DNA

Question 1

What is the basic building block of DNA?

Answer 1

A nucleotide, consisting of a phosphate, a pentose sugar (deoxyribose), and a base.

Question 2

Describe the structure of a DNA nucleotide.

Answer 2

A phosphate group, a pentose sugar group (deoxyribose), and a base.

Question 3

Describe how a DNA strand is formed.

Answer 3

Formed by two or more mononucleotides, being joined together, by a condensation reaction, thus forming a phosphodiester bond between the phosphate group, and pentose sugar. By the action of DNA polymerase.

Question 4

What are the central bases joined together by in DNA?

Answer 4

Hydrogen bonds.

Question 5

Describe the code for which bases pair with each other.

Answer 5

A with T
C with G

Question 6

Describe all the structure of DNA, and relate this to its structure.

Answer 6

1. Base sequence : stores genetic information.
2. Large : Stores massive amount of genetic information.
3. Helix: Allows it to be compact
4. Sugar phosphate backbone: provides stability and protection, thus reducing mutations.
5. Hydrogen bonds between bases: break and reform, in order to allow replication and photosynthesis.

Question 7

Identify all the similarities, between Structure of DNA in prokaryotes, and structure of DNA in eukaryotes.

Answer 7

1. The nucleotide structure is identical.
2. The nucleotides are joined together by phosphodiester bonds.

Question 8

Identify all the differences, between Structure of DNA in prokaryotes, and structure of DNA in eukaryotes.

Answer 8

1. Eukaryotes contain both introns and exons, whereas prokaryotes contain only exons.
2. Eukaryotic DNA is long and linear, whereas prokaryotic DNA is short and circular.
3. Eukaryotic DNA is associated with histones/proteins, whereas prokaryotic DNA is not associated with proteins/histones.

Question 9

Why is DNA replication, known as semi-conservative?

Answer 9

Occurs by semi conservative replication, meaning that each newly formed DNA molecule, contains one strand from original DNA molecule, and one newly formed strand.

Question 10

Describe the whole process of semi-conservative DNA replication.

Answer 10

1.DNA helicase, breaks hydrogen bonds between complementary base pairs, in DNA molecule, thus leading two strands, and exposing their bases.

2. Floating DNA nucleotides in the nucleus, are then attracted to complementary bases on the newly. revealed template strands. Hydrogen bonds then form between complimentary DNA nucleotides and bases.

3.DNA polymerase, then joins these nucleotides together, by a condensation reaction, thus forming a phosphodiester bond between nucleotides.

4. This process repeats, until two completely identical cells are left, which coil to form two helixes.