Transcript The Story of Fertilization

The Story of Fertilization
Egg (gamete) + sperm (gamete) = zygote
Look Who’s Talking
https://www.youtube.com/watch?v=65BV5dXXxzM
1. The Sperm and the
Egg
Sperm/Egg - Where? Size? Quantity? And why?
Egg
Size - 0.1mm
Number – 1/2/3
Sperm
Size - 0.005 mm
Number – 40120 million
and then...
BBC bitesize -http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/reproduction/revision/3/
BBC http:///www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/reproduction/revision/2
2. The Journey
Egg
Sperm
•
through the cervix
•
through the uterus
•Lining of womb gets
thicker
•
through the fallopian
tube
•Not capable of
movement but brushed
down the fallopian tubes
over 12-24 hours
•
to the egg
•
Takes about an hour
•FSH causing follicle
growth
•LH causes ovulation
3. The Battle For the Egg
There can be only one
Egg Anatomy
• One of largest cells in
human body
• Contains small amount of
yolk (= cytoplasm) – fats
and proteins
• The egg jelly (zona
pellucida) releases
chemicals to attract
sperm – species specific?
Sperm Anatomy
•
•
•
•
Motile tail
Mitochondria
Pointed head
Enzymes which
enable the sperm to
pierce the zona
pellucida (egg jelly)
it to fertilize it
(acrosomal action)
4. Securing the Gates
Granules seal the deal
The exterior of the egg hardens once a sperm
has entered so no more can enter.
4. Getting the Numbers
Right
46 is the magic number for making a viable zygote
Chromosomes
sperm and egg nuclei fuse
now there are 46 chromosomes within
the fertilized egg
Which is called a z….......
Now what?
http://www.dnatube.com/video/451/Animation-of-egg-fertilization
5. Twins!
two ways to make 2 (or more)
Megan!
For Tomorrow:
Generate at least one excellent question about
the reproductive system, reproductive strategies
and mating behavior.