Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y2 Biostructures > Metabolism > Flashcards

Metabolism Flashcards

1
Q

How are globular proteins arranged?

A

Spherical, hydrophobic on the inside, hydrophilic outside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the main ways energy can be lost from polypeptides?

A

Not having peptide bonds
Hydrogen bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is enthalpy?

A

Energy available from bonding interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which sorts of reactions usually produce energy?

A

Catabolic reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is CO2 an important by-product of reactions?

A

By-product of energetically favourable reactions. Increases entropy
CO2 has very stable bonds (enthalpic)
Easily escapes site of reaction
Difficult to reincorporate, so it is a committed step

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an anaplerotic reaction?

A

Reaction which forms intermediates in a metabolic pathway
Usually replenishes carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is the micheales menton constant calculated?

A

(Vmax[S])/(Km + [S])

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is vitamin B a carrier for?

A

NAD
FAD
Acyls
CO2
Aldehydes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are vitamins

A

Nutrients humans cannot synthesise themselves. Presumably from pathways lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does biotin act as a carrier for?

A

Bicarbonate group
Pyruvate carboxylase catalyses the formation of oxaloacetate from pyruvate and COO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does folic acid (vitamin B9) act as a carrier?

A

The polyglutamyl chain has a high negative charge which attracts to the enzyme surface.
Used to convert dUMP to dTMP (nucleotide precursor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Outline folate catalysing dTMP production

A

Folate is converted to DH4-Folate. This is activated to TH4-Folate by dihydrofolate reductase and NADPH.
This is converted to 5, 10-Methylene-folate which catalyses dUMP to dTMP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where does folic acid take its methyl group from?

A

Serine -> glycine conversion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can dihydrofolate reductase inhibitors be used as?

A

Anticancer drugs as they prevent dTMP synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does folic acid carry?

A

Methyl groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What carries C2 units?

A

Panthotheic acid
Coenzyme A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why are thioester bonds more favourable than esters for carriers?

A

Thioester bonds are less stable, making it easier to transfer the acetyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are 5 carbon molecules usually used for?

A

Steroids
Terpenes
Vitamin A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are N2 groups usually donated from?

A

Glutamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are primary metabolic pathways?

A

Basic housekeeping pathways. Mainly happen constitutively

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are secondary metabolic pathways?

A

Pathways for specialised functions. Inducible, e.g antibiotics and plant oils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are terpenes?

A

Unsaturated hydrocarbons produced by plants. (C5H8)n for n>1
Lipid derived
Terpenoids are modified terpenes containing additional functional groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are terpenes used to synthesis?

A

Natural rubber, rosin.
Rosin can be used for inks, varnishes and adhesives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How are isoprene units made in plants?

A

Dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) are produced in the melvonate pathway
This creates C5 units from acetyl-CoA and non-sterols such as heme-A and ubiquinone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Outline glycolysis

A

Glucose is phosphorylated to fructose 1,6 bisphosphate with 2 ATP. This splits into 2 glyceraldehyde 3-phosphate molecules and for each, NAD is used to form pyruvate, producing 2 ATP and 1 NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the net gain of glycolysis of one glucose molecule?

A

2 ATP, 2NADH

27
Q

What is substrate channelling?

A

Process where substrates are passed from one enzyme to the next

28
Q

What pathways can pyruvate move into?

A

Fermentation
Lactate formation
Link reaction

29
Q

What is gluconeogenesis used for?

A

Maintaining blood glucose levels when they run down
Reverse glycolysis

30
Q

How is α-ketoglutarate produced?

A

Glutamate + Pyruvate -> Alanine + α-ketoglutarate.
Catalysed by alanine transaminase

31
Q

Where does gluconeogenesis mainly take place?

A

Liver

32
Q

What are the end products of the pentose phosphate pathway?

A

Pyruvate and intermediates

33
Q

In gluconeogenesis, what does pyruvate initially react with?

A

Oxaloacetate

34
Q

Outline the steps of gluconeogenesis

A
  1. Pyruvate reacts with oxaloacetate and CO2 is lost to form a 6 carbon intermediate
  2. A series of reactions is undergone, using 2ATP until fructose 1,6-bisphosphate is reached.
  3. This is dephosphorylated to glucose-6-phosphate
  4. Glucose-6-phosphatase convers this to glucose
35
Q

What stimulates the need for the pentose phosphate pathway?

A

Need for ribulose

36
Q

What is acetyl CoA used for?

A

Krebs cycle, terpene production and fatty acid synthesis

37
Q

What is the link reaction?

