Download 2/06/06

Let’s talk about SEX ….
GENETICS, SEXUAL REPRODUCTION AND MEIOSIS
http://www.pbs.org/wgbh/nova/miracle/program_adv.html
https://www.youtube.com/watch?v=czMmSBaVI4I
Sexual reproduction occurs when 2 haploid cells form a diploid cell
(zygote), which receives 1 of each chromosome from the sperm and 1 of
each chromosome from the egg.
Meiosis has 2 distinct cell division cycles.
Meiosis I -
Meiosis II-
Meiosis I
Prophase I
 Homologous pairs of chromosomes are connected by a protein
bridge, which results in 4 chromatids stuck together called a
TETRAD.
THIS TETRAD IS EXETREMELY IMPORTANT IN THE
PROCESS OF CROSSING OVER.
 Along the length of the tetrad, non-sister chromatids exchange
DNA fragments causing sister chromatids to now be non-identical.
THIS IS CALLED CROSSING OVER.
REMEMBER: ________________________________________________
Metaphase I
 The homologous pair of chromosomes moves together to the
midline of the cell.
At the end of MEIOSIS I
 THESE CELLS ARE NOW CONSIDERED ________________
 Daughter cells now have 23 replicated chromosomes
ANAPHASE 1
TELOPHASE 1
MEIOSIS II
A process very similar to mitosis, in which the replicated nonidentical sister chromatids separate.
The process of meiosis is completed, producing four (UNIQUE)
haploid daughter cells as a final result.
List and explain the 3 unique features of meiosis
*****There are a total of 7 tutorials on this page, these would be great to watch and take
the quizzes to better understand meiosis
http://old-www.hartnell.edu/tutorials/biology/meiosis.html
http://highered.mheducation.com/sites/0072495855/student_view0/chapter3/an
imation__how_meiosis_works.html
http://highered.mheducation.com/sites/0072495855/student_view0/chapter3/an
imation__random_orientation_of_chromosomes_during_meiosis.html
http://highered.mheducation.com/sites/0072495855/student_view0/chapter3/an
imation__stages_of_meiosis.html
http://highered.mheducation.com/sites/0072495855/student_view0/chapter3/an
imation__unique_features_of_meiosis.html
Compare and contrast mitosis to meiosis
http://highered.mheducation.com/sites/0072495855/student_view0/chapter3/an
imation__comparison_of_meiosis_and_mitosis__quiz_1_.html
http://highered.mheducation.com/sites/0072495855/student_view0/chapter3/an
imation__comparison_of_meiosis_and_mitosis__quiz_2_.html
In the background of all of the classical genetics stuff we have been doing
recently is the process that chooses which genes (on which chromosomes) get
into the gametes (SPERM OR EGG) and on to the offspring. That process is
called MEIOSIS and it’s time to delve into that process a little bit
Mitosis and Meiosis Comparison Essay
Write an essay that compares and contrasts mitosis to meiosis. You may want to use the Venn diagram
from class to get you started. Be sure to include final outcomes of each process and where each process
occurs.
Here are some guidelines to use while writing your essay.
You should have:
 A topic sentence and a concluding sentence in each paragraph
 Written at least three supporting sentences in each paragraph
 At least three PARAGRAPHS
1st one to introduce major theme/focus/direction of essay
2nd one for the relationship/support/evidence for first paragraph
3rd one to conclude/summarize/reflect
 Carefully corrected grammar, spelling, and punctuation errors
 Used appropriate vocabulary to COMPARE & CONTRAST Mitosis to Meiosis