Transcript Sex Cell Production - Marblehead High School

Sex Cell Production
Meiosis
11-4
Sex cells = Gametes
Egg cell
+
Sperm cell
Where have they been mentioned before?
By the end of this you should
know…..
1) What occurs during each stage of
meiosis
2) The difference between meiosis and
mitosis
Answer me this….
1) How many chromosomes do you
have?
2) How many chromosomes do your
parents have?
3) How many chromosomes do the egg
cell and the sperm cell have?
4) How did they form?
Terms to know:
• Homologous
chromosomes - the
male AND female
parent chromosomes
containing the same
information – found in
diploid cells
• Which set of
information is
expressed in you?
Mom or Dad?
Diploid cells - 2N
Are gametes diploid too?
• Haploid contain a single
set of
information (N)
Gamete containing
information from one
parent

How do we know this?
What is
in the
circle?
And before that???
• The “father of
genetics”, Gregor
Mendel used pea
plants to show us
the same basic
ideas that
technology has
proved to us today
Mendel Vocab you need to know…
Traits = a characteristic that is determined
by your genetic information
Genes = sections of DNA that determine
your traits
Alleles = the different versions of a gene
Mendel Vocab you need to know…
Traits = eye color
Gene that
determines eye
color is found
here on your
chromosome
Now that you are an
expert on genetic
vocabulary…
Let’s talk meiosis!!!!!!!!!!!!
How does the process of meiosis
produce haploid sex cells?
• 2 Divisions are involved
o Meiosis I - the chromosomes are
replicated & homologous chromosomes
separated into different cells
o Meiosis II - the sister chromatids are
separated from each other
It looks like this…
Meiosis I
Prophase I*
Metaphase I*
Anaphase I
Telophase I
Cytokinesis
* = makes sex
cells unique
In Prophase I…..
• Tetrads line up - chromosomes from
mom and dad containing the same
information (homologous pairs);
contains 4 chromosomes
What happens then?
• Crossing over occurs - portions of
homologous chromosomes are
exchanged resulting in a new
combination of alleles
And during Metaphase I???
• Independent Assortment - tetrads
can line up in many different ways
allowing for many different
combinations of the parents traits to
form in the sex cells
Independent Assortment
Meiosis I Review:
• Are homologues present at the end?
• Do the cells contain one set or two
sets (one from Mom & one from Dad)
of chromosomes at the end?
• So are they haploid or diploid?
Meiosis II
No INTERPHASE!!!
Prophase II
Metaphase II
Anaphase II
Telophase II
Cytokinesis
What other process does this look like?
Meiosis II Review
• What happened to
the sister
chromatids?
• Are the end cells
haploid or diploid?
• Remind me…..why
are they called
unique?
Check these out….
• http://www.cellsalive.com/meiosis.htm
• http://highered.mcgrawhill.com/sites/0072495855/student_view0
/chapter28/animation__how_meiosis_work
s.html
Any differences? Egg vs.
Sperm?
Meiosis Review:
• How many daughter cells are produced?
• Are they identical to the parents? Why or
why not?
• Are the haploid or diploid?
Start your meiosis coloring
Classwork/Homework
Meiosis Coloring:
• You will design a meiosis coloring sheet to use as
a study guide
• Diploid cells (2n) have green cell membranes;
haploid cells (n) have purple cell membranes
• One Side: Interphase & Meiosis I
– Divide into 6 boxes (use one box as a key with color
codes)
– Use pencil first and then color in
– Draw 3 homologous pairs (red for maternal
chromosomes and blue for paternal chromosomes)
– Label: homologous chromosomes, tetrads, crossing
over, independent assortment, centrioles, spindle fibers,
nucleus, sister chromatids
Classwork/Homework
Meiosis Coloring:
• Backside: Meiosis II
–
–
–
–
Divide onto 4 boxes
Use pencil first and then color in
Keep the previous chromosome color and number
Label: centrioles, spindle fibers, nucleus, sister
chromatids, chromosomes
• If complete, they can be used for your meiosis
quiz on _______________.