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MCM Final > Erythrocyte Biochemistry > Flashcards

Erythrocyte Biochemistry Flashcards

1
Q

Human adults have _____ RBCs

We produce _____ RBCs per second

___% of hemoglobin is synthesized before the nucleus is extruded

The remaining ___% is made in the reticulocyte

A

25 trillion

2.4 million

65%

35%

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2
Q

Hemoglobin is a tetramer made of 2 _______ chains and 2 ________ chains

Hemoglobin contains 4 units of _______, which each contain a _______ iron atom, and they carry O2, heme is hydro______

A

Alpha-globin

Beta-globin

Heme

Ferrous (Fe2+)

Phobic

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3
Q

When there is a substitution of valine for glutamic acid at amino acid position #6 in B-globin, we see __________

A

Sickle cell anemia

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4
Q

Sickle cell anemia causes __________ of hemoglobin and ________ shaped RBCs which ____________ (also associated with __________ anemia)

A

Polymerization

Sickle-shaped

Impede circulation

Hemolytic

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5
Q

Hemoglobin in the muscle is called _________

It has a _______ affinity for O2 than Hemoglobin and has a _________ curve

A

Myoglobin

Higher

Hyperbolic

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6
Q

The steepest part of the dissociation curve of hemoglobin and oxygen affinity is from ______ pO2 with the low end corresponding to the onset of _________ and the high end corresponding to the onset of _______

A

20-40 torr

Exercise

Rest

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7
Q

The Oxygen dissociation curve of hemoglobin is shifted to the right by what factors?

A

Exercise, increased temperature, increased CO2, increased 2,3-BPG and decreased pH

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8
Q

What does positive cooperativity mean in regards to hemoglobin?

A

As one O2 binds to one heme, it facilitates the binding of O2 to another heme. Hb binds to O2 in a cooperative fashion.

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9
Q

When the ODC shifts to the right, Hb is giving up _______ to the _________

A

More O2

Tissues

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10
Q

Fetal Hemoglobin has a __________ affinity for O2 than the mother’s Hb because …

The fetal hemoglobin (HbF) curve is to the left or right of the normal Hb curve?

A

Higher

Because the baby needs to steal the mom’s O2 to get any

HbF is to the left

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11
Q

Iron readily exchanges _______and is the ideal catalyst for ______-________ reactions taking the dietary form of iron, ________ to a form usable in the blood, ____________.

A

Ions

Oxidation-reduction

Ferric 3+

Ferrous 2+

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12
Q

Because iron cannot freely diffuse across membranes, it involves several proteins. Name four.

A

Ferrireductase

DMT1 (divalent transporter)

Hephaestin

Ferroportin

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13
Q

Fe3+ is reduced to Fe2+ by ________

A

Dcytb. (Duodenal cytochrome b)

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14
Q

fe2+ is transported into the enterocyte by ________ on the apical surface

A

DMT1

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15
Q

Fe2+is transported outside the enterocyte cell into the blood by __________ with also requires _________ to perform the transport (changing Fe2+to Fe3+)

A

Ferroportin

Hephaestin (a ferroxidase)

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16
Q

_________ carries iron to tissues where it is needed, including the bone marrow undergoing erythropoiesis

It binds to iron with a _______ affinity and delivers iron safely in a ________ form.

A

Transferrin

High

Non-toxic

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17
Q

TfR stands for Transferrin Receptor and these mediate ___________

_________ have 800,0000 TfR per cell

In the cell, heme is made in the ___________

__________ is the protein that transports iron out of the endosome

A

Endocytosis

Erythroblasts

Mitochondria

DMT1

18
Q

Organ disfunction due to iron overload is called ___________and may present as …

Treatment is _________

A

Hemochromatosis

Cirrhosis, arthritis, endocrinopathy, skin pigmentation, cardiomyopathy

(Usually manifest in 6th decade)

