DNA (T3)

Question 1

What are chromosomes?

Answer 1

Chromosomes exist inside the nucleus of our cells and are made from DNA.

They are long molecules which are wound around a protein framework of about two metres in length.

They are made up of about 30,000 genes.

Question 2

What are genes and the genetic code?

Answer 2

Genes are sections of DNA.

Each gene codes for a particular protein by specifying the order in which amino acids must be joined together.

The information contained in genes is in the form of coded instructions called the genetic code.

The genetic code controls cell activity, which means that it also controls some characteristics of the organism.

Question 3

Describe DNA…

Answer 3

DNA molecules are very large and incredibly complex.

They carry the genetic code that determines the characteristics of every living organism.

Every persons DNA is unique (identical twins are an exception) which is why people can be identified by the police using DNA finger printing.

DNA controls the production of different proteins which are needed for the growth and repair of cells.

Question 4

Briefly describe the discovery of DNA..

Answer 4

James Watson and Francis Crick, working at the university of Cambridge, discovered the structure of DNA back in 1953.

However the initial info and discoveries of the DNA molecule go further back.

Watson and Crick were only able to propose the structure of DNA due to the work done by other scientists such as Rosalind Franklin.

Question 5

Describe the structure of DNA..

Answer 5

• the DNA molecule is made up of two strands of nucleotides, making it a polynucleotide.
• the DNA molecule is also a double helix structure as there are two chains wound into a helical structure.
• each nucleotide of each DNA strand is made up of chemicals; a sugar molecule, a phosphate group and a nitrogenous base.
• there are four different types of bases:

A (adenine)

T (thymine)

C (cytosine)

G (guanine)

Question 6

What are the four different types of bases in DNA?

Answer 6

A (adenine)

T (thymine)

C (cytosine)

G (guanine)

Question 7

Describe the ‘complimentary base pairs’ of DNA..

Answer 7

The four bases of the DNA molecule always pair up in a particular way.

This is called complimentary base pairing.

A-T

G-C

Question 8

What is the DNA base code?

Answer 8

It is the sequence of the DNA bases which determine the structure of a protein.

A protein is made by joining together many amino acids.

Each amino acid is coded by the sequence of three bases.

Eg:

The bases GGT code for the amino acid glycine

The bases TCA code for the amino acid serine

Question 9

What is the sequence of bases that code for the amino acid glycine?

Answer 9

GGT

Question 10

What sequence of bases codes for the amino acid serine?

Answer 10

TCA

Question 11

What is the nucleus of a cell nicknames and why?

Answer 11

The nucleus is a cell is nicknamed the “control centre” of the cell.

This is because the nucleus contains the DNA which controls all cellular functions by controlling the production of proteins, some of which function as enzymes.

Question 12

Name two things that each gene in a molecule of DNA contains…

Answer 12

• a different sequence of bases
• codes for a particular protein

Question 13

Name the four bases found in DNA..

Answer 13

• adenine
• thymine
• guanine
• cytosine

Question 14

In which combination do DNA base pairs always pair up?

Answer 14

A - T

G - C

Question 15

What is the full name of DNA?

Answer 15

Deoxyribose nucleic acid