proteins part 2

Question 1

What are the different types of proteins?

Answer 1

structural e.g. keratin
enzymatic e.g. digestive enzymes
contractile e.g. myosin
receptor e.g. g proteins
defensive e.g. immunoglobulins
hormonal e.g. insulin
storage
transport e.g. haemoglobin

Question 2

What is post translational modification?

Answer 2

subsequent modification after protein been transcribed

Question 3

What is co translational modification?

Answer 3

modification at same time as translation

Question 4

What are the three types of conjugated proteins?

Answer 4

glycoproteins
lipoproteins
metalloproteins

Question 5

What are glycoproteins?

Answer 5

Proteins with ≥1 carbohydrate molecule(s) covalently attached

Co-translational or post-translational
modification where oligosaccharide chains are attached to a protein

Question 6

Effects of glycosylation?

Answer 6

1.Stability
2.Solubility
3.Cell signalling
4.Orientation

Question 7

How is blood transfusion compatibility achieved?

Answer 7

The immune system recognizes the combo of carbs present upon or absent from the surface of an erythrocyte

if deemed by immune system to be foreign, immune system secretes particular antibodies to effectively clump the foreign red blood cells together

Question 8

Why can we use glycoproteins for diagnostic purposes?

Answer 8

patients with undiagnosed diabetes mellitus have high levels of glucose in blood

excess glucose binds to haemoglobin within erythrocytes forming glyco proteins

can detect the concentration of these glycoproteins in a patient’s blood

and since erythrocytes only stay in circulation for 100 days , conc will correlate with patients blood sugar levels occurring over that period of time

therefore patients with diabetes or suspected allow clinicians to obtain a useful snapshot of average blood glucose control

Question 9

HbA1C?

Answer 9

pathological glycoprotein

Question 10

What are lipoproteins?

Answer 10

proteins combined with lipids

Question 11

Where are lipoproteins found?

Answer 11

In cell membranes and transporting hydrophobic molecules around aqueous bloodstream

Question 12

What are apolipoproteins?

Answer 12

lipoproteins with other lipoproteins

Question 13

What do apolipoproteins do?

Answer 13

transport fat, fat soluble vitamins and fat soluble hormones around the body within blood and cerebral spine fluid

Question 14

What are metalloproteins?

Answer 14

Protein molecules with a metal ions within
their structures (co-factors)
Various functions (e.g. enzymatic, signal
transduction, storage and transport

Question 15

Describe structure of haemoglobin?

Answer 15

large quaternary structure, four polypeptide chains , two alpha subunits and two beta subunits.
The interfaces where subunits meet are usually non polar and this plays important role in transmitting information
Each subunit contains an organic molecule called heme and inside heme molecule sits an atom of iron

Question 16

What allows haemoglobin to transport one mol of oxygen?

Answer 16

Interaction between iron, heme and polypeptide subunit. Each haemoglobin mol with four subunits can carry four mols of oxygen

Question 17

What does the amount of oxygen that can be dissolved in blood depend on?

Answer 17

partial pressure of oxygen within lung alveoli.

Question 18

How much oxygen does plasma in working normally lungs have?

Answer 18

plasma leaving lungs has almost as much dissolved oxygen as is possible
plasma can only carry a max of 3ml oxygen per l

Question 19

What are the effects of sickle cell blood disease?

Answer 19

sickle cells struggle to pass through capillaries and inefficient in delivery oxygen to end tissues

Question 20

How does sickle cell disease arise?

Answer 20

GAG in normal beta chain changes to GTG, changes tertiary and quaternary.
Polar glutamine becomes non polar valine

Question 21

What are the the types of protein based on structure?

Answer 21

globular
fibrous
membranous

Question 22

What are the functions of globular Proteins?

Answer 22

storage
enzymes
hormones
transporters
structural

Question 23

What is myeloma?

Answer 23

antibody-producing white blood cells secrete abnormally large amounts of immunoglobulins

Question 23

Give examples of where fibrous proteins are commonly found ?

Answer 23

muscle fibre and connective tissue

Question 23

What is the cause of scurvy?

Answer 23

body unable to produce twisted collagen fibres- important in maintaining structural integrity.
Result of a deficiency in vitamin C

Question 23

Why is scurvy a result of vitamin C deficiency?

Answer 23

vitamin c is an essential co factor in the production of collagen.
Without vitamin C, post translational modification of amino acids proline and lysine cannot occur and cannot be converted to hydroxyproline and hydroxylysine.

Question 24

What other conditions are a result of disorders of collagen synthesis ?

Answer 24

osteogenesis imperfecta - DNA mutation results in the substitution of the small amino acid glycine for a different larger amino acid
Substitution results in weak collagen produced- brittle bones and sclera of eyes easily damaged

Question 25

What are membraneous proteins?

Answer 25

proteins that are embedded within cell membranes

Question 26

What is function of membraneous proteins?

Answer 26

important role in transporting substances into and out of cells
also play important role in signalling

Question 27

What features of familial hypercholesterolemia?

Answer 27

high levels of LDL cholesterol circulate due to genetic disposition

Question 28

symptoms of FH?

Answer 28

excess cholesterol can be deposited around the eyes (xanthelasma)
and around tendons known as xanthoma

Question 29

How does FH exert its effects?

Answer 29

FH most commonly affects the LDL receptor protein
which sits within the cell membranes of many cells
depending on the specific mutation that causes FH
could be that no LDL receptor protein can be manufactured
or receptor never emerges from cell membrane
or receptor unable to bind to LDL cholesterol
or receptors can’t internalize LDL cholesterol
can’t release LDL after internalized