nucleotides

Question 1

What is a nucleotide?

Answer 1

The monomer of a nucleic acid.

Question 2

What does a nucleotide consist of?

Answer 2

• A pentose sugar
• A nitrogenous base
• A phosphate group

Question 3

What are the 4 bases DNA contains?

Answer 3

• Adenine
• Guanine
• Cytosine
• Thymine

Question 4

Which of the 4 bases are purines and which are pyrimidines?

Answer 4

• Adenine and guanine - purine
• Cytosine and thymine - pyrimidine
  Remember : PURE as gold
  purine

Question 5

What 4 bases does RNA contain?

Answer 5

Adenine and Guanine - purine
Cytosine and Uracil - Pyrimidine

Question 6

What bases are paired together during replication?

Answer 6

Adenine - Thymine / uracil
Cytosine - Guanine

Question 7

What does ATP and ADP contain?

Answer 7

ADP - adenine base, ribose sugar, 2 phosphate groups
ATP - adenine base, ribose sugar, 3 phosphate groups

Question 8

What is ATP synthesised from?

Answer 8

• Synthesised from ADP and inorganic phosphate, using the energy from an energy releasing reaction e.g breakdown of glucose in respiration.

Question 9

How is ATP created?

Answer 9

• ADP is phosphorylated to from ATP and a phosphate bond is formed.

Question 10

What bond is formed when the nucleotides join up between the phosphate group of one nucleotide and the sugar of another?

Answer 10

Phosphodiester bond

Question 11

What is the bond that joined two DNA polynucleotide strands together?

Answer 11

Hydrogen bond

Question 12

What are the stages of DNA semi- Conservative replication?

Answer 12

1- DNA helicase unzips DNA, separating two strands by breaking hydrogen bonds between complementary bases.
2- Free DNA nucleotides are attracted to their exposed bases by complementary base pairing.
3 -Free nucleotides joined together through phosphodiester bonds by DNA polymerase - Forms sugar- phosphate backbone and new DNA strand.
4- Two DNA molecules produced from 1 new and 1 old strand.

Question 13

What is a genetic code?

Answer 13

When DNA must code for a sequence of amino acids.

Question 14

What is a triplet code?

Answer 14

A sequence of three bases called a codon.

Question 15

What is a gene?

Answer 15

A section of DNA that contains the complete sequence of bases to code for an entire protein.

Question 16

What does it mean by the genetic code is universal?

Answer 16

All organisms use the same code, although the sequences of the bases coding for each individual protein will be different.

Question 17

How many different base triplets or codons are possible?

Answer 17

64

Question 18

What signals the start and end of the sequence and how many of each?

Answer 18

start codon: 1
stop codon: 3

Question 19

What does it mean by the code is degenerate?

Answer 19

Many amino acids can be coded for more than one codon.

Question 20

What the sense and antisense strand?

Answer 20

Sense strand - The strand of DNA that contains the code for the protein to be synthesised runs from 5’ to 3’.
Antisense strand - Complementary copy of sense strand and does not code for protein runs from 3’ to 5’.