A1.2 Nucleic Acids

Question 1

Nucleic Acid

Answer 1

DNA, different types of RNA and ATP

Question 2

Gene

Answer 2

A length of DNA that codes for a polypeptide, which forms a protein.

Question 3

Why are viruses not considered living organisms?

Answer 3

Because they require living host cells to replicate their DNA and synthesise their proteins.

Question 4

DNA and RNA are polymers of ____

Answer 4

Nucleotides

Question 5

What do nucleotides contain

Answer 5

• phosphate group
• nitrogen base
• sugar

Question 6

What type of bonds join the parts of a nucleotide?

Answer 6

Covalent bonds

Question 7

What forms the backbone of DNA

Answer 7

Sugar-phosphate bonds

Question 8

How are nucleotides of DNA/RNA joined?

Answer 8

condensation reactions

Question 9

What are the 5 nitrogenous bases?

Answer 9

Adenine, Thymine, Guanine, Cytosine, Uracil

Question 10

DNA vs RNA bases

Answer 10

Both: Adenine, Guanine, Cytosine
DNA: Thymine
RNA: Uracil

Question 11

Nucleotide sugar in DNA

Answer 11

Deoxyribose

Question 12

Nucleotide sugar in RNA

Answer 12

Ribose

Question 13

Anti-parallel

Answer 13

The way DNA strands run. Parallel but in opposite directions.

Question 14

What shape is DNA

Answer 14

Double helix

Question 15

What are the three kinds of RNA?

Answer 15

• Messenger RNA (mRNA)
• Transfer RNA (tRNA)
• Ribosomal RNA (rRNA)

Question 16

How are bases in DNA held together?

Answer 16

Weak H bonds

Question 17

How many H bonds are there between adenine and thymine?

Answer 17

2

Question 18

How many H bonds are there between guanine and cytosine?

Answer 18

3

Question 19

Why is the genetic code stored in DNA said to be universal?

Answer 19

The same DNA triplet codes for the same amino acids in every organism

Question 20

Which direction does DNA/RNA synthesis go in.

Answer 20

The 5’ to 3’ direction

Question 21

What DNA bases are purines?

Answer 21

Adenine and guanine

Question 22

What DNA bases are pyrimidines?

Answer 22

Thymine and cytosine

Question 23

How do purines and pyrimidines bond?

Answer 23

Double ring purines always bond to single ring pyrimidines.

Question 24

Nucleosome

Answer 24

DNA is wound around histones which are grouped into bead like structures of 8 molecules with other histones on the outside of DNA.

Question 25

Linker DNA

Answer 25

The DNA that links the nucleosome "beads"

Question 26

Where is DNA found

Answer 26

- The nucleus -Chromosomes and in the nucleus of eukaryotes and the plastids of prokaryotes -mitochondria - chloroplasts

Question 27

Hershey-Chase Experiment

Answer 27

Bacteriophages were grown in 2 different cultures, one labelled the phages with radioactive Phosphorus 32 in the DNA the other labelled the outer protein coat with Sulfur 35. When the bacteriophages infected E.coli they detected P32 in them. Providing evidence that DNA is the genetic material.

Question 28

Chargaff's experiment

Answer 28

Showed the same relative amounts of purines and pyrimidines in DNA. Showed that approximately 1:1 ratios of adenine and thymine and cytosine and guanine exist in DNA.