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Fundamentals Of Living Cells > Membrane Structure And Function 2 > Flashcards

Membrane Structure And Function 2 Flashcards

1
Q

What is the major function of the plasma membrane?

A

Barrier, transport, signal transduction

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2
Q

What is the major function of the mitochondrial inner membrane?

A

Energy transduction

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3
Q

What is the major function of the mitochondrial outer membrane?

A

Physical barrier

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4
Q

What is the major function of the rough ER membrane?

A

Translation and protein processing

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5
Q

What is the major function of the smooth ER membrane?

A

Synthesis of complex lipids

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6
Q

What is the major function of the Golgi membrane?

A

Post-translational modification and processing for secretion

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7
Q

What is the major function of the nuclear membrane?

A

Attachment of chromatin

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8
Q

What is the major function of the lysosomes membrane?

A

Hydrolytic enzymes

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9
Q

What is the major function of the peroxisome membrane?

A

Fatty acid oxidation

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10
Q

What does the ratio of the protein: lipid depend on?

A

The type of membrane and its function

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11
Q

Why is the lipid content of the myelin so high?

A

Insulator

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12
Q

What are the two membranes that have similar functions and a 50:50 ratio of lipid to protein?

A

Erythrocyte and hepatocytes

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13
Q

What are the membrane ratios in the mitochondrial membranes?

A 
Outer = 50:50 cuz barrier role
Inner = 75:25 protein: lipid due to electrons used in ATP production
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14
Q

In a purely phospholipid membrane what is the permeability of lipid soluble molecules?

A

Move either way

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15
Q

Name some lipid soluble molecules

A

Hydrophobic, small uncharged or polar molecules

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16
Q

How do lipid soluble molecules move through the phospholipid membrane?

A

Simple diffusion from high conc to low conc

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17
Q

Name the passive non mediated mechanism

A

Simple diffusion

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18
Q

Name the passive carrier mediated mechanism

A

Uniporters

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19
Q

What is a co transport symporter?

A

Molecules that are generally transported in the same direction

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20
Q

What does a cotransport symporter need to work?

A

Both molecules

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21
Q

What is a cotransport antiPorter?

A

Molecules move in opposite directions

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22
Q

What does a small amount of solute do to the rate of solute transport in carrier mediated transport?

A

A huge increase in transport rate

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23
Q

What does a small amount of solute do to the rate of solute transport in simple diffusion?

A

It is a straight line

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24
Q

What happens to carrier mediated when there is an excess of solute?

A

It plateaus because it gets saturated

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25
Q

What happens to simple diffusion when there is an excess of solute?

A

The rate of solute transfer keeps increasing

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26
Q

What is the Kt?

A

Affinity of the transporter for the substrate

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27
Q

Which of simple diffusion and carrier mediated movement is driven by concentration gradient?

A

Both

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28
Q

Which of simple diffusion and carrier mediated movement needs energy?

A

Neither

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29
Q

Which of simple diffusion and carrier mediated movement needs specificity?

A

Carrier mediated

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30
Q

Which of simple diffusion and carrier mediated movement is slow and which is fast?

A

Simple diffusion is slow, carrier mediated is fast

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31
Q

Which of simple diffusion and carrier mediated movement is capacity limited?

A

Carrier mediated

32
Q

What is the resting circulating concentration of glucose?

A

4mM

33
Q

What is the circulating concentration of glucose after a meal?

A

10-15mM

34
Q

Where are GLUT 1 and 3 found?

A

In all mammalian tissues

35
Q

What is the kt of GLUT 1 and 3?

A

1mM

36
Q

When are GLUT 1 and 3 fully active?

A

At resting concentration

37
Q

What GLUT protein is activated at High glucose concentrations?

A

GLUT 2

38
Q

Where is GLUT2 found?

A

Liver and pancreatic beta cells

39
Q

What is the kt of GLUT 2?

A

15-20 mM

40
Q

What do liver cells do?

A

Take glucose up and store as glycogen or fatty acids

41
Q

What do pancreatic beat cells do?

