1. Sexual Reproduction
Mr. Mitcheltree

2. Sexual reproduction 2 gametes “parents”
Sperm Pollen
Ovule
= male
Egg
Sexual reproduction
2 gametes “parents”
- Many organisms produce both gametes (Ex: plants)
and sexually reproduce themselves
Offspring genetically different from parent
Provides genetic variation within a species
- Allows for evolution – “survival of the fittest genes”
= female

3. 2n multicellular organism
Meiosis n 4
Haploid Gametes 23 chromosomes
All X 2n
Zygote
fertilization
Diploid 23 pairs = 46
Mitosis
1 of each homolog
from each parent
= 23 pairs
All cells genetically
identical – somatic stem cells specialize 2n
Meiosis n 4
Haploid Gametes 23 chromosomes
1/2 X, 1/2 Y
Diploid 23 pairs = 46

4. Allele = alternate form of a gene A = dominant a = recessive
sex chromosomes – determine sex of the offspring
- XX = female
- XY = male XX
Meiosis 4 X XX
Gametes
Fertilization XY
Meiosis X XY 2 Y 2
Gametes

5. Mitosis vs. Meiosis

6. What else could have happened?
Disjunction
Homologs separate and move randomly
- crossing over may occur
2 homologous chromosome
pairs carrying dominant and
recessive genes
Equator A A a
A A a a a A a
A A a a
A A
a a b B b B
B B B b
b b B B
b b
b b B B
Diploid “Parent” Cell
What else could have happened?

7. What else could have these been?
Equator
A A A A
A A A b A b
b b
b b b b
4 haploid gametes
What else could have these been?
a a
a a a a a B B a B
B B
B B B
Meiosis Overview

8. Chromatids in a tetrad crossing over – one cause of genetic change
- mutation and variation: 1) Crossing Over
2) Independent Assortment
3) Random fertilization
Chiasma

9. Random movement during disjunction and Crossing Over
Variation of offspring
In humans, 64 trillion combinations after fertilization
1 in every 1,200 to 1,500 bases different
You have new mutations from your parents – most neutral (silent)

10. Mitosis Meiosis Sister Chromatids -Tetrads
Replicates Separate Ana Homologs separate Ana I
2 Diploid, genetically identical Haploid, genetically
daughter cells different gametes

11. Internal Fertilization : Mammals and birds
Sperm and egg fuse inside the females body
Mammals fertilization – copulatory organ
Bird fertilization – a few with copulatory organ, most cloaca to cloaca
Sperm can’t fly, it only swims!!!

12. Internal fertilization of reptiles
Copulatory organs in most, cloaca in snakes
Lizards
Crocodiles and alligators
Turtles
Snakes

13. Internal Fertilization in Terrestrial Insects
Why do they need internal fertilization?

14. Internal fertilization of fish: sharks, skates, rays and land based amphibians : salamanders
– better chance of not having eggs in a marine/aquatic nest or free-floating eaten?
Land salamander egg mass that came out of a female quite in proportion to her body size, then absorb water to swell up 20 times bigger.
Male shark with claspers to transfer sperm packets

15. External fertilization in MOST amphibians
– a gravid female
Amplexus – a male squeezing eggs
out of a female prior to sperm
release
Fertilized eggs undergoing oviparious
development

16. External fertilization in MOST fish
Release of
Eggs and
milt (sperm)
Oviparous development

17. External fertilization of many marine (oceanic)
and aquatic (fresh water)
invertebrates
Sponge dumping gametes
Some jellyfish
Non-parasitic mussels
All oviparous =
egg development outside
of the body

18. Hermaphrodite – both male and female sex organs
Typically don’t self-reproduce (a few parasites do)
- reduced genetic diversity if they do self –repro.

19. Animal Development Oviparous – nutrition from yolk
Viviparous – nutrition from placenta (female’s blood), live birth
Ovoviviparous – nutrition from yolk, live birth

20. Site of meiosis
Ovule = female gamete
Pollen = male gamete
Site of meiosis
Pollination
Fertilization

21. - The Characteristics of Seed Plants

22. Fungi Reproduction spores are gametes
Secondary mycelium – diploid
Haploid spores formed by meiosis in fruiting body
fertilization
haploid
Primary mycelium - haploid

23. Conjugation – exchanging DNA producing new genetic individuals in Protists

24. Bacteria genetic
recombination

25. Horse
Donkey
A mule is the offspring of a male donkey and a female horse.[1] Horses and donkeys are different species, with different numbers of chromosomes. Of the two F1 hybrids between these two species, a mule is easier to obtain than a hinny (the offspring of a male horse and a female donkey). All male mules and most female mules are infertile.
Mule

26. Lamarck’s Inheritance of Acquired Traits
NOT TRUE

27. Darwin’s Finches
Diversification – speciation due to a lack of competition

28. Horse Evolution Speciation due to environmental change
Why do giraffes have long necks?

29. - Evidence of Evolution
Speciation due to geographic isolation

30. - The Fossil Record 430 million years ago 66 million years ago
1 billion years ago
3.5 billion years ago

31. Unicellular to Animal Evolution

32. The Genetic Basis of Evolution
Thomas Morgan – genes on chromosomes

34. Chromatids in a tetrad crossing over
– one cause of genetic change
- mutation

35. DNA change allows for evolution according to modern theory
- The DNA Connection
DNA change allows for evolution according to modern theory
99.9% are neutral or bad, .1% makes an organism better adapted
Copy Errors

38. Crash Course Biology
Meiosis
Study Island Review 6a