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Y1 PRINCIPLES > BioChem > Flashcards

BioChem Flashcards

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1
Q

The most strong type of bond is…

A

Covalent

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2
Q

The five main types of bonds are…

A 
Covalent
Ionic
Hydrogen
Hydrophobic PD-PD interaction
LDFs/ Van der Waals - interaction of electrons in non-polar substances
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3
Q

Electronegativity is…

A

The attractive force that an atomic nucleus exerts on electrons

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4
Q

EN carbon is greater than EN hydrogen. Which is reduced?

A

Carbon has a greater attractive force for electrons, so it gains electrons, therefore it is reduced and hydrogen is oxidised

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5
Q

Reducing agents are themselves oxidised. True/False?

A

True`

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6
Q

First law of thermodynamics?

A

Energy is neither created or destroyed

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7
Q

Second law of thermodynamics?

A

When energy is converted to another form, some of it is lost (never 100% efficient)

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8
Q

∆G = the change in free energy = ?

A

∆H - T∆S ∆G°’ + RTln([C][D]/[A][B])

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9
Q

Exergonic reactions are where…

A

Products have less free energy than the reactants ∆G is -ve

Reaction can occur spontaneously

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10
Q

Endergonic reactions are where…

A

Products have greater free energy than the reactants ∆G is +ve
Reaction cannot occur spontaneously

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11
Q

The difference between normal standard conditions and biochemical standard conditions is…

A

pH = 7

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12
Q

At equilibrium ∆G = 0. This is characteristic of readily reversible reactions. True/False?

A

True

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13
Q

Reaction spontaneity can be achieved by…

A

Changing concn of reactants/products
Coupling with highly favourable processes (e.g. with hydrolysis of ATP)
Both of the above help ∆G become -ve (EXERGONIC IS FAVOURABLE)

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14
Q

Distinguish between catabolism and anabolism

A

Breaking down complex molecules into smaller ones to give out energy (favourable)
Synthesise complex molecules out of smaller ones, requires energy

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15
Q

What is the hydrophobic effect?

A

Tendency of non-polar substances to aggregate in aqueous solutions (in centre) and exclude water molecules

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16
Q

Amino acids are subdivided into 4 groups, which are?

A

Non-polar hydrophobic
Polar uncharged
Acidic (-COOH)
Basic (-NH)

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17
Q

The N-terminal of a peptide chain is -ve. True/False?

A

False It is +ve due to NH3

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18
Q

The C-terminal of a peptide chain is -ve. True/False?

A

True due to COO-

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19
Q

A zwitterion has which type of charge?

A

None! No net charge - AA with charged side groups in neutral solutions

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20
Q

Ka = acid dissociation constant = ?

A

[H+][A-]/[HA]

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21
Q

pH = measurement of how many H+ in a solution = ?

A

-log10[H+]

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22
Q

Henderson Hasselbach Equation connects Ka of a weak acid with the pH of a solution containing this acid. The equation is…

A

pH = pKa + log[A-]/[HA] pKa - pH = log[HA]/[A-]

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23
Q

Primary protein structure describes…

A

The specific sequence of amino acids in a chain

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24
Q

Secondary protein structure describes…

A

The hydrogen-bonded 3D arrangement of the chain α-helix (one peptide chain spiralled; right-handed) B-stranded-sheet or B-pleated-sheet