A

Regulate the production of insulin

42
Q

What do GLUT 4 and 5 do?

A

Maintain the glucose levels in normal cells so they can function

43
Q

Where is GLUT 4 found, and what is its kt?

A

Muscle and adipose tissue- kt = 5mM

44
Q

Where is GLUT 5 found?

A

Small intestine

45
Q

How do carrier mediated transporters function?

A

Binds to the transporter, which undergoes a series of conformational changes allowing the molecule to move across the membrane. The transporter then returns to its original confirmation

46
Q

How is the gradient of glucose maintained?

A

Glucose -> G6P

47
Q

Which glucose isoform is transported?

A

D-glucose

48
Q

How can you increase the transport of glucose?

A

Increasing the number of transporters on the cell surface

49
Q

How are GLUT4 transporters increased on muscle and adipocytes?

A

Insulin

50
Q

What is the conc of Na+ Ions outside the cell?

A

143mM

51
Q

What is the Na+ conc inside the cell?

A

14mM

52
Q

What does the active transport of Na+ require?

A

An integral membrane protein

53
Q

What does SGLUT1 do?

A

Transports glucose when sodium is present

54
Q

What enzyme is involved in the Na+/K+ cotransport mechanism?

A

NA+ - K+ ATPase

55
Q

What is SGLUT1?

A

A Na+-glucose symporter

56
Q

How is cellular asymmetry in cells maintained?

A

The plasma membrane of adjacent cells coming together to form tight junctions

57
Q

What do tight junctions prevent?

A

The redistribution of transport proteins around the cell?

58
Q

What is rehydration therapy?

A

Therapy to combat the loss of water, electrolytes and food nutrients during bouts of diarrhoea

59
Q

What is rehydration therapy made of?

A

1L water, 8tsp sugar and 1tsp salt

60
Q

What does rehydration therapy do?

A

Means the sodium and glucose is absorbed into the gut and the glucose can be used as an energy source. Sodium also draws in water to rehydrate the individual

61
Q

What is compartmentalisation and what does it enable?

A

Intracellular membranes create local environments to separate reactions. It enables electrochemical gradients to be established

62
Q

What does the inner mitochondrial membrane being very impermeable allow?

A

The concentration gradient of ATP to fall

63
Q

What are the lysosomes full of, and what pH do they work best at?

A

Hydrolytic enzymes work best at pH 4 or less

64
Q

What is the cytosolic pH?

A

7.2

65
Q

How do lysosomes maintain their low pH?

A

Have a proton pump which pumps H+ into the lumen

66
Q

What does the lysosomal proton pump require, and what does it mean?

A

Requires the hydrolysis of ATP but means the activities of the enzymes can be maximised

67
Q

What are peroxisomes important for?

A

The breakdown of long chain fatty acids

68
Q

How many enzymes are present within peroxisomes?

A

Over 50

69
Q

What is the internal pH of peroxisomes?

A

6.5-7.1

70
Q

How is a protein directed towards a specific organelle?

A

Signal sequences that target them to specific organelles

71
Q

How many amino acids long are the protein signal sequences?

A

2-3 amino acids

72
Q

How do you prove protein direction?

A

Tag a cytosolic protein with a fluorescent marker.
Add a small nuclear localising sequence to it
It is then not seen in the cytoplasm but in the nucleus

73
Q

What happens if you add a carbohydrate signal to a protein?

A

Protein is made, post translationally modified to add a mannose signal. The mannose is then phosphorylated, which directs the hydrolytic enzymes to the lysosome

74
Q

What happens if the protein responsible for the phosphorylation of mannose is absent?

A

This particular enzymes will not appear in the lysosome but will be secreted into the cytoplasm, so the substrate will accumulate in the lysosome

75
Q

What does I- cell disease do?

A

Leads to cellular disfunction

76
Q

What happens if there is I-cell disease?

A

Significant neurological impairment

Fundamentals Of Living Cells (41 decks)

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