Transcript Meiosis Notes

Take 5: 11/9/11
• What is a gene?
• What does meiosis produce?
• What are the 2 divisions of Meiosis?
Meiosis Notes
Ch 10
Mendel's Principle of Genetics
• 1. Each organism must inherit a
________ copy of every gene from each
of its parents.
• 2. Each organism produces its own
gametes (aka sex cells) and each gamete
has _____ set of genes.
Diploid vs. Haploid
• A cell with two copies of each
chromosome = __________ or _______
• A cell with only one copy of each
chromosome = ___________ or ______
Diploid vs. Haploid
2n = 6
n = ___
Number of
Chromosomes in
various
organisms…
One chromosome from Dad
• The two
chromosomes of
each pair in a
diploid cell are
called
One chromosome from Mom
One chromosome from Dad
• Each pair of
homologous
chromosomes
has genes for
the SAME traits
• example:
Chromosome
pair #1 could
code for eye
color
One chromosome from Mom
So how do you get
one chromosome
from each parent?
Well, I think
you already
know that.
Fertilization, right?
Yep!
So that must mean
that the sperm and
egg cell are haploid.
Yep!
Are there any
other cells in your
body that are
haploid?
Nope!
How do you
make haploid
cells?
Through
meiosis
What’s that?
The way you
produce a
haploid cell
from a diploid
cell.
• Definition:
Meiosis is the process in
which the number of
chromosomes in a cell is cut
_______ due to a separation
of homologous chromosomes
in a diploid cell.
(2n  1n cell)
Meiosis involves two
distinct divisions
• __________
• __________
• Meiosis turns a single diploid cell into
________________
Meiosis I
• Prior to meiosis I: each chromosome
is ______________
Prophase I
• Each chromosome pairs
with the corresponding
homologous
chromosome to form a
structure called a
________
– There are ______
chromatids in a tetrad
Prophase I
• In addition to pairing up and
forming tetrads, they ALSO
exchange portions of their
chromatids in a process
called _______________
• The results in an
___________ of alleles to
produce new
______________ of alleles
•NOTICE: This is one
difference from mitosis. In
mitosis the chromosomes
line up __________. In
meiosis, they ______
Metaphase I
• The pair of homologous chromosomes
_________________________
Anaphase I
• The homologous chromosomes
randomly ________.
Telophase I
• Two new cells are formed.
Now these two cells
enter Meiosis II
UNLIKE THE FIRST DIVISION,
these cells DO NOT UNDERGO
___________
• Prophase II:
• ______________________________
• Metaphase II:
______________________________
• Anaphase II:
_____________________________
• Telophase II:
________________ are produced.
http://www.youtube.com/watch?v=D1_-mQS_FZ0
Gamete Formation
• In MALES, haploid gametes produced
are called ______. In plants it is called
_______
• In FEMALES, only ______ of the cells
produced is involved in reproduction
– AKA ______
– Other three = _______________and are not
used in reproduction
http://www.cellsalive.com/meiosis.htm
The Simplified Version:
Let’s fill this in…
Crossing over
Chapter 12
Patterns of Heredity and Human
Genetics
Pedigree
• A graphic representation of genetic
inheritance
Incomplete Dominancephenotype is a mixture between
those of 2 homozygous parents
Codominance- both alleles are
expressed equally
Sex Linked
Inheritance
Karyotype- normal male
Karyotype
- Down
Syndrome
(Trisomy)
•
http://www.youtube.com/watch?v=ycrPCT
P2mFE
http://www.youtube.com/watch?v=ldjb-FR-PKo
Karyotype
–Turner
Syndrome
(monsomy)