enzymes new

Question 1

enzymes definition

Answer 1

biological substances
- usually protein molecules made by living cells

Question 2

catalyst definition

Answer 2

• substance which speeds up a chemical reaction without itself being chemically changed at the end of the reaction

Question 3

how may enzymes should a typical human cells have?

Answer 3

several thousands

Question 4

enzymes purpose

Answer 4

catalyse a vast number of chemical reaction at temperature suitable for living organisms

Question 5

hydrolase types: (3)

Answer 5

carbohydrases
protease
lipase

Question 6

carbohydrases purpose

Answer 6

• digests carbohydrates
• hydrolysis of glycosidic bonds
  eg:
• salivary amylase in the mouth
• pancreatic amylase int he pancreas
• cellulase digests cellulose

Question 7

protease purpose

Answer 7

digests proteins
hydrolysis of peptide bonds
eg:
- pepsin in the stomach

Question 8

lipase purpose

Answer 8

digests lipids
hydrolysis of ester bonds
eg:
- lipase in pancreatic juice

Question 9

enzymes can be found…

Answer 9

• inside (intracellular)
• outside (extracellular)

Question 10

intracellular enzymes

Answer 10

• in the nucleus
• attached to the plasma membrane
• inside membranous organelles

Question 11

extracelullar

Answer 11

• enzymes that are produced by the cell but are pakaged to be secreted from the cell and work externally
  eg: digestive enzymes

Question 12

substrate definition

Answer 12

chemical which an enzyme work on
eg: starch

Question 13

enzyme + substrate

Answer 13

• binding of substrate to the active site of the enzyme is brief and reversible
• no covalent bond formation
• the proximity of the enzyme with the substrate in the complex greatly increases the chances of a reaction occurring

Question 14

example of enzyme + substrate

Answer 14

enzyme: protease
substrate: protein
reaction: protease breaks peptide bonds in the protein
products: amino acids
hydrolysis where water is used to break bonds

Question 15

enzyme substrate complex

Answer 15

• enzyme and substrate are in random motion
• substrate must collide with the active site of the enzyme at the correct orientation and with sufficient energy to form the ES complex
• short livid
• the faster the speed of reaction, the more ES complexes are formed per unit time

Question 16

enzyme product complex

Answer 16

• after the enzymatic reaction, ES complex is converted to EP complex
• short livid

Question 17

enzyme + product

Answer 17

• EP complex dissociates to form enzyme and product
• enzyme remains unchanged at the end of the reaction and is free to interact with other substrate molecules

Question 18

enzyme pathway

Answer 18

1) the binding of a substrate to an enzyme to form an enzyme substrate complex
2) the conversion of ES to the enzyme product complex
3) the release of the product from EP, to yield free p and fee e
4) E+S and ES is in equilibrium because when the collision partners form an activated complex, they might not go on and form products
- instead, the may fall apart back to the reactants

Question 19

types of metabolism

Answer 19

• anabolic reactions
• catabolic reactions

Question 20

anabolic reactions

Answer 20

• use a simpler molecules to synthesise complex substances
• use energy harnessed from catabolic activities
  eg: formation of muscle/bone tissues
  eg: skin regeneration
  like condensation

Question 21

catabolic reactions

Answer 21

• breaks down complex food substances into small simpler molecules
• generates a useful form of energy for the cell
  eg: cell respiration
  eg: breakdown of hydrogen peroxide to water and oxygen via catalse action

Question 22

anabolic definition

Answer 22

• cells build up or synthesise complex substances from simpler ones

Question 23

catabolic reaction

Answer 23

• cells break down complex substances to simpler substances

Question 24

slide 16-17

Question 25

enzyme properties (6)

Answer 25

1. enzymes are globular proteins 2. enzymes are coded for by DNA 3. enzymes are highly efficient 4. enzymes are highly specific 5. catalysed reaction is reversible 6. enzyme activities are affected by multiple factors

Question 26

enzymes are globular protiens

Answer 26

- soluble in water - due to hydrophilic R groups of amino acid residues on the exterior surface of the enzyme molecules - usually involved in metabolic

Question 27

enzymes are coded for by DNA (go through)

Answer 27

- genes code for proteins including enzymes - cells which do not have a gene which codes for a specific enzyme will not be able to produce that enzyme

Question 28

enzymes are highly efficient

Answer 28

- a very small amount of enzymes bring about the change of a large amount of substrate - this is because they remain unchanged in the reaction they catalyse - the same enzyme molecule can be used over and over again

Question 29

enzymes are highly specific

Answer 29

- generally catalyse only a single - some enzymes are specific to a group of substrates with similar chemical groups, bonds, or moieties - due to specific 3D configuration of its active site that is compatible to specific substrate structures

Question 30

catalysed reaction is reversible

Answer 30

- enzymes can catalyse both the forward and reverse reactions. - direction of reaction depends on the concentration of reactants and products - enzymes always catalyze the reaction in the direction of equilibrium

Question 31

enzymes activities are affected by multiple factors

Answer 31

- enzymes work best at optimum pH and temperature - enzyme can be denatured at extreme pH or temperature - as the enzyme concentration is increased, so will be the rate of the enzyme reaction - increasing enzymatic activity by increasing substrate will eventually be limited by the amount of enzyme available

Question 32

enzyme incr rate of reaction by decr activation energy of reaction

Answer 32

slide 25

Question 33

active site

Answer 33

- active sites are depressions or "pockets" on the surface of an enzyme molecule into which the substrate can fit - the amino acid R groups that form the active sites are arranged to interact specifically with the substrate in an attractive manner - only small portion of the enzyme molecule (ranging from 3 to 12 amino acid residues) into direct contact with the substrate - the enzyme's active site is complementary in shape to its substrate

Question 34

activation energy explained

Answer 34

- energy required to make the substances react - the greater the activation energy, the slower the reaction at any particular temperature - if the activation energy of a reaction decreased, the rate of reaction would be increased

Question 35

lock and key concept

Answer 35

- substrate is a key whose shape is complementary to the enzyme/lock - active site has the specific shape - once product is formed, the products no longer fit the active site and escaped into the surrounding medium, leaving the active site free to receive other substrate