Meiosis and producing genetically diverse
offspring
Bonus #1 and #2 are posted
CB 17.3
Protein
CB 13.5
{Meiosis:
producing gametes}
For life to exist,
the information
(genes) must be
passed on.
{Mitosis:
producing more cells}
CB 12.4
Mitosis:
A DNA
Perspective
Mitosis plays a role in:
• Growth and Development
• Repair and Turnover of Cells
• Reproduction
–Asexual
CB 12.5
The Cell Cycle
start
of
mitosis
CB 12.6
CB 13.5
{Meiosis:
producing gametes}
For life to exist,
the information
(genes) must be
passed on.
{Mitosis:
producing more cells}
Asexaul
Reproduction
extremely low
genetic diversity
vs.
Sexaul
Reproduction
greater genetic
diversity
How does sexual reproduction generate
genetic diversity?
Gene for
growth
hormone
Gene for
brown hair
pigment
G
h
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QuickTime™ and a
Graphics decompressor
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Gene for
blue eye
pigment
G
DN
e
n
e
A
fo
p
r
oly
Haploid
chromosomes
m
e
r
ase
Allele for
low express
(short)
Gene for
growth
hormone
Allele for
high express
(tall)
Allele for
black hair
Gene for
hair color
Allele for
black hair
Allele for
sickle cell Hb
Gene for
hemoglobin
Allele for
normal Hb
Diploid
chromosomes
Each pair of
chromosomes
is comprised
of a paternal
and maternal
chromosome
sister chromatids= replicated DNA (chromosomes)
tetrad= pair of sister chromatids
CB 13.4
CB 13.7
Meiosis splits apart the
pairs of chromosomes.
X 23
in humans
haploid
X 23
in humans
X 23
in humans
diploid
X 23
in humans
Inheritance = The interaction between genes
inherited from Mom and Dad.
Asexaul
Reproduction
extremely low
genetic diversity
vs.
Sexaul
Reproduction
greater genetic
diversity
How does sexual reproduction generate
genetic diversity?
CB 13.7
Meiosis splits apart the
pairs of chromosomes.
X 23
in humans
CB 13.11
Crossing-over
(aka Recombination)
DNA cut and
religated
DNA cut and
religated
CB 13.11
Crossing-over:
Proteins in the cell cut
and religate the DNA,
increasing the genetic
diversity in gametes.
CB 13.10
Independent Assortment
(aka Random Assortment)
CB 13.10
Independent Assortment
2 possibilities
for each pair,
for 2 pairs
22 = 4
combinations
CB 13.10
Independent Assortment
2 possibilities
for each pair,
for 23 pairs
223 =
8,388,608
combinations
CB 13.9
Crossingover
Meiosis:
In humans,
crossing-over and (Ind. Assort.)
independent
assortment lead to
over 1 trillion
possible unique
gametes.
(1,000,000,000,000)
Meiosis I
Meiosis II
4 Haploid cells, each unique
Asexaul
Reproduction
extremely low
genetic diversity
vs.
Sexaul
Reproduction
greater genetic
diversity
How does sexual reproduction generate
genetic diversity?