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Mock paper 3 > 3 Proteins and enzymes > Flashcards

3 Proteins and enzymes Flashcards

1
Q

what are the six functions of proteins?

A

enzymes

antibodies

cell membranes

structure

hormones

transport

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2
Q

what is the monomer unit for a protein?

A

an amino acid

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3
Q

what is the bond formed between two amino acids? what is the resulting molecule called?

A

condensation reaction between C-N producing a peptide bond and expelling H(2)O

dipeptide formed

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4
Q

what is the biruet test and its results?

A

presence of proteins

copper (II) sulfate solution added drop by drop - turns lilac in the presence of proteins

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5
Q

what is the primary structure of proteins?

A

the sequence of amino acids (a.a.) in a polypeptide chain

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6
Q

what is the secondary structure of proteins?

A

alpha helices

beta pleated sheets

held in place by H bonds between -NH and -C=O

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7
Q

what is the tertiary structure of proteins?

A

interactions between R groups to hold the chain in place:
- H bonds between -C=O and -NH

  • disulfide bridges between the sulfurs on 2 cysteine a.a.
  • ionic bonds between carboxyl and amino groups on R groups
  • hydrophobic interactions between non-polar R groups in a.a. (in centre of protein)
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8
Q

what is the quaternary structure of proteins?

A

more than one polypeptide chain joined together

may require the addition of a prosthetic group

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9
Q

what are the differences between fibrous and globular proteins? give an example of each

A

fibrous:

  • long and insoluble
  • structural roles
  • e.g. collagen/keratin/elastin

globular:

  • compact and soluble
  • metabolic roles
  • e.g. haemoglobin/enzymes/hormones
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10
Q

what is chromatography?

A

separation of chemicals according to their solubility in different mediums

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11
Q

what is the retardation factor?

A

the distance travelled by the chemical / the distance travelled by the solvent

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12
Q

which compound is used to identify amino acids in chromatography?

A

ninhydrin

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13
Q

what are the features of enzymes?

A

globular proteins

biological catalysts

specific

sensitive to temperature and pH

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14
Q

how do enzymes lower the activation energy of a reaction?

A

alternative metabolic pathway

bring reactants together to form an enzyme-substrate complex

puts strain on the reactants ∴ bonds break/form more easily

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15
Q

why does high temperature cause an enzyme to denature?

A

high kinetic energy changes the tertiary structure which changes the shape of the active site by causing bonds between a.a. to break

∴ substrate no longer complementary to the active site

∴ enzyme can no longer catalyse reactions

∴ rate of reaction decreases

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16
Q

what is the difference between anabolic and catabolic enzymes?

A

anabolic = joining small molecules in condensation reactions ∴ endergonic

catabolic = breaking large molecules down in hydrolysis reactions ∴ exergonic

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17
Q

what are the five most common types of enzymes?

A

dehydrogenases

decarboxylases

proteases

lipases

carbohydrases

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18
Q

what is the turnover rate?

A

the amount of molecules that can be converted in a given period of time by a single catalytic site

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19
Q

what is a cofactor?

A

a non-protein molecule that aids enzyme function

20
Q

how does a cofactor increase the efficiency of enzyme-controlled reactions?

A

cause an allosteric change to the active site, making it more complementary

21
Q

what is a competitive inhibitor?

A

a molecule that competes with the substrate for the active site

22
Q

what is a non-competitive inhibitor?

A

a molecule that binds to the enzyme not at its active site, altering its structure and shape of active sites

23
Q

what are poisons?

A

irreversible inhibitors that cause a permanent change to the active site

24
Q

why is coagulation of blood necessary?

A

prevent excess bleeding

prevent entry of pathogens

seal wounds and maintain blood volume

25
Q

what are the risks of uncontrolled blood clotting?

A

DVT

can get stuck in heart/brain (–> stroke)

can block lung tissue (pulmonary embolism)

blood can accumulate behind stuck clots –> swelling and pain

26
Q

what is blood clotting stimulated by?

A

damage to blood vessels exposes collagen fibres and connective tissue

27
Q

outline the process of blood clotting

A

damages exposes collagen fibres

platelets activated –> cohesion and adhesion to damages vessel walls and fibrin fibres to ‘plug’ wound

leucocytes collect at the site of damage

tissue below endothelium releases thromboplastin

thromboplastin catalyses prothrombin into thrombin in the presence of Ca2+

thrombin and Ca2+ hydrolyses fibrinogen into fibrin fibres

fibrin fibres form a mesh over the wound –> clot

28
Q

what is hypovolaemic shock?

A

shock due to severe blood loss and fluid due to trauma/exposure

29
Q

how is antithrombin used in medicine?

A

competitive inhibitor of thrombin in presence of heparin

prevents formation of fibrin/blood clots when not needed

30
Q

how is blood amylase used in medicine?

A

diagnosis of pancreatic disorders

pancreatic enzymes attack the pancreas (acute pancreatitis) –> swelling and haemorrhaging

increases blood amylase concentration

31
Q

how is lactic acid dehydrogenase used in medicine?

A

diagnostic of tissue damage

can pinpoint location of damage - e.g. LDH 1 is primarily from heart muscle/erythrocytes

32
Q

how is aspirin used in medicine?

A

inhibits cyclooxygenase (COX) which catalyses formation of prostaglandins

aspirin adds an acetyl (-CH(2)CHO) group to amino acid close to site of COX ∴ prostaglandins can’t be produced

33
Q

how is warfarin used in medicine?

A

inhibits synthesis of regulating factors (Vitamin K dependant)

inhibits epoxide reductase ∴ reduced Vit K production ∴ glutamyl carboxylase –> reduced prothrombin production

34
Q

what are the four main blood groups?

A

A

B

AB

O

35
Q

what determines a person’s blood group?

A

the antigens present on the surface of their erythrocytes

36
Q

how is a person’s blood group identified?

A

mixed with different samples containing different antibodies

if agglutination occurs, corresponding antigen must be present

37
Q

why must a person’s blood group be identified before they receive blood group?

A

an incorrect match would cause an immune response

38
Q

what is ‘whole blood’? how long can it be stored for?

A

plasma + erythrocytes + leucocytes

< 24 hours

39
Q

what is ‘leuco-depleted blood’? how long can it be stored for?

A

plasma + erythrocytes

< 42 days

40
Q

what are ‘packed red cells’? how long can they be stored for?

A

erythrocytes diluted with NaCl, adenine, glucose + mamitol

< 35 days

41
Q

when are platelets given?

A

bone marrow failure

post-transplant

chemotherapy

leukaemia

42
Q

why is blood screened?

A

to prevent the transfer of infection

43
Q

what are three blood-borne diseases that are routinely screened for?

A

syphillis

Hepatitis B (and C)

HIV

44
Q

when can blood screens be requested?

A

following travelling abroad

following skin piercings

45
Q

what is the structure of a triglyceride?

A

3 fatty acids attached to a glycerol in esterification (a condensation reaction releasing 3 H(2)O molecules)

Mock paper 3 (8 decks)

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