Amino acids and proteins

Question 1

Which amino acid does not show optical activity?

Answer 1

Glycine (not chiral)

Question 2

Disulphide bonds are formed between which amino acids?

Answer 2

Cystine to form Cysteine

Question 3

Why is binding of oxygen to haemoglobin said to be cooperative?

Answer 3

The binding of one molecule of oxygen causes a structural change in the Hb that makes it easier for other molecules of oxygen to bind.

Question 4

What is the effect of decreased pH on oxygen binding to Hb?

Answer 4

This lowers the affinity of Hb for oxygen, so the oxygen is released in tissues that are producing lactic acid or have high CO2 levels.

Question 5

Why does bisphosphoglycerate concentration in red blood cells increase at high altitude?

Answer 5

BPG reduces oxygen affinity to Hb. At high altitude there is less oxygen available, so it is better for the Hb to release the oxygen in tissues that are low in oxygen.

Question 6

Haemophillia A is defective in which protein

Answer 6

Factor VIII

Question 7

Favism is a defect in which protein?

Answer 7

Glucose 6-phosphate deydrogenase

Question 8

What type of inhibition is caused by covalent modification of amino acid side chains in the active site?

Answer 8

irreversible, competitive

Question 9

What type of enzymes phosphorylate proteins?

Answer 9

Protein kinases

Question 10

How is a zymogen activated?

Answer 10

Proteolysis

Question 11

Creatine Kinase which condition?

Answer 11

MI

Question 12

By convention which end of an amino acid is written first?

Answer 12

The amino end

Question 13

Alpha helix secondary structure is stabilised by what?

Answer 13

H bonds

Question 14

Does the R group of a B pleated sheet lay inside or outside the plane of the chain?

Answer 14

Outside

Question 15

Tertiary, structure important for what?

Answer 15

Active sites!

Question 16

Where is myoglobin mostly stored?

Answer 16

In muscles

Question 17

What are the six iron ligands?

Answer 17

4 N from porphyrin, N from proximal His, O2 atom.

Question 18

In haemoglobins tense state there are more what?

Answer 18

Salt bridges

Question 19

What is the Bohr effect

Answer 19

Decrease in pH decreases affinity of Hb for oxygen

Question 20

Foetal haemoglobin binds haemoglobin how compared to normal?

Answer 20

A lot more strongly?

Question 21

in order to make collagen what amino acid must be in every third residue?

Answer 21

GLYCINE

Question 22

Enzymes involved are prolyl hydroxylase and lysyl hydroxylase which co factor is required?

Answer 22

Ascorbic acid (vit C)

Question 23

Enzymes have what effect on equilibrium?

Answer 23

Quicker to reach but does not shift!

Question 24

What is irreversible inhibition?

Answer 24

Covalent modification of side changes

Question 25

What do nerve agents do (binding)

Answer 25

Bind to serine amino acid sites

Question 26

What are the two types of competitive inhibition?

Answer 26

Competitive and non competitive

Question 27

In competitive inhibition how is Vmax and Km changed?

Answer 27

Vmax unchanged but Km is increased

Question 28

Why is non competitive inhibition different?>

Answer 28

Alters enzyme, can bind simultaneously to substrate different place to active site alters conformation.

Question 29

Non competitive how is Vmax and Km changed?

Answer 29

Vmax decreased Km same

Question 30

which of competitive and non competitive is affected by high substrate concentration?

Answer 30

non competitive

Question 31

G6p dehydrogenase affects the production of ?

Answer 31

NADPH

Question 32

Who shouldnt receive certain antimalarials?

Answer 32

those suffering from G6p dehydrogenase deficiency

Question 33

Common triad of amino acids in serine proteases is?

Answer 33

His Ser Asp

Question 34

Pancreatic trypsin inhibitor important because?

Answer 34

Tightly binds and stops activation so the pancreas doesnt digest itself

Question 35

High levels of amylase could indicate?

Answer 35

Acute Pancreatitis

Question 36

High levels of Acid phosphatase?

Answer 36

Prostatic carcinoma

Question 37

Alkaline phosphatase high levels

Answer 37

Liver disease or rickets

Question 38

GOT (glutamate oxaloacetate high levels)

Answer 38

MI or liver damage

Question 39

GPT (glutamate pyruvate)

Answer 39

Liver damage

Question 40

LDH high levels?

Answer 40

Cardiac damage

Question 41

Creatine Kinase high levels

Answer 41

MI or muscular disease

Question 42

Difference between cytosolic and mitchondrial enzyme release?

Answer 42

Cytosolic = small damage mito = severe

Question 43

Raised Creatine kinase after an MI peaks at how many days

Answer 43

12 days

Question 44

H4 (LDH 1 ) indicative of damage where?

Answer 44

Cardiac origin ... LDH2 is the predominant form in serum

Question 45

LDH is made of how many sub units ?

Answer 45

4

Question 46

How is paracetamol measured in the blood?

Answer 46

Bacterial degredation of paracetamol to P-aminophenol which reacts with o-cresol = coloured and quantifiable

Question 47

What happen in paracetamol overdose?

Answer 47

cytochrome metabolises the paracetamol to a toxic quinine derivative, glutathione makes this harmless but runs out quickly.

Question 48

What is the main way mini glucose monitors work?

Answer 48

Coupled reaction of glucose and glucose oxidised make peroxide which then reacts to give a coloured product which is quantified.

Question 49

What is the treatment for childhood lymphoblastic leukaemia?

Answer 49

Asparaginase (an eznyme) stops asparagine, the cells cannot make it and so die

Question 50

What enzyme is used in dialysis machines?

Answer 50

Urease