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BIOC192 > Labs > Flashcards

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

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18
Q

What is the equation for the reaction involving ADH

A

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

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19
Q

What is reaction initial velocity

A

Initial velocity of reaction: V0 = ΔA / Δt

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20
Q

What is used to measure reaction initial velocity

A

V0: progress curve for absorbance against time

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21
Q

What graph is used to measure Km and vmax

A

v vs [s] curve

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22
Q

What do competitive inhibitors do to Km and Vmax

A

Increase Km, don’t affect vmax

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23
Q

What do pure non competitive inhibitors do to Km and vmax

A

Don’t affect Km, decrease vmax

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24
Q

What do mixed non competitive inhibitors do to Km and vmax

A

Increase Km and decrease vmax

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25
Which structural component of starch is responsible for the blue black colour in the iodine-starch test
Amylose
26
What does a dilution factor of 6 mean
1 part solution, 5 parts water TOTAL of 6
27
What is a standard curve
Concentration of molecule against absorbance at particular wavelength
28
A standard curve should be roughly
Linear
29
When using enzyme assays to analyse complex solutions for specific molecules, it is assumed that
the reaction goes to completion.
30
What is a progress curve
Absorbance against time
31
What is the shape of a progress curve
Linear to begin with, then exponential decay as substrate concentration decreases over time
32
What unit should V0 be in (progress curves)
ΔA/min
33
Volume of enzyme in enzyme assay is directly proportional to
Reaction initial velocity
34
What are the two forms of starch
Amylose and amylopectin
35
Which amino acid can easily be charged or uncharged at physiological pH and why
Histidine as it has a side chain pKa around 6
36
Why do some chemicals appear colourless in solution
Because they absorb/reflect wavelengths outside the spectrum our eyes can see
37
Lambert's law indicates that for monochromatic light passing through an absorbing solution, the intensity of transmitted light
Decreases exponentially with increasing pathlength
38
What is a reference sample (spectrophotometry)
Contains everything in an assay except the compound being measured. Used to blank spectrophotometer
39
What can a standard curve be used for
To determine the concentration range over which the Beer-Lambert law applies for a particular molecule
40
Why do we want an absorbance maxima that doesn't overlap with other molecules'
So that we can measure the concentration of a single molecule
41
What wavelengths does haemoglobin absorb and reflect
Absorbs blue and yellow, reflects red (hence blood appears red)
42
Describe the oxy haemoglobin absorbance spectra
2 peaks
43
Describe the deoxy haemoglobin absorbance spectra
1 peak
44
Why do oxy and deoxy haemoglobin have different absorbance spectra
Because one has oxygen so absorbs light differently
45
How can you best measure a molecule of interest in a mixed solution
By measuring absorbance at a wavelength with the greatest difference (e.g secondary peak)
46
What are the 4 types of receptors
Ligand gated ion channels, GPCRs, receptor proteins coupled to phosphorylation enzymes (RTKs) and nuclear receptors
47
What is gluco/hexokinase
Monomeric enzyme that catalyses phosphorylation of glucose to glucose-6-phosphate
48
What is MODY2 (maturity onset diabetes of the young)
A glucokinase variant resulting in decreased sensitivity of pancreatic beta cells to glucose, resulting in less insulin secretion and higher blood glucose levels
49
What glucokinase variant is associated with MODY2
E339K (causes ATP binding pocket of enzyme to be blocked)
50
What is a restriction enzyme
DNA cutting enzyme which recognises and cuts DNA at its specific site
51
What is DNA gel electrophoresis
Separation of DNA fragments by size
52
What is PCR (polymerase chain reaction)
Amplification of gene of interest. DNA primers bind upstream and downstream of gene of interest, many copies of a small portion of DNA are made
53
At what level does the body maintain blood glucose
3-7 mmolL-1
54
What is a fasting and non fasting blood glucose level indicative of type 2 diabetes
>11mmolL-1 and >8mmolL-1
55
What does HbA1C give a good depiction of
Glucose levels over the previous 3 months
56
Extracellular water is approximately ___% of our body weight
20
57
What is the unit for HbA1C
mmol/mol, because expressed as a ratio of glycosylated haemoglobin to total haemoglobin
58
What HbA1C levels indicate diabetes
>50
59
What HbA1C levels indicate pre diabetes
41-49
60
What HbA1C levels are normal
<40
61
What is the equation for working out the concentration of a sample when given the absorbance of the sample and reference, and the concentration of the reference
conc(sample) = A(sample)/A(reference) * conc(reference)
62
What does the density of lipoproteins refer to
Proportion of lipids to proteins in the lipoprotein complex
63
What is "bad" cholesterol and why
LDL (carries the majority of cholesterol, can deposit into arterial walls if too high concentration)
64
What is "good" cholesterol and why
HDL (carries cholesterol to liver where it is broken down and excreted from the body)
65
How are LDL levels decreased
Reducing saturated fat intake
66
How are HDL levels increased
Increased exercise, eating poly or monounsaturated fats
67
How can cholesterol levels be measured by an enzyme assay
Series of reactions resulting in formation of quinoneimine which is red and absorbs light at 500nm
68
How are proteins electrophoresed
Based on isoelectric point (different charges at certain pH allows separation by charge)
69
What assumption is made in order to calculate the concentration of cholesterol in a sample
All cholesterol is present in its free form

BIOC192 (5 decks)

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