Erythrocyte Biochemistry Flashcards Preview

MCM Exam 2 > Erythrocyte Biochemistry > Flashcards

Flashcards in Erythrocyte Biochemistry Deck (58)
Loading flashcards...
1

What makes R-Binder proteins?

Gastric mucosa cells in the stomach

2

Where does nonheme iron come from?

Plant products

3

Oxygen Dissociation curve for hemoglubin

Sigmoidal curve

4

The uptake of transferin by cells is done by what process?

Receptor mediated endocytosis via transferin receptor (TfR).

5

B12 deficiency is often caused by what.

What impact can this deficiency have?

Dietary lack is not often the cause, 3 ug dailly allowance 

85% of cases are the lack of a protein called intrinsic factor.

Causes megaloblastic anemia because of the decrease of N5,10-methylene-THF and on DNA synthesis 

 

 

6

What is the efficiency of hemoglobin in delivery of oxygen to from lung to tissue.

Drops from 7.4 to 7.2 pH

66%

7

Describe B12 Absorbtion

B12 binds to R-binder proteins in somach

Degraded by proteases in the dudenom releasing B12

Intrinsic factor carries B12 to ileum where it is absorped by receptors.

8

In what form foes ferritin store iron?

As Fe3+

9

What converts Fe3+ in non-heme iron to Fe2+

Ferric Reductase

10

What is the generation of erythrocytes known as?

Erthropoiesis

11

Where does heme iron come from?

Animal products

12

Why is HbF in the fetus higher in affinity the HbA in the mother?

Oxygen travels mother to fetus.

HbF does not bind well to 2,3-BPG so this cannot decrease its affinity as much.

13

What happens to affininty for oxygen as pH decreases. How does this work and what is this effect called?

O2 affinity decreases as pH decreases

His 146 picks up H+ from tissue and causes a conformational change in Hg.

Called the Bohr Effect

14

How do internalized endosomes get transferin to the mitchondira for heme synthesis?

Clatherin coated endosome transiently docks and DMT1 helps to facilitate the transport of iron out of the endosome.

15

2,3-Biphosphoglycerate has what effect on O2?

Reduces the affinity of O2 so Hb gives up more O2 to tissues

16

What form of folate is dietary?

Dihydrofolate (DHF)

17

What is portential therapy for sickle cell anemia?

What are the worries in this?

Changing HbS to HbF using hydroxyurea

This is a toxic chemotherapeutic agent

18

What cell features are observed in megaloblastic anemia?

Large erythrocytes >100 fL (normal is 80-100) (same ratio of hematocrit)

Large erythroblasts

Hyper-segmented neutrofills (more then 5 lobes, 3-4 normal)

19

How is B12 transported into and throughout the blood

Intrinsic factor bound to cobalin is taken up by receptor-mediated endocytosis.

 

Cobalin circulates through the blood by transcobalamin

20

Stem cells and commited cells of erthropoiesis

Hemocytoblast

Proerythroblast

21

What can result as part of Hereditary Hemochromatosis?

 Organ dysfunction due to iron overload: cirrhosis, arthritis, endocrinopathy, skin pigmentation, cardiomyopathy

22

What is the function of THF?

Transfers carbon units from donors to acceptors

Is vital for DNA synthesis

23

What transports iron in the blood?

Transferrin

24

What enzyme refuces folate to DHF and THF?

Dihydrofolate reductase

Oxidizes NADPH to NADP

Add 2 electons + hydrogens at a time

25

Describe folate metabolism.

THF to N5,10-methylene-THF as the carbone side chain of a serine is transfered

 

Carbon of N5,10-methylene-THF is transfered to deoxyuridylate (dUMP) to form deoxythmidylate (dTMP) during which DHF is made

 

26

How does positive cooperativity work?

The binding of O2 to Fe of a globin subunit pulls the proximal F8 histindine down ==> this pulls the globin FG-helix and changes the interaction with the other globin chain in Hb

27

What converts free iron to Fe3+?

Hephaestin/cerruplasmin

28

Dysregulation of iron uptake and export by enterocyte

15g of Total iron body weight

What is the disease and treatment?

 

Hereditary Hemochromatosis

Blood letting

 

29

What is the fetal hemoglubin and when does it peak?

Hb F (a2g2) 

Gamma chain peaks right before birth and then subsides.

Alpha continually increases up untill birth where it levels off.

30

What makes Intrinsic factor?

Pariatal cells in the stomach.