2.1 Nucleic acids

Question 1

What monomer units make up nucleic acids?

Answer 1

Nucleotides

Question 2

Which nucleotides are pyrimidines?

Answer 2

Cytosine, Uracil and Thymine

Question 3

Which nucleotides are purines?

Answer 3

Guanine and Adenine

Question 4

How do you remember which nucleotides are pyrimidines?

Answer 4

“PYRamids have sharp edges that CUT your finger”

Question 5

Are pyrimidines single ring or double ring?

Answer 5

Single ring

Question 6

Are purines single ring or double ring?

Answer 6

Double ring

Question 7

Describe the process of RNA polymerisation

Answer 7

In a 5’ to 3’ direction, nucleotides are added to the 3’ end as it passes through an enzyme called RNA polymerase

Question 8

At which end are nucleotides added when lengthening the strand?

Answer 8

The 3’ end everytime, whether it be DNA or RNA

Question 9

Give a brief description of mRNA

Answer 9

Carries a copy the genetic code from DNA in the nucleus to the ribosome

Question 10

What does the m in mRNA stand for?

Answer 10

Messenger

Question 11

Give a brief description of tRNA

Answer 11

Carries amino acids from the cytoplasm to ribosomes and pairs with the complementary codon carried by mRNA

Question 12

What does the t of tRNA stand for?

Answer 12

Transfer

Question 13

Give a brief description of rRNA

Answer 13

Combines with proteins to make the organelle ribosome

Question 14

What does the r of rRNA stand for?

Answer 14

Ribosomal

Question 15

What are the main differences between DNA and RNA?

Answer 15

• DNA is double stranded, RNA is single
• DNA contains deoxyribose, RNA ribose
• DNA includes thymine, RNA uracil
• DNA is contained within membrane-bound organelles, unlike RNA

Question 16

Explain anti parallel using 3’ and 5’

Answer 16

Strands run opposite directions to one another, yet are still parallel. 2 strands of DNA run anti parallel to one another. One strand is upside down, compared to the other.

Question 17

What are the pairing rules for nucleotides in DNA?

Answer 17

A and T pair together, C and G pair together

Question 18

How many hydrogen bonds do adenine and thymine share?

Answer 18

2

Question 19

How many hydrogen bonds do cytosine and guanine share?

Answer 19

3

Question 20

Briefly describe the process of DNA polymerisation

Answer 20

In 5’ to 3’ direction, nucleotides are added to the 3’ end, as it passes through an enzyme called DNA polymerase. Nucleotides will pair to their complementary base.

Question 21

What is a nucleic acid?

Answer 21

A biomacromolecule, made up of smaller monomers called nucleotides. Examples of a nucleic acid is NDA and RNA

Question 22

What is a nucleotide made up of?

Answer 22

A phosphate, pentose sugar and a nitrogenous base

Question 23

What is a condensation polymerisation reaction?

Answer 23

The synthesis of a polymer and releases water as a by product

Question 24

Why do the two DNA strands run antiparallel?

Answer 24

Because if the negatively charged phosphates were opposite each other, they would repel one another

Question 25

What type of bond holds nucleotides together.

Answer 25

A phosphodiester bond

Question 26

How is DNA wrapped more compactly?

Answer 26

Winds around histones, then 8 histones cil to make nucleosomes, then nucleosomes fold to form chromatin fibre which makes loops. Lastly, the loops are compressed and create the chromatid of a chromosome

Question 27

What is RNA?

Answer 27

A single strand of nucleotide monomers, bonded by phosphodiester bonds. Includes messenger RNA, transfer RNA and ribosomal RNA