proteins

Question 1

what hormone is responsible for cells signalling?

Answer 1

insulin

Question 2

what are the two enzymes involved in digestion and what are their functions?

Answer 2

trypsin-breaks down proteins
amalyse- breaks down starch into sugars

Question 3

what are the two proteins involved in metabolism called and what are their functions?

Answer 3

alcohol dehydrogenase- metabolises ethanol
ICZA hexokinase- adds a phopsphate to glucose after glucose is taken up by the cell.

Question 4

what is the oxygen transport protein called?

Answer 4

hemoglobin- binds to oxygen in the lungs and carries it in the blood to tissues for use in metabolism

Question 5

what makes up an amino acid

Answer 5

an amino group, a carboxyl group and an R group side change which differs between different amino acids.

Question 6

what does the PKA value indicate

Answer 6

the PKA is the ph at which ionisable group on an amino acid or protein is 50% ionised

Question 7

what does the PI value indicate

Answer 7

isoelectric point is the PH where the net charge on an amino acid is zero

Question 8

what is phosphorlylation doing

Answer 8

adding a phosphate group which controls enzyme activity, chemical on/off switch.

Question 9

what is hydroxylation doing

Answer 9

needed to prevent connective tissue diseases and scurvy, often proline and lysine

Question 10

what is carboxylation needed for

Answer 10

needed for blood clotting, glutamate often involved

Question 11

what are the three peptide bond properties

Answer 11

planar, trans and dipole

Question 12

what is the process of adding glucose to amino acids called?

Answer 12

glycosylation

Question 13

what type of bond is a N-Ca and what are its features

Answer 13

a phi bond. free rotation, angle can be anywhere between 0 and 180.
can lead to O-O collisions

Question 14

what type of bond is a C-Ca bond and what are its features?

Answer 14

a psi bond, free rotation.
can lead to NH-NH collisions

Question 15

what is a omega bond and what is its properties?

Answer 15

C-N bond. Very limited rotation. closer to either 0 or 180.
a partial double bond

Question 16

features of an Alpha helix

Answer 16

main chain spirals around central axis, right handed spiral
hydrogen bonds form between n+4 eg 3-7

Question 17

how much is hydrogen bond energy and what is its purpose?

Answer 17

12-28kjmol and they help to stabilise a helix structure

Question 18

features of a beta structure

Answer 18

each section of a B structure= a b strand
hydrogen bonding occurs between adjacent strands
2-10 strands per sheet
antiparallel= linear hydrogen bonds
parallel= non linear hydrogen bonds

Question 19

what is a supersecondary structure and what are some common examples of them

Answer 19

helices and strands connected by turns and loops
helix- turn- helix
beta hairpin
greek key
strand-helix-strand

Question 20

what is a protein domain?

Answer 20

supersecondary structure elements that have combined to form domains, these are independently folded regions that have specific functions within a protein

Question 21

what are some examples of different protein families

Answer 21

alpha domain-helical,globin fold
alpha/beta family- mis of alpha and beta structure, can make baskets
anti-parallel beta family- mostly anti-parallel beta family

Question 22

describe Anfinsen experiment

Answer 22

using chemicals he broke the hydrogen bonds to make his protein into a long chain. letting air oxidise the sulfides he found that the protein folded itself back up.

Question 23

what conclusions about protein folding can be made from Anfinsens experiement

Answer 23

concluding that proteins do their own foldings based on their sequences.

Question 24

key steps involved in the folding of a protein

Answer 24

1) formation of short secondary structure segments
2) subdomains form
3) subdomains come together to form a partly folded domain- molten globule that can rearrange
4) final domain structure emerges. Small conformational adjustments to give final structure

Question 25

how is a protein fold stabilised?

Answer 25

non-covalent interactions collectively contribute to protein stability.

Question 26

what is the role of the hydrophobic core?

Answer 26

the most important non covalent contributor to protein stability

Question 27

what is a chaperone and what role do they play?

Answer 27

a chaperone is a structure that is able to assist a protein to fold

Question 28

what factors can lead to a protein unfolding?

Answer 28

change in ph
heat
detergents
organic solvents
urea
guanidium HCL

Question 29

what are some diseases associated with protein misfolding

Answer 29

BSE, CJD and Kuru- abnormal form of prion protein PrP
Alzheimers, type 2 diabetes- amyloid abormally folded