Lecture 35 Developmental Genetics

What is the process of development?

The process of development begins as a single cell where it has the potential to become any type of cell, the cell quickly becomes SPECIFIED

What are the 3 primary stages of Drosophila development?

1. Axis Determination - anterior-posterior axis, dorsal-ventral axis

2. Segmental Determination - Number and orientation of the segments

3. Segment Identification - Function and morphology of each segment

How does the gene “dorsal” cause the dorsal-ventral axes to form? What protein does the gene dorsal encode? What does it mean that dorsal is of maternal origin?

dorsal causes the dorsal-ventral axes to form by encoding a transcription factor (Dorsal Protein)

the dorsal gene encodes the DORSAL PROTEIN regulates DECAPENTAPLEGIC (induces dorsal structures)

The MOTHERS GENOME supplies the dorsal gene

How do bicoid and hunchback determine the anterior-posterior axis?

The bicoid gene is CONCENTRATED at the ANTERIOR end, STIMULATES HUNCHBACK

The hunchback gene then stimulates the formation of head and thorax

What do homeotic genes do? How is the order of homeotic gene expression determined? Identify a set
of homeotic genes shared by all vertebrates

Homeotic genes determine the identity of individual segments by initiating segment specific gene expression

GIVE CELLS THEIR ADDRESS OR LOCATION INFORMATION

Gene order is the same as order of expression in the body

VERTEBRATES SHARE: HoxA, HoxB, HoxC, and HoxD

How is apoptosis a critical part of development?

apoptosis is a critical part of development since it is controlled cell death, regulated by genes

Define Totipotent

Totipotent is the potential for a cell to become any type of cell, becomes millions or trillions of different cells

Define Morphogens

Morphogens are proteins that create a concentration gradient that affects the developmental fate of the surrounding region

Define Caspases

Caspases are ENZYMES THAT CLEAVE OTHER PROTEINS