1. Many biological processes involved in growth, reproduction and dynamic homeostasis include temporal regulation and coordination. 2E

2. Temporal regulation
a type of regulation of gene expression in which a gene is only expressed at a specific time in development; for example, genes that are only expressed in the light or during flower development

3. Cell differentiation
1. Cell differentiation results from the expression of genes for tissue-specific proteins, and the induction of transcription factors during development results in sequential gene expression. Cell differentiation also results from specific silencing of gene expression
Transcription factors are proteins that determine what genes are turned on or off in the genome of an organism

4. 2. Explain an example of specific silencing of gene expression
Homeotic genes determine developmental patterns and sequences in organisms. A homeotic gene is one of a series of “master switch” genes that determine the form of segments developing in the embryo.
Homeotic genes contain a sequence of DNA known as a homeobox, which encodes a segment of 60 amino acids within the homeotic transcription factor protein. If a mutation occurs in the homeobox of any of the homeotic genes, an organism will not develop correctly.
For example, in fruit flies (Drosophila), mutation of a particular homeotic gene results in altered transcription, leading to the growth of legs on the head instead of antenna; this is known as the antennapedia mutation.

5. 3. Genetic transplantation experiments support the link between
Gene expression
Mutations
Development of the organism
Programmed cell death (apoptosis) plays a role in normal development and differentiation.

6. 4. Give 2 examples of how plants respond to interactions
Photoperiodism and Phototropism

7. Organisms respond to changes in their environment through behavioral and physiological mechanisms.
• Photoperiodism and phototropism in plants
Define Photoperiodism
Long-day plants
Short-day plants
Define Phototropism

8. Photoperiodism - physiological reaction of organisms to the length of day or night. It occurs in plants and animals - amount of uninterrupted darkness is what determines the formation of flowers on most types of plants
Phototropism - directional growth of organisms in response to light (plants and some fungi

9. If the long night of late fall is artificially interrupted by a flash of light – the clover will bloom, not the cocklebur

10. FIG 41.6

11. Coleoptile - A protective sheath enclosing the shoot tip and embryonic leaves of grasses

12. 5. Give 2 examples of how animals respond to interactions
circadian rhythm
seasonal responses

13. 6. List 3 animal behaviors triggered by environmental cues
Hibernation
Migration
Estivation (dormancy of an animal during hot or extremely dry periods)

14. 7. Photoperiodism occurs in plants due to changes in critical night length.
8. Cooperation and communication within or between populations contributes to the survival of individuals and the population.

15. Essential knowledge 2.E.1: 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.

18. Stems cells and Differentiation

19. a. Observable cell differentiation results from the expression of genes for tissue specific proteins.

20. b. Induction of transcription factors during development results in sequential gene expression

21. Read Induction can lead to cell differentiation on pg 377-378 and summarize
Induction – change in cell fate due to interaction with an adjacent cell. Induction occurs when one cell type produces signal molecules that induce gene expression in neighboring target cells.
In frogs, cells from animal and vegetal poles do not develop into mesoderm when isolated.
Blastomeres (one of the cells of the of a blastula)from one pole (end) of the embryo(the “animal pole” or yolk-poor hemisphere) develop features of the ectoderm. Blastomeres from the opposite pole (“vegetal pole” or yolk-rich hemisphere) develop features of endoderm

23. In tunicates, signaling of the growth factor FGF induces mesoderm development.

24. 1. Homeotic genes are involved in developmental patterns and sequences
Define Homeotic genes
one of a series of “master switch” genes that determine the form of segments developing in the embryo.

25. 2. Embryonic induction in development results in the correct timing of events
Read Cells become determined prior to differentiation & tracking determination pg and summarize
The process of determination commits a cell to a particular developmental pathway prior to its differentiation. This is not visible, but can be tracked experimentally. Determination is due to differential inheritance of cytoplasmic factors or cell-to-cell interactions.
Embryonic induction in development results in the correct timing of events

26. 3. Temperature and the availability of water determine seed germination in most plants.
What are the two factors that most commonly lead to seed germination? Correct temperature and the availability of water

27. 4. Genetic mutations can result in abnormal development.
Describe three ways that mutations in genes can lead to abnormal development
To function correctly, each cell depends on thousands of proteins to do their jobs in the right places at the right times.
Sometimes, gene mutations prevent one or more of these proteins from working properly.
By changing a gene’s instructions for making a protein, a mutation can cause the protein to malfunction or to be missing entirely.
When a mutation alters a protein that plays a critical role in the body, it can disrupt normal development or cause a medical condition.
A condition caused by mutations in one or more genes is called a genetic disorder.

28. 5. Genetic transplantation experiments support the link between gene expression and normal development.
6. Genetic regulation by microRNAs plays an important role in the development of organisms and the control of cellular functions

29. c. Programmed cell death (apoptosis) plays a role in the normal development and differentiation.
Define apoptosis
the process of programmed cell death; used to produce planned and orderly elimination of cells that are not destined to be present in the final tissue

31. Read Programmed cell death is a necessary part of development and summarize
Apoptosis, programmed death of cells, removes structures once they are no longer needed