2.0 Nucleic acids

Question 1

What are the two types of nucleic acid?

Answer 1

RNA and DNA

Question 2

What is the role of DNA?

Answer 2

Carries genetic information

Question 3

What is the role of RNA?

Answer 3

Carries genetic information from DNA to the ribosomes

Question 4

Name the monomer of a nucleic acid

Answer 4

Nucleotide

Question 5

State the three components of a nucleotide

Answer 5

Penrose sugar, phosphate group, nitrogen-containing base

Question 6

State the five possible bases for a nucleotide

Answer 6

Adenine, thymine, cytosine, guanine, uracil

Question 7

What is a pentose sugar?

Answer 7

A sugar containing 5 carbons

Question 8

What pentose sugar is present in DNA?

Answer 8

Deoxyribose

Question 9

What pentose sugar is present in RNA?

Answer 9

Ribose

Question 10

What reaction combines the pentose sugar, organic base, and phosphate group?

Answer 10

Condensation reaction

Question 11

What reaction combines two nucleotides?

Answer 11

Condensation reaction

Question 12

What bond is formed when two nucleotides are combined?

Answer 12

Phosphodiester bond

Question 13

What is one nucleotide called?

Answer 13

Mononucleotide

Question 14

What are two bonded nucleotides called?

Answer 14

Dinucleotide

Question 15

What is a long chain of bonded nucleotides called?

Answer 15

Polynucleotide

Question 16

Describe the structure of DNA

Answer 16

1. Double helix
2. Two polynucleotide chains held together by hydrogen bonds between complimentary base pairs

Question 17

State the complimentary base pairings

Answer 17

1. Adenine and Thymine
2. Cytosine and Guanine

Question 18

How is the structure of DNA related to its functions?

Answer 18

1. Two separate strands held by weak hydrogen bonds allows for separation
   2 large molecule so carries a lot of information
2. Sugar phosphate backbone to protect genetic information

Question 19

How many hydrogen bonds form between Adenine and Thymine?

Answer 19

2

Question 20

How many hydrogen bonds form between Cytosine and Guanine?

Answer 20

3

Question 21

Describe the structure of RNA

Answer 21

Relativity short polynucleotide chain

Question 22

What are the three differences between DNA and RNA?

Answer 22

1. DNA is double stranded, RNA is single stranded
2. DNA has deoxyribose, RNA has ribose
3. DNA has thymine, RNA has uracil

Question 23

How does complimentary base pairing allow is to work out the frequency of relative bases?

Answer 23

Knowing the frequency of one allows us to find out the frequency of its complimentary base, frequency of all bases equal 100% which allows others to be calculated

Question 24

State the mechanism of DNA replication

Answer 24

Semi-conservative replication

Question 25

Describe semi-conservative replication

Answer 25

1. DNA helicase breaks hydrogen bonds which unwinds the double helix 2. Free floating nucleotides bind to their complimentary pair 3. DNA polymerase forms new phosphodiester bonds between adjacent nucleotides

Question 26

Why is semi-conservative replication important in the genetic continuity between cells?

Answer 26

There will always be a strand of the former DNA molecule used as a template

Question 27

What are the main stages ofDNA replication?

Answer 27

1. DNA unwinds 2. Hydrogen bonds break 3. Each strand acts as a template 4. New nucleotides attach to the template strand 5. Condensation reactions bond nucleotides together

Question 28

State the two enzymes involved in DNA replication

Answer 28

1. DNA helicase 2. DNA polymerase

Question 29

What does DNA helicase do?

Answer 29

Unwinds the DNA by breaking hydrogen bonds

Question 30

What does DNA polymerase do?

Answer 30

Catalyses the condensation reaction which forms phosphodiester bonds between adjacent nucleotides

Question 31

In what direction do DNA strands in the double helix run?

Answer 31

Anti parallel

Question 32

What are the new strands of DNA formed from?

Answer 32

Free floating nucleotides

Question 33

How do free floating nucleotides get in the right order to form a complimentary strand?

Answer 33

Original strand acts as a template and the free nucleotides attach to their complimentary base pair

Question 34

How was semi-conservative replication proven to be correct?

Answer 34

1. DNA marked with heavy nitrogen isotope then replicated with a light nitrogen isotope 2. Mass of DNA determined by which isotopes it contained 3. DNA spun in a centrifuge, results showed the strands were separating and forming a new strand each generation

Question 35

Why is ATP a suitable energy source for cells?

Answer 35

1. Releases manageable amounts of energy 2. Phosphorylates other compounds 3. can be rapidly re synthesised

Question 36

State the roles of ATP

Answer 36

1. Metabolic processes 2. Movement 3. Active transport 4. Activation of molecules

Question 37

What are the properties of water?

Answer 37

1. Dipolar molecule 2. Hydrogen bonds to other molecules 3. High specific heat capacity 4. Cohesion and surface tension

Question 38

What is the importance of water to living organisms?

Answer 38

1. Hydrolyses complex molecules 2. Universal solvent