Lecture 7: Developmental Genetics

Question 1

Homebox containing genes

Answer 1

• Hox genes
• Pax genes
• POU genes
• Lim protein genes
• Dlx genes

Question 2

What’s a homebox?

Answer 2

Contain a highly conserved sequence of 180 nucleotides called the homeobox which codes for the 60 amino acid homeodomain found in homeodomain transcription factor proteins.

Question 3

More homebox details:

Answer 3

• Play a major role in vertebrates with regard to cranio-caudal segmentation, not only along main body axis but within the development of many organs.
• Activated in a 3’ to 5’ direction (opposite of transcription direction).
• Loss-of-functionmutations:
• Result in posterior to anterior transformations
• Gain-of-functionmutations:
• Result in anterior to posterior transformations.

Question 4

T-box genes (Tbx):

Answer 4

• Contains a conserved T-box coding 180 to 200 amino acids
• Family includes up to 100 genes.
• Plays role in inducing mesodermal germ layer and in coordinating the outgrowth of the arm or leg.

Question 5

Helix-loop-helix genes:

Answer 5

• Code for basic helix-loop-helix transcription factors.
• Basic regions of proteins bind to DNA.
• Helix-loop-helix involved in homodimerization and heterodimerization.
• Important in myogenesis.

Question 6

Forkhead (Fox) genes:

Answer 6

• Type of helix-loop-helix family.

* Expressed in many developing organs throughout the body.

Question 7

Zinc finger transcription factors:

Answer 7

• These proteins have zinc ions bound to polypeptide chain that cause the chain to form finger-like projections that can be inserted into the DNA helix.
• Gene families:
  * Soxgenes
  * WT1

Question 8

Gene Hierarchy in Drosophila

Answer 8

• Materna leffect genes
• Segmentation genes:
  * Gap genes
  
  • Pair-rule genes
  • Segment-polarity genes
• Homeotic genes:
• Antenna pedia complex (Hox genes)
• Bithorax complex (Hox genes)

Question 9

Note: I put these cards together just to have a complete set of cards for the first test. This lecture is very cartoon intense… make sure to read the book and rematch lecture. I don’t have the time to make up random questions.

Answer 9

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