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AQA A-Level Biology > Chapter 4 - Transport Across Cell Membranes > Flashcards

Chapter 4 - Transport Across Cell Membranes Flashcards

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1
Q 
List the structures in the cell surface membrane:
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A
  • cholesterol
  • Chanel
  • hydrophobic tail
  • hydrophilic head
  • Chanel protein molecule
  • glycoprotein
  • glycolipid
  • protein molecules
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2
Q

Define fluid Mosaic

A

Fluid is an individual phospholipid molecule that can move

Mosaic is a protein embedded in the phospholipid bilayer varieting in shape, size and pattern

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3
Q

Describe cholesterol

A
  • add strength
  • hydrophobic
  • reduce lateral movement
  • membrane less fluid
  • prevents leakage of water
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4
Q

Describe hydrophobic tails and hydrophilic head

A
  • repelled by water

* attracts water

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5
Q

Describe phospholipid bilayer

A
  • allows lipid – soluble substances to leave or into the cell
  • Prevents water soluble entering and leaving
  • Makes membrane flexible and self-healing
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6
Q

Described channel protein molecules

A
  • Allows water soluble ions to diffuse across membrane

* intrinic - active transport

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7
Q

What three things are cell membrane made out of?

A

Proteins, lipids and carbohydrates

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8
Q

Describe glycoprotein

A
  • cell recognition
  • carbohydrates + proteins
  • receptor sites for proteins
  • help attach cellaring form tissues
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9
Q

What does the phospholipid stop from entering?

A

Charged and large

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10
Q

What can pass through the bilayer?

A

Small and uncharged molecules

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11
Q

Describe a glycolipid

A
  • made of carbohydrate covalently bonded
  • cell-surface receptor
  • helps maintain stability
  • help cells attach to form tissue
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12
Q

Describe protein molecules

A
  • mechanical support

* cell receptor for molecules

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13
Q

How does a channel protein work?

A

Carrier proteins bind to ions or large molecules carrying them across against the concentration gradient.

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14
Q

Explain why diffusion is higher at higher temperatures?

A

At a higher temperature, the kinetic energy has increased causing the rate of diffusion to increase as the more collisions

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15
Q

What is diffusion?

A
  • high to low concentration gradient

* no metabolic energy = passive transport

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16
Q

Define Fick’s Law

A
  • rate of diffusion in a given direction actors an exchange surface
  • rate of diffusion = (surface x difference in concentration) / length of diffusion path
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17
Q

What is facilitated diffusion?

A
  • uses carrier/channel proteins
  • high to low
  • passive transport = no ATP used
  • allows large and uncharged molecules
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18
Q

What is osmosis?

A
  • high to low
  • water potential in the pressure created from water molecules
  • water goes from a high water potential to a region of low (more negative) water potential
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19
Q

What has the highest water potential?

A
  • pure water

* 0kPa

20
Q

What is hypertonic?

A

Where water is drawn out of the cell to a solution which is more negative - cell swirls up

21
Q

What is isotonic?

A

Where there is an equal water potential

22
Q

What is hypotonic?

A

Where, the water drawn into the cell due to the solution having a lower negative potential than the cell - cell bursts

23
Q

What is active transport?

A
  • transfers large and charged molecules
  • phosphate group from the molecule ATP attaches to the carrier protein causing it to change shape
  • low to high
  • ATP from aerobic respiration (mitochondria + oxygen)
24
Q

What kind of transport across membranes which requires ATP energy?

A

Active transport

25
Q

Type of protein which moves molecules from one side of the membrane to another

A

Carrier protein

26
Q

Process describing the net movement of molecules from high to low concentration

A

Diffusion

27
Q

Bulk movement of substances into a cell by means of formation of a vesicle

A

Endocytosis

28
Q

Way in which substances and moves from the cell within a vesicle which fuses with the plasma membrane

A

Exocytosis

29
Q

Type of diffusion which requires carrier protein molecules to move molecules across the cell membrane

A

Facilitated diffusion

30
Q

Protein bound to polysaccharides

A

Glycoprotein

31
Q

A molecule which will mix with water but not with fat

A

Hydrophilic

32
Q

A molecule which will mix with fate but not with water

A

Hydrophobic

33
Q

These are used to increase the surface area of a cell to facilitate diffusion

A

Microvillie

34
Q

Describes a cell when water has left it causing the cytoplasm to shrink away from the cell wall

A

Plasmolyed

35
Q

Describe A cell which is pumped up full of water

A

Turgid

36
Q

What is the job of amylase and where is this enzyme produced?

A
  • starch to sugar

* salivary glands/small intestine/pancreas

37
Q

What is the job of maltase and where is this enzyme produced?

A
  • Maltose to glucose

* small intestine

38
Q

What is the job of sucrase and where is this enzyme produced?

A
  • sucrose to fructose and glucose

* small intestine

39
Q

What is the job of lactase and where is this enzyme produced?

A
  • lactose to galactose + glucose

* small intestine

40
Q

What is the job of protease and where is this enzyme produced?

A
  • Proteins to amino acids

* stomach, small intestine and pancreases

41
Q

What is the job of lipase and where is this enzyme produced?

A
  • lipids to fatty acid + glycerol

* small intestine, pancreases

42
Q

What is the small intestine adaptation for efficient absorption?

A
  • microvilli
  • protein carrier/channels
  • diffusion/facilitated diffusion
  • active transport (co-transport)
  • length of diffusion pathway
  • capillary network
43
Q

What is co-transport?

A

Two molecules are actively transported or facilitated diffusion

44
Q

Describe co–transport

A

1) Na+ ions actively transport (using ATP) out of cell into blood
2) therefor low concentration of Na+ inside cell
3) therefore Na+ diffuse in from lumen of gut bringing glucose with it

45
Q

Explain how the transport of sodium ions is involved in the absorption of glucose by epithelial cells?

A
  • Co-transport
  • sodium leaves the epithelial cells by active transport whilst a K+ enters
  • carries away by capillary network causing slow concentration of Na+
  • diffused from a high to low concentration
  • glucose and Na+ enter at the same time
46
Q

Explain why the diffusion of chloride ions involve a membrane protein and the diffusion of oxygen does not

A
  • diffusion of chloride ions involve carrier proteins
  • charges molecule cannot diffuse a cross bilayer
  • oxygen does not need membrane protein as small and uncharged can diffuse across the bilayer

AQA A-Level Biology (22 decks)

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