Protein

Question 0

what is the arrangement like in alpha helices?

Answer 0

side chains always facing outwards
N-H bonds always face upwards and the C=O bonds always face downwards
looks like a coil with a very repetitive arrangement of amino acids- 3.6 amino acids for every coil

Question 1

what is the secondary structure of proteins?

Answer 1

different folding by hydrogen bonds

beta pleated sheets and alpha helices

Question 2

what do beta-pleated sheets look like ?

Answer 2

rows of amino acids on top of one another, running in anti-parallel directions

Question 3

what does the tertiary structure of proteins involve?

Answer 3

3D folding of the secondary structure

bonds involved are ionic bonds, hydrogen bonds, van der waals forces and also sulphur bridges

Question 4

which strand of DNA is mRNA a copy of ?

Answer 4

coding strand

Question 5

which direction is the RNA strand elongated in during transcription?

Answer 5

5’ to 3’ direction

Question 6

why is it not a problem that transcription is a lot less accurate than DNA replication?

Answer 6

because a lot more RNA can be produced and also the DNA has to store genetic info indefinitely

Question 7

what are the different types of RNA polymerase ?

Answer 7

type 1,2 and 3
1 + 3 are used to transcribe genes encoding rRNA and tRNA
2 is used to transcribe all other proteins

Question 8

what is needed to allow RNA polymerase to transcribe a gene ?

Answer 8

transcriptional activators to activate RNA polymerase
requires mediators to communicate between different proteins
chromatin modifying enzymes to allow DNA to be reached from inside chromatin

Question 9

what is the process called that splices exons together ?

Answer 9

transesterification

Question 10

how many different combinations of codons are there for an RNA strand?

Answer 10

64 because there are 4 different nucleotides and they are read in threes

Question 11

what does it mean by the genetic code being redundant ?

Answer 11

there are 64 combinations of codons but only 20 different amino acids therefore different codons can code for the same amino acid

Question 12

what enzyme attaches the correct amino acid to the tRNA molecule?

Answer 12

aminoacyl-tRNA synthetase

Question 13

what is fetal haeomoglobin made up of and what effect does this have ?

Answer 13

made up of 2 alpha-2 subunits and 2 gamma-2 subunits
makes it have a higher affinity for oxygen compared to maternal adult haemmoglobin so it is able to extract oxygen from the maternal circulation

Question 14

what chromosomes are the embryonic Hb gene, alpha gene, delta gene, beta gene and gamma fetal gene present on ?

Answer 14

embryonic and alpha gene- chromosome 16

delta, beta and fetal gamma gene- chromosome 11

Question 15

which type of glycosylation is most common?

Answer 15

N-glycosylation -90%

Question 16

what effects can phosphorylation have on a protein ?

Answer 16

addition of a phosphate molecules causes the addition of 2 negative charges which causes conformational changes in the protein
negative charges can attract positively charged molecules which can affect ligand binding of the protein

Question 17

what is myristoylation?

Answer 17

attachment of a myristate molecule to a glycine amino acid
myristate is a 14 carbon fatty acid molecule
occurs in cytosol
important in interactions of proteins with the membrane and other proteins

Question 18

what is ubinquitation ?

Answer 18

addition of a ubiquitin molecule to a protein

normally attaches to lyseine

Question 19

what is sickle cell anaemia ?

Answer 19

autosomal recessive disorder

develops when fetal Hb is being converted into adult Hb due to a mutation in the beta subunit

Question 20

what does sickle cells anemia cause ?

Answer 20

it causes deoxygenated Hb to produce insoluble filaments within RBCs causing their disfiguration so they cant pass through capillairies very easily
if they get blocked they can cause oxygen depletion at tissues