Homework #2 is due 10/17 Bonus #1 is due 10/24 FrakenFlowers

Vertebrate Development: from zygote to adult

All humans are female for the first nine weeks of development

Each whorl expresses a specific combination of three genes CB 21.20

Hox genes regulate the identity of body parts Fig 12.4

embryo adult Expression of hox genes in the embryo give rise to different adult body parts. Fig 12.4+.6

Drosophila and vertebrate Hox protein show striking similarities (500 million years since common ancestor) Fig 12.9

Many hox proteins have common sequences (these are from Drosophila) Fig 12.8

helix-turn-helix: a common DNA-binding motif Fig 10.28+.29

Many developmental genes are transcription factors Tbl 12.1 these are from Drosophila

Interaction of genes can set gradients in cells/organisms that signal how different regions should develop. Fig 12.18

Reporter gene: coding region promoter protein promoter reporter gene (luciferase, etc) easily visualized protein Fig 12.19

Interaction of genes can set gradients in cells/organisms that signal how different regions should develop. Fig 12.18

Mutants in Drosophila embryo segment development Fig 12.14

Gap genes affect formation of continuous blocks of segments Fig 12.14

Pair-rule genes regulate pairing of segments Fig 12.14

Segment-polarity genes regulate patterning of the segments. Fig 12.14

Hox genes regulate not segment patterns, but what each segment will become Fig 12.14

Why change gene expression? Different cells need different components Responding to the environment Replacement of damaged/worn-out parts

The order of Hox genes parallels the order of body parts in which they are expressed Fig 12.10

How are genomes organized? 25,000 12

Comparison of Fugu and human huntingtin gene: (green indicates transposons prevalent in human version) 7.5 X bigger both have 67 exons, connected by lines (puffer fish) Figure 7-113 Molecular Biology of the Cell, 4th ed by Alberts et al (Adapted from S. Baxendale et al., Nat. Genet. 10:67–76, 1995.)

rRNA is arranged in repeated transcription units

Most cells in an organism have the same DNA Most cells in an organism have the same DNA. Which cells have different DNA?

DNA is rearranged in B-cells during antibody production

Each B-cell produces a unique antibody

DNA rearrangements in B-cells allow each B-cell to produce a unique antibody

Homework #2 is due 10/17 Bonus #1 is due 10/24 FrakenFlowers