biochemistry

Question 1

normal p50 of Hb

Answer 1

26 Torr

Question 2

p50 of Hb at altitude

Answer 2

~31 Torr

Question 3

Functions of cholesterol

Answer 3

Membrane permeability and fluidity Component of bile acids, steroid hormones and vitamin D Contributes to the formation of atherosclerosis

Question 3

how much red blood cell dry weight is Hb

Answer 3

97%

Question 4

Where is cholesterol stored

Answer 4

In the liver as cholesterol esters In the gall gladder as bile acids In the membranes

Question 4

what protein is characteristic for LDL

Answer 4

ApoB-100 -> tissues have Rs for it to take up LDL

Question 5

Formation of atherosclerosis with LDL

Answer 5

1. LDL accumulates in the artery wall 2. Endothelial cells react by displaying adhesion molecules –> monocytes and T cells invade tissues and secrete inflammatory cytokines 3. Macrophages engulf modified LDL - become engorged with fat and cholesterol to form foam cells 4. Fibrous tissue develops to trap foam cells 5. Cap can rupture –>> exposing tissue factor –> coagulation via extrinisic pathway

Question 6

what is the structure of myoglobin?

Answer 6

8 right handed alpha helices (A-H) with hydrophobic residues on the inside and hydrophillic residues on the outside = highly water soluble

Question 7

how is carbon dioxide carried in the blood

Answer 7

15% as carbaminohaemoglobin - binds to beta-terminal amino groups of deoxyHb 85% as carbonate ions

Question 9

What does BPG do to Hb?

Answer 9

the 5 negative charges on BPG bind to 5 positive charges on deoxyHb and stabilises deoxyHb, locking out oxygen from rebinding

Question 10

What is the T and R forms of Hb?

Answer 10

T (tense) - deoxyHb R (relaxed) - oxyHb

Question 11

measure of allosteric co-operation of Hb

Answer 11

Hill coefficient

Question 11

What protein is characteristic for HDL

Answer 11

ApoA-1 Activates LCAT –> converts free cholesterol into cholesterol esters

Question 13

why does the Bohr effect move the oxygen dissociation curve to the right?

Answer 13

the acid makes the histadines on E7 and F8 more positively charged and therefore lock deoxyHb stronger

Question 14

How is Fe2+ bound in Hb?

Answer 14

E and F helices provide 2 histadine molecules with Nitrogen residues poking out F8 anchors the Fe2+ E7 exludes water from Fe2+ and allows O2 to bind

Question 15

simplified synthesis of cholesterol

Answer 15

acetyl CoA –> HMG-CoA –> mavalonate –> isoprene –> squalene –> cholesterol

Question 16

what does altitude do to the oxygen dissociation curve?

Answer 16

moves the curve to the right

Question 18

Function of ACAT

Answer 18

Helps form VLDL in the liver

Question 19

What causes familial hypercholesterolaemia

Answer 19

inherited dominant disorder of mutations in the LDL R gene

Question 20

What happens to Fe2+ in the plane of Hb in oxyHb?

Answer 20

O2 binding pulls Fe2+ into the plane on Hb forming H bonds. F8 is also pulled and changes the tertiary structure of the entire subunit which affects adjacent subunits = co-operativity

Question 20

What regulates the level of cholesterol that each person makes

Answer 20

The level of HMG-CoA reductase

Question 21

What happens to Fe2+ in the plane of Hb in deoxyHb?

Answer 21

In DeoxyHb - Fe2+ pulled out of the plane and binds E7 forming 8 salt bonds and H bonds between alpha and beta subunity

Question 23

enzyme that catalyses the formation of carbonate ions in the blood

Answer 23

carbonic anhydrase

Question 24

What is the structure of Hb?

Answer 24

tetrameric - a2b2 = HbA

Question 25

General structure of cholesterol

Answer 25

4 hexagonal rings with OH on carbon 3. Rest of the molecules (YVY) is hydrophobic and planar

Question 26

why does altitude move the oxygen dissociation curve to the right?

Answer 26

altitude causes increased BPG in the blood –> stabilising deoxyHb more

Question 27

Adaptation of foetal Hb

Answer 27

binds oxygen with greater affinity than HbA

Question 28

what does the Bohr effect do?

Answer 28

when you decrease pH - moves the curve to the right –> makes deoxyHb more stable

Question 29

what is the amino acid change causing sickle cell anaemia?

Answer 29

glutamic acid changed to valine