Control of gene expression

Question 1

What are housekeeper genes?

Answer 1

• enzyme which are necessary for reactions present in metabolic pathways like respiration are constantly required
• the genes that controll these are called housekeeper genes
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Question 2

What are tissue specific genes?

Answer 2

• protein-based hormones (required for the growth an development of an organsim of enzymes) are only required by certain cells at certain times to carry out a short-lived response
• they are coded for by tissue-specific genes

Question 3

What is the problem with the genome of prokaryotic cells?

Answer 3

• the entire genome of an organism in found in every prokaryotic cell
• this includes genes not required by that cell so the expression of genes and the rate of synthesis of protein products like enzymes and hormones has to be regulated

Question 4

How is expression of genes regulated?

Answer 4

• genes can be turned on or off
• the rate of products synthesis is increased or decreased depending on demand
• this also occurs in bacteria in response to stimuli
  
  • prevents vital resources being wasted

Question 5

How is gene regulation in prokaryotes and eukaryotes?

Answer 5

• essentially the same
• eukaryotes
  
  • need to respond to internal and external stimuli
  • gene regulation needs to work in a coordinated way
  • required for cells to specialise

Question 6

What are the way in which genes are regulated?

Answer 6

• transcriptional
  
  • genes turned on or off
• post-transcriptional
  
  • the mRNA can be modified which regulates translation and the types of proteins produced
• translation
  
  • can be stopped or started
• post-translational
  
  • proteins can be modified after synthesis which changes their function