lecture 17 - red blood cells and plasma proteins

Question 1

albumin knowledge critical for…

Answer 1

drug design. must bind drug to “drive” it around the body

Question 2

B-cells produce?

Answer 2

each make antibodies specific to an antigen and make membrane-bound versions, specific to the same antigen

Question 3

order the following from smallest to largest (#AA)

• serum albumin
• haemoglobin
• Immunoglobulin
• lysozyme

Answer 3

smallest
- lysozyme ~129 amino acids
- haemoglobin ~574 amino acids
- serum albumin ~585 amino acids
- immunoglobulin ~1294 amino acids
Largest

Question 4

serum albumin concentration

Answer 4

Concentration of 35mg/mL in serum. Main component of plasma proteins.

Question 5

structure of antibody

Answer 5

• y-shaped
• 2 heavy amino acid chains, 2 light amino acid chains
• built from 12 immunoglobulin (IgG) domains
• chains held by disulphide bridges (cystine responsible)

Question 6

secondary structure of haemoglobin

Answer 6

alpha helical

Question 7

concentration of haemoglobin in blood (overall)

Answer 7

150mg/mL

Question 8

where are immunoglobulins made?

Answer 8

B-lymphocytes (white blood cell) [aka B-cells]

Question 9

how many O2 molecule carried by haemoglobin?

Answer 9

= 4

there are four chains each with their own heme group which binds 1 O2 molecule to the iron.

Question 10

what is the same and what changes in antibodies with different specificities?

Answer 10

• variable region changes (different arangemnt of the emd 2 IgG domains)
• constant region stays the same

Question 11

who discovered haemoglobin and how?

Answer 11

Max Perutz, by protein crystallography

Question 12

erythrocytes made in?

Answer 12

reticulocytes (myeloid stem cells in the marrow)

Question 13

albumin structure

Answer 13

single amino acid chain. All α-helices (secondary structure)

Question 14

albumin function

Answer 14

carrier for small insoluble molecules (lipids, hormones, steroids, man-made drugs)

Question 15

diameter, shape and cellular components/contents of RBC?

Answer 15

• 8μm
• biconcave disc
• no nucleus, no organelles
• heaps and heaps of haemoglobin (340mg/mL)

Question 16

how is the antigen recognised?

Answer 16

by its EPITOPE binding to the antigen-binding site

Question 17

sickle cell anaemia vs. malaria

Answer 17

carrying 1 copy of the mutated gene causes resistance to malaria.

Question 18

blood type determined by?

Answer 18

blood group antigens present on membrane of erythrocytes

Question 19

role of immunoglobulin in immune system? (analogy)

Answer 19

prior knowledge - can bind to all sorts of bacteria/virus. millions of different binding specificities

Question 20

hematocrit level?

Answer 20

volume of red blood cells: volume of blood. Higher in males because testosterone increases EPO = more RBC production.

Question 21

lifetime of red blood cells?

Answer 21

120 days

Question 22

sickle cell anaemia mutation cause? results?

Answer 22

point mutation of single nucleotide A to T in haemoglobin sequence. Results in what should be GIutamic acid, being replaced with Valine. Protein produced forms fibres which disfigure erythrocytes into the sickle shape.

Question 23

concentration of immunoglobulin/antibodies in serum

Answer 23

20mg/mL

Question 24

immunoglobulin domain?

Answer 24

• small length of amino acids folded into c-shape held by disulphide bridge
• All β-pleated sheets.

Question 25

proteins recap

Answer 25

linear polymers of amino acids joined by peptide bonds

Question 26

structure of haemoglobin

Answer 26

• 2 amino acid sequences (α and β not secondary structures)
• 4 subunits (ααββ)
• 4 heme groups (1 per chain)
• Alpha helical secondary structure

Question 27

how many of the domains are variable?

Answer 27

4 (2 on each end)