Nucleotides and nuclei acids

Question 1

What are nucleic acids?

Answer 1

Large molecules contained in the nucleus of cells

Question 2

What are the monomers that make up DNA?

Answer 2

Nucleotides

Question 3

What does DNA stand for?

Answer 3

Deoxyribonucleic acid

Question 4

What are the two types of nucleotide chains?

Answer 4

• RNA= Ribonucleic acid

- DNA= Deoxyribonucleic acid

Question 5

What are the 3 components that make up nucleotides?

Answer 5

• A phosphate group
• A penthouse sugar
• Nitrogenous base

Question 6

What elements are found in nucleic acids?

Answer 6

• carbon
• hydrogen
• oxygen
• nitrogen
• phosphorus

Question 7

Describe how 2 nucleotides are joined together

Answer 7

A phosphodiester bond will form between the phosphate group of one nucleotide, and the pentose sugar of the adjacent nucleotide. This bond is formed through a condensation reaction, producing water as a product, and is catalysed by DNA polymerase

Question 8

What is meant by the sugar-phosphate backbone?

Answer 8

The part of the nucleotide (phosphate group and pentose sugar) which the base attaches to. The 2 backbones are what coil to create the double helix structure of DNA.

Question 9

What is a chain of nucleotides called?

Answer 9

Polynucleotide

Question 10

What is a purine?

Answer 10

• A larger, 2 carbon-nitrogen ring structured base

- Examples= Adenine / Guanine

Question 11

What is a pyrimidine?

Answer 11

• A smaller, single carbon-nitrogen ring structured base

- Examples: Cytosine/ Thymine / Uracil

Question 12

Why must a purine bind with a pyrimidine?

Answer 12

Their relative sizes means that they must pair with each other to keep the 2 strands the same distance apart. (Small with big = same distance but big with big= strands aren’t kept same distance)

Question 13

How many hydrogen bonds are there between Adenine and Thymine, and Cytosine and Guanine?

Answer 13

A and T= 2

C and G=3

Question 14

Why is it important that the hydrogen bonds between complementary bases can be broken?

Answer 14

-Both strands are used in DNA replication

Question 15

What is meant by the DNA strands being anti-parallel?

Answer 15

• The 2 strands run in opposite directions

- 5 prime to 3 prime down on left, but 5 prime to 3 prime up on right

Question 16

What Purines and Pyrimidines are found in DNA?

Answer 16

Purine:
Adenine
Guanine

Pyrimidine:
Cytosine
Thymine

Question 17

What Purines and Pyrimidines are found in RNA?

Answer 17

Purine:
Adenine
Guanine

Pyrimidine:
Cytosine
Uracil

Question 18

What is the function of DNA and how is it adapted to carry out this function?

Answer 18

-DNA controls the sequence of amino acids in proteins + heredity material responsible for passing genetic information from cell to cell

• it’s stable= (2 strands with specific base pairings, large numbers of H bonds, and helix shape reduces chance of molecular damage)
• 2 strands can separate so it can self-replicate
• Base pairings prevent corruption from outside chemicals or physical forces
• Large molecule so can carry lots of information

Question 19

What are the 5 steps of semi-conservative DNA replication?

Answer 19

1) Original DNA molecule is about to undergo replication
2) The enzyme DNA helicase causes the 2 strands of DNA to separate (unzip) by breaking the hydrogen bonds to form 2 single strands
3) DNA helicase completes the splitting of the strand. Meanwhile the free nucleotides are attracted to the exposed complementary bases on the original strand (which acts as a template)
4) Once the activated nucleotides are lined up, they are joined together through hydrogen bonds, by the enzyme DNA polymerase, forming the sugar phosphate backbone
5) All the nucleotides are joined to form a complete polynucleotide chain using DNA polymerase, this creates two identical strands of DNA. Each new molecule of DNA is composed of one original strand and one newly formed strand= semi-conservative replication