Genetics, diversity, and classification

Question 1

Describe two differences between the structure of a tRNA molecule and the structure of an mRNA molecule.

Answer 1

-tRNA has a clover leaf shape whereas mRNA is linear.
-tRNA has hydrogen bonds, whereas mRNA does not
-tRNA has an amino acid binding site, whereas mRNA does not
-tRNA has anticodon, whereas mRNA has codon

Question 2

In a eukaryotic cell, the structure of the mRNA used in translation is different from the structure of the pre-mRNA produced by transcription.
Describe and explain a difference in the structure of these mRNA molecules.

Answer 2

-mRNA has fewer nucleotides
Or
-mRNA has only externs and no introns
-Because of splicing

Question 3

Describe how one amino acid is added to a polypeptide that is being
formed at a ribosome during translation.

Answer 3

-tRNA brings specific amino acid to ribosome
-Anticodon on tRNA brings to codon on mRNA
-Amino acids join together by condensation reaction using ATP
Or
-Amino acids join to form a peptide bond using ATP

Question 4

Describe how mRNA is produced from an exposed template strand of DNA.

Answer 4

-Free RNA nucleotides form complimentary base pairs
-Phosphodiester bonds form
-By action of RNA polymerase

Question 5

Describe how mRNA is formed by transcription in eukaryotes.

Answer 5

-Hydrogen bonds between DNA bases break
-One DNA strand acts as a template
Free RNA nucleotides align by complimentary base pairing
-Uracil is used instead of thymine
-RNA polymerase joins adjacent RNA nucleotides
-By phosphodiester bonds
-Pre-mRNA is spliced to form mRNA-introns are removed.

Question 6

Describe how a polypeptide is formed by translation of mRNA.

Answer 6

-mRNA attaches to ribosomes
or
-mRNA attaches to rough endoplasmic reticulum
-Ribosome moves to/finds the start codon
-tRNA anticodons find to complimentary mRNA codons
-tRNA brings a specific amino acid
-Ribosome moves along to next codon
-Amino acids join by peptide bonds
-With the use of ATP
-tRNA released after amino acid joined to polypeptide
-Ribosome moves along the mRNA to form the polypeptide.

Question 7

What is the proteome of a cell?

Answer 7

-The proteome is the full range of / number of different proteins that a cell is able to produce at a given time
OR
-The proteome is the full range of / number of different proteins the genome / DNA is able to code for

Question 8

Give the two types of molecule from which a ribosome is made.

Answer 8

-Ribsosomal RNA
-Ribosomal proteins/polypeptide