Transcript cellular_reproductionx

Cellular Reproduction
Cell Division
What would happen
if cells stopped
dividing?
Could your skin
function in
protection?
Would wounds heal
or your body grow?
Two Types of Cell Division
Asexual
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Simple division of one
cell (mitosis)
Does not involve
fertilization
“Daughter” cells are
genetically identical
Sexual
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Requires 2 unique
cells
Zygote is genetically
distinct
Cell Division
Chromosomes are
structures that
become visible during
division
Chromosomes have
the DNA of the cell
DNA Packing
Cell Division
Chromosomes must
replicate before
division occurs
Cell Division
Some new terms:
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Chromatin: combination
of DNA and protein
fibers (not visible)
Sister chromatids:
copied chromosome
Centromere: where the
sister chromatids are
joined
The Cell Cycle
The Mitotic Phase
Four phases
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Prophase
Metaphase
Anaphase
Telophase
Cytokinesis occurs
at the end of
telophase
Things to Know
Describe what
happens in each
phase of mitosis.
Identify key
structures that are
assembled or
disassembled.
Cytokinesis: Animals
and Plants
Control of Cell Division
Cancer: cells with severely deranged cell
cycles
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Malignant tumor: lump produced from cancer cells
Metastasis: spreading of cancer cells beyond original
site
Control of Cell Division
Normal cells are
in your body are
controlled
mitotically as to
when and where
division occurs
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Cell Cycle Control
System
Chemotherapy
Vinblastine
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First obtained from
periwinkle plant
Rainforest of
Madagascar
Taxol
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Yew tree
Sexual Reproduction
Mitosis produces two
daughter cells that
are identical
Reproduction
between two
individuals are
similar but not
exact…why?
Sexual Reproduction
Offspring receive genetic inheritance from
two parents
Sperm and egg cells each carry half the
number of chromosomes
Fertilization is the combining of egg and
sperm genetics (and thus the two parents)
Meiosis is the production of sperm and egg
cells (specialized cells only used for
reproduction)
Meiosis Terms
Somatic cell: typical
body cell
Gamete: sperm or
egg cell
Homologous
chromosomes: Each
somatic cell
contains two of each
chromosome (one
from mom; one from
dad)
Meiosis Terms
Karyotype:
arrangement of
homologous
chromosomes
(biggest to smallest)
Diploid: part of the
life cycle that
contains two
homologous sets of
chromosomes
Meiosis Terms
Diploid: part of the life
cycle that contains two
homologous sets of
chromosomes
Haploid: part of the life
cycle that contains a
single chromosome set
Zygote: the product of
fertilization (diploid)
How Meiosis Halves
Chromosome Number
Genetic Diversity
Why is it important that meiosis produce
a high degree of genetic diversity in its
final product?
Three main methods of increasing
genetic diversity
Crossing Over
 Independent Assortment
 Random fertilization
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Crossing Over
Random Fertilization
When Meiosis Goes
Wrong
Errors in the meiotic stages can
produce sperm and egg cells with an
abnormal number of chromosomes
When Meiosis Goes Wrong
When Meiosis Goes
Wrong
Down Syndrome
Trisomy 21
1 out of 700 children
Down Syndrome
What does this graph show us?
Can you explain the results of this graph?
Meiotic Errors and
Evolution
Many plants are known
to be polyploidy
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Remember what
haploid and diploid is?
Since plants can selffertilize, polyploidy can
be quite common
Hugo de Vries and his
primroses
Meiotic Errors and
Evolution
What about animals?
Very rare since most
animals can’t selffertilize
The red viscacha rat
from Argentina
possibility?