DNA and Protein Synthesis - Genetics, Biodiversity and Classification

Question 1

What is the genome?

Answer 1

The complete set of genetic information contained in the cells of an organism.

Question 2

What is the proteome?

Answer 2

The complete set of proteins that can be produced by a cell.

Question 3

Describe the structure of messenger RNA (mRNA).

Answer 3

A long, single strand. Its base sequence is complementary to the DNA it was transcribed from.

Question 4

Suggest advantages of using mRNA rather than DNA for translation.

Answer 4

● shorter & contains uracil = breaks down quickly so no excess polypeptide forms
● single-stranded & linear = ribosome moves along strand & tRNA binds to exposed bases
● contains no introns

Question 5

Describe the structure of transfer RNA (tRNA).

Answer 5

A single strand of around 80 nucleotides that is folded over into a clover leaf shape. On one end is an anti-codon, on the opposite end is an amino acid binding site.

Question 5

Where does transcription take place?

Answer 5

In the nucleus.

Question 6

What is produced by transcription?

Answer 6

mRNA.

Question 7

Outline the process of transcription.

Answer 7

● DNA uncoils into two strands with exposed bases. One used as a template. - by breaking the hydrogen bonds

● Free nucleotides line up next to their complementary bases, and are joined together by RNA polymerase until a stop codon is reached. - by forming phosphodiester bonds

it is called pre-mrna until splicing occurs the it is called mrna - removing introns

in rna uracil is used in place on thymine

Question 8

What happens to mRNA after transcription?

Answer 8

In eukaryotic cells, pre-mRNA must be spliced to remove introns, leaving only the coding regions. Then it moves out of the nucleus and attaches to a ribosome.

Question 9

What is produced by translation?

Answer 9

Proteins.

Question 10

Where does translation take place?

Answer 10

In the cytoplasm (on ribosomes).

Question 11

Outline the process of translation.

Answer 11

● The anti-codon of tRNA attaches to complementary bases on the mRNA.
● Amino acids bonded to tRNA form peptide bonds, continuing to form a polypeptide chain until a stop codon is reached.
● This process requires ATP.

or the process from PMT:

(b) 1. (mRNA attaches) to ribosomes
OR
(mRNA attaches) to rough endoplasmic reticulum;
2. (tRNA) anticodons (bind to) complementary (mRNA) codons;
3. tRNA brings a specific amino acid;
4. Amino acids join by peptide bonds;
5. (Amino acids join together) with the use of ATP;
6. tRNA released (after amino acid joined to polypeptide);
7. The ribosome moves along the mRNA to form the polypeptide;