Chapter 6 Bio Myo and Hemoglobin

Question 1

Myoglobin general

Answer 1

Globular protein found in skeletal muscle and cardiac muscle. Higher O2 affinity than hemoglobin. Store O2 and uses it as a reserve for when demand cannot be met by Hb.
High amounts of myoglobin allow organism to hold their breath for an extended time under water.

Question 2

Myoglobin structure

Answer 2

O2 is bound on a heme group found on its single polypeptide chain. 80% alpha helix. No quaternary structure, monomer of 1 chain. Folding of Mb chain places the nonpolar residues on the interior. Polar aa residues are exterior, making Mb a H20 soluble globular protein.

Question 3

Globular proteins

Answer 3

Hydrophilic and H20 soluble

Question 4

Heme group

Answer 4

prosthetic group, non protein part. Sits on a crevice lined by nonpolar aas. Fe contain protein responsible for the colour of meat.

Question 5

Muscle injury myoglobin

Answer 5

Myoglobin is released into the blood within 2-3 hours. 10 hours after injury, Mb levels peak. Sometimes excreted through urine.
Mb can bind only one molecule of O2 since it contains one heme group.

Question 6

Hemoglobin (Hb)

Answer 6

4 polypeptide chains, 2 alpha and 2 beta
1,2,3 structure similar to Mb. Each chain has a heme group with it’s own Fe2+ ion. When Hb is deoxygenated, BPG is held in the central cavity.

Question 7

Hb can bind to __ also.

Answer 7

Carbon monoxide and Carbon dioxide.
HbCO and HbCO2
Carboxyhemoglobin and carbaminohemoglobin

Question 8

Hemoglobin main job

Answer 8

Transport O2 from the lungs to the tissue capillaries. Exclusively found in RBC. Tetramer

Question 9

HB Cooperative binding

Answer 9

When O2 binds to Hb, many salt bridges are broken which causes conformation to change. O2 binds more easily. HB is an allosteric protein.
Binding in Mb is not cooperative.
When 4 O2 molecules are bound, the other subunits release more readily.

Question 10

Release of O2 Mb vs Hb

Answer 10

Mb shows no change in O2 binding over a wide pH and CO2 range.
Hb dumps its O2 off when in need (during rapid muscle contraction).

Question 11

Bohr effect

Answer 11

CO2 and H promotes the release of O2 or Hb has decreased it’s affinity for O2. Hb’s oxygen binding decreases as the amount of CO2 and H+ increase.

Question 12

Low pH effect on hemoglobin

Answer 12

Shifts its curve to the right. It dumps off it’s O2.

Question 13

BPG (2,3-DPG) and Hb

Answer 13

Increase binding capacity of Hb by a factor of 26. BGP molecule is synthesized from an intermediate in the glycolysis pathway. It binds to the positively charged groups on the beta chain of the deoxy form of Hb.

Question 14

Hb shift to the right

Answer 14

Hb is releasing of fO2 to the tissues in need

Question 15

Fetal Hb

Answer 15

Has a higher O2 affinity than does adult Hb
1) Adult has 3 alpha chains and 2 beta chains
Fetal Hb has 2 alpha chains and 2 gamma chains
2)Fetal Hb binds BPH less strongly than does adult Hb

Question 16

HbFetal and BPG

Answer 16

HbF does not hold BPG as tightly. Preferred conformation will be to have O2 dumped off
Hb curve for HbFetal is shifted to the left since it will keep its O2

Question 17

Mb vs Hb O2 dissociation curves

Answer 17

Mb- hyperbolic
Hb- sigmoidal
Mb holds on to O2 tigheter and with higher affinity

Question 18

The Haldane Effect

Answer 18

The deoxyform of Hb increases its ability to carry CO2. The removal of O2 from Hb will increase its affinity for CO2.
Hb-CO2 = carbamino hemoglobin. Co2 binds to the amino groups of lysine and arginine residues in H.

Question 19

What shifts the Hb curve to the right?

Answer 19

Increase in temp, BPG, CO2, H+ or decrease in Ph, acidity. Bohr effect
Shift left = fetal Hb, alkalosis

Question 20

Carbon monoxide and Hb

Answer 20

Hb binds to CO 240x more readily than with O2. There is a lower potential for Hb to bind O2

Question 21

Sickle Cell Anemia

Answer 21

Glutamic acid is converted to Valine.

Mutation is on a Hb Beta chain.

Question 22

Electrophoresis

Answer 22

Anode is +

Cathode is -