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Enzymes Flashcards

1
Q

What is metabolism

A

All the chemical reactions happening in an organism’s body.

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2
Q

What is a metabolic pathway?

A

A sequence of enzyme-controlled reactions, where the product of one reaction becomes the reactant of the next.

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3
Q

What are anabolic reactions?

A

Reactions that build up molecules.

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4
Q

What are catabolic reactions?

A

Reactions that break down molecules

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5
Q

What is a catalyst?

A

A chemical that speeds up the rate of chemical reactions without undergoing permanent changes or being used up

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6
Q

What is an enzyme?

A

A globular protein that acts as a biological catalyst.

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7
Q

What is the turnover number of an enzyme?

A

The number of reactions per second that an enzyme can catalyze.

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8
Q

Why is the tertiary structure of enzymes important?

A

It determines the shape and function of their active site.

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9
Q

What is the active site of an enzyme?

A

The specific 3D shape site on the enzyme molecule where the substrate binds by weak chemical bonds.

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10
Q

Where is the active site located in the enzyme mechanism diagram?

A

The active site is the region where the substrate fits and binds with the enzyme, forming the enzyme-substrate complex.

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11
Q

What is the primary structure of an enzyme?

A

The sequence of amino acids in a polypeptide chain. Determined by the gene encoding the enzyme.

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12
Q

What type of bonds stabilize the secondary structure of an enzyme?

A

Hydrogen bonds, forming alpha-helices or beta-pleated sheets.

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13
Q

What interactions contribute to the tertiary structure of an enzyme?

A

Hydrogen bonds, ionic bonds, and disulfide bonds, creating the overall 3D shape.

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14
Q

What is quaternary structure (in proteins)?

A

The arrangement of multiple polypeptide chains (subunits) in a protein complex. Many enzymes exhibit this.

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15
Q

What type of protein are enzymes generally classified as?

A

Globular proteins; they are typically spherical and soluble in water.

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16
Q

What type of bond links amino acids together?

A

Peptide bonds

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17
Q

What is the active site of an enzyme?

A

The specific region on an enzyme where the substrate binds and the catalytic reaction occurs

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18
Q

Where do extracellular enzymes function?

A

Outside the cell; they are secreted via exocytosis.

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19
Q

Where are intracellular enzymes found?

A

Inside the cell; they can be free in the cytosol or membrane-bound.

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20
Q

What type of R-groups contribute to enzyme solubility?

A

Hydrophilic R-groups (water-loving side chains)

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21
Q

What is an enzyme?

A

A biological catalyst (protein) that speeds up chemical reactions without being consumed. They are highly specific to their substrates.

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22
Q

What is a substrate?

A

The molecule(s) upon which an enzyme acts. The substrate undergoes a chemical change during the reaction

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23
Q

What is the active site?

A

The specific region on the enzyme where the substrate binds. Its shape is crucial for enzyme specificity.

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24
Q

Describe the Lock and Key Model.

A

A simple model explaining enzyme-substrate interaction. The enzyme’s active site (lock) has a specific shape that only fits a particular substrate (key)

