydrate chains with varying lengths and sizes, they play a role in adhesion and cell signaling (neurotransmitters, peptide hormones (insulin, glucagon))

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10
Q

What is cell signaling?

A

When a chemical binds and elicits a cascade response inside the cell

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11
Q

What are glycolipids?

A

Extrinsic lipids with attached carbohydrate chains that act as cell markers and antigens

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12
Q

What are extrinsic proteins?

A

Proteins that are on one side of the plasma membrane

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13
Q

What are the roles of the plasma membrane?

A

Environment, transport, cell to cell signaling, detecting changes in the environment, site of chemical changes, pseudopodia, anchorage for the cytoskeleton, cell to cell joining

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14
Q

How does the plasma membrane effect the environment?

A

Maintains a fixed set of conditions inside the cell

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15
Q

How does the plasma membrane effect transport?

A

Provides a partially permeable membrane to control which substances enter and exit the cell

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16
Q

How does the plasma membrane effect cell to cell signaling?

A

Have either glycoproteins or lipoproteins to interact between cells

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17
Q

How does the plasma membrane effect detection of environment changes?

A

Signal transduction- so having proteins that can act as receptors for hormones

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18
Q

How does the plasma membrane effect chemical reactions?

A

Proteins in the membranes may act as enzymes

19
Q

What is pseudopodia?

A

When plasma membranes are used for feeding and movement in single celled organisms like amobea

20
Q

How does cholesterol effect the plasma membrane?

A

Maintains stability and fluidity

21
Q

What is an amphipathic molecule? Give two examples

A

A molecule with hydrophilic and hydrophobic regions, phospholipids and cholesterol

22
Q

How does cholesterol effect the fluidity of the plasma membrane?

A

It reduces the fluidity by filling the gaps when the fatty acid tail bends more and therefore prevents crystallisation

23
Q

What are the components in the plasma membrane?

A

Phospholipids, channel proteins, carrier proteins, glycoproteins, peripheral proteins, cholesterol

24
Q

What are the structural properties of the phospholipid bilayer?

A

7.5 nanometres thick, held by weak hydrophobic interactions, have hydrophobic and hydrophilic layers that restrict entry and exit, allow for membrane fluidity,

25
Q

What are the roles of intrinsic proteins?

A

Passive and active transport, active transport often includes a change in shape

26
Q

What are the roles of extrinsic proteins?

A

Acting as receptors

27
Q

What are the roles of intrinsic glycoproteins?

A

Cell signaling

28
Q

What are the roles of intrinsic channel proteins?

A

Passive movement and diffusion of polar molecules and ions

29
Q

What is active transport?

A

Movement of molecules or ions into our out of a cell from a region of a lower concentration to a region of a higher concentration

30
Q

What is osmosis?

A

The diffusion of water across a partially permeable membrane

31
Q

What is diffusion?

A

Net movement from a region of a higher concentration to a region with a lower concentration

32
Q

What is a facilitated diffusion?

A

Movement down gradient across a membrane through protein channels

33
Q

What is bulk transport?

A

Active movement of large molecules

34
Q

How does temperature affect diffusion rate?

A

Increases rate due to an increase of kinetic energy

35
Q

How does concentration gradient affect diffusion rate?

A

Increases rate due to the increase of substances to be diffused

36
Q

How does surface area affect diffusion rate?

A

Increases the rate due to greater area to diffuse across

37
Q

How does membrane thickness affect diffusion rate?

A

An increase of membrane thickness decreases the rate of diffusion due to the greater distance to diffuse across

38
Q

What is facilitated diffusion?

A

The passive movement of molecules across the cell membrane via the aid of a membrane protein

39
Q

How does facilitated diffusion work?

A

Used by molecules that are unable to cross the phospholipid bilayer (large molecules, ions) and is mediated by two types of intrinsic proteins, carrier and channel

40
Q

How do solvents affect membrane structure?

A

Solvents dissolve the phospholipids which disrupts the membrane and causes it to be leaky

41
Q

How does temperature affect the membrane structure?

A

The increase in temperature increases the kinetic energy, which causes the phospholipid fatty acid tails to vibrate more, which disrupts the membrane

42
Q

Describe active transport

A

1 - Molecule or ion binds to receptor
2 - On the inside of the cell, ATP binds to the carrier protein
3 - This causes the protein to change shape
4 - Molecule or ion is transported into the cell
5 - The leftover phosphate molecule reforms ATP from ADP
6 - Carrier protein returns to old shape

43
Q

What is water potential?

A

Pressure exerted by water molecules colliding with sides in kPa

Biology A-Level OCR (26 decks)

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