proteins and proteins as enzymes

Question 1

what are enzymes

Answer 1

biological catalysts

Question 2

what type of protein are enxymes

Answer 2

globular

Question 3

metabolic pathways

Answer 3

controlled by enzymes in a biochemical cascade of reactions

virtually every metabolic reaction is catalysed by an enzyme

Question 4

intra vs extracellular

Answer 4

active inside or outside the cell

Question 5

how do extracellular enzymes catalyse reactions outside cells

Answer 5

secreted by cells

Question 6

monomer of proteisn

Answer 6

amino acids

Question 7

bond formed between amino ocids

Answer 7

peptide bond

formed when a hydroxide is lost from carboxyl group and hydrogen of another lost from amine group

releases water
condensation

Question 8

3 groups in amino acids

Answer 8

amino group
carboxyl
repeat chain

Question 9

dipeptides are

Answer 9

formed by two amino acids

Question 10

polypeptides are

Answer 10

formed by many amino acids

Question 11

four levels of protein structure

Answer 11

primary
secondsary
tertiary
quaternary

Question 12

primary structure

Answer 12

sequence of amino acids bonded by peptide bonds

DNA determines the sequence of amino acids

Question 13

secondary structure how does it occur

Answer 13

occurs when a weak negatively charged nitrogen and oxygen atoms interact with the weak positive hydrogen atoms - forming hydrogen bonds (because they are coiled/ sheets)

Question 14

when does an alpha helix occur

Answer 14

hydrogen bonds form between every fourth peptide bond

Question 15

beta pleated sheet occurs when

Answer 15

protein folds so that 2 parts of the polypeptide are parallel

allowing hydrogen bonds to form between the parallel chains

Question 16

how to break hydrogen bonds

Answer 16

high temperatures and PH changes

Question 17

what does secondary structure only refer to

Answer 17

the formation of hydrogen bonds

Question 18

how does tertiary structure occur

Answer 18

additional bonds form between the R groups

additional bonds are
hydrogen
disulphide
ionic
weak hydrophobic interactions

Question 19

how do Quaternary structures occur

Answer 19

proteins that have more than one polypeptide chain working together as a macro molecule

Question 20

disulphide bonds

Answer 20

strong covelant
form between cystine repeat groups
strongest in proteins but less frequent

Question 21

how top break disulphide bridges

Answer 21

broken by reduction

Question 22

ionic bonds

Answer 22

between positive amine and negative carboxyl groups

stronger than hydrogen bonds but less frequent

Question 23

hydrophobic interactions how do they form

Answer 23

form between non polar R groups

Question 24

biuret test for proteins

Answer 24

sample is treated with sodium to make it alkaline

copper sulphate (blue) added to sample

or scrap both steps and add biurets which already has those in

colour goes from blue to lilac

might need white tile as subtle colour change

only shows as present if there is two or more peptide bonds present - only works in polypeptides

Question 25

globular proteins structure

Answer 25

spherical compact soluble in water often have prosthetic group eg haemoglobin

Question 26

why are globular proteins soluble

Answer 26

non polar groups orient away from surroundings polar groups orient twoards surroundings

Question 27

importance of soluble globular proteins

Answer 27

can be easily transported around organisms and be involved in metabolic reactions

Question 28

friborous proteins

Answer 28

long strands of polypeptide chains insoluble strong and suitable for structural roles eg. collagen

Question 29

how enzymes work (catabolic)

Answer 29

active site is complomentary to substrate substrate binds to active site active site morphs around substrate enxyme substrate complec formed substrate is broken into two products

Question 30

anabolic enzyme reaction

Answer 30

2 substrate enters active site one substrate product formed

Question 31

how do enzymes work

Answer 31

provide an alternate path of lower activation energy allowing more products to be formed

Question 32

how could you measure enzyme activity

Answer 32

oxygen measured in gas syringe amylase in spotting tile - blue-black iodine solution

Question 33

affect of temperature on rate

Answer 33

lower temperatures slow reactions down less KE - less e-S formation enzyme and substrate collide with less energy so less likely to create bonds higher temps increase KE Enzyme begins to denature - hydrogen bonds in the enzyme begin to break apart tertiary structure (active site) of enzyme breaks apart substrate can no longer bind

Question 34

effect of PH on rate

Answer 34

acidic or alkali solutions denature enzymes hydrogen and ionic bonds are broken apart by excess OH / H+ alters active site shape denatured

Question 35

to measure effect of pH

Answer 35

use buffer solutions with different pHs they maintain this pH even during reaction

Question 36

PH equation

Answer 36

pH = -log₁₀ [H⁺]

Question 37

Rate: Enzyme Concentration

Answer 37

more enzymes = more active sites available more likelyhood of e-s if substrate is infinite then =rate increases linearly if finite then it will level out as all substrates used up

Question 38

Rate: Substrate Concentration

Answer 38

the more substrate , the more reaction enzyme is limiting factor active sites become saturated and any more substrate will not increase rate