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Biology Module 2 > 2.1.5 > Flashcards

2.1.5 Flashcards

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1
Q

What is the purpose of membranes?

A
  • separate cell contents from environment

- separate organelles from each other and cytosol

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2
Q

What is meant by compartmentalisation?

A

Formation of separate membrane bound areas in cell

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3
Q

What is the purpose of compartmentalisation?

A
  • Allows specific conditions for cellular reactions

- protects vital cell components

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4
Q

What is the plasma membrane made of?

A

Phospholipid bilayer

  • hydrophilic phosphate heads on either side
  • sandwiching the hydrophobic fatty acid tails
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5
Q

Why is it called fluid mosaic model?

A
  • Phospholipids are free to move within layer relative to each other (making membrane fluid)
  • different proteins are embedded (like mosaic tiles)
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6
Q

What are intrinsic proteins?

A
  • Integral
  • Have amino acid’s with hydrophobic our groups on external surfaces, so I kept in place as it interacts with hydrophobic cool.
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7
Q

Give four examples of intrinsic proteins

A

-Channel proteins
– carrier proteins
– glycoproteins
– glycolipids

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8
Q

What do channel proteins do?

A

Provide hydrophilic channel that allows passive movement of polar molecules and ions down conc. gradient through membrane

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9
Q

How are channel proteins held in place?

A

Hydrophobic R-groups that interact with hydrophobic core

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10
Q

What do carrier proteins do?

A

Passive and active transport (up a conc. gradient)

Involves protein changing shape

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11
Q

Where are glycoproteins found?

A

Embedded in membrane attached to carbohydrate (sugar) chains

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12
Q

What are the two uses of Glycoproteins?

A
  • Cell adhesion

- receptors for chemical signals

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13
Q

How do you glycoproteins work as receptors for chemical signals?

A

-When a chemical binds to it it evokes a response from cell
-may cause direct response/set of series of events inside cell
Known as: cell signalling/cell communication

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14
Q

What do glycolipids do?

A
  • Cell markers/antigens

- can be recognised by cells of the immune system As either self or non-self

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15
Q

What are extrinsic proteins?

A

Peripheral

Have a Hydrophilic R groups so interact with phospholipid heads or intrinsic proteins

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16
Q

Where are extrinsic proteins found?

A

In either layer or in between

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17
Q

What is cholesterol?

A

A lipid with a hydrophobic and hydrophilic end

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18
Q

What is the function of cholesterol and how does it do this?

A

-Regulates membrane fluidity
-add stability as it is in between the phospholipid tails of the bilayer limiting the amount that they can move
Prevents membrane from becoming too rigid by stopping phospholipid getting too close and crystallising

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19
Q

What effect does temperature have on the membrane?

A

An increase in temperature means more kinetic energy so more movement
Membrane is more fluid and so begins to lose its structure

20
Q

What happens if the temperature is too high?

A

Carrier and channel proteins denature

21
Q

What does a lot of structure mean for a membrane?

A

It means the membrane becomes more permeable

22
Q

What affect the solvents have on the membrane?

A 
Polar solvents (water) interacts with the charged phosphate keeping bilayer in tact
Organic solvents (less polar/nonpolar) dissolve membranes distracting the cell and making it more permeable
23
Q

What is effect does alcohol have on the membrane?

A

Pure/strong alcohols are toxic and destroy cells
Alcohol solution is of a lower concentration don’t but still cause damage
When neuronal membranes are disrupted nerve impulses are not transmitted as normal which is why a drunk person’s behaviour changes

24
Q

What is diffusion?

A

Net movement of particles down a concentration gradient

25
Q

Why does diffusion happen?

A

Due to kinetic energy

26
Q

When do you particles stop diffusing?

A

When there is a concentration equilibrium between two areas

movement is equal in both direction

27
Q

How does distance affect diffusion rate?

A

Over a short distance it is fast

As distance increases diffusion slows down as more collisions are taking place

28
Q

What factors affect the rate of diffusion and how?

A

Temperature-more kinetic energy higher rate of diffusion

Concentration difference-greater the difference faster the rate of diffusion as overall movement is larger

29
Q

When can diffusion across membranes happen?

A

-If membrane is permeable to particles
Hydrophobic interior repels substances with a charge
Smaller molecules pass through easier than large ones (partially permeable)

30
Q

What two factors affect diffusion across the membrane?

A

Surface area-larger equals higher rate

Thickness of membrane-thinner of the membrane higher the rate

31
Q

What is facilitated diffusion?

A

Diffusion across a membrane through channel proteins (selectively permeable-specific to one molecule/iron)

32
Q

What factors affect the rate of facilitated diffusion?

A

-Temperature
-concentration gradient
-membrane surface area
–membrane thickness
Number of channel proteins present

33
Q

What is active transport?

A

Movement of molecules/irons against a concentration gradient using:

  • energy
  • carrier proteins
34
Q

How does active transport happen?

A

-Molecule/ion binds to receptors in channel of carrier protein
-ATP binds to carrier protein (then hydrolysed into ADP and phosphate)
-the binding of the phosphate causes protein to change shape opening the inside of the cell
-Molecule/ion is released
Carrier protein returns to original shape
Phosphate is released and re-combines with ADP->

35
Q

What is bulk transport is used for?

A

Large molecules

36
Q

What happens in endocytosis?

A

-Cell membrane invaginates enfolding of the material eventually the membrane fuses forming a vesicle
Vesicle pinches off and moved into cytoplasm

37
Q

What is phagocytosis and what is pino cytosis?

A

Phagocytosis:Is for solids
Pinocytosis: is for liquids

38
Q

What happens in exocytosis?

A

Vesicle is made by Golgi move towards membrane and fuse.

Contents are then released outside of the cell

39
Q

Why is ATP required for bulk transport (three reasons)?

A
  • vesicle movements
  • changing shape of cell to engulf
  • fusion
40
Q

What is water potential?

A

Pressure exerted by water molecules as they collide against the membrane/container

41
Q

What are the measurements for water pressure give an example?

A

Pascals/kilopascals
Pure water= 0 kPa (highest possible or to potential)
If there is a solutes in the water then the water potential gets lowered

42
Q

What is hydrostatic pressure?

A

Pressure of solution in an enclosed system

43
Q

What happens to animal cells when in a solution with higher water pressure?

A

Water moves in so hydrostatic pressure increases

Cell membrane will break out the cell will burst: cytolysis

44
Q

What happens to animal cells In a solution with lower water potential?

A

Water moves out the volume reduces meaning the membrane puckers: crenation

45
Q

How do you multicellular animals always prevents either extreme?

A

They have control mechanisms that insure cells are continuously surrounded by isotonic aqueous solutions

46
Q

What happens to a plant cell in a solution with higher water potential?

A

Water moves in hydrostatic pressure against cells increases creating turgor pressure.
As it increases the cell resist entry of any more water making the cell turgid

47
Q

What happens to plant cells went in a solution with lower water potential?

A

Water is lost to the cytoplasm volume decreases

This causes the cell surface membrane to be pulled inwards away from the cell wall: cell is plasmolysed

Biology Module 2 (5 decks)

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