Cellullar control

Question 1

What is a mutation?

Answer 1

An alteration to the DNA base sequence that arises randomly during DNA replication

Question 2

What are addition and deletion mutations?

Answer 2

One more more nucleotide in the DNA base sequence is either inserted or deleted, changing the amino acid sequence

Question 3

What is a substitution mutation?

Answer 3

A nucleotide in the DNA sequence is replaced by another, usually a neutral mutation so has no affect on the amino acid sequence

Question 4

How is gene regulation regulated at the transcriptional level?

Answer 4

Transcription factors. These are proteins that either initiate or inhibit transcription of genes so only certain parts of DNA are expressed

Question 5

Describe the function of the lac operon in low lactose concentrations

Answer 5

E.coli uses lactose as a respiratory substrate via the use of an enzyme

When lactose concentration is low, the lac operon binds to the gene that makes this enzyme, inhibiting its expression

Question 6

Describe the function of the lac operon in high lactose concentrations

Answer 6

Lactose binds to the operon causing it to change shape and unattach from the gene.

This allows RNA polymerase to bind allowing the gene to be expressed

Question 7

How is gene expression regulated at the post transcriptional level?

Answer 7

Splicing

Primary mRNA has coding regions (exons) and non coding regions (introns).

Introns are removed the produce mRNA ready for translation

Question 8

How is gene expression regulated at the post translational level?

Answer 8

Activation of proteins

E.g adrenaline, binds to a receptor and then prompts an enzyme (converts ATP to cyclic AMP) which prompts another enzyme, which activates the protein

Question 9

How is development controlled by the homeobox genes?

Answer 9

They code for transcription factors that activate genes during the development of a zygote. (development of a ‘body plan’)

Question 10

How is development controlled by mitosis?

Answer 10

Allows cell growth and tissue repair.

Genes regulating mitosis respond to external and internal stimuli to determine growth

Question 11

How is development controlled by apoptosis?

Answer 11

Programmed cell death prevents cancer and keeps cell division at a constant and stable rate