Nucleic Acids And DNA Replication

Question 1

Who first proposed the model of DNA structure

Answer 1

James Watson and Francis Crick

Question 2

What does DNA stand for

Answer 2

Deoxyribonucleic acid

Question 3

What does RNA stand for

Answer 3

Ribonucleic acid

Question 4

What is the basic job of DNA and RNA in all living cells

Answer 4

DNA holds genetic information and RNA transfers genetic information from DNA to the ribosomes

Question 5

What makes up ribosomes

Answer 5

rRNA and proteins

Question 6

What is the monomer of DNA? Draw and label the structure of this.

Answer 6

DNA nucleotides

Question 7

What is the monomer of RNA? Draw and label the structure of this.

Answer 7

RNA nucleotides

Question 8

What are the two types of bases

Answer 8

Purines and pyrimidines

Question 9

Give the bases that are purine and that are pyrimidine

Answer 9

Adenine and guanine are purines

Cytosine and Thymine are pyrimidines.

Question 10

What type of base do purines bond to

Answer 10

Pyrimidines

Question 11

What does the sequence of bases change

Answer 11

The sequence of bases codes for the sequence of amino acids formed which determines the tertiary structure and secondary structure of the protein, determining it’s overall shape.

Question 12

What is the pentose sugar in DNA nucleotides

Answer 12

Deoxyribose

Question 13

Give all the nitrogen containing bases that DNA contains

Answer 13

Adenine
Thymine
Cytosine
Guanine

Question 14

Give all the nitrogen containing bases that RNA contains

Answer 14

Adenine
Uracil
Cytosine
Guanine

Question 15

Draw part of a DNA molecule

Answer 15

Question 16

Where are phosphodiester bonds in DNA and how are they formed

Answer 16

Formed by a condensation reaction between the phosphate groups and deoxiriboses in the adjacent nucleotides , which is catalysed by DNA polymerase.

Question 17

Where are hydrogen bonds in DNA

Answer 17

Between complimentary base pairs

Question 18

What makes up an RNA molecule

Question 19

Give the 3 main types of RNA molecules

Answer 19

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

Question 20

What is the basic shape of mRNA

Answer 20

Linear in shape

Question 21

What is the basic shape of tRNA

Answer 21

Clover leaf shape

Question 22

Which RNA types contain hydrogen bonds

Answer 22

tRNA and rRNA

Question 23

What is a codon

Answer 23

3 amino acids, which code for a specific amino acid

Question 24

What RNA types contains anticodons and what are these

Answer 24

tRNA contains anticodons - these are made of 3 bases, and bind to codons on mRNA to transfer them

Question 25

What holds the tRNA in the clover shape

Answer 25

Hydrogen bonds

Question 26

Which type of RNA has an amino acid binding site

Answer 26

tRNA

Question 27

Draw a picture of mRNA

Answer 27

Question 28

Draw and label a picture of tRNA

Answer 28

Question 29

How long is a strand of mRNA and why

Answer 29

It can be various lengths, as it's not a copy of the whole DNA- it's a copy of the genes which are various lengths

Question 30

Describe the size and stability of mRNA

Answer 30

large, but not as large as DNA Unstable

Question 31

Describe the size and stability of tRNA

Answer 31

Very small, Relatively stable

Question 32

Give 4 differences between DNA and mRNA

Answer 32

DNA contains deoxyribose sugars, whereas mRNA contains ribose sugars. DNA contains the base thymine but in mRNA it's replaced with uracil DNA is made of a long polynucleotide chain but mRNA is made of a short one DNA is double stranded but mRNA is single stranded DNA contains hydrogen bonds but mRNA doesn't

Question 33

Give 6 structural facts about prokaryotic DNA that makes it different to eukaryotic DNA

Answer 33

1) It's DNA is shorter 2) There are fewer genes 3) DNA is circular not linear 4) DNA isn't associated with histones 5) There are no introns present 6) There are sometimes additional plasmids

Question 34

How many rings does the structure of purines have

Answer 34

2 rings

Question 35

How many rings does the structure of pyrimidines have

Answer 35

1 ring

Question 36

How many hydrogen bonds do Adenine and Thymine form between them

Answer 36

2 hydrogen bonds

Question 37

How many hydrogen bonds do Cytosine and Guanine form between them

Answer 37

3 hydrogen bonds

Question 38

What is Chargaff's rule

Answer 38

DNA must be kept parallel, by always pairing a purine with a pyrimidine- this prevents damage to the DNA

Question 39

What are the two enzymes involved in semi-conservative DNA replication, and what does each one do

Answer 39

DNA helicase- breaks the hydrogen bonds between bases DNA polymerase- forms new DNA by forming phosphodiester bonds

Question 40

Outline Semi-conservative DNA replication

Answer 40

1) DNA helicase breaks the hydrogen bonds between the complimentary bases in the polynucleotide strands, unwinding the DNA double helix, 2) This leaves single stranded DNA with exposed bases that can act as a template, determining the order of nucleotides on the newly synthesised strand, 3) New DNA nucleotides are attracted to the exposed bases on the template strands and form complimentary base pairs (Adenine and Thymine, Cytosine and Guanine), held in position by hydrogen bonds 4) DNA polymerase joins adjacent nucleotides by condensation reactions, forming phosphodiester bonds. 5) After replication, each DNA molecule contains one original template strand and one newly synthesised strand.

Question 41

Explain why the DNA polymerase bonds to opposite sides of the two polynucleotide strands in DNA

Answer 41

DNA is antiparallel, meaning the two strands run in opposite directions. One end is 5' and one end is 3'. DNA polymerase only complimentary to the 3' end.