Topic 6a- DNA

Question 1

What does DNA stand for?

Answer 1

deoxyribonucleic acid

Question 1

Where is DNA found in the cell?

Answer 1

nucleus

Question 2

What is the shape of DNA

Answer 2

a double helix

Question 3

What is a gene

Answer 3

a gene is a small secion of DNA found on a chromosome

Question 4

What does each gene do?

Answer 4

Each gene codes fofr a particular sequence of amino acids which are put together to make a specific protein

Question 5

How many different types amino acids are used by genes to make proteins?

Answer 5

20

Question 6

Define a genome

Answer 6

A genome is the entire set of genetic material in an organism

Question 7

What are chromosomes made up of?

Answer 7

Coils of DNA

Question 8

Why are DNA molecules described as double helixes?

Answer 8

They are shaped in a double stranded spiral

Question 9

What is within one nucleotide of DNA

Answer 9

a phosphate, a sugar and a base

Question 10

How many types of bases are there (in DNA)

Answer 10

4

Question 11

What are the repeating units in DNA called?

Answer 11

Nucleotides

Question 12

What is the base in DNA bound to?

Answer 12

The sugar

Question 13

What two chemicals form the ‘backbone’ of DNA?

Answer 13

The sugar and phosphate

Question 15

How many bases in a gene code for an amino acid?

Answer 15

3

Question 16

Which bases pair together (which are complimentary)

Answer 16

A-T
C-G

Question 17

What are non-coding parts of DNA?

Answer 17

Parts of DNA that don’t code for proteins. Some og these non-coding parts switch genes on and off and control whether a gene is expressed (used to make a protein).

Question 19

Where are proteins synthesised in the cell?

Answer 19

The ribosomes

Question 20

Why can’t the DNA simply go directly from the nucleus to the ribosome so that it can synthesise the protein? What is used instead?

Answer 20

• The DNA is too big to and cannot move in and out of the nucleus.
• mRNA can however as it copies the code from the DNA and acts as a messenger between the DNA and the ribosome

Question 21

Explain the process of protein synthesis

Answer 21

1. The DNA in the nucleus of the cell is too large to exit and go to the ribosome
2. Instead, the molcule mRNA copies the DNA and carries the code to the ribosome
3. The correct amino acids are brought to the ribosome in the correct order by carrier molecules
4. From this, the ribosome assembles the chain of amino acids that fold into a unique shape which allows the protein to perform the task it’s meant to do

Question 22

What is a mutation?

Answer 22

A mutation is a random change in an organism’s DNA .

Question 23

What do mutations do to the sequence of DNA bases in a gene? What is the effect of this?

Answer 23

• Mutations change the sequence on the DNA bases in a gene which produces a genetic variant (a different form of the gene).
• Most mutations will have very little effect or no effect on the protein, while others could code for an altered protein and affect its ability to perform its function.

Question 24

What are the types of mutation?

Answer 24

• Insertion- when a new base is inserted into the DNA base sequence where it shouldn’t be (knock on effect on the sequence)
• Deletion- when a random base is from the sequence (knock on effect on the sequence)
• Substitution- when a random base in the DNA base sequence is changed to a different base (only affects that one )