DNA and Protein Synthesis

Question 1

Define gene

Answer 1

Section of DNA containing coded information to make polypeptide and functional DNA

Question 2

Define Locus

Answer 2

The fixed location of a particular piece of DNA

Question 3

What are the three main features of DNA

Answer 3

Code is degenerate
Code is read one way and non -overlapping
Code is universal

Question 4

Why is the chromosomes measured in kilobase pairs

Answer 4

DNA is double stranded

Each base on one strand is complementary

Question 5

Why do different genes have different lengths

Answer 5

Varying number of Amino acids

different number of non coding introns

Question 6

When are chromosomes visible?

Answer 6

only when dividing

Question 7

Define allele

Answer 7

alternate form of a gene

Question 8

Define codon

Answer 8

sequence of 3 bases on mRNA that codes for a single amino acid

Question 9

Define genome

Answer 9

complete set of genes in a cell

Question 10

Define proteome

Answer 10

Full range of proteins produced by the genes

Question 11

Define the structure of messenger RNA

Answer 11

single helix
template for protein synthesis
Codon = 3 bases of mRNA
complementary to DNA

Question 12

Define the structure of transfer RNA

Answer 12

relatively short
single strand folded into a clover shape
tRNA specific to one amino acid

Question 13

Describe Translation

Answer 13

1. mRNA associates with a ribosome / ribosome
   attaches to mRNA;
2. Ribosome moves to / finds the start codon /
   AUG;
3. tRNA brings / carries (appropriate / specific)
   amino acid;
4. Anticodon (on tRNA complementary) to codon
   (on mRNA);
5. Ribosome moves along to next codon;
   OR
   Ribosome ‘fits’ around two codons / can fit two
   tRNAs;
6. (Process repeated and) amino acids join by
   peptide bonds / condensation reaction (to form
   polypeptide)

Question 14

Describe Transcription

Answer 14

Helix unzipped by DNA helicase by breaking the hydrogen bonds between the bases.
One chain acts as a template
Free complementary mRNA nucleotides joined by RNA polymerase
preMRNA spliced and leav via nuclear pore

Question 15

Name two structural differences between mRNA and tRNA1.

Answer 15

mRNA does not have hydrogen bonds / base
pairing, tRNA does;
OR
mRNA is linear / straight chain, tRNA is
cloverleaf;
2. mRNA does not have an amino acid binding site,
tRNA does;
3. mRNA has more nucleotides;
4. (Different) mRNAs have different lengths, all
tRNAs are similar / same length;
5. mRNA has codons, tRNA has an anticodon;