Gene expression

Transcription is the process whereby:

  

• a piece of messenger RNA is produced complementary to the DNA code for a gene

• amino acids in the cytoplasm are placed, by transfer RNA, into the correct sequence for protein synthesis

• the DNA for a gene unzips

• the Golgi apparatus converts the polypeptide chain into a specific protein

The question below refers to the image

The correct sequence of lettered parts in the missing half of this molecule is:

  

• TAGACT

• AGTCTA

• TCAGAT

• GACTGC

The question below refers to the image.

If the molecule portion were being transcribed, the correct sequence of lettered parts in the new molecule would be:

 

• AGUCUA

• UGTCTU

• UAGUGA

• AUCUGA

The question below refers to the image.

The highest number of amino acids coded for by the molecule shown is:

• 1

• 2

• 3

• 6

Genes mainly exert their control over cellular activity by:

• preventing the passage of materials into the cell through its membrane

• producing transcription factors that block production of mRNA

• contributing to epigenetic histone modification

• controlling cellular metabolism

DNA methylation is a process that:

   

• is instigated by regulatory genes to increase the rate of transcription

• works in the same way as a histone modification

• epigenetically blocks expression of a gene

• tightens the coiling of a nucleosome

Describe how the Hox gene can be used to explain why insects and humans have a common ancestor.

Answer explanation

The Hox gene determines the type of appendages that will form on a body segment. Studies were conducted on insects with mutations in the Hox genes and there were issues with appendages and segmentation. Humans also have a Hox gene, which infers that it is conserved between animals and insects, indicating there is a common ancestor.

A certain protein is composed of 1500 amino acids. Determine how many base pairs the gene responsible for its synthesis would have.

Answer explanation

If a protein contains 1500 amino acids, there would have been 4500 base pairs in the gene.

Compare structural and regulatory genes.

Answer explanation

Structural genes are sections of DNA that contain the instructions for protein production, whereas regulatory genes are non-coding sections of the DNA that produce transcription factors to control the expression of DNA.

The genetic code is generally accepted as being provided by the linear arrangement of:

• amino acids in chromosome proteins

• sugar units in DNA

• nucleotide bases in DNA

• nucleotide bases in RNA