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Mrs Smith S3 -L4/5 Unit 1: Cell biology > 5. Proteins > Flashcards

5. Proteins Flashcards

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1
Q

What is a protein?

A

Chemical in living things that are made of amino acids

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2
Q

Remember SHARE!

What are proteins needed for?

A

Some functions of proteins in the human body can be remembered using the acronym SHARE.

S Structural
H Hormones
A Antibodies
R Receptors
E Enzymes

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3
Q

Which of the following is not a function of protein molecules?
A - Acting as enzymes
B - Carrying chemical messages from one part of the body to another
C - Storing genetic information

A

C - Storing genetic information

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4
Q

Why is the structure of a protein important?

A

Each protein is made of a precise sequence of amino acids and the protein will only work properly if it is the correct shape

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5
Q

A mutration is a change in the base sequence

What would happen to a protein if it had a mutation?

A

A change (mutation) in the base sequence, can cause a change in the amino acids sequence that makes the protein. The protein may be a different shape and not work properly.

The structure is no longer suitable to fufil its function!

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6
Q

Define enzyme

A

Biological catalysts made by all living cells. Made of Protein. “A catalyst is something that speeds up a chemical reaction without being changed itself”.

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7
Q

Which type of substance are enzymes made of?
1. Carbohydrate
2. Fat
3. Protein

A
  1. Protein
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8
Q

How does an enzyme speed up chemical reactions in cells.

A

It lowers the energy needed to start the reaction

Lowers the activation energy!

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9
Q

What it the ACTIVE SITE?

of an enzyme.

A

The part of the enzyme that binds to the substrate.

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10
Q

Define substrate

A

The molecule at the start of the reaction.

The one that will either be broken down of built up

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11
Q

Define complementary

In referance to enzymes

A

“Fits together”. e.g., The active site is complementary to the substrate.

The active site only fits one specific subsrtrate

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12
Q

What is a product(s)

In a enzyme reaction!

A

The molecule(s) produced at the end of the reaction.

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13
Q

What is a degradion reaction?

A

A break down reaction.

The substrate is broken down into two or more products

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14
Q

What is a synthesis reaction?

A

A build up reaction

More than one substrate is built-up into a bigger product

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15
Q

Define enzyme substrate complex

A

The term used when the enzyme has bonded to the substrate.

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16
Q

EXTENTION NAT5 PAST PAPER QUESTION

Q. Describe enzyme action

3 MARKS

A
  • An enzyme is a biological catalyst.
  • Enzymes bind with their substrates at their active
    site. The active site has a complementary shape to the substrate. This allows them to
    fit together.
  • An enzyme-substrate complex forms and the reaction takes place.
  • Product(s) are formed and released by the enzyme. The enzyme can now be used again.
17
Q

Define Optimium

when talking about enzymes

A

Enzymes are most active when given their OPTIMAL conditions. This is the conditions where the enzyme works the best, at its maximum rate.

18
Q

What 4 factors affect enzyme activity

A
  1. Temperature
  2. pH
  3. Substrate Concentraton
  4. Enzyme concentration

The first two are more imortant at your level

19
Q

Describe this graph which shows the effect of temperature on enxyme activity.

A

As the temperature is increased enzyme activity increases to a maximum value at the optimum temperature (around 37oC for most human enzymes). As the temperature is increased above the optimum temperature enzyme activity decreases.

20
Q

Explain why enzyme reactions slow down at very high temperatures

A

At high temperatures the active site changes shape and no longer fits its substrate it is said to be denatured.

21
Q

Describe this graph which shows the effect of pH on enzyme activity.

A
  • Enzymes are also sensitive to pH.
  • The working range of this enzyme wouuld be pH 6 to 10
  • Between pH 6 and 8 the enzyme activity increases to a maximum value at the optimum pH of 8 (for this enzyme).
  • At pH 8 to 10 the enzyme activity decreases.
  • If the pH of this enzymes surroundings are too acid or alkali the shape of the active site will change (It will become denatured, no loger fitting its substrate - this is permanent.
22
Q

Describe the term working range

when talking about the effect of pH on enzyme activity.

A

Each enzyme has an optimum pH but it also has a working range of pH values at which it will still work well.

23
Q

Extenstion question!!!

Can you describe this graph which shows the effect of pH on enzymes involved in digestion?

Clue think of working ranges and where we find each enzyme!

A
  • The enzyme pepsin breaks down proteins in the acidic conditions of the stomach. Pepsin has an optimum of pH 2.5 and a working range of between pH 1-4.
  • Catalase has an optimum pH of 9 and a working range of between pH 7-11.
  • Most other enzymes function within a working pH range of about pH 5-9 with neutral pH 7 being the optimum.
24
Q

What happens to a enzyme at very acidic and alkaline pH’s

A

At very acidic and alkaline pH values the shape of the enzyme is altered so that it is no longer complementary to its specific substrate.

This effect can be permanent and irreversible. IT IS SAID TO BE DENATURED.

25
Q

What is the name of a substance that speeds up the rate of a chemical reaction, but is unchanged by the process?
1. Catalyst
2. Product
3. Substrate

A
  1. Catalyst
26
Q

What is the name of a substance upon which an enzyme acts?
1. Biological catalyst
2. Product
3. Substrate

A
  1. Substrate
27
Q

What happens during an enzyme catalysed reaction?

  1. An enzyme binds to the active site of its specific substrate and the reaction occurs
  2. A specific substrate binds to the active site of an enzyme and the reaction occurs
  3. The active site of a specific substrate binds to the active site of an enzyme and the reaction occurs
A
  1. A specific substrate binds to the active site of an enzyme and the reaction occurs
28
Q

Which word describes the relationship between the shape of the active site of an enzyme and the shape of its specific substrate?
1. Complementary
2. Denatured
3. Weak

A
  1. Complementary
29
Q

What term describes the conditions in which an enzyme is most active?
1. Complementary
2. Optimum
3. Specific

A
  1. Optimum
30
Q

What effect does denaturation have on the activity of an enzyme?

  1. Increased
  2. Decreased
  3. No change
A
  1. Decreased
31
Q

The graph shows the effect of pH on the time taken for an enzyme-catalysed reaction to occur.

A graph showing the effect of pH on time taken for an enzyme-catalysed reaction to occur
What is the optimum pH of the enzyme?

  1. 2
  2. 8
  3. 10
A
  1. 8

The time taken for the enzyme reaction to occur was quicker

Mrs Smith S3 -L4/5 Unit 1: Cell biology (12 decks)

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