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25
Tertiary protein structure describes...
The arrangement of the chain in space and forces stabilising the structure - H bonds, salt bridges, covalent disulphide bonds
26
Quaternary protein structure describes...
Association of non-protein groups to the chain e.g. haemoglobin, myoglobin with multiple subunits
27
Give the number of bonds between bases A?T and C?G...
A-T = 2, C-G = 3
28
What is the central dogma?
DNA is transcribed to RNA, which is translated into protein
29
A nucleoside has...
5C sugar + organic base
30
A nucleotide has...
5C sugar + organic base + phosphate group(s)
31
Pol II synthesises only stable RNA. True/False?
False Pol II (specific promotor - binds to TATA box creating a kink in DNA --- transcription) synthesises all RNA. Pol I and III synthesise only stable RNA
32
DNA polymerase has 3 important characteristics
Can only add to existing nucleic acids Cannot start synthesis on its own Requires an RNA primer to start replication
33
Differentiate between leading and lagging strands of DNA
``` Leading = 3-5, free 3 end for next nucleotide Lagging = 5-3, uses short okazaki fragments ```
34
Nucleotides only add to the free 3' end of a strand? True/False
True
35
Describe the structure of ribosomes
4 rRNA molecules - EXIT, PEPTIDYL (peptides held), AMINOACYL (where tRNA goes to bind) area
36
Enzymes can affect the equilibrium position of a reaction. True/False?
False
37
How do enzymes lower the activation energy of a reaction?
Bind to and stablise the transition state and provide alternative reaction pathways
38
Enzyme without a cofactor is called a...
Apoenzyme
39
What is a cofactor?
Inorganic metal ions e.g. Zn, Fe, Cu that stabilise transition states
40
Enzyme with a cofactor is called a...
Holoenzyme
41
What are coenzymes?
Organic molecules derived from vitamins
42
Induced fit model describes enzyme-substrate interaction by...
Binding of substrate induces a conformational change in the enzyme, resulting in complementary fit
43
Trypsin and chymotrypsin work in the ____ and have an optimum pH of _
Small intestine, 7
44
What are isozymes?
Catalyse same reactions as enzymes but have different properties and structure
45
CK is an isozyme. The M form is produced in ____ and the B form is produced in the ___. MB form is produced in the ___
Skeletal muscle, brain, heart
46
Which enzymes carry out phosphorylation?
Kinases
47
What are zymogens?
Inactive precursors of an enzyme
48
Where are trypsinogen and chymotrypsinogen formed? Why is it important they are produced inactive?
Pancreas | They would digest the pancreas if active
49
Which enzyme activates trypsinogen? Where does this occur?
Enteropeptidase | Small intestine
50
Vmax is?
The maximal rate of reaction at unlimited substrate concn
51
Km is?
The concn of substrate which gives 50% maximal rate, i.e. 0.5Vmax
52
A low Km means...
An enzyme only needs a little substrate to work at 0.5Vmax (it has high affinity)
53
Vmax can be obtained from a Lineweaver-Burk plot by looking at the interesection with the X axis. True/False?
False | Intersection with X (horizontal) axis is Km; intersection with Y (vertical) axis is Vmax
54
In competitive inhibition, Vmax is ___ and Km is ___
The same, increased
55
In non-competitive inhibition, Vmax is ___ and Km is ___
Decreased, the same
56
Orthosteric enzymes follow M-M kinetics and the curve is shaped like a ____
Hyperbola
57
Allosteric enzyme do not follow M-M kinetics and the curve is shaped like a ___
Sigmoid
58
Hexokinase has a low Km (0.5) for glucose while glucokinase had a Km of 5. What does this tell you about their affinity for glucose?
Hexokinase has a higher affinity for glucose than glucokinase - needs less enzyme to work at 50% of Vmax
59
GLUT3 is located in the...
Brain
60
GLUT5 is located in the...
Gut
61
In glycolysis, glucose (6C) is converted into...
2 x pyruvate (3C each)
62
In glycolysis, there is a net gain of how many ATP?
2 ATP (4 gained, 2 lost)
63
The _, _ and _ reactions in glycolysis are control points (irreversible as they are very exergonic)
1st, 3rd and final
64
3 enzymes involved in the glycolysis control points
Hexokinase (GLUCOSE), phosphofructokinase (FRUCTOSE), pyruvate kinase (PYRUVATE)
65
We must reoxidise NADH to form __ in order to continue ATP synthesis after glycolysis
NAD+
66
Pyruvate conversion to lactate occurs when?
Low oxygen - muscle cells work very hard to allow glycolysis to continue NAD+ is regenerated by oxidation of NADH
67
What is Warburg effect?
Upregulation of anaerobic glycolysis in cancer cells
68
What is the substrate for the TCA cycle?
Acetyl-CoA
69
Where does TCA cycle occur?
Mitochondria (mainly central matrix and then cristae)
70
What is the fate of pyruvate before TCA cycle?
Enters mitochondria, where PDC catalyses oxidative decarboxylation of pyruvate to acetyl-CoA 2CO2 released in total
71
Citric acid (6C) is formed by the combination of which 2 molecules?
Oxaloacetate (4C) + Acetyl-CoA (2C)
72
How many cofactors are reduced in total in TCA cycle?
4 - 3x NAD+ and 1x FAD+
73
How does pyruvate enter the TCA cycle?
Via the H+ gradient from the cytosol into the matrix of the mitochondria
74
GDP conversion to GTP is known as...
Substrate level phosphorylation
75
Succinate hydrogenase uses FAD+ as a cofactor. It is the one enzyme of TCA cycle that is located in the central matrix. True/False?
False It is the only enzyme located in the cristae - all others located in the central matrix
76
Lipids are converted to ______ and then ____ which enters TCA cycle
Fatty acids, Acetyl-CoA
77
Each turn of TCA cycle involves the uptake and release of how many carbon atoms, and in what form?
C uptake as Acetyl-CoA, 2C released as 2CO2
78
Glycolysis + PDC + TCA cycle reactions = _NADH, _H+, _FADH2
10NADH, 10H+, 2FADH2
79
Each NADH and FADH2 molecule contains how many electrons?
2
80
A -ve electron transfer potential means...
Substance is more likely to donate electrons than hydrogen
81
What is the function of Co-enzyme Q?
Pick up electrons from Complex 1 or 2 and donate them to Complex 3
82
Transfer of electrons through the respiratory chain is coupled to transport of _ from the mitochondrial matrix to the intermembrane space
H+
83
Key point of oxidative phosphorylation: Electrons from NADH and FADH2 reduce O2 to __ e- energy is used to pump protons from the matrix to the _____, causing matrix pH to ____ Protons follow their concn and flow across the membrane - this energy is used to phosphorylate ___ to ___
H2O Intermembrane space, pH to increase (and intermembrane space pH to decrease) ADP to ATP
84
1 glucose molecule yields how many ATP molecules in total?
30-32 ATP
85
How does NADH from cytoplasm enter mitochrondia to be oxidised into NAD+?
Using shuttles - glycerol 3 phosphate, malate aspartate
86
Electron transport and ATP synthesis happens ______ using ____ pumps
Simultaneously | (Seperate) H+
87
Explain the process of uncoupling electron transport and phosphorylation...
Brown adipose tissue contains uncoupling protein thermogenin

Y1 PRINCIPLES (10 decks)

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