1. Genetics of Development

2. All Cells in an Organism Contain the Same DNA
Come from the same zygote dividing over and over again

3. Cells Are Different Because they Express Different Genes
Each cell generates different proteins and at different times
Very complicated, focus of research currently

4. Homeotic/Hox Genes Control developmental patterns and sequences
Determine where each body part develops

5. Very Well Conserved in Animals
We have almost the same exact Hox genes as fruit flies
But we have more copies due to gene duplication

6. What do Hox genes do? Code for transcription factors
Turn on or off combinations of genes in different regions of the embryo

7. Emma…

8. Will you go to prom…

9. With

10. Embryonic Induction
Cells stimulate nearby cells to express certain genes
E.g. as the eye forms, one cell causes others to express the genes necessary to make eye cells
Transplantation experiments showed adding one cell could change cells around it

11. How Induction Works One cell specializes, likely due to Hox genes
It triggers further development of nearby cells
Likely produces proteins that act on the genes of nearby cells
Ensures proper timing and development

12. Spemann-Mangold Experiment

14. All Cells Originally Can Be Anything
But over time processes restrict what genes can be expressed
DNA methylation and other processes shut off many genes
Processes like induction shut off gene expression or turn on gene expression long-term.
When new cells form they usually have the same genes shut off as their parent cell

15. MicroRNAs Regulatory molecule that blocks translation of RNA
Controls development and cellular organization

16. MicroRNAs Appear to help fine- tune development
Prevent certain genes from being expressed in certain cells

17. Apoptosis As organisms grow, some cells must be destroyed
Apoptosis= programmed cell death
E.g. originally there are cells between your fingers- they die, separating the fingers

18. Other Examples of Apoptosis
Destruction of WBCs that attack the body
Destruction of neurons that are not used (pruning)
Destruction of mutated cells
Recycling of mature cells
50-70 billion cells apoptosize each day