Chapter 5 - Biological Membranes Flashcards

1
Q

Roles of membranes within cells

A
  • selective permeability
  • surface for enzyme attachment
  • form vesicles
  • compartmentalisation
  • create concentration gradients
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2
Q

Roles of membranes at cell surfaces

A
  • Plasma membranes are partially permeable
  • Create barriers to substances
  • cell recognition and signalling
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3
Q

Three. Intrinsic proteins.

A

Carrier channel, Glyco

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4
Q

Channel proteins

A

Diffusion of polar molecules or ions through membranes

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5
Q

Carrier proteins

A

Active transport of molecules into cells

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6
Q

Glycoproteins

A

Cell adhesion and receptors for cell signalling

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7
Q

Glycolipids

A

Cell markers, or antigen is to be recognised by the immune system

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8
Q

Cholesterol

A

Regulates membrane, fluidity and stability by preventing phospholipids, grouping and crystallising

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9
Q

What factors affect membrane permeability

A

Solvent and temperature

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10
Q

How to solvents affect membrane permeability

A

Organic solvents, dissolve membranes and disrupt cells creating gaps in membranes, which increases fluidity and permeability

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11
Q

How does temperature affect membrane permeability

A

Increasing temperature increases, kinetic energy of phospholipids increases fluidity, so the membrane loses structure

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12
Q

The effect of extreme temperatures on membrane permeability

A

Membrane breaks down completely channel, proteins, denature, so transport is limited

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13
Q

Define diffusion

A

The net movement of particles down a concentration gradient

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14
Q

What factors affect the rate of diffusion?

A

Temperature
concentration difference,
surface area
membrane thickness

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15
Q

Simple diffusion

A

Diffusion across a membrane without using channel proteins

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16
Q

Facilitated diffusion

A

Diffusion across a membrane through channel proteins

17
Q

Active transport

A

Movement of molecules or ions against a concentration gradient, requiring energy from ATP and carrier proteins

18
Q

Types of active transport

A

Endocytosis and exocytosis (bulk transport)

19
Q

What is bulk transport?

A

Vesicle movement requiring ATP

20
Q

Endocytosis

A

Into cells
Cell surface membrane, bends in forming a vesicle that pinches into the cytoplasm

21
Q

Exocytosis

A

Out of cell
Versicles fuse with the cell surface membrane and the contents is released out of the cell

22
Q

Osmosis

A

Diffusion of water across a partially permeable membrane down a water potential gradient

23
Q

What is the highest water potential (pure water)

A

0 kPa (gets more negative)

24
Q

Terms for animal cell, bursting, and shrivelling

A

Bursting – cytolysis
Shrivelling – crenation

25
Terms for plant cell, bursting and shrivelling
Bursting – plant cells don’t burst due to the cell wall, they become turgid Shrivelling – plasmolysis the cell surface membrane, shrinks away from the cell wall
26
Hypertonic
More solute than water, lower water potential
27
Hypotonic
Less solute than water, high water potential
28
Isotonic
Solute and water equal