Nucleic Acids (B)

Question 1

What is the structure of DNA like?

Answer 1

DNA consists of two polynucleotide strands joined together by hydrogen bonding between complementary nitrogenous bases. These two strands twist to form a double helix

Question 1

What is each DNA nucleotide made up of?

Answer 1

A pentose sugar, deoxyribose
One of four nitrogen containing bases: A, T, C or G
A phosphate group

Question 2

What are the purine bases?

Answer 2

Adenine
Guanine

Question 3

What are the pyrimidine bases?

Answer 3

Thymine
Cytosine

Question 4

What reaction forms the phosphodiester bonds in DNA?

Answer 4

Condensation reactions form the phosphodiester bonds

Question 4

What is the nature of hydrogen bonds in DNA?

Answer 4

Hydrogen bonds are individually weak but due to their large number they collectively maintain a stable structure

Question 4

What are the complementary base pairings for DNA?

Answer 4

Adenine – Thymine
Guanine – Cytosine

Question 5

How are bases joined together in DNA?

Answer 5

Hydrogen bonds

Question 6

What type of bond joins nucleotides within each strand of DNA?

Answer 6

Phosphodiester bonds formed in condensation reactions join nucleotides

Question 7

What forms the backbone of the DNA polynucleotide strands?

Answer 7

The sugar and phosphate form the backbone

Question 7

How are nitrogenous bases oriented in the structure of DNA?

Answer 7

The bases are oriented towards the centre of the helix to protect them

Question 8

What is the significance of complementary base pairing in DNA?

Answer 8

It ensures stability and function by pairing specific bases

Question 8

How is the DNA helix further organised to store genetic information?

Answer 8

The DNA helix is further coiled to produce a super helix, providing a compact storage of genetic information

Question 9

What are genes, and what do they contain?

Answer 9

Genes are sections of DNA that contain coded information as a specific sequence of basesq

Question 10

What is the relationship between DNA mutations and evolution?

Answer 10

Genetic diversity from DNA alterations provides the basis for natural selection and evolution

Question 10

What do genes code for?

Answer 10

Genes code for polypeptides that determine the nature and development of organisms

Question 10

What essential process does DNA undergo for cell division?

Answer 10

DNA has the ability to self-replicate, which is essential for cell division

Question 11

How does DNA contribute to genetic diversity?

Answer 11

Alterations in the base sequence of DNA can occur, providing genetic diversity

Question 11

How is the structure of DNA adapted for its function?

Answer 11

The sugar phosphate backbone: gives strength
The double helix structure: gives a compact shape
Being double stranded: so replication can occur semi-conservatively
Being a large molecule: Means that a large amount of information can be stored
Many hydrogen bonds: gives stability to the molecule as well as with the individual hydrogen bonds being weak it allows the helix to unzip easily for replication
Sequence of bases: codes for a specific sequence of amino acids in a polypeptide
Complementary base pairing: enables information to be replicated accurately