red blood cell structure and function

Question 1

how many polypeptide chains does heamoglobin contain

Answer 1

4

Question 2

what are the 4 polypeptide chains

Answer 2

2 alpha globin chains

2 beta globin chains

Question 3

where does ferrous iron come from

Answer 3

circulating transferring and protoporphyrin

Question 4

what is the synthesis of red blood cells called

Answer 4

erythropeoisis

Question 5

what does carbon dioxide combine with and what does this create

Answer 5

water to produce carbonic acid

Question 6

what enzyme produces carbonic acid

Answer 6

carbonic anhydrase

Question 7

what is the chloride shift

Answer 7

carbonic acid breaks down into H+ and HCO3-

HCO3- moves out in exchange with Cl-

Question 8

what is most CO2 transported as

Answer 8

bicarbonate

Question 9

how is haemoglobin produced

Answer 9

Glycine and succinyl coA react to produce protoporphyrin - this is synthesised by ALA-synthase pyroxidine

protoporphyrin then combines with Fe+ to form the haem group

this then combines with globin to produce heamoglobin

Question 10

what is the first recognisable RBC precursor in the bone marrow

Answer 10

proerothroblast

Question 11

what does the proerothroblast undergo maturation into in the marrow

Answer 11

late normoblast

Question 12

what happens to form a reticulocyte

Answer 12

the nucleus is extruded when pushed into the blood - this contains some residual ribosomal RNA and so can still synthesise some haemoglobin (however after a couple of days in the blood the RNA degrades and the mature RBC cannot synthesise any more heamoglobin)

Question 13

what stimulates erythropoiesis

Answer 13

erythropoietin

Question 14

what is erythropoietin

Answer 14

a glycosylated peptide mostly produced in the kidney

Question 15

when is there major production of erythropoietin

Answer 15

when theres low oxygen tensions

Question 16

how does lower oxygen tensions cause the release of erythropoeiten

Answer 16

because RBCs give oxygen to the kidneys which have oxygen sensors
if oxygen levels are low then this causes the peritubular interstitial cells of the outer cortex to release more erythropoietin

Question 17

when does erythropoietin act on

Answer 17

the later stages of RBC maturation when it still has a nucleus

Question 18

what is special about the RBC membrane

Answer 18

lipid bilayer

Question 19

what does the inside of the lipid bilayer contain

Answer 19

spectrin
ankyrin 
actin 
protein 4.1
band 3 proteins (anion channels) 
carbohydrate chains

Question 20

how do RBC derive their energy

Answer 20

from glycolytic pathways

Question 21

what controls the oxygen-deoxygynation of haemoglobin

Answer 21

2,3, DPG

when haemoglobin is oxygenated there is no space for 2,3 DPG to fit in

when deoxygenated 2,3 DPG can fit in the middle and allow rapid release of O2

Question 22

where is prenatal heamoglobin synthesised

Answer 22

in the yolk sac, then the liver and then the spleen.

Question 23

RBC’s under normal circumstances are broken down how

Answer 23

extravascularly in macrophages

Question 24

what is protoporphyrine converted into

Answer 24

bilirubin

Question 25

how does RBC lysis occur abnormally

Answer 25

intra-vascular

Question 26

where are the hydrophilic AA’s postitioned

Answer 26

project outwards making RBC soluble

Question 27

where are the hydrophobic AA’s positioned

Answer 27

project inwards making interior of Hb water repellant

Question 28

what is protoporphyrine anchored by

Answer 28

F8 histadine

Question 29

what are the chemical bonds that hold the quaternary structure of haemoglobin together

Answer 29

ionic, hydrogen and van der waals