Protein synthesis, Mutations, Enzymes

Question 1

What are the two stages of protein synthesis?

Answer 1

Transcription and translation.

Question 2

Where does transcription take place?

Answer 2

The nucleus.

Question 3

Where does translation take place?

Answer 3

Cytoplasm when the mRNA attaches to a ribosome.

Question 4

What are the two main steps of transcription?

Answer 4

1. A section of DNA is unwound and the 2 strands separate.

2. Free complementary bases pair with the open bases on the DNA strand. (the free bases join to make complementary mRNA)

Question 5

When the ribosome moves along the mRNA how many bases does it read and what are they called?

Answer 5

3, codons.

Question 6

What does the mRNA pair with in the ribosome?

Answer 6

tRNA.

Question 7

What do the tRNA molecules bring to the ribosome?

Answer 7

Amino acids.

Question 8

What does the amino acid attached to each tRNA depend on?

Answer 8

The order of the bases in the tRNA.

Question 9

What is a chain of amino acids joined closely together called?

Answer 9

Polypeptide.

Question 10

What are the 5 main steps of translation?

Answer 10

1. Ribosome moves along the mRNA reading one codon at a time.
2. tRNA molecules bring amino acids to the ribosome.
3. Complementary bases of tRNA pair with the bases on the nRNA strand.
4. The amino acids that are close together are joined to make a polypeptide.
5. The tRNA is free to collect another amino acid.

Question 11

What replaces thymine in RNA?

Answer 11

Uracil.

Question 12

What must happen for the polypeptide to turn into a protein?

Answer 12

It has to fold up in a complicated 3D way.

Question 13

The ______ of a protein affects the way it works.

Answer 13

Shape.

Question 14

What is meant by the word mutation?

Answer 14

It is a change in the sequence of bases in the genetic code.

Question 15

When can a mutation sometimes be useful?

Answer 15

In bacteria, so that they can gain immunity or resistance to certain things.

Question 16

What are examples of globular shaped proteins?

Answer 16

• Enzymes
• Hormones
• Haemoglobin

Question 17

What are examples of fibrous/long shaped proteins?

Answer 17

• Keratin (hair, nails)

- Collagen (tendons, ligaments)

Question 18

What could the 3 possible outcomes of a change in an amino be?

Answer 18

• No effect; it doesn’t change the shape of the protein or how it works.
• Beneficial effect; causes the protein to work better.
• Harmful effect; causes the protein to change shape sp it doesn’t work well.

Question 19

Give an example of the result of harmful change in protein shape.

Answer 19

The allele that causes sickle cell. (The allele for sickle cell disease has one base different than the normal allele for haemoglobin).

Question 20

Enzymes are biological _______.

Answer 20

Catalysts.

Question 21

Give examples of enzyme controlled reactions inside and outside cells.

Answer 21

Inside cells: Enzymes catalyse the splitting apart of the 2 DNA strands and the joining of the bases to make new strands in transcription and translation.

Outside cells: Digestive enzymes are secreted into the alimentary canal to break down large food molecules into smaller ones.

Question 22

What is the ‘lock and key’ hypothesis?

Answer 22

Describes the way a substrate fits ,like a key, into the enzymes active site, the lock.

Question 23

At optimum temperature the enzyme is working at its ________ rate.

Answer 23

Fastest.

Question 24

High temperatures can cause the active site to change shape, which means the enzyme can’t hold the ________ as tightly causing the reaction to ______ _______.

Answer 24

Substrate, slow down.

Question 25

If the temperature is too high the enzyme ________ because it’s _____ _____ breaks up.

Answer 25

Denatures, active site.

Question 26

True or false:

As the substrate concentration increases so does the rate of reaction until all the enzyme molecules are busy.

Answer 26

True.