A

1
Cell with 2 chromosomes The gene for earlobes
come in 2 alleles A attached a unnattached
(Aa attached) This is a pair of homologous
chromosomes.
A
a
2
The DNA (chromosomes) get copied.
A
a
3
The DNA (chromosomes) get copied.
A
A
a
a
4
Metaphase of mitosis the chromosomes line up
single file.
A
A
a
a
5
Metaphase of mitosis the chromosomes line up
single file.
A
A
a
a
6
Mitosis anaphase, the sister chromatids separate.
A
A
a
a
7
End result identical cells made each with 2
chromosomes (Aa) attached ear lobes
A
A
a
a
8
Meiosis metaphase In metaphase of meiosis, the
chromosomes line up in their homologous pairs.
a
A
a
A
9
Meiosis anaphase Chromosomes separate
a
A
a
A
10
Meiosis anaphase Chromosomes separate
a
a
A
A
11
Meiosis 2 cells are made, but they start again.
a
a
A
A
12
Meiosis another anaphase where chromatids
separate
a
a
A
A
13
Meiosis another anaphase where chromatids
separate
a
a
A
A
14
The end result of meiosis 4 cells made, each
with ½ the number (1) of Chromosomes as the
beginning (2)
a
a
A
A
Notice that each cell only has one allele.
15
Meiosis vs. Mitosis
16
Mitosis Meiosis

• Goal make a reproductive cell (egg/sperm) which
  has ½ of the persons DNA (1 allele for each
  trait).

• Goal to make ensure an exact copy of DNA gets
  into each cell (2 alleles for each trait).

• Chromosome at the end 23 chromosomes (no
  pairs)

• Chromosome at the end all 46 chromosomes (23
  pairs)

• Location in body reproductive organs

• Location in body all cells in all organs

• Metaphase chromosomes line up single file

• Metaphase chromosomes line up in pairs for
  metaphase 1