Nucleic Acids And Nucleotides

Question 1

What are the three parts of a nucleotide

Answer 1

A Penrose sugar
A base (sometimes called a nitrogenous base as they contain nitrogen)
A negatively charged phosphate group

Question 2

What are the elements that are found in nucleotides

Answer 2

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus

Question 3

Draw a nucleotide in its simple form with the symbols for the carbons

Answer 3

DRAW IT

Question 4

What are nucleotides used to make

Answer 4

Both DNA and RNA

Question 5

What is a difference between the nucleotides of DNA and RNA

Answer 5

In DNA the pentose sugar is deoxyribose whereas in RNA the pentose sugar is ribose

Question 6

What are the 4 different bases that are found in DNA

Answer 6

Thymine, Adenine, Guanine and Cytosine

Question 7

Which two bases are purines and why

Answer 7

Adenine and Guanine both have a double ring structure so they are purines

Question 8

Which two bases are pyramidines and why

Answer 8

Thymine and cytosine have a single ring structure - these bases are called pyramidines

Question 9

What is a difference in the bases that are in DNA and RNA

Answer 9

RNA similarly contains adenine, guanine and cytosine. However, it doesn’t contain the base thymine and instead contains the base uracil.

Question 10

What is the bond that forms between nucleotides and between what parts of the nucleotide

Answer 10

A bond forms between the phosphate group on the 5’ carbon on one nucleotide and the hydroxyl group on carbon 3 of the pentose sugar of another nucleotide

Question 11

What is the bond that forms between two nucleotides called

Answer 11

It is called a phosphodiester bond

Question 12

What is it called when two nucleotides and bonded together and when more than two nucleotides are bonded together

Answer 12

Two - dinucleotide
More than two - Polynucleotide

Question 13

What type of reaction is the reaction that form the phosphodiester bond

Answer 13

It is a condensation reaction as water is released

Question 14

How can the phosphodiester bond be broken

Answer 14

It can be broken by adding back water - this is called a hydrolysis reaction

Question 15

How do polynucleotides form

Answer 15

They form as the nucleotides continue to be added by forming phosphodiester bonds

Question 16

What are both DNA and RNA

Answer 16

They are both polynucleotides

Question 17

What does DNA consist of

Answer 17

It consists of two polynucleotide strands with the sugar-phosphate backbone on the outside with the bases in the centre.

Question 18

What are the two polynucleotides held together by

Answer 18

They are held together by hydrogen bonds that form between the bases on opposite strands.

Question 19

What are the bases on one strand in terms of the other strand

Answer 19

The bases on one strand are complementary to the bases on the other strand

Question 20

What are the different complementary bases pairs

Answer 20

Guanine and cytosine
Thymine and adenine

Question 21

What is a rule for the base pairs and what does it mean for DNA

Answer 21

A purine on one strand will always pair with a pyramidine on the other strand. It means that the distance between the sugar phosphate backbone is constant all down the DNA molecule.

Question 22

What are the two polynucleotides in relation to each other

Answer 22

They are anti parallel which means that they run in opposite directions.

Question 23

What does antiparallel mean in terms of the phosphate groups, carbon and the hydroxyl group

Answer 23

On one side the top the phosphate group is attached to carbon 5 of the deoxyribose sugar and at the bottom is the hydroxyl group attached to carbon 3. Whereas on the other strand the phosphate attached to carbon 5 is at the bottom and the hydroxyl group attached to carbon 3 is at the top.

Question 24

What do the different base pairs form

Answer 24

They form different numbers of hydrogen bonds

Question 25

How many hydrogen bonds does guanine and cytosine form

Answer 25

It forms 3 hydrogen bonds

Question 26

How many hydrogen bonds does adenine and thymine form

Answer 26

2 hydrogen bonds

Question 27

Because of complementary base pairing what occurs in terms of ratio

Answer 27

The ratio/proportion of guanine and cytosine is the same and the proportion of adenine/thymine is also the same.

Question 28

What do the polynucleotide strands of DNA do

Answer 28

They twist around each other to form a double helix.

Question 29

What does a double helix consist of

Answer 29

A sugar phosphate backbone on the outside and base pairs in the centre

Question 30

What are the first 3 differences between DNA and RNA

Answer 30

DNA contains deoxyribose whereas RNA contains ribose
DNA contains the base thymine whereas RNA contains uracil
DNA is found in chromosomes in the nucleus whereas RNA is found in the cytoplasm

Question 31

What are the last two differences between DNA and RNA

Answer 31

DNA is an extremely long molecule whereas RNA is a relatively short molecule.
DNA consists of two polynucleotide strands in a double helix RNA consists of one polynucleotide strand

Question 32

What is uracil and how many bonds does it form

Answer 32

It is also a pyramidine and forms two hydrogen bonds with adenine.

Question 33

How do RNA nucleotides form polymers

Answer 33

Through the formation of phosphodiester bonds in condensation reactions

Question 34

What is RNA’s role

Answer 34

It plays an essential role in the transfer of genetic information from DNA to proteins.

Question 35

What happens to RNA after protein synthesis

Answer 35

RNA molecules degrade in the cytoplasm and its phosphodiester bonds are hydrolysed and the nucleotides are released and reused.