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OCR BIOLOGY (MODULE 2) > ENZYMES > Flashcards

ENZYMES Flashcards

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1
Q

Define active site

A

Indented area on surface of enzyme molecule

Complementary shape to substrate molecules

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2
Q

Define catalyst

A

Chemical that speeds u the rate of reaction and remains unchanged and reusable at the end of the reaction

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3
Q

Define metabolism/metabolic

A

Chemical reaction that takes place inside living cells or organisms

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4
Q

Define product

A

Molecule produced from substrate molecule by an enzyme

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5
Q

Define substrate

A

Molecule that is altered by an enzyme catalysed reaction

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6
Q

Define metabolites

A

Reactants immediate and products in enzyme controlled reactions

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7
Q

What type of protein are enzymes?

A

Globular

Shape determined by tertiary structure

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8
Q

What does intracellular mean?

A

Enzymes work inside cells, most catalysing reactions that occur in series

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9
Q

What does extracellular mean?

A

Enzymes work outside the cells, catalysing hydrolysis reactions to break down macromolecules into small, soluble molecules that can be absorbed `

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10
Q

What is an example of intracellular enzymes?

A

Catalase protects cell from damage by reactive oxygen by breaking down hyperovide into water and oxygen

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11
Q

What is an example of extracellular enzymes?

A

Amylase- salivary glands, digest starch into maltose
Trypsin- pancreas acts in lumen of small intestines to digest proteins into smaller peptides by hydrolysing peptide bonds

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12
Q

How do enzymes work?

A

Speed up metabolic reactions
Enzymes make substrates into products and the reactions are either:
Catabolic- substrates broken down
Anabolic- substrate joined to form larger product

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13
Q

What does lactase break down into?

A

Glucose and galactose monomers

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14
Q

What does catalase break down down?

A

Hydrogen peroxide to water and oxygen

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15
Q

What is rubisco catalyse?

A

Binding of carbon dioxide to ribulose biphosphate in plants

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16
Q

What is activation energy?

A

Energy stored in bonds between atoms
Allow reactions= bonds break
Activation energy required

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17
Q

How is an anabolic reaction started?

A

If two molecules need to be joined, attaching to the enzyme holds them close together, reducing any repulsion between the molecules so they can bind more easily

18
Q

How is a catabolic reaction started?

A

If enzyme is catalysing a breakdown reaction, fitting into active site puts strain on bonds in substrate
Strain means substate molecule breaks up more easily

19
Q

What is meant by lock and key?

A 
Complementary shape of active site and substrate molecule are like lock and key 
Enzyme + substrate enters active site 
Enzyme-substrate complex 
Enzyme-product complex 
Product
(older model)
20
Q

What its mean by induced fit?

A 
Enzymes active site changes slightly upon collisions, active site fits closer to substrate 
Substate entering active site or enzyme 
Enzyme-substrate complex 
Enzyme-product complex 
Product leaving active site or enzyme
21
Q

What is the kinetic energy and collision theory?

A
  1. KE means collisions happen at random
  2. as fluid heated= more KE= molecules move faster= more frequent collisions
  3. collisions occur with more energy (travelling faster) so collide with a greater force
  4. enzyme-substrate complexes only form when substate molecules collide with active site of enzyme
  5. if KE of both molecules has increased, there will be more collisions= increase rate of reaction and more product formed
22
Q

What is denaturation?

A

Where the tertiary structure of enzyme is changed to the point that the enzyme doesn’t work

23
Q

What is the effect of heating?

A
  • molecules vibrate, vibrations strain bonds holding molecule together
  • vibrations can break hydrogen and ionic bonds
  • said bonds are vital in keeping active site shape and tertiary structure
  • as heat increases, more bonds break and thus lowers the rate of reaction
24
Q

What is the formula for working out the rate of reaction?

A

1/time taken to reach end point

25
Q

What does the temperature coefficient refer to?

A

The increase in the rate of a process when the temperature is increased by 10 degrees
Q10= rate of reaction (T+10) degrees/rate of reaction at T-degrees

26
Q

What does pH measure?

A

Measure of H+ ion concentration
Higher the H+ ion concentration, the lower the pH value
H+ ions affect the ionic and hydrogen bonds in tertiary structure because of their piste charges
0-6= acidic (low pH)
8-14= alkali (high pH)

27
Q

What are buffers?

A

Resist changes in pH

28
Q

Whats the affect of pH on enzymes

A

Higher the H+ ion concentration the lower the pH value

H+ ions affect the ionic and hydrogen bonds in the tertiary structure because of the positive charge

29
Q

Explain optimum pH on enzymes

A

Max rate of reaction

Concentration of H+ ions gives the tertiary structure the best shape- complementary active site to substrate shape

30
Q

Explain pH and denaturation on enzymes

A

Minor changes don’t denature enzymes, the bonds are disrupted bu can reform if the pH returns to the optimum
Denaturation only occurs in extreme pH changes away from the optimum

31
Q

Define a cofactor

A

Aids certain enzymes as some will only work with a non protein substance bound to them

32
Q

Explain an inorganic cofactor

A

Not permanently bound to the enzyme
Help enzyme and substrate bind together, increasing rate of reaction
Don’t participate in reactions so aren’t used up or changed

33
Q

Explain organic cofactors

A

Small non protein molecules that bind temporarily to active site
Take part in reactions and are changed in some way
Recycled and used again

34
Q

Define enzyme inhibitors

A

Substance or molecule that slows down rate of reaction

Their effects can be reversible or irreversible

35
Q

How do strength of bonds determine if an inhibitor is reversible or irreversible

A

Covalent- can’t be easily removed, irreversible

Hydrogen/ionic- weaker, able to be removed, reversible

36
Q

Explain a competitive inhibitor

A

Similar shape to substrate
Compete with substrate to bind to active site, no reaction takes place
Block active site
High conc of inhibitor will take up nearly all the active sites

37
Q

Explain a non-competitive inhibitor

A

Bind to molecule away from active site- region known as allosteric site
Causes change to tertiary structure
Causing active site to change shape so substate can’t bind to it
Decreases rate of reaction
Increasing conc of inhibitor will make no difference as enzyme will still be inhibited

38
Q

How do medicinal drugs work

A

Exploit enzymes to treat illnesses and location they are applied to

39
Q

Briefly state and explain some drugs and their functions

A

Aspirin- salicylic acid binds to enzymes to form prostaglandins, lack of prostaglandins means nerve cells and muscle tissues are less sensitive
ATPase inhibitors- Inhibit NA-K pump in cell membranes of heart cells, allowing calcium to enter, calcium increases muscle contractions which strengthens heart beat

40
Q

Explain metabolic poisons

A

Interfere with metabolic reactions causing damage or illness
Cyanide- noncompetitive- inhibits cytochrome C (catalyses respiration reactions)
Malonate- competitive- succinate dehydrogenase (catalyses reparation reactions)

41
Q

What is venom

A

Mixture of toxins and different enzymes
E.g:
Phosphodiesterase- interferes with heart causing drop in blood pressure
ATPase- breaks down ATP, disrupts prey’s use of energy

OCR BIOLOGY (MODULE 2) (6 decks)

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