Chem final

Question 1

What is the diff between myoglobin and hemoglobin

Question 2

Structurally, what are the similarities between Hb and myoglobin

Answer 2

Both are composed of a heme complex that have a coordinated Fe ….

Question 3

T/F: Heme on its own is soluble

Answer 3

False

Question 4

What ligands can attach to heme? (4)

Answer 4

1. oxygen
2. CO
3. CO2
4. Cyanide (cytochromes)

Question 5

In regards to oxygen binding, what is the diff between myoglobin and Hb?

Answer 5

1. Myoglobin has a higher affinity to oxygen, is monomeric, non cooperative binding
2. Hemoglobin is tetrametric (4 domains), cooperative binding,

Question 6

A rightward shift on an association curve for oxygen binding means?

Answer 6

less affinity for oxygen

Question 7

When does myoglobin release oxygen?

Answer 7

When levels in muscles are very low

Question 8

T/F: Hemoglobin can bind to oxygen multiple times

Answer 8

true

Question 9

The sigmoidal shape of the hemoglobin curve signifies

Answer 9

cooperative binding

Question 10

When does oxygen affinity increase for Hb?

Answer 10

as more oxygen is bound to heme (saturation increases)

Question 11

Why do we see an increase in oxygen binding affinity with hemoglogin?

Answer 11

As oxygen binds, there is a shift in the heme and shift in protein structure
(Tense “t” state to Relaxed “r” state)

Question 12

Binding always leads to ________ and with Hb this causes more _______

Answer 12

confirmational change
oxygen affinity

Question 13

What is the R state?

Answer 13

4 oxygen have bound to Heme

Question 14

what is the diff between fetal Hb and adult Hb

Answer 14

fetal has a higher affinity for oxygen

Question 15

Why is there a higher affinity for oxygen in fetal Hb?

Answer 15

1. Structural differences ( adult have 2 alpha and 2 beta)
2. 2,3 BPG

Question 16

Does 2,3 BPG bind to fetal Hg?

Answer 16

No

Question 17

Why does 2,3 BPG do to adult Hb?

Answer 17

preturbe oxygen from binding to Heme

Question 18

What charge is on histadine rings in adult Hb?

Answer 18

positive

Question 19

What charge is on serine residue in fetal Hb?

Answer 19

no charge

Question 20

Why is there no ion-dipole intermolecular force between 2,3 BPG and fetal hemoglobin

Answer 20

The distance is too great because the serine is small

Question 21

2,3 BPG which stabalizes the structure of Hb, can also be a

Answer 21

competitive inhibitor

Question 22

Shifting equilibrium to the left means? Would 2,3 BPG binding to adult Hb cause this?

Answer 22

higher affinity for oxygen
no; there would be a shift to the right

Question 23

Where does 2,3 BPG come from

Answer 23

our bodies produce it

Question 24

What does 2,3 BPG essentially do?

Answer 24

prevent conformational change and disallow more oxygen from binding

Question 25

T/F: Both adult and fetal hemoglobin curves are sigmoidal

Answer 25

true

Question 26

Shifting equillibrium to the left means oxygen favors the

Answer 26

T state

Question 27

how can heme overcome binding of 2,3 BPG?

Answer 27

increasing pressure of O2

Question 28

What are the 3 ways Co2 is transported throughout the blood? Which is primary?

Answer 28

1. dissolved gas (10%) 2. bicarb (blood buffering system)* 3. bound to protein of the Hb

Question 29

The n terminus of an amino acid is ________ while C is ________

Answer 29

nucleophilic electrophilic

Question 30

CO2 bound to Hb is called?

Answer 30

Carbaminohemoglobin

Question 31

Where does CO2 bind on Hb?

Answer 31

the apoprotein, not the heme

Question 32

High affinity for CO2 causes a _______ affinity for O2

Answer 32

low

Question 33

What happens when RBC starts to bind to CO2

Answer 33

localized changes in pH of the environment (Bohr-Haldane Effect)

Question 34

Oxygen dissociation is increased by (3)

Answer 34

1. Increasing temp 2. Lowering blood pH 3. increasing partial Pco2

Question 35

What affects does increasing Pco2 have in the blood? (3)

Answer 35

1. Increase H concentration 2. protonates certain amino acid residues 3. leads to conformational change of protein

Question 36

CO binds _____ times more strongly to heme than O2

Answer 36

200-300

Question 37

T/F: CO2 binds to the same site as oxygen and CO does not

Answer 37

False CO binds to the same site as O2 on heme and CO2 does not CO2 prevents conformational change

Question 38

Is binding reversible once CO bound to heme? how?

Answer 38

yes; increase the O2 levels or pressure

Question 39

When does fetal Hb dissipate in children and convert to adult Hb?

Answer 39

around 6 months