Session 2-protein structure and affinity

Question 1

what is the name for improper folding of a protein?

Answer 1

amyloidoses

Question 2

which bonds are involved in the different levels of the protein structure?

Answer 2

primary-covalent peptide
secondary-hydrogen
tertiary-hydrogen,VDW, hydrophobic and philic,disulphide,ionic .

Question 3

what are they key features of an alpha helix?

Answer 3

• right handed helix
• 3.6 amino acids per turn
• small hydrophobic amino acids like alanine and leucine are strong helix formers
• proline breaks helix due to its arrangements

Question 4

what are they key features of a beta pleated sheet?

Answer 4

• parallel or anti

- multiple interstrand h bonds

Question 5

describe myoglobin

Answer 5

• single subunit protein containing one haem group that binds to ONE O2 molecule
• hyperbolic

Question 6

describe Hb

Answer 6

• 2 alpha and 2 beta subunits
• 4 haem groups with 4 O2s able to bind
• sigmoidal curve

Question 7

which state of Hb has a high affinity for oxygen and which has a low affinity?(Hbs affinity for O2 increases as more O2 binds)

Answer 7

Relaxed state=high affinity

tense state=low affinity

Question 8

what effect does BPG have on HB affinity for o2 and why?

Answer 8

• decreases affinity for o2
• BPG increases at high altitudes promoting o2 release at tissues
• produces during metab so o2 is released more readily in high metabolism areas

Question 9

what effect does co2 and H+ have on o2 affinity?

Answer 9

• decreases affinity

- at sites of low ph and high h+ conc, and increased co2 (e.g. muscle tissue) more o2 released (Bohr)

Question 10

what is secondary structure?

Answer 10

polypeptide chains that form alpha helices and beta sheets and bonding

Question 11

what amino acid is substituted in sickle cell anaemia?

Answer 11

glutamate to valine

Question 12

what are thalassaemias?

Answer 12

group of genetic disorders where there is an imbalance of alpha and beta subunits

Question 13

which thalassaemias appear before and which appear after birth?

Answer 13

Beta=after birth

alpha=before birth

Question 14

give an example of a non polar amino acid

Answer 14

glycine

Question 15

give an example of an uncharged polar molecule

Answer 15

glutamine

Question 16

give an example of a charged polar amino acid

Answer 16

histidine

Question 17

What are motifs?

Answer 17

Folding pattern containing 1 or more elements of secondary structure (e.g. Beta,alpha,beta)

Question 18

What type of inheritance is sickle cell anemia?

Answer 18

Autosomal recessive

Question 19

What is amyloidoses?

Answer 19

Improper folding of protein- normally soluble protein becomes insoluble

Question 20

What are the 2 properties of sickle cells?

Answer 20

• more prone to lyse (break down)

- more rigid (block microvasculature)

Question 21

Name 5 things that cause a sickle cell crisis.

Answer 21

• low temps, cold
• dehydration
• hypoxia (reduced o2 to tissues)
• infection
• acidaemia (acidic blood)

Question 22

What are the consequences of a sickle cell crisis?

Answer 22

Blockage of vessels causing infarction and thus necrosis (due to no blood supply,disease or injury and so cell death occurs)

Question 23

How to combat sickle cell crisis

Answer 23

• warmth
• IV fluids
• O2
• treat infection
• analgesics