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IB Biology > C1 > Flashcards

C1 Flashcards

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1
Q

Catalyst

A

Substance that increases rate of chemical reactions without being used up

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2
Q

Metabolism

A

Set of interacting and independent chemical reactions that happen in the body

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3
Q

Active site

A

Region of an enzyme where substrate molecules bind. Formed by tertiary folds of proteins to create unique shape with exposed R groups that are chemically compatible with substrate

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4
Q

Substrate

A

Reactant in the enzyme-catalysed reaction/initial chemical that binds to the active site and is transformed into a product

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5
Q

Induced-fit model

A

Idea that shape of an active site/enzyme can be adjusted to fit bonding. They need to be chemically compatible but not an exact fit

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6
Q

Activation energy

A

Energy needed to get reactants into a transition state by breaking existing bonds

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7
Q

Enzyme-substrate complex

A

Temporary molecule formed when a substrate bunds to an enzyme’s active site. Complex must form for bonds in a substrate to be broken and a reaction in progress.

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8
Q

Enzyme-substrate specificity

A

Each enzyme acting on one or a group of specific substrates that are chemically compatible with the active site of that enzyme may

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9
Q

What makes enzymes unique to other catalysts?

A

Made up of protein and within a living organism

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10
Q

How does the shape of a globular protein make them ideal for acting as enzymes

A

Folded complex spherical shape allows for folding to create specific grooves that have R groups exposed that are chemically attracted to the substrate

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11
Q

How do enzymes affect activation energy?

A

Lower activation energy by breaking bonds which means less energy is required to progress. This means reactions can occur more quickly and spontaneously (ie increasing rate of reaction)

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12
Q

Exergonic reaction

A

Released energy stored in reactants

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13
Q

Endergonic resctions

A

Consume energy to produce higher energy products

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14
Q

Anabolic reactions / anabolism

A

Two or more substrates to create one product

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15
Q

Catabolism / catabolic reaction

A

One substrate -> two or more products

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16
Q

Examples of anabolic enzymes

A

DNA and RNA polymerase
ATP synthase

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17
Q

What does the induced fit model allow that the lock and key model doesn’t?

A

Allows the substrate to be a group and allows for regulation by inhibitors

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17
Q

Example of catabolic reaction

A

Enzyme = sucrase. Breaks the bonds of sucrose, making the substrate reactive and increasing the reaction race. Produces fructose and glucose

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18
Q

Example of endergonic reaction

A

Photosynthesis

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19
Q

Role of enzyme

A

Lower activation energy

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20
Q

Example of exergonic reaction

A

Respiration

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21
Q

Collision theory

A

Substrate and enzyme must collide and in the correct orientation for substrate to be chemically aligned to bond to active site

22
Q

Denaturation

A

Temporary shape change of proteins due to extreme environments that break weak bonds

23
Q

What role does molecular motion play in enzyme activity?

A

Motion provides an opportunity for substrate to collide into an enzyme

24
Q

How can enzymes and substrates be immobilised to increase activity?

A

Can work well to have one stationary well-placed active site and a moving substrate (or vice versa)

25
Q

How does temperature impact the effectiveness of enzymes?

A

Increased temperature = increased kinetic energy = more successful collisions = increased reaction rate. At very high temperatures, weaker bonds in the tertiary structure of an enzyme can break and denaturation occurs

26
Q

How can rate of a reaction be measured?

A

Disappearance of a reactant or appearance/accumulation of product

27
Q

What is the optimum temperature for organism?

A

Different for each organism

28
Q

What is the optimum temperature

A

Temperature with highest rate of reaction

29
Q

What is the effect of pH on enzymes?

A

Below optimum pH = excess H+ ions can disrupt ionic bonds of an enzyme, so the active site changes shape and the substrate can no longer bond. Above optimum temperature and the same thing happens with OH- ions above pH.

30
Q

Optimum pH of enzymes

A

Usually ~7 but exceptions

31
Q

Optimum pH of pepsin

A

2

32
Q

Effect of substrate concentration on enzymes

A

Increases rate of reaction until saturation point, where the maximum rate of reaction is reached as all active sites are occupied and cannot act at a faster rate

Assuming that the concentration of enzymes is fixed

33
Q

Equation to measure rate of enzyme reactions

A

Change in product / change in time

34
Q

Multi enzyme complexes

A

Multiple enzymes located close to one another to work on one metabolic pathway

35
Q

Inhibitor

A

Molecule that temporarily binds to an enzyme, halting activity while the inhibitor is bound

36
Q

Allosteric site

A

2nd key site on an enzyme that can be used for regulation or to (in)activate an enzyme

37
Q

Feedback inhibition

A

Inhibitors as products to prevent them working when not needed

38
Q

Difference between an intracellular and extra cellular enzyme-catalysed reactikn

A

Intra = inside cells
Extra = secreted outside cells

39
Q

Why is heat loss from metabolic reactions useful for endotherms?

A

Heat loss stays in the body therefore can be used to maintain constant internal temperature

40
Q

Difference between a linear and cyclical metabolic pathway

A

Linear = no recycling of reactants

Cyclical = some reactants are recycled during reactions

41
Q

How do statins act as an inhibitor

A

Medication to reduce high cholesterol by acting as a competitive inhibitor, binding to active site of the enzyme that synthesis cholesterol

42
Q

Example of a linear pathway

A

Glycolysis

42
Q

Competitive inhibition

A

Inhibitor blocks active site by occupying it. Therefore, the substrate cannot enter. Temporary

43
Q

Examples of cyclical pathway

A

Krebs Cycle

44
Q

What happens to competitor inhibitors when substrate concentration is increased

A

Less inhibition as competing

45
Q

Non competitive inhibition

A

Inhibition binds to allosteric site which changes the shape of the active site, so the substrate cannot hind.

Temporary

46
Q

Effect of substrate concentration on non-competitive inhibition

A

None

47
Q

Example of non-competitive inhibition

A

Cyanide poisoning, binds to last step enzymes in cellular respiration

48
Q

What is end product inhibition

A

When the end product of a reaction acts as an inhibitor for the first enzyme

49
Q

General type of end product inhibition

A

Non-competitive

50
Q

Threonine to isoleucine pathway

A

Threonine -> intermediate -> intermediate -> intermediate->
intermediate
-> isoleucine

51
Q

How does end product inhibition work for the threonine-isoleucine pathway?

A

Excess isoleucine (from pathway build up or diet) binds to the allosteric site of the first enzyme, which stops the pathway. When isoleucine levels are low, it is removed from the allosteric site and the pathway starts again

52
Q

Benefits of end product inhibition with threonine- isoleucine pathway

A

Natural regulation of levels
Binds to first enzyme so unnecessary intermediates are not used

IB Biology (10 decks)

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