2. 44 XY 44 XX
44 XY
22 X 22 X22 Y
44 XX
SPERMS
OVULES
SEX DETERMINISM
IN HUMANS
HETEROGAMETIC SEX HOMOGAMETIC SEX

3. 4646
23
23
46
46
46 46

4. Variability causes in Meiosis
1.Homologous Chromosomes
Separation during ANAPHASE
I.

6. A A A A
B B b b
C C C C
D D D D
E E e e
F
G
F F F
G g g

7. A
B
C
D
E
F
G
A
B
C
D
e
F
g
AA
b
C
D
e
F
g
b
C
D
E
F
G

8. Variability causes in Meiosis
2. Crossing over
RECOMBINATION OF GENES

9. Random Crossing over between
homologous chromosomes, as a
result........

10. Imagine that Recombination takes place
only in one pair of Chromosomes. From
the mother cell after Meiosis would
appear four types of ovules.

12. MEIOSIS I
MEIOSIS: A GENERAL VISION
MEIOSIS II

13. 23 from father
23 from mother.

14. A
B
C
D1
E
F3
G2
H9
A
B
C
D1
E
F3
G2
H9
I
J
K
L
M
N1
O1
P
Q
I
J
K
L
M
N1
O1
P
Q
A
b
C
D2
E
F1
G2
H9
A
b
C
D2
E
F1
G2
H9
i
J
k
L2
m
N1
O3
P
q
i
J
k
L2
m
N1
O3
P
q
They take genes for
the same Traits but
can take different
versions.
Observe the Example.

16. Crossing over and Recombination

18. The main events in Meiosis
2. Random Crossing
over between
homologous
chromosomes
1.Homologous
Chromosomes
Separate during
ANAPHASE I

19. 1
2
34
5
6

20. HOMOLOGOUS
HOMOLOGOUS
CHROMOSOMES
ALIGN ALONG
METAPHASE PLATE
PROPHASE I

21. d) Anaphase I

22. PROPHASE II

23. i) Anaphase II

24. Variability causes in Meiosis
1. Crossing over
3.Separation of sister
Chromatides during ANAPHASE II
2.Homologous Chromosomes
Separation during ANAPHASE I

26. A
B
C
D
E
F
G
A
B
C
D
e
F
g
AA
b
C
D
e
F
g
b
C
D
E
F
G

27. 1. Crossing over
Exchange of Genetic Material between
Homologous Chromosomes

28. 2.Homologous
Chromosomes
Separation during
ANAPHASE I
Either
or
A B
A B

29. A1
A2
A1 A2
A3 A4 A3
A4
ANAPHASE II
3.Separation of sister Chromatides during
ANAPHASE II

30. A B A A B B
C C C C
REPLICATION
S
H
O
M
O
L
O
G
O
U
S

31. C C C C
SYNAPSIS

32. C C C C
SYNAPSIS

33. C C C C
SYNAPSIS

34. CCCCCC