L10

Question 1

Fives phases of development

Answer 1

1. Fertilization
2. Maternal effect phase
3. Formation of segments
4. Segments take on identity
5. Tissue and organ formation

Question 2

Fertilization and maternal effect phases

Answer 2

Fert: egg contributes haploid genome, proteins and mRNAs, spread contributes haploid genome

Maternal factors control the initial steps of development

Question 3

Segmentation

Answer 3

Formation of anatomical segments: maternal-effect genes, gap genes, pair-rule genes, segment-polarity genes (all toolkit genes, which encode TFs and signalling proteins)

Question 4

Segments take on identity via Hox genes

Answer 4

Hox genes are a fifth group of toolkit genes

Question 5

Signalling proteins:

Answer 5

• act as secreted ligands

- can directly influence adjacent cells

Question 6

Transcription factors

Answer 6

• bind DNA in the nucleus

- cannot directly influence adjacent cells (cell autonomous)

Question 7

Transcription Factors: Hox proteins as an example

Answer 7

• TFs act cell-autonomously- TFs have a DNA binding domain