Amino Acid to polypeptides to protein.

Question 1

Amino acids are joined during translation by peptidyl transferase (main function of ribosome). what brings amino acids to ribosome?

Answer 1

tRNA bring AA to ribosome, which reacts to other tRNA. Carboxyl group reacts with amino group on new amino acid, there is a condensation reaction -OH- lost from carboxyl & -H+ lost from amino.

Question 2

What is the smallest & largest proteins?

Answer 2

TAL in fruit flies, 11aa.
Titin in humans 34,350 aa.

Question 3

Explain secondary structure.

Answer 3

hydrogen bonds between N-H & C=O, there is a a-helix (coiled strand), & a Beta-sheet, parallel or anti depending on alignment of strands, anti-parallel is more stable.

Question 4

Explain tertiary structure.

Answer 4

most stable, lowest energy. held by interactions between R-groups ; disulphide bridges, ionic bonds, hydrogen bonds, van Der Waals interactions.

Question 5

What is incorrect folding or misfiling of proteins often related to?

Answer 5

Protein aggregation & fibrillogenesis which is connected to diseases such as; BSE, Huntingtons and Alzheimers disease.

Question 6

How do you figure out how proteins fold?

Answer 6

You find out how they denature. An unfolding process and not a disruption of the peptide bonds.

Question 7

what is it called when hydrophobic groups come together to avoid water?

Answer 7

Hydrophobic collapse.

Question 8

what are oligomeric proteins made up of?

Answer 8

Multiple proteins held together by non-covalent bonds.oligomeric proteins are easier to repair.

Question 9

alanine to pyruvate.

Answer 9

alanine loses its amino group by transamination to form pyruvate catalysed by alanine aminotransferase.

Question 10

asparagine to oxaloacetate.

Answer 10

asparagine to hydrolysed by asparaginase liberating ammonia and aspartate. aspartate loses its amino group by transamination via the enzyme aspartate aminotransferase to form oxaloacetate.

Question 11

amonitransferases catalyse the reversible transamination between an amino acid and a ketone acid, giving rise to 1 of 3 non essential amino acids…

Answer 11

a-ketoglutarate-glutamate.
pyruvate - alanine.
oxaloacetate - aspartate.

Question 12

what is the prosthetic group?

Answer 12

Compounds bound to enzymes and their change from 1 form to another and back takes place in a single catalytic cycle.

Question 13

pyridoxal phosphate is the active form of what?

Answer 13

pyridoxine (vitamin b6)

Question 14

glutamine is converted to glutamate and ammonia by enzyme glutaminase…

Answer 14

glutamate is converted to a-ketoglutarate by oxidative deamination by glutamate dehydrogenase.

Question 15

threonine and serine can have amino group directly converted to ammonium. (NH4+)

Answer 15

Serine to pyruvate by serine dehydratase & threonine to a-ketaglutarate by threonine dehydratase.

Question 16

Describe dehydratase enzymes.

Answer 16

H2O is lost in these reactions, serine loses H+ & -OH group from a- and b- carbons respectively, forming unstable intermediate aminocrylate. H2O is then added back, producing the products. PLP is cofactor.

Question 17

Urea cycle, what’s steps in mitochondria ?

Answer 17

1) Carbamoyl phosphate synthase & 2) ornithine transcarbamylase.

Question 18

Urea cycle ; what’s the in cytosol?

Answer 18

3) arginosuccinate synthase
4) arginosuccinate lyase
5) arginase

Question 19

The urea cycle and Krebs cycle are interlinked through…

Answer 19

argininosuccinate.

Question 20

The c3 family are converted to pyruvate, name the three groups.

Answer 20

serine, alanine, cysteine.

Question 21

The c5 family, enter the citric acid cycle as a-ketoglutarate through glutamate.

Answer 21

Proline, histidine, glutamine, arginine.

Question 22

What are non-polar amino acids forming succinylcholine CoA?

Answer 22

Leucine, isoleucine, valine.

Question 23

isoleucine & valine

Answer 23

Propionyl-CoA to succinyl-CoA

Question 24

Leucine

Answer 24

Acetoacetate and acetyl-CoA for ketone body production.

Question 25

The first step to forming succinyl-coa is a transaminase reaction producing the appropriate a-keto acid. Creating a branched chain a-keto acid dehydrogenase complex.

Answer 25

Followed by a series of oxidation/reduction reactions similar to TCA cycle.