Treatment is blood-letting

19
Q

A regulator of iron homeostasis that binds to ferroportin and causes internalization of ferroportin and its destruction by proteolysis is called ____________

This peptide is made by the ________

A

Hepcidin

Liver

20
Q

When iron is high, hepcidin expression ________

And ferroportin levels ________

A

Increases

Decrease

21
Q

When hepcidin decreases and ferroportin increases, iron must be _______ in the body

A

Low

22
Q

HFE regulates _________ expression by binding to ________ which turns on ___________ expression

A

Hepcidin

TfR2

Hepcidin

23
Q

If HFE is mutated, it cannot bind to _______ and there is no control over ________ because ________ wasn’t turned on

A

TfR2

Ferroportin activity

Hepcidin

24
Q

The production of RBCs is dependent on which two vitamins?

A

Vitamin B12
&
Vitamin B9

25
Q

Vitamin B12 is also known as _________

Vitamin B9 is also known as ________ or __________

A

Cobalamin

Folate or folic acid

26
Q

Deficiency of vitamin B12 and folate causes ____________ anemia, which occurs as a result of diminished ___________ of __________ in the bone marrow erythroblasts

A

Megaloblastic

Synthesis

DNA

27
Q

__________ anemias are characterized by large RBCs

What is another sign of this anemia on a slide

A

Macrocytic

Megaloblastic macrocytic anemia is seen as very large erythroblasts in the bone marrow as well as hypersegmented neutrophils (more than 5 lobes)

28
Q

Folic acid, or pteroylglutamic acid, has 3 parts. Name them.

A

Pteridine

P-amino-benzocaine acid (PABA)

Chain of glutamate residues

29
Q

Folate can exist as__________ which can be reduced to the active form of ________ by ___________

A

FH2

THF

Dihydrofolate reductase

30
Q

The function of THF is to _________ ________ units (e.g. _______ groups) from doors to acceptors.

THF plays a vital role in _____ synthesis

A

Transfer

Carbon

CH3

DNA

31
Q

THF becomes _____________ when the carbon side chain of serine is transferred to it, this is then transferred to ________to form ______ during which DHF is made and is then reduced by _________ to THF to restart the cycle

A

N5,10-methylene-THF

Deoxyuridylate (dUMP)

Deoxythymidylate (dTMP)

Dihydrofolate reductase

32
Q

Folate is available as an N5-methyl-THF that needs to be ___________ in order to enter the folic acid cycle as THF. _________ is needed in order for this process to happen.

A

Demethylated

Cobalamin (B12)

33
Q

If B12 is not available,the folate is stuck as ________

A

N5-methyl-THF

34
Q

Cobalamin transfers the methyl group from N5-methyl-THF to ________ to create _________using the enzyme, ____________

A

Homocysteine

Methionine

Methionine synthase

35
Q

Because a dietary deficiency of Vitamin B12 is rare, 85% of B12 deficiency is due to the lack of a protein called _______________

A

Intrinsic factor

36
Q

In B12 absorption, dietary B12 binds to proteins called ________ made by gastric mucosa cells

A

R-binder proteins

37
Q

Parietal cells of the stomach make ___________ and proteases from the pancreas degrade ________proteins in the duodenum, releasing ______

Then _________ carries B12 to the ileum where receptors bring it to the body

A

Intrinsic factor (44 kDa protein encoded by gene of Chr 11)

R-binder proteins

B12

Intrinsic factor

38
Q

B12 receptor is _______

Cobalamin circulates through the blood carried by ___________

A

Cubulin

Transcobalamin

39
Q

Pernicious anemia is a _____________ deficiency due to a lack of ____________ (which is necessary for absorption of the vitamin above)

This is a __________ __________ anemia

A

B12

Intrinsic factor

Megaloblastic macrocytic anemia

40
Q

In order to determine whether a B12 deficiency is due to a failure of diet or absorption, the ___________ is used

A

Schilling Test

MCM Final (7 decks)

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