A

Pyruvate + NAD+ -> Acetyl CoA + CO2 + NADH

38
Q

What are some of the products of the krebs cycle used for?

A

Oxaloacetate and α-ketoglutarate are used for amino acid biosynthesis
Succinyl CoA is used in haem, chrorophyll and vitamin b12
Citric acid is a fatty acid precursor

39
Q

When fatty acids are degraded, where do the products go?

A

They are oxidised into acetyl groups which move to the link reaction
NADH and FADH2 move to the krebs cycle

40
Q

Describe fatty acid synthase

A

7 different functions in 1 polypeptide chain
Dimeric
Fatty acids join at one point and pass around the different active sites. The fatty acids extends in a cyclic process until it is long enough

41
Q

Outline fatty acid biosynthesis

A

Acetyl groups join together. Each addition of a monomer creates a ketone group which is subsequently reduced

42
Q

How is glutamate synthesised?

A

α-ketoglutarate is taken from the krebs cycle and ammonia is added.
Adding the amine group os the most difficult part

43
Q

What is the cofactor in dUMT production?

A

Folic acid

44
Q

How are pyrimadines synthesised?

A

Bases ae assembled from the pentose phosphate pathway and amino acids. Ribose is then attached

45
Q

How are purines synthesised?

A

Rings are assembled onto ribose, then groups are added bit by bit.
Ribose activation is very energy intensive: the first committed step requires a hydrolysis of ATP to AMP
Ribose pyrophosphate is used
2 ATP are required to activate the bicarbonate and add it on

46
Q

How is metabolism generally controlled?

A

Feedback inhibition. This is to avoid unnecessary energy wasting

47
Q

Describe how aspartate transcarbamoylase is inhibited

A

Carbamoyl +aspartate <-> N-carbamoyaspartate <-> cyditine triphosphate (CTP)
CTP is an allosteric inhibitor of N-carbamoylaspartate formation

48
Q

How is isoleucine production regulated?

A

When pyruvate is converted to valine, isoleucine synthesis is promoted.
Isoleucine blocks its own production from pyruvate and threonine

49
Q

What are isozymes?

A

Enzymes which are the same but encoded by different genes to work in certain tissues. These arise from alternatively spliced genes

50
Q

Describe the different isozymes of lactate dehydrogenase

A

Pyruvate <-> lactate
4 subunits which can be H (heart) or M (muscle) depending on the isozyme.
The H form is allosterically activated by pyruvate. The H form is promoted by endurance training

51
Q

What is glutamine synthetase inhibited by?

A

Glutamine
α-ketoglutarate

52
Q

What is the most common type of regulating enzymes by covalent modification?

A

Reversible phosphorylation

53
Q

Outline the mechanism of glycogen phosphorylase

A

When active, it removes glucose from glycogen. Glycogen kinase phosphorylates glycogen, making it inactive. Glycogen phosphorylase removes the phosphate groups and the inactive shape reverts to the active shape.

54
Q

How is the lac operon regulated?

A

Presence of lactose and absence of glucose removes the repressor, switching on gene expression

55
Q

How is tryptophan regulated?

A

If there is enough tryptophan, it binds to the Trp repressor and shuts it down. The trp operon is activated, leading to a 23-fold increase of expression
Positive feedback

56
Q

What are the 4 ways metabolism can be controlled?

A

Enzyme multiplicity (isozymes)
Cumulative control of a single enzyme
Enzyme expression regulation
Change in substrate concentration

57
Q

What is the flux coefficient?

A

An enzyme’s importance in the overall rate through the whole pathway. Changing substrate concentration has little effect on overall flux

58
Q

What is an example of enzyme concentration having little effect on reaction rate

A

Overexpressing phosphofructokinase in glycolysis results in almost no change

59
Q

How is urea produced?

A

Breakdown of amino acids in the urea cycle

60
Q

How is carbamoyl phosphate synthase regulated in the urea cycle?

A

Regulated allosterically by NAG (N-acetylglutamate)
Covalent modification

61
Q

What reaction does carbamoyl phosphate synthase catalyse?

A

Conversion of ammonia and CO2 to carbamoyl phosphate

62
Q

Outline the urea cycle

A
  1. Ammonia and CO2 react in a reaction catalysed by carbamoyl phosphate synthase to form carbamoyl phosphate
  2. This reacts with ornithine in the mitochondrial matrix, forming citrulline
  3. Citrulline reacts with aspartate to form arginino-succinate
  4. This splits into arginine and fumarate
  5. Arginine reacts with water, forming urea and ornithine
63
Q

Where does glycolysis take place?

A

Respiring cells

Y2 Biostructures (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions