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Biology > Enzymes (1st year) Topic 4 > Flashcards

Enzymes (1st year) Topic 4 Flashcards

1
Q

What is an enzyme?

A

An enzyme is a protein catalyst which speeds up the rate of a specific biological chemical reaction.

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2
Q

What is a catalyst?

A

A catalyst is a substance increases the speed of a chemical reaction.

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3
Q

Therefore,what can we call enzymes?

A

Biological catalyst which speed up chemical reactions taking place in the body.

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4
Q

Without enzymes,the reactions taking place inside of the body would be too slow to maintain life. So what is another role that enzymes have?

A

They serve to reduce the ammount of energy needed for a chemical reaction to take place.

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5
Q

What are the reactions inside all of the cells called?

A

Metabolism

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6
Q

What are the 2 types of metabolism and give examples.

A

Catabolism and Anabolism.

Catabolism : biological chemical reactions which break things down. For example: Glucose is broken down into carbon dioxide and water to produce energy.

Anabolism: biological chemical reactions which build things up. For example: Glucose is built into glycogen for storage

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7
Q

Mention some properties of enzymes

A

1) Enzymes are highly specific because they work on a particular substrate
2) All enzymes are protein because they are coded by DNA.
3) Catalysists: increase the rate of a reaction without being used up so they can be used over and over again.
4) The activity of enzymes can be influenced by their environment : ph,temperature,availability of coenzyme molecules (vitamins),substrate concentration or enzyme concentration
5) The catalysed reaction is reversible

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8
Q

What do we call an enzyme + substrate?

A

Enzyme substrate complex

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9
Q

What is the substance on which an enzyme acts on?

A

Substrate

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10
Q

Name the part where the chemical reaction takes place on the enzyme.

A

Active site.
The active site is made up of amino acid side chains which give the enzyme a 3D dimensional shape,this is what makes enzymes highly specific.

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11
Q

What is the concept that enzymes work by?

A

The Lock and key concept

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12
Q

Which is the “lock” and which is the “key”?

A

The enzyme is the “lock” and the substrate is the “key”. The substrate will fit into the region of the active site

The reaction takes place and the product/s are formed,the enzyme can take up another substrate molecule

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13
Q

What type of fit can we use to describe the chemical reaction taking place

A

The substrate connects with the enzyme in an induced fit,forming the enzyme substrate complex

The substrate will often chnage into the shape of the active site fitting into what we call an induced fit.

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14
Q

What is the enzyme substrate complex converted into?

A

An enzyme product (ES) = (EP)

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15
Q

What exactly happens in catabolic reactions?

A

These types of catabolic enzymes speed up those reactions which beak down large molecules into smaller ones. For example in digestion when maltose is broken down into glucose and glucose

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16
Q

What does the enzyme amylase act upon?

A

Starch to produce maltose

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17
Q

What do we call the new substance/s ?

A

Product/s

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18
Q

Define exactly what happens in anabolism.

A

These are types of enzymes whch speed up the rate of specific biological chemical reactions by gathering small molecules and making them into larger ones. These are usually important to build molecules which are needed by our cells ex: glucose and glucose are build up to make maltose

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19
Q

Distinguish between intracellular and extracellular enzymes.

A

Intracellular enzymes are enzymes: enzymes which have been produced in a cell to be used in the same cell.

Ex: enzymes which have been made in a cell,which are needed for respiration,they will be used in the mitochondria of that same cell.

Extracellular enzymes: enzymes which have have been made in a cell,but are going to be used somwhere else in the body outside of that same cell.

Ex:in the digestive system of animals,extra cellular digestive enzymes are released into the stomach and intestines to figest the food

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20
Q

Where are all enzymes made?

A

In the cells

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21
Q

What is activation energy?

A

The energy needed to form a high energy-intermediate to form a reactant to a product

The reactants do not have the same ammount of energy as the products

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22
Q

What is the transition state?

A

Its when the reaction is taking place but the reactants have not uite fully formed into the products yet.

The reactants need to have a sufficient form of energy in order to be able to overcome the barrier of the transition state between the reactant and the product

23
Q

True or false. enzymes do not change the free energies of the reactants or the products and therefore,do not chnage the equlibrium of the reaction

A

True

24
Q

The higher the activation energy,the slower and harder the chemical reaction would be to occur.

A

True

25
Q

The lower the activation energy,the easier it is for the reactants to overcome the energy barrier to pass over the transition state ,allowing the reaction to occur

A

True

26
Q

How can enzyme activity be regulated?

A

By inhibition or by activating it according to the needs of the cell/body

27
Q

Mention some factors which influence the velocity of an enzymatic reaction.

A

Temperature,ph,substrate concentration,enzyme concentration

28
Q

At what optimum temperature do enzymes work the best in?

A

37-40 degrees celscius

29
Q

What will happen if the temperature is below 37-40? (not the optiumum temperature)

A

The rate of enzyme action is slow (inactive/dormant)

30
Q

What will happen if the temperature increases to 37-40 degrees celsicus?

A

The rate of enzyme reaction is faster. Thereofre,the reaction will taker shorter to finish and occur,because the speed of the reaction increases and the molecules of the reacting substances move faster and come closer together

The enzymes have a lot of kinetic energy

31
Q

What will happen if the temperature rises above 40 degrees?

A

The enzymes become denatured. This is because when the temperature increase the molecules start to move so much that the heat destroys the hydrogen bonds and covalent bonds of the enzyme become destroyed. The active site also becomes destroyed so the enzyme cannot take in the substrate,because the enzyme is denatured. The enzyme has chnaged shape. Proteins are denatured by heat.

32
Q

What is peak temperature?

A

This is the optimum temperature at which enzymes work the best at.

The temperature increases until a peak velocity is reached.

33
Q

Sketch a graph to show this demonstration.

A
34
Q

What do we mean by the term ph?

A

We are referring to the acidicity or alkilinity of a solution.

Furthermore we are referring to the ammount of hydrogen ions present in order for a specific enzyme to work optiumuley.

35
Q

Different enzymes work best in different ph,mention some examples.

A

The enzyme pepsin found in the stomach works best at a ph of 2

The enzyme salivary amylase works best at a neutral ph of 7 in the mouth.

36
Q

True or false. Enzymes become denatured in extreme changes of ph.

A

True.

The active site becomes unfunctional due to the hydrogen bonds being denatured.

37
Q

At which ph do most enzymes work the best in?

A

7

Neutral ph

38
Q

Sketch a graph to show optimum ph for enzymes

A
39
Q

What will happen if substrate concentration is increased? How will it affect the rate of enzyme action?

A

The rate of reaction increases with increasing substrate concentration,HOWEVER up to a maximum limiting value.

Any further increase in substrate concentration will produce no change

40
Q

Explain why it increases up to a point.

A

This is because all of the active sites of the available enzymes present are all occupied by the substrates. The enzyme substrate complex needs to dissociate before it can take up a new substrate.

All the enzymes are in an enzyme substrate complex state.

41
Q

Sketch a graph to prove this

A
42
Q

Explain why increasing enzyme concentration influences the rate of enzyme reaction

A

As the enzyme concentration increases,there are more active sites available. This increases the rate of reaction,therefore making reaction time short.

43
Q

Sketch a graph to show how this happens

A
44
Q

Why does the rate of reaction increase?

A

This is because if a substrate concentration is present,and more enzymes are increasing (enzyme concentration is increasing) the chnace that the molecules will bump into each other is higher,and forming an enzyme substrate complex is higher

45
Q

However why after maximal velocity is reached,adding more enzyme molecules will not increase the rate of reaction.

A

This is because if the enzyme concentration continues to increase, the concentration of substarate might diminish. So then not all enzyme molecules will find a substrate to bind to. So the rate will not increase

46
Q

What are inhibitors?

A

Any substance that can diminish an enzymatic chemical reaction taking place is called an inhibitor

47
Q

Name the 2 types of inhibition

A

Competitive and non-competitve

48
Q

Describe what is reversible inhibition and non-reversibile inhibition

A

Reversible inhibition: inhibitors which bind to enzymes but then dissociate,allowing the enzyme to work again.

Non-reversible inhibition: inhibited enzymes do not re-gain activity (permanent) (inhibitor doesnt dissociate)

49
Q

Define competitive inhibition

A

The inhibtor binds reversibly to the active site that the substrate would normally occupy,therefore the inhibtor is competing with the substrate to occupy the active site.

Inhibtor has the same shape as the substrate

50
Q

How is the effect of a competitive inhibtor stopped?

A

By increasing substrate concentration

51
Q

Define non-competitve inhibition

A

Occurs when the inhibtor and the substrate bind at diffrent sites on the enzyme.

Inhibtor has a diffrent shape

effect on vmax.

Non-competitve inhibition cannot be easily hnaged by increasing substarte concentration

52
Q

How does the non-competitve inhibtor prevent the reaction from occuring?

A

By chnaging the active site’s structure.

53
Q

We can find enzymes in everyday life. For example in industrial processes. Mention some examples where enzymes are used in everyday life.

A

They can be used to make bread,wine,youghurt, cheese

They can be used in biological washing powders. Enzymes do not need very high temperatures to work so electricity is saved. Enzymes break down and dissolve stains on the clothing fabric.

The enzyme rennin is used to make cheese and clot milk

Biology (19 decks)

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