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
n
n
2n
zygote
2n
mitosis
?
• 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
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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.
Arrow is where sperm
entered
2.
The embryo forms a blastula, which is a single layer
of cells in a hollow-ball type structure.
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!
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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?
Look closely!
Isn’t art amazing?
Isn’t art amazing?
Isn’t art amazing?
Isn’t art amazing?
Isn’t art amazing?
Just For Fun!
Image Sources
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Egg and sperm - http://130.102.208.100/FMRes/FMPro?-db=images.fp3&key=32931&-img
Fertilization - www.zoology.ubc.ca/.../Greg/stage1.htm .
Turtle mating - www.wildlife-pictures-online.com/200609.html
Swans - www.dailymail.co.uk/sciencetech/article-12460...
Fish spawning clip art - www.arthursclipart.org/.../biology/page_03.htm
Sunfish spawning - http://gwsphotos.com/images/547.JPG
Sunfish nests - http://www.dfwandme.com/wp-content/uploads/2008/06/spawning.jpg
Nest - http://www.bbc.co.uk/tyne/content/images/2007/06/05/birds_nest_470x353.jpg
Penguins - http://images.google.com/imgres?imgurl=http://curiousanimals.net/wp-content/uploads/2008/02/familiespenguins.jpg&imgrefurl=http://curiousanimals.net/funnies-bunnies/one-day-from-life-of-apenguin/&usg=__ux6DqnDXEtq620bMmlDAgclhTow=&h=375&w=500&sz=66&hl=en&start=3&um=1&itbs=1&tbnid=8O_6OyyzkHS3EM:&
tbnh=98&tbnw=130&prev=/images%3Fq%3Dpenguins%2Bwith%2Bbabies%26um%3D1%26hl%3Den%26sa%3DG%26rlz%3D1T4ADB
S_enUS301US303%26tbs%3Disch:1
Cleavage, gastrula - worms.zoology.wisc.edu/urchins/SUcleavage_mon
Diagram - www.ekcsk12.org/.../regbio/development1.gif
Face fish - http://thinkorthwim.com/index.php?tag=fish
Cartoon - http://www.cartoonstock.com/lowres/wda1241l.jpg