Norm fxn- Biochemistry Flashcards
True or False: Mb has a higher affinity for O2 than Hb.
True
True or false: Hb is made of 2 different pairs of subunits put together.
False. They’re identical subunits.
How many alpha and beta subuntis are there in Hb?
2 alpha
2 beta
Which state of Fe can accept the O2 in the middle of the Hb? (Fe++ or Fe+++)
Ferrous state (Fe++)
True or False: when 1 O2 binds to a Hb subunit, it facilitates the binding of subsequent O2’s to the same Hb.
True
big point here
How much stronger does CO bind to Hb than O2?
200x stronger (essentially irreversible)
This is the type of Hb in 98% of adults, and is composed of a2b2
HbA
This is the type of Hb in 2% of adults where the subunit structure is a2d2
HbA2
This is the type of Hb where the subunit structure is a2g2, and is the trpincipal form of Hb from ~7mo before birth unity ~1mo after birth.
HbF
True or False: HbF has a slightly lower O2 affinity than HbA.
False. It’s higher to ensure O2 delivery from mom’s blood to fetal blood.
Since most CO2 is transported as HCO3 in the blood, what is the role of the Hb?
Hb binds the H+ forming HHb
Bohr effect
Does the affinity of Hb for O2 increase or decrease with an increase in pH?
Increase
Since Hb can bind to H+ ions and O2 ions, what is it’s role in the blood for regulation?
Buffer
True or False- 2,3-DPG is a toxin that should never be present as it lowers the affinity for Hb binding to O2.
False- it’s a normal glycolysis product and is vital for regualting binding of O2 to Hb
Does DPG bind to the oxygenated or deoxygenated form of Hb?
Deoxygenated
How many DPG molecules bind to 1 Hb?
1
When Hb is oxygenated, the central cavity becomes smaller, and what happens to DPG?
It’s expelled
True or False: DPG binds HbF less strongly, giving a higher affinity of HbF for O2 than HbA.
True
What replaces Glu at position 6 in the B-chain to cause sickle cell (HbS)?
Val
In which state (deoxy or oxy) does the HbS become sticky by transforming the RBC into the sickle-cell shape?
Deoxygenated
Do homozygous or heterozygous individuals get sickle-cell anemia?
Homozygous (it’s recessive)
What is the incidence of SCA in african americans?
~1/500
True or False: heterozygous sickle cell individuals are always asymptomatic.
False. they get symptomatic at high altitudes
Heterozygous individuals are at an advantage when there is a prevalence of what?
Malaria
What are the 2 ways of Dx SCA?
- blood smear
2. protein electrophoresis
In HbC, what replaces the Glu on position 6 of the B-chain?
Lys
When HbC crystalizes, what is the common pathology?
viscous blood and mild hemolysis
Is HbC milder or more severe than HbS?
Milder
True or False: metHb is a daily occurance where it’s made and then reduced back to normal Hb.
True
What is the enzyme to reduce metHb to Hb?
NADH-dependent methemoglobin reductase
What is the condition where there is a deficiciency in the reductase or HbM?
Methemoglobinemia
HbM favors which state of Fe?
Fe+++
HbM can only exist in which state, heterozygous or homozygous? Why?
Heterozygous because homozygous is incompatible with life.
What is the biggest Sx for methemoglobinemic patients?
Cyanosis
This is a group of disorders where the synthesis of either Hb chain is reduced or absent.
Thalassemias
What types of mutations typically cause a-Thalassemias?
deletions
What types of mutations typically cause B-Thalassemias?
point mutations
Which thalassemia is always fatal (a or B)?
alpha
This is the group of disorders where the a-globin is reduced or absent.
a-thalassemia
How many a-genes are missing in a-thalassemia 1?
1
Is a-thalassemia 1 symptomless?
yes
Mild anemia is present with a-thalassemia 2 because of how many a-genes missing?
2
3 missing a-genes can cause which disease which causes moderately severe hemolytic anemia?
HbH disease
4 missing a-genes (like we talked about before) is fatal and shows up with what condition as a fetus?
Hydrops fetalis
This is the increased concentrations of red cells, usually from hemoglobinopathies which favor the oxyHb state.
Polycythemia
Since the oxyHb is so strong in polycythemias, what happens to peripheral tissues?
Hypoxia from inadequate O2 supply
This is a useful index for diabetes because of the glycosylated Hb.
HbA1c