Labs Flashcards

1
Q

How does a P1000 pipette work

A

100/1000, add a zero to make measurement in the thousands

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2
Q

How does a P200 pipette work

A

20/200, reading on pipette is measurement in µL (measurement in the hundreds)

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3
Q

How does a P20 pipette work

A

2/20, last number is a zero. Measurement in the 10s

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4
Q

How can dilution factor be calculated

A

Final total volume (V2) / volume of undiluted solution (V1)
Or
Undiluted concentration (c1) / Diluted concentration (c2)

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5
Q

How are C1, C2, V1 and V2 related

A

C1V1 = C2V2

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6
Q

How does heat affect protein structure

A

Increased kinetic energy of molecules, weaker non covalent interactions disrupted

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7
Q

How does pH affect protein structure

A

Ionisable side chains affected, disruption of non covalent interactions (ionic: electrostatic)

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8
Q

What is spectrophotometry

A

Different molecules absorb light at different wavelengths, so spectrophotometry is used to identify molecules present in a solution (based on measurement at a specific wavelength) or to identify unknown molecules in a solution based on their absorbance characteristics

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9
Q

What is an absorbance maxima

A

The particular wavelength that a specific chemical absorbs more than any other wavelength

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10
Q

What is the absorbance reading

A

The log ratio of incident and transmitted light (ratio, so no units)

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11
Q

What is Beer’s law

A

Concentration of a solution is linearly proportional to the absorbance of that solution

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12
Q

What is Lambert’s law

A

The intensity of the transmitted light is linearly proportional to the pathlength

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13
Q

What is the Beer-Lambert Law

A

A = εcl

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14
Q

What are the units of ε

A

L/mol/cm

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15
Q

What is ε

A

Molar absorption coefficient: a measure of how strongly a chemical absorbs light at a particular wavelength. Intrinsic property of the molecule

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16
Q

What is an enzyme assay

A

Measuring enzyme catalytic activity based on appearance of product or disappearance of substrate

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17
Q

What is alcohol dehydrogenase (usually involved in redox, needs a coenzyme for reaction to proceed)

A

An enzyme produced in the liver which breaks down primary alcohols into aldehydes

18
Q

What is the equation for the reaction involving ADH

A

ethonal + NAD+ -> acetalydehyde +NADH/H+

19
Q

What is reaction initial velocity

A

Initial velocity of reaction: V0 = ΔA / Δt

20
Q

What is used to measure reaction initial velocity

A

V0: progress curve for absorbance against time

21
Q

What graph is used to measure Km and vmax

A

v vs [s] curve

22
Q

What do competitive inhibitors do to Km and Vmax

A

Increase Km, don’t affect vmax

23
Q

What do pure non competitive inhibitors do to Km and vmax

A

Don’t affect Km, decrease vmax

24
Q

What do mixed non competitive inhibitors do to Km and vmax

A

Increase Km and decrease vmax

25
Q

Which structural component of starch is responsible for the blue black colour in the iodine-starch test

A

Amylose

26
Q

What does a dilution factor of 6 mean

A

1 part solution, 5 parts water
TOTAL of 6

27
Q

What is a standard curve

A

Concentration of molecule against absorbance at particular wavelength

28
Q

A standard curve should be roughly

A

Linear

29
Q

When using enzyme assays to analyse complex solutions for specific molecules, it is assumed that

A

the reaction goes to completion.

30
Q

What is a progress curve

A

Absorbance against time

31
Q

What is the shape of a progress curve

A

Linear to begin with, then exponential decay as substrate concentration decreases over time

32
Q

What unit should V0 be in (progress curves)

A

ΔA/min

33
Q

Volume of enzyme in enzyme assay is directly proportional to

A

Reaction initial velocity

34
Q

What are the two forms of starch

A

Amylose and amylopectin

35
Q

Which amino acid can easily be charged or uncharged at physiological pH and why

A

Histidine as it has a side chain pKa around 6

36
Q

Why do some chemicals appear colourless in solution

A

Because they absorb/reflect wavelengths outside the spectrum our eyes can see

37
Q

Lambert’s law indicates that for monochromatic light passing through an absorbing solution, the intensity of transmitted
light

A

Decreases exponentially with increasing pathlength

38
Q

What is a reference sample (spectrophotometry)

A

Contains everything in an assay except the compound being measured. Used to blank spectrophotometer

39
Q

What can a standard curve be used for

A

To determine the concentration range over which the Beer-Lambert law applies for a particular molecule

40
Q

Why do we want an absorbance maxima that doesn’t overlap with other molecules’

A

So that we can measure the concentration of a single molecule