Presentation on theme: "Connect! What are the green cells? The big gold cell? What process is shown?"— Presentation transcript:
Connect! What are the green cells? The big gold cell? What process is shown?
Part 2: Fertilization is the union of a monoploid sperm nucleus and a monoploid egg nucleus producing a fertilized egg called a zygote nn 2n zygote mitosis 2n ?
A diploid zygote is produced and the species number of homologous chromosomes (2n) is restored. For ex, when a sperm cell of a fruit fly containing 4 chromosomes joins with an egg cell of a fruit fly containing 4 chromosomes, the resulting zygote has 8 chromosomes.
There are two types of fertilization: external and internal.
A. EXTERNAL FERTILIZATION when gametes fuse (join) outside of female’s body occurs in many aquatic vertebrae such as fish and amphibians (toad photos) usually large numbers of eggs are required to insure species survival
A. INTERNAL FERTILIZATION when gametes fuse in the moist reproductive tract of the female occurs in most terrestrial (land) vertebrae animals fewer eggs
Chunk Define fertilization. What is the fertilized egg called? Is the fertilized egg haploid or diploid? What are the two types of fertilization? What type of organisms carry out external fert? What type of organisms carry out internal fert? Which type of fert usually produces few eggs Why? What does the term “terrestrial” mean?
Connect The series of changes which occurs as a living thing reaches its final form is called development. These chicks went through many changes during their development before they hatched. They will continue to change as they develop into adult penguins. What changes have you gone through during the course of your development? Are you still going through the developmental process? How does a zygote turn into a baby, then an adult?
PART 3: Embryonic Development The Steps of Development 1.The zygote starts dividing by mitosis. This is called cleavage. At this point, the zygote becomes an embryo. 2.The embryo forms a blastula, which is a single layer of cells in a hollow-ball type structure. Arrow is where sperm entered
3.When one side of the blastula becomes indented the gastrula is formed, which has 3 layers: endoderm – inner layer mesoderm – middle layer ectoderm – outer layer
4. Gastrulation (forming a gastrula) is a very important part of development bc it is now when the cells of each layer differentiate, meaning they each get a specific job. Each cell becomes part of the various organs and systems of the multicellular animal. Review! How does each cell turn into a different type? How do we end up with neurons, white blood cells, etc…?
Differentiation Endoderm – becomes the linings of the digestive and respiratory tracts, parts of the liver and pancreas (guts) Mesoderm – becomes muscle, circulatory system, skeleton, excretory system, and gonads Ectoderm – becomes nervous system and skin 5. Growth is an increase in cell number as well as cell size.
Chunk! Define zygote cleavage. Does it involve meiosis or mitosis? Explain. When does the zygote become an embryo? What is a blastula? What is a gastrula? Name the 3 layers of a gastrula, and what each layer differentiates into. What is gastrulation? Identify all of the parts of this diagram: Explain how genes influence differentiation. What are 2 ways growth can occur?