Transcription Factors + Homeobox Genes

Question 0

What are homeobox genes?

Answer 0

• the proteins that control body plan development are coded for by genes called homeotic genes
• homeotic genes are similar in plants, animals and fungi
• homeotic genes have regions called homeobox sequences that code for part of the protein called the homeodomain
• the homeodomain binds to specific sites on DNA enabling the protein to work as a transcription factor
• the proteins bind to DNA at the start of developmental genes, activating or repressing transcription and so altering the production of proteins involved in the development of the body plan

Question 1

What could a mutation in homeobox genes do?

Answer 1

• Can have a big impact as it could affect the fate of cells and body plans.
• e.g. Drosophila having legs where antenna should be

Question 2

What is a transcription factor?

Answer 2

• it is a protein that binds to DNA and switches genes on or off by increasing or decreasing the rate of transcription

  - factors that increase the rate are called activators 
  - factors that decrease the rate are called repressors