1. Timing and Development of Growth
Big Idea 2E: Many bio processes involved in growth, reproduction, and homeostasis include temporal regulation and coordination

2. Essential Knowledge
2E1: Timing and coordination of specific events are necessary for the normal development of an organism, and these events are regulated by a variety of mechanisms.
2E2: Timing and coordination of physiological events are regulated by multiple mechanisms.

3. All Cells in an Organism Contain Same DNA
Came from same zygote dividing over and over again

4. DNA Review 1 molecule of DNA forms a chromosome
Each chromosome contains many segments of DNA called a gene
1 gene codes for one polypeptide (portion of a protein)
Only about 1% of DNA consists of genes

5. Gene Expression DNA in nucleus is transcribed into RNA
RNA exits nucleus and is translated into a polypeptide by ribosomes

6. Control of Transcription
Enzyme that transcribes DNA (RNA Polymerase) requires transcription factors
Activation of transcription factors triggers transcription  expressing gene.

7. Cells Are Different Because they Express Different Genes
Each cell generates different proteins and at different times
Very complicated!!

8. During Development Different Genes Are Expressed
Homeotic (hox) genes control develop. patterns and sequences  Determine where body parts develop

9. Messing with HOX genes Example

10. Embryonic Induction
As cells develop and mature  cause other cells to express certain genes at correct time
Ex: as eye forms, one cell causes others to express genes necessary to make eye cells

11. For Plants…
Temp and water availability determine seed germination and embryo growth.

12. All Cells Originally Can Be Anything!
But over time processes (DNA methylation/ induction) restrict what genes are expressed
Can be inherited from parents

13. DNA methylation shuts off many genes!!

14. Genetic Mutations and Development
Synpolydactyly (SPD) is a genetic disorder that results from mutations in one of the HOX genes. The phenotypes are shown in the pictures below, which usually involves developmental disorders in the fingers and toes resulting in fusion and malformation.
Minor mutations in homeotic genes  BAD!

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

17. As orgs grow, some cells must be destroyed
Apoptosis
Programmed cell death
As orgs grow, some cells must be destroyed

18. Originally there are cells between your fingers- they die, separating the fingers