Proteins

Question 1

what are H bonds in the tertiary structure of a protein between

Answer 1

Between the polar R groups (between the Oxygen and Hydrogen atoms)

Question 2

What are disulphide bonds between in the tertiary structure of a protein

Answer 2

covalents bonds between sulphurs in the R group of the amino acid Cysteine

Question 3

Ionic bonds in tertiary structure?

Answer 3

Between positive and negatively charged R groups of amino acids

Question 4

Hydrophobic interactions in the tertiary structure ?

Answer 4

Hydrophobic interactions between non polar R groups which typically cluster together toward the centre of the molecule (to avoid water)

Question 5

what allows a protein to perform its role

Answer 5

Its shape

Question 6

why do enzymes active site denatured under heat?

Answer 6

Heating increases Ek of molecules. Vibrate more. Break some of the bonds( which are quite weak e.g H bonds) holding tertiary structure together. 3D shape unravels. Permanently denatured so cant perform

Question 7

Prosthetic groups?

Answer 7

‘non protein bits’ bonded to proteins e.g 4 haem groups (iron ions) in haemoglobin

Question 8

example of a transport protein?

Answer 8

haemoglobin

Question 9

What amino acid makes up 35% of collagen

Answer 9

Glycine, every third amino acid

Question 10

A reason collagen is so strong?

Answer 10

Cross links of covalent between collagen molecules for fibres= strength

Question 11

Structure of collagen

Answer 11

Tripple helix of 3 identical strands

Question 12

Lock and key model

Answer 12

Active site of a SPECIFIC shape, COMPLEMENTARY to substrate. They bind, ENZYME SUBSTRATE COMPLEX formed. Product is released. Active site reverts

Question 13

Induced fit model e.g lysozyme

Answer 13

Substrate COLLIDES with/ apporaches active site. Active site CHANGES SHAPE to fit substrate. ENZYME SUBSTRATE COMPLEX formed. Change in enzyme shape places STRAIN on bonds in substrate, weakening them, REDUCING activation energy. Products dont fit active site, therefore diffuse away

Question 14

catalyst?

Answer 14

substance that speeds up a reaction, without being used up

Question 15

why is the induced fit model better?

Answer 15

enzymes arent rigid structures, the enzyme-substrate complex slightly changes shape, ensures tighter bonding in the active site

Question 16

denature

Answer 16

H bonds are broken causing the active site to change shape permanently so the substrate can no longer fit in it

Question 17

what holds the substrate on place in the active site?

Answer 17

Oppositely charged groups on the amino acids in the active site

Question 18

catabolic reactions

Answer 18

Hydrolysis of larger molecules into smaller e.g polypeptide to amino acids

Question 19

anabolic reactions?

Answer 19

Condensation of smaller molecules into larger e.g monosaccharides into disaccharides

Question 20

intracellular enzymes?

Answer 20

Remain inside cells to function e.g respiratory enzymes, like glucose isomerase. There is intracellular in solution or membrane-bound

Question 21

extracellular enzymes?

Answer 21

enzymes secreted from cells (by exocytosis) to function elsewhere e.g digestive enzymes like amylase

Question 22

enzyme turnover number?

Answer 22

Maximum number of substrate molecules an enzyme can convert to products per unit time

Question 23

Activation energy?

Answer 23

Minimum energy required to enable a chemical reaction to occur

Question 24

Lysozyme?

Answer 24

Induced fit enzyme: antibacterial as it hydrolysis the carb peptidoglycan in bacterial cell walls