2.1.3 Nucleotides and Nucleic Acids

Question 1

What the 4 main types of nucleic acids?

Answer 1

1. DNA
2. RNA
3. ATP
4. ADP

Question 2

What is a nucleic acid made out of?

Answer 2

Polymer of nucleotide monomers

Question 3

What does a nucleotide contain?

Answer 3

1. Pentose monosaccharide
2. Phosphate group
3. Nitrogenous base

Question 4

How do nucleotides bond?

Answer 4

Condensation; phosphate (5’) reacts with OH- (3’)

Phosphodiester bond formed

Question 5

How are nucleic acids broken down?

Answer 5

Hydrolysis

Question 6

What is the structural difference between DNA and RNA? (3)

Answer 6

1. Deoxyribose/ ribose- 1 less O
2. Adenine/ Uracil
3. Double stranded/ single

Question 7

Name the 4 bases of DNA

Answer 7

1. Thymine
2. Cytosine
3. Adenine
4. Guanine
   The Cat Ate Grapes

Question 8

Which DNA bases are complementary and how many H bonds are formed?

Answer 8

C+G -> 3
A+T -> 2
3 cars in the garage

Question 9

Which 2 groups of DNA bases are there? Size?

Answer 9

1. Pyrimidines- smaller

2. Purines- bigger

Question 10

How are the polynucleotide chains joined in the DNA helix?

Answer 10

Hydrogen bonding between complimentary bases

Question 11

Why are the polynucleotide chains in DNA antiparallel?

Answer 11

Chains are in opposite direction

Question 12

What sugar is in a RNA nucleotide?

Answer 12

Ribose

Question 13

What sugar is in a DNA nucleotide?

Answer 13

Deoxyribose

Question 14

What base in DNA is replaced in RNA?

Answer 14

Thymine -> Uracil

Question 15

Why do cells replicate?

Answer 15

1. Growth

2. Repair

Question 16

What catalyses the ‘unzipping’ of the DNA helix?

Answer 16

DNA helicase

Question 17

What catalyses the phosphodiester bonds between new nucleotides?

Answer 17

DNA polymerase
Poly -> Polynucleotide
-ase -> Enzyme

Question 18

What happens, during DNA replication, when the DNA helix is ‘unzipped’?

Answer 18

Free DNA nucleotides in the nucleus complementary pair to the ‘original’ DNA strand- hydrogen bonding

Question 19

Why is DNA replication semi- conservative?

Answer 19

Two molecules of DNA are produced, each containing an ‘original’ strand and a ‘new’ strand

Question 20

What experiment confirmed DNA replication to be semi- conservative?

Answer 20

• Free nucleotides of N-15
• 1st gen: half-half of N-15 and N-14
• 2nd gen: half of N-15/N-14 and half of pure N-15

Question 21

How does a mutation occur during DNA replication?

Answer 21

Free DNA nucleotides match with the wrong bases- incorrect sequence

Question 22

What is a codon?

Answer 22

3 bases on the DNA/ RNA strand that codes for a specific amino acid

Question 23

What is a gene? (DNA replication)

Answer 23

Contains all the codon to make an entire protein

Question 24

Why is the genetic code a degenerate code?

Answer 24

Different combinations of bases can code for the same amino acid

Question 25

Which codons aren’t for amino acid production?

Answer 25

3 Stop codons

Question 26

What codon codes for 2 different things?

Answer 26

AUG: Start/ Read and Methionine

Question 27

How are genetic mutations prevented in DNA replication? Accuracy is maintained? (2)

Answer 27

1. Semi- conservative replication- original strand

2. DNA polymerase can proofread and correct

Question 28

Why is RNA essential for protein synthesis?

Answer 28

DNA too large to leave nuclear envelope

Question 29

What is a sense strand, in protein synthesis?

Answer 29

Contains the correct coding for the amino acid sequence (from 5’ to 3’)

Question 30

What is a anti-sense/ template strand, in protein synthesis? Carbon numbers?

Answer 30

Complementary to the sense strand (from 3’ to 5’)

Question 31

What happens during transcription of protein synthesis? (3)

Answer 31

1. Helicase unzips
2. mRNA made from anti-sense strand- RNA polymerase joining
3. mRNA leaves through nuclear pore

Question 32

What happens during translation of protein synthesis? (4)

Answer 32

1. mRNA binds to ribosome
2. tRNAs with complementary anticodons bind to mRNA’s specific codons- 2 at a time
3. Amino acids form peptide bonds- Peptidyl transferase
4. ‘Stop’ codon- can go to golgi for modification

Question 33

What is tRNA?

Answer 33

Type of RNA in ribosome; contains specific anti-codons to translate mRNA to synthesis proteins

Question 34

What is an anti-codon?

Answer 34

A sequence of 3 bases on a tRNA complementary to a specific codon on mRNA; carries specific amino acid

Question 35

Where does the peptidyl transferase come from?

Answer 35

Enzymatic component of ribosome

Question 36

ATP and ADP are ____ nucleotides

Answer 36

Phosphorylated

Question 37

What is ATP short for?

Answer 37

Adenosine triphosphate

Question 38

What is ADP short for?

Answer 38

Adenosine diphosphate

Question 39

What’s the structure of ATP?

Answer 39

1. Nitrogenous base- Adenine
2. Pentose sugar- Ribose
   3 3 inorganic phoshate groups

Question 40

What’s the difference between ATP and ADP?

Answer 40

ADP has 2 phosphates instead of 3

Question 41

How does ATP release energy?

Answer 41

Hydrolysis

ATP + H20 -> ADP + energy

Question 42

Why is ATP a bad long-term energy store?

Answer 42

Instable phosphate groups

Question 43

Why is ATP a good immediate energy store?

Answer 43

Easily regenerated

Question 44

Why does the ATP hydrolysis reaction have a low activation energy?

Answer 44

Negatively charged phosphate groups rebel and are unstable

Question 45

What are useful features of ATP? (4)

Answer 45

1. Small- in/out cells
2. Water soluble- aqueous environments
3. Energy released in small quantities- not wasted
4. Easily regenerated- good immediate energy

Question 46

What reaction is ADP to ATP?

Answer 46

Condensation

Phosphorylation