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Bioc2101 > Practical Test > Flashcards

Practical Test Flashcards

1
Q

In spectrophotometry, we know there is a linear relationship between A and c because:

A

ɛ and l are fixed.

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2
Q

True or false, c=nv

A

False, n = cv

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3
Q

What is the name of the law pertaining to spectrophotometry absorption?

A

Beer-Lambert

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4
Q

What is coefficient ɛ in the Beer Lambert-Law?

A

Molar absorption coefficient

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5
Q

What units is ɛ in?

A

L mol-1cm-1

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6
Q

With a higher l (path length), would there be more or less light transmitting through the solution?

A

Less, as the light is travelling further and hitting more molecules.

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7
Q

What is V0 in enzyme kinetics?

A

The initial reaction velocity.

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8
Q

What is on the X axis of a standard curve?

A

Amount or concentration.

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9
Q

In thin layer chromatography, is the cellulose plate polar or non-polar?

A

Polar.

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10
Q

Why do polar amino acids travel less far on cellulose plates?

A

Polar groups form H bonds with the cellulose.

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11
Q

What is normal resting blood glucose?

A

4-6mM

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12
Q

What are three qualities of an enzyme that make it ideal for a lab setting?

A
  1. Stability after extraction from tissue
  2. Easily quantifiable and reproducible activity
  3. Obtainable in sufficient quantity
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13
Q

Why is V0 the only meaningful measurement of enzyme activity for the lab?

A

After a point, the activity is altered too much by pH, temperature, and concentrations.

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14
Q

Which requires more complex equipment - a continuous or stopped assay?

A

Continuous assay.

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15
Q

What is the major assumption of a stopped assay?

A

Enzyme activity is linear over the time period of the assay.

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16
Q

What was the substrate in the enzymes lab?

A

P-NPP (p-nitrophenol phosphate)

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17
Q

How was P-NPP converted to P-NP in lab 3?

A

Phosphatase removed a phosphate.

18
Q

What is the dual purpose of adding NaOH in the stopped assay of Lab 3?

A
  1. Denature phosphatase to stop the reaction.
  2. Ionise P-NP to produce a yellow colour.
19
Q

Glycolysis is the pathway that converts glucose to ______.

A

Pyruvate.

20
Q

Why is lactate measured in the glycolysis lab?

A

The amount of lactate formed is a measure of glycolytic activity.

21
Q

Why is perchloric acid added to the muscle extract incubation in the glycolysis lab?

A

To denature the enzymes and terminate glycolytic activity.

22
Q

True or false, the rat muscle extract incubation is followed by lactate assays in the glycolysis lab.

A

True.

23
Q

What purpose does the LDH enzyme serve in the lactate assay of the glycolysis lab?

A

LDH oxidises lactate to pyruvate, in turn reducing NAD+ to NADH.

24
Q

How is absorbance at 340nm a useful measurement in the lactate assay of the glycolysis lab?

A

LDH reduces NAD+ to NADH, and NADH absorbs strongly at 340nm. Thus, changes in absorbance at 340nm help us determine the amount of lactate produced in the initial muscle extract incubations, as the amount of NADH formed is equal to the amount of lactate.

25
Q

What is the overall purpose of the muscle extract incubations and lactate assays in the glycolysis lab?

A

To reveal the cofactor requirements for glycolysis.

26
Q

Why is TLC so good at separating different amino acids?

A

Different side chain polarities.

27
Q

Which one carries the mixture (of amino acids, say) up the absorbent plate - stationary or mobile phase?

A

Mobile phase (consisting of solvents)

28
Q

What does the foil do in TLC?

A

Prevents the evaporation of the solvent.

29
Q

What is the Rf value in TLC?

A

Distance travelled by solute (amino acid) over distance travelled by solvent.

30
Q

Would polar amino acids have a lower or higher Rf value?

A

Lower.

31
Q

What is phenylketonuria?

A

Mutation that prevents the conversion of phenylalanine to tyrosine, leading to an accumulation of phenylalanine. Untreated, it will lead to intellectual disabilities and low life expectancy.

32
Q

How does the GTT work?

A

Patient is given a large single dose of glucose. The following hyperglycaemia (increase in blood sugar) is measured and compared to healthy levels.

33
Q

In a healthy patient, does the ingestion of glucose lead to secretion of insulin?

A

Yes.

34
Q

What does insulin do, in regards to hyperglycaemia?

A

Increases glucose uptake, storage, and metabolism in tissues (especially liver, muscle, and adipose tissues).

35
Q

Type 1 diabetes is a failure to respond to insulin, Type 2 is a result of low insulin secretion. T or F?

A

False, other way around.

36
Q

No coffee, tea, nicotine, or alcohol before GTT… why?

A

These substances (and excitement) affect adrenaline action, which increases blood glucose. Caffeine also inhibits the breakdown of cyclic-AMP.

37
Q

What are the two enzymes involved in the blood glucose concentration assay?

A

Hexokinase and glucose 6-phosphate dehydrogenase.

38
Q

How are glucose levels measured in the blood glucose concentration assay? (hint: similar to another lab)

A

For every molecule of glucose converted by the two enzymes, an NADH is formed. This can be measured spectrophotometrically at 340nm.

39
Q

What is the purpose of the glycine/hydrazine buffer in the glycolysis lab lactate assay?

A

Raise pH significantly and add NAD+ to the solution, pushing the reaction equilibrium to favour NADH production which we can measure spectrophotometrically.

40
Q

The addition of which co-factor leads to more lactate formation, GAP or 1,3BPG?

A

GAP produces a lot of lactate, 1,3BPG produces barely any.

41
Q

Why does starting the glycolytic pathway from 1,3BPG lead to very little lactate formation?

A

1,3BPG does not recycle NAD+ to NADH (like GAP does). Thus, the reaction simply consumes this cofactor and does not regenerate NAD+ for continuous formation of lactate.

Bioc2101 (3 decks)

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