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25
How does the lock and key model explain enzyme specificity?
The complementary shapes of the active site and substrate ensure that only the correct substrate can bind, resulting in high enzyme specificity.
26
Define Enzyme Specificity.
An enzyme's ability to catalyze only a specific reaction with a specific substrate. This is due to the unique shape and chemical properties of its active site.
27
What does "complementary" mean in the context of the lock-and-key model?
The enzyme's active site and the substrate have shapes that fit together precisely, like a lock and key
28
What does "specific" mean in the context of enzyme-substrate interactions?
The enzyme only binds to one (or a very limited number of) specific substrates.
29
Describe the binding process in the lock-and-key model.
The substrate binds to the active site of the enzyme, forming an enzyme-substrate complex. This allows the reaction to proceed.
30
What is the lock-and-key model of enzyme action?
A model of enzyme action where the enzyme's active site has a rigid, pre-existing shape perfectly complementary to the substrate. Binding occurs immediately.
31
What is the induced-fit model of enzyme action
A model of enzyme action where the enzyme's active site is flexible and changes shape upon substrate binding, optimizing the interaction.
32
How do the lock-and-key and induced-fit models differ in terms of enzyme structure?
Lock-and-Key: Rigid. Induced-Fit: Flexible.
33
How do the lock-and-key and induced-fit models differ in terms of active site shape?
Lock-and-Key: Pre-formed, perfectly complementary to substrate. Induced-Fit: Changes shape upon substrate binding.
34
How do the lock-and-key and induced-fit models differ in how the substrate binds?
Lock-and-Key: Immediate. Induced-Fit: Induced by substrate binding.
35
What is the primary experimental evidence supporting the induced-fit model?
X-ray crystallography showing conformational changes in enzymes upon substrate binding; Kinetic studies supporting the dynamic interaction.
36
What is a major limitation of the lock-and-key model?
Limited evidence; considered an oversimplification; doesn't account for enzyme flexibility.
37
Give an example of an enzyme whose function is well explained by the induced-fit model.
Lysozyme; Its structure changes upon binding to its substrate, facilitating the reaction. (A diagram would be helpful here – you could draw one or find a suitable image online)
38
Comparing and contrasting 2 graphs: start
1. Which starts with the highest amount? Data -> what’s the difference quote/data 2. Gradient- which is steeper (most rapid increase/decrease)
39
Comparing and contrasting 2 graphs: middle
1. What is the highest/ lowest points reached for each? 2. What does the gradient do in the middle? Which is the most rapid increase/decrease/stay constant 3. Is the trend/pattern fluctuating?
40
Comparing and contrasting 2 graphs: end
1. Which is the highest amount at the end? 2. What is the gradient doing here for each graph?
41
What is an immobilised enzyme?
Enzyme molecules bound to an inert material, over which substrate molecules can move
42
How are immobilised enzymes structures?
A) the enzymes can be fixed, bound, or trapped on sodium alginate beads or cellulose microfibrils. B) the beads are then packed into glass columns C) the substrate is added at the top of the column and as it trickles down the substrate it forms E-S complexes with then enzyme active sites in the bead surface inside the bead (and can diffuse into the bead)
43
Explain why smaller beads give a faster rate of reaction
Larger SA:Vol ratio, More SA exposed, more enzyme active site exposed
44
Explain why enzymes immobilised in heads have a lower rate of reaction than those immobilised on a membrane surface
Takes time for substrate to diffuse into bead
45
Why are enzymes widely used in industry
Because they have a higher turn-over number, are very specific and are more economical because they work at lower temps compared to inorganic catalysts
46
Stare the advantage of using immobilised enzymes
Doesn’t contaminate end products Beads stabilises them for use in industry- protecting from extreme ph & temp changes
47
How can temp affects rate of enzyme controlled reactions
Too high can denature enzymes & break bonds holding the enzyme structure. Low temps slow down reactions by reducing kinetic energy if molecules OPTIMAL TEMPERATURE
48
How can substrate conc affect rate of enzyme controlled reactions
Less substrate increases the reaction rate as more substrate is available to bind to the enzyme. Once all the enzyme active sites are occupied, adding more substrate won’t increase the rate
49
How can PH affect rate of enzyme controlled reactions
Each enzyme has optimal PH; extreme PH levels can denature it
50
How can enzyme conc affect rate of enzyme controlled reactions
More enzymes mean more active sites available to speed up reactions, provided there’s enough substrates. If substrate is limited, enzyme conc won’t have affect
51
How can inhibitors have an affect on enzyme controlled reactions
Competitive inhibitors compete with the substrate for the enzymes active site, slowing rate of reaction. Non-competitive inhibitors bind to another part of the enzyme, changing its shape & making it less effective
52
Describe a graph about the effect of temperature on enzyme action
As temp increases, rate of reaction increases up until 40°c, which is the optimal temperature. After this point, as temp increases, rate of reaction decreases until it stops at ..
53
Explain the graph
High temp= kinetic energy increases with frequency of collisions when moving faster, more ES complexes formed (faster rate). Reach optimum temps, enzymes at maximum turnover rate. Increased temp breaks H+ bonds, causing enzymes to denature (active site changes shape) & no longer complementary to substrate
54
Give 3 reasons why our body temp is 37°c not 40°c
Enzymes work best at 37°c. Higher temps denature enzymes optimum. Lee-way for temp to increase when sick (fever)/ exercise Eat regular amount
55
Every 10°c the rate of reaction _____?
Doubles
56
Why do reactions stop at very low temperature
Insufficient energy for collisions Enzymes inactivated due to molecules having very low kinetic energy and can’t form ES complexes
57
What is the lowest structure of a a protein that will be unaffected by desaturation.? Explain the answer
Primary structure No H bonds
58
What is PH. Give example
Measure of the H ion conc of a solution. It is an inverse relationship. I.e acids have a high free H ion conc and therefore a low PH
59
What does small PH changes around the optimum cause
Small reversible changes in enzyme structure and reduced activity, but extremes of PH change during denaturatuon
60
Explain acid/ alkali H+ ion link
Acids= H+ donators Alkalis= OH- donators, H+ acceptors

Biology (13 decks)

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