Meiosis is the type of cell division by which germ cells eggs and sperm are produced One parent cell produces four daughter cells Daughter cells have half the number of chromosomes found in the parent cell ID: 927733
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Slide1
MEIOSIS
Q2 WK3 D2
Slide2Meiosis
Meiosis is the
type of
cell division by which
germ cells
(eggs and sperm)
are produced.
One parent cell produces
four
daughter cells.
Daughter cells have half the number of chromosomes found in the parent cell
Meiosis
During meiosis, DNA replicates
once
, but the nucleus divides
twice
.
There are 2 parts to Meiosis:
Meiosis 1
Meiosis 2
The 4 new daughter cells have variation of the parent DNA; this is genetic variation
Slide4Meiosis Terminology
Karyotype: Arranging of chromosomes from largest to smallest; pairing up the homologous chromosomesAutosomes: All non-sex chromosomes
; (#1-22 for humans)
Sex Chromosomes:
Chromosomes that determine the sex
of an organism (#23 for humans)
Set (n):
# of different chromosomes.
REMEMBER:
Haploid = 1set, Diploid= 2 sets
Slide5Amniocentesis
Slide6Karyotype of a human
Is this person male or female?
How many sex chromosomes are present?
How many autosome chromosomes are present?
How many homologous
pairs
of chromosomes are present?
Slide7Background on Meiosis
Meiosis involves 2 divisions of the nucleusMeiosis 1 & Meiosis 2Meiosis STARTS with HOMOLOGOUS CHROMOSOMESHomologous Chromosomes: They are
similar in shape, size & genetic content
Slide8Meiosis 1: 1st Division of Meiosis
Prophase I: Chromosomes condense, nuclear envelope breaks, homologous chromosomes pair at ends.
***Cross-Over:
Part of chromatid on 1 homologous chromosome exchanges with the other chromosome
***
DRAW ME
This is
Genetic variation
Slide9Meiosis 1: 1st Division of Meiosis
Metaphase I: Homologous chromosomes move to center of the cell by the spindle fibers.
Anaphase I
:
Homologous chromosomes separate
and move to opposite poles
,
BUT sister chromatids stay together.
A set of chromosomes moves to each pole
Telophase I
:
The spindle fibers disappear, cells begin to cleave;
still, two sets of chromosomes are at opposite poles
Slide10Meiosis 1
Slide11End of Meiosis I
Once Meiosis I is complete, cytokinesis occurs and the cell splits into 2 haploid cells. These 2 cells enter Meiosis II
Slide12Meiosis I: STOP & THINK
1. What is the purpose of Meiosis?2. Describe genetic variation
3. Explain purpose of karyotyping
4. Explain cross-over
5. What major event occurs in Anaphase I ?
6. Are the daughter cells haploid or diploid? Explain
Slide13Any questions
on Meiosis I
?????
Slide14Meiosis I: Videohttp://www.youtube.com/watch?v=D1_-mQS_FZ0
Slide15Meiosis II
Prophase II: A new spindle forms around the chromosomes (no longer HOMOLOGOUS CHROMOSOMES)Metaphase II: Chromosomes line up at center & spindle fibers attach to centromere
Anaphase II:
Centromeres split,
chromatids move to opposite poles of cell
Telophase II:
Nuclear envelope forms around each set of chromosomes
& spindles retracts, cell begins cytokinesis
Slide16Result of Meiosis II
4 HAPLOID cells form as a result of Meiosis IIHaploid = cell containing 1 set of chromosomes
Slide17Meiosis II: 2nd
division of Meiosis
Slide18Prophase II
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Metaphase II
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Telophase II
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Meiosis I & II Venn Diagram
Meiosis I
Meiosis II
Slide22Meiosis Booklet
1. Everyone needs 3 sheets of blank paper
2.
Fold each one hotdog style
3.
Cut straight up the fold
(You should have 6 long sheets, only use 5)
4.
Label each square with the phases of meiosis the same as the mitosis booklet
Slide23Meiosis Review Questions
What type of cells are used in Meiosis? Give examples of these cells.2.
Meiosis is used in sexual reproduction.
E
xplain the process of “cross-over”
3. Draw homologous chromosomes going through cross-over.
4.Meiosis
is divided into two parts, why?
5
. Define “Haploid”
6
. Compare and Contrast Meiosis to Mitosis.
In your notebook!
Slide24Mitosis & Meiosis
Comparison Worksheet
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
http://www.usoe.k12.ut.us/curr/science/sciber00/7th/genetics/sciber/animatin.htm
Meiosis & Genetic Variation
Q2 WK4 D2
Nov. 5
th
, 2013