Date: March 7th, 2017-period 5 Aim # 56: How does an embryo develop? HW: Daily Review of Class Notes Sexual Reproduction Review due Tuesday Castle Learning due Thursday Test Friday(Textbook Homework for Extra Credit due) Do Now: The joining of egg and sperm is called ___________. What is another term for a fertilized egg? Is this cell diploid or haploid cell? What are the only haploid cells in a living organism? How are the produced?

Date: March 7th, 2017-period 1 Aim # 56: How does an embryo develop? HW: Daily Review of Class Notes Sexual Reproduction Review due Wednesday Castle Learning due Thursday Test Thursday Do Now: The joining of egg and sperm is called ___________. What is another term for a fertilized egg? Is this cell diploid or haploid cell? What are the only haploid cells in a living organism? How are the produced?

Aim #56: How does an embryo develop?

How does the zygote form? Zygote – A fertilized egg

1) What happens to the zygote after it is formed? Mitosis – causes the zygote to repeatedly divide producing the developing embryo.

2) Embryonic Development: Fertilization Mitosis + Sperm Egg Zygote Embryo- the stage in human development from the first division of the zygote until about nine weeks after fertilization.

4) Cleavage The term used to describe the early cell division associated with embryonic development. During this time period, the number of cells increase tremendously.

5) The result of cleavage is an embryo that is ….. Morula A solid ball of cells which moves towards the uterus

6) Mitosis continues & the embryo becomes…… Blastocyst A hollow ball of cells

Cell division continues & the embryo starts to …. Gastrula Fold inwardly

7) Gastrulation Three layers Each layer will eventually form the different organ systems

8) CELLULAR DIFFERENTIATION Due to gene expression, cells undergo cellular differentiation, in which the cells become increasingly specialized in structure & function.

9) Gene Expression Genes that are being expressed are “on” Though all genes of the genome are present in every type of cell, only a small, specific fraction of these genes are actually expressed in each type of cell.

10) What makes some cells turn “on” some genes while other genes are “off”? Environmental influences from within the cell, from surrounding cells, or from outside the organism.

These seeds carry the same genes for chlorophyll: Why are they different? Grown in light Grown in dark These seeds carry the same genes for chlorophyll: ENVIRONMENT AFFECTS GENE EXPRESSION

11) What is the end result of differentiation? An embryo with many different types of cells

12) What are Stem Cells Stem cells are embryonic cells that can turn into any type of cell in the body

13) How can stem cells help us? Can be used to make any type of cell that needs to be replaced in our bodies

Why is the use of stem cells so controversial? They are often taken from fetuses. Opponents believe that you are killing a life.

Are stem cells only embryonic? No, there are some adult stem cells, but they don’t have the potential to become any kind of cell

A Cell Stem Story Award-winning 15 minute video introduction to stem cell research http://www.eurostemcell.org/films