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biology > C5 - Plasma membrane > Flashcards

C5 - Plasma membrane Flashcards

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1
Q

What is compartmentalisation

A

Formation of separate membrane-bound areas in cells

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2
Q

What is a plasma membrane

A

All the membrane of cells which have same basic structure described by fluid mosaic model

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3
Q

What is a phospholipid bilayer

A

Arrangement of phospholipids found in cell membranes
Hydrophilic phosphate heads form inner and outer surface of membrane
Hydrophobic phosphate tails form hydrophobic core

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4
Q

What is the fluid mosaic model

A

Model of the structure of a cell membrane in which phospholipids within the bilayer are free to move and proteins are embedded in various positions

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5
Q

Phospholipid bilayer diagram

A
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6
Q

Fluid mosaic model diagram

A
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7
Q

What is a membrane protein

A

Protein component of cell-surface membrane

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8
Q

What are the two types of membrane proteins

A

Intrinsic: embedded through both layers of a membrane, contain amino acids with hydrophobic R groups than interact with hydrophobic core
Extrinsic: present of one side of bilayer, contain hydrophilic R groups and interact with polar heads

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9
Q

What are examples of intrinsic proteins

A

Channel proteins
Carrier proteins
Glycoproteins

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10
Q

What is a channel protein

A

Intrinsic protein that provides hydrophilic channel allowing passive movement of polar ions and molecules down a conc gradients through membranes

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11
Q

What are carrier proteins

A

Intrinsic proteins that transport substances through membrane actively, against a concentration gradient

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12
Q

What are glycoproteins and their role

A

Intrinsic proteins embedded in cell surface membrane with attached carbohydrate chains

Play a role in cell adhesion and as receptors for chemical signals (cell signalling- response triggered after chemical bound to receptor)

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13
Q

What are glycolipids and their function

A

Lipids attached to carbohydrate chains

Cell markers/antigens - recognised by immune system as self / non-self

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14
Q

What is cholesterol

A

Lipid with hydrophilic and hydrophobic end

Regulates fluidity of membrane and adds stability by positioning itself between phospholipids and pulling them to her
Prevent phospholipids from getting to close and crystallising

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15
Q

What affect does temperature have in the cell membrane

A

Phospholipids have increased KE
Move more
Membrane becomes more fluid and loses its structure

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16
Q

What happens to membrane permeability when temp inc

A

Permeability increases

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17
Q

What happens to carrier and channel proteins when temp inc

A

Denature (membrane permeability inc)

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18
Q

What type of solvents disrupt cell membranes

A

Non-polar solvents

19
Q

How do you investigate the permeability of cell membrane

A

Cut five equal cuboids of beetroot
Wash them
Place them in 100ml of distilled water in a boiling tube
Place these boiling tubes in water baths of different temperatures for five minutes
Measure absorbance of each sample using blue filter
Plot a graph

20
Q

What is passive transport

A

Transport that does not require energy and does not use energy from cellular respiration

21
Q

What is simple diffusion

A

Net movement of particles from a region of high concentration to low concentration, down a concentration gradient

22
Q

What are factors affecting diffusion

A

-Inc temperature: Higher rate of diffusion, particles have more KE, move faster
-Larger concentration gradient: Faster rate of diffusion, overall movement larger

23
Q

Does diffusion require energy

A

No, it’s a passive process

24
Q

Why are membranes referred too as partially permeable

A

Only non-polar molecules diffuse freely
Hydrophobic interior repels charged substances (diffuse at much slower/not at all)

25
Q

What affects the rate at which molecules/ions diffuse across a membrane

A

Surface area: larger, higher rate
Thickness of membrane: thinner, higher rate

26
Q

What is facilitated diffusion

A

Diffusion across a plasma membrane through protein channels

27
Q

What is selectively permeable

A

Plasma membrane with protein channels that allow specific substances to cross only

28
Q

What factors affect facilitated diffusion

A

Temperature
Concentration gradient
Surface area
Thickness
Number of protein channels present

29
Q

What is active transport

A

Movement of particles across a plasma membrane against a concentration gradient, requiring energy

30
Q

Describe active transport

A

1) Molecule/ion binds to receptors in channel of carrier protein outside cell
2) Cell ATP binds to carrier protein and is hydrolysed into ADP and phosphate
3) Phosphate binds to carrier protein changing shape of protein, opening up cell
4) Molecule/ion released inside cell
5) Phosphate molecule released from the carrier protein and recombines with ADP to form ATP
6) Carrier protein returns to original shape

31
Q

What is bulk transport

A

Form of active transport where large molecules/whole bacterial cells are moved into or out of a cell by endocytosis or exocytosis

32
Q

What is endocytosis

A

Bulk transport of material into the cell.
Phagocytosis - solids
Pinocytosis - liquids

Cell surface membrane comes invaginates when it comes into contact with the material to be transported
Membrane enfolds until membrane fuses becoming vessicle
It pinches off and moves into cytoplasm

33
Q

What is exocytosis

A

Reverse of endocytosis. Vesicles usually formed by Golgi apparatus and fuse with cell membrane, then vesicles released outside of the cell

34
Q

What is necessary for the movement formation and function of vesicles

A

Energy in the form of ATP

35
Q

What is water potential

A

Pressure exerted by water molecules as they collide with a membrane or a container
(symbol is psi/trident)

36
Q

What is water potential measured in

A

Pa/kPa

37
Q

What is pure water

A

Water potential of 0 kPa (highest possible value)

38
Q

What is osmosis

A

Net movement of water through a partially permeable membrane down a water potential gradient, passive process

39
Q

What is hydrostatic pressure

A

Pressure created by water in an enclosed system

40
Q

What happens when an animal cell is placed in a solution with a higher water potential

A

Net movement of water into the cell
Cell swells and bursts
Cytolysis

41
Q

What happens when an animal cell is placed in a solution with a lower water potential

A

Net movement of water out of cell
Cell shrinks
Crenation

42
Q

What happens when an plant cell is placed in a solution with a higher water potential

A

Net movement of water into cell
Cell swells
Becomes turgid

43
Q

What happens when an plant cell is placed in a solution with a lower water potential

A

Net movement of water out of cell
Cell shrinks
Plasmolysed

44
Q

What is turgor

A

Pressure exerted by cell surface membrane against cell wall in a plant cell

biology (15 decks)

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