DNA, Genes & Protein Synthesis (Chapter 8)

Question 1

What is a triplet code?

Answer 1

3 bases which code for an amino acid.

Question 2

What is a degenerate?

Answer 2

Amino acid which has more than one triplet code

Question 3

What is an intron?

Answer 3

Non-coding sections of DNA

Question 4

What is an exon?

Answer 4

Coding section of DNA

Question 5

What is meant by a universal code?

Answer 5

Each triplet codes for the same amino acid in all organisms (indirect evidence for evolution).

Question 6

What is meant by non-overlapping DNA?

Answer 6

Each base in the sequence is read only once.

Question 7

What is a gene?

Answer 7

A section of DNA that codes for the amino acid sequence of a polypeptide and functional RNA.

Question 8

What is the locus?

Answer 8

The fixed position on a DNA molecule that a gene occupies.

Question 9

What is a genome?

Answer 9

Complete set of genes in a cell.

Question 10

What is a proteome?

Answer 10

A complete set of proteins that a cell can produce.

Question 11

What is splicing?

Answer 11

The removal of introns from pre-mRNA to make mRNA in eukaryotes.

Question 12

Describe the process of DNA transcription

Answer 12

1) DNA helicase causes the H bonds between the bases to break and the DNA strand to unwind. One strand acts s a template.
2) RNA nucleotides attracted to exposed bases and bind with complementary pairs.
3) RNA polymerase then moves along the template strand causing RNA nucleotides to join each other.
4) DNA rewinds as RNA detaches.
5) The RNA polymerase will stop when it reaches a triplet code.
6) Pre-mRNA is formed

Question 13

What is DNA transcription?

Answer 13

The production of mRNA from DNA.

Question 14

Describe the process of DNA translation

Answer 14

1) Ribosomes attach to mRNA at the starting codon.
2) tRNA molecule arrives and it’s complementary anticodon binds to mRNA codon. Meanwhile, it brings amino acid.
3) Another tRNA molecule does the same thing.
4) Ribosomes move along mRNA. The amino acids are joined together by a peptide bond. Energy from hydrolysis is used to do this.
5) Ribosomes move to 3rd codon and the first tRNA is released etc.

Question 15

Compare the difference in structure between mRNA & tRNA

Answer 15

• mRNA is longer/has more nucleotides than tRNA
• mRNA is a straight molecule but tRNA is folded/clover-leaf shaped molecule
• mRNA contains no paired bases/hydrogen bonds but tRNA has some paired bases/hydrogen bonds
• mRNA does not have an amino acid binding site but tRNA does