which animal will stay warm longer, a mouse or an elephant? 1
TRANSCRIPT
Which animal will stay warm longer, a mouse or an elephant?
1
Define in your own words (p. 275) Meiosis Diploid Haploid Gamete Crossing Over Chromosomes
2
Daily Question
Draw a chromosome. Explain what a chromosome is.
Why is crossing over important?
3
Eukaryotic Chromosomes
All eukaryotic cells store genetic information in chromosomes
Human body cells have 46 chromosomes or 23 identical pairs
4
Chromosomes in Dividing Cells
Two sides of a chromosome are called chromatids & are held together by the centromere
5Called Sister Chromatids
Chromosome Structure
Chromosomes contain DNA and Protein packed together to form chromatin.
Chromatin is made of DNA that is wrapped around the protein, histones.
Histone and DNA forms clusters called nucleosomes.
6
Boy or Girl?
7
Y - Chromosome
X - Chromosome
The Y Chromosome Decides
Daily Question
Explain the differences between homologous chromosomes and sister chromatids.
8
Cell Reproduction
9
MeiosisFormation of Gametes (Eggs & Sperm)
10
Facts About Meiosis Two meiotic divisions ---
Meiosis I and Meiosis II
Original cell is diploid (2n)
Four daughter cells produced that are haploid (1n)
11
Meiosis: Two Part Cell Division
12
Homologsseparate
Sister chromatidsseparate
Diploid
Meiosis I
MeiosisII
Diploid
Haploid
Meiosis I: Reduction Division
13
Nucleus Spindlefibers Nuclear
envelopeEarly Prophase I(Chromosome number
doubled)
Late Prophas
e I
Metaphase I Anaphas
e ITelophase I (diploid)
Interphase
Before Meiosis Begins DNA replication occurs
14
Nucleus
Prophase I
15
Crossing over occurs- homologous chromosome- Form Tetrad
Tetrads Form in Prophase I
16
Homologous chromosomes
(each with sister chromatids)
Join to form a TETRAD
Crossing-Over
Pieces of genes are exchanged
17
Homologous Chromosomes During Crossing-Over
18
1. Crossing-over occurs during:A. anaphase 1 B. Metaphase 1C. Prophase 1 D. Prophase 22. Which of the following cells undergo meiosis?A. Sperm Cells B Liver CellsC. Unicellular organismsD. All of the above
19
Quiz Explain all parts of a
chromosome, in words and drawings.
Define diploid, chromatin, sister chromatids, and centromere. Extra Credit: What phase is
technically not part of meiosis? Why?
20
Metaphase I
21
Homologous pairs of
chromosomes align along the equator of the
cell
Anaphase I
22
Homologs separate and move to opposite poles.
Sister chromatids remain attached at their centromeres.
Break
What is the difference between Metaphase and Anaphase?
What is the job of the centrioles?
23
Telophase I
24
Nucleus reassembles.
Spindle fibers disappear
Cytokinesis divides cell into two.
Break
What is the difference between Interphase and Prophase?
25
Daily Question
Explain what occurs in Meiosis I, in your own words.
26
Meiosis II
Only one homolog of each chromosome is present in the cell.
27
Meiosis II produces gametes with one copy of each chromosome and thus one copy of each gene.
Sister chromatids carry identical genetic information.
Gene X
Meiosis II: Reducing Chromosome Number
28
Prophase II
Metaphase II
Anaphase II
Telophase II 4 Identical
haploid cells
Prophase II
29
Nuclear envelope disappears.
Spindle forms.
Half the number of chromosomes as original in each cell
Break
What is the difference between Prophase I and Prophase II?
What is the difference between the cells at the end oogenesis and spermatogenesis?
30
Daily Question
At the very end of meiosis II each cell has 23 chromosomes.
How many chromosomes are created during Interphase?
How many chromosomes does the cell have at the very start of Prophase I?
31
Metaphase II
32
Chromosomes align along equator of cell.
Anaphase II
33
Sister chromatids separate and move to opposite poles.
Equator
Pole
Break
What is the difference between Anaphase I and Anaphase II?
34
Telophase II
35
Nuclear envelope assembles.
Cytokinesis II
36
Gametes (egg & sperm) form
Four haploid cells with one copy of each chromosome
Different combinations of different genes
Hybrid offspring
37
Meiosis results in _____A. 2 haploid daughter cells B. 4 haploid
daughter cellsC. 2 diploid daughter cells D. 4 diploid
daughter cells
The picture depicts what stage of meiosis?
A. Prophase 1 B. Anaphase 1
C. Metaphase 1 D. Metaphase 2
38
Name of Process in Gametes
Egg: OogenesisFormation of 1 true egg and 3 polar bodies
Sperm: SpermatogenesisFormation of 4 true sperm cells 39
Winter Break Extra Credit
Make an information pamphlet about one specific genetic diseases. The following must be included:
What is the disease? What does the disease do to the body it is affecting?
When was the disease discovered? Who discovered it? What type of mutation causes the disease? What are the tests to see if a person has the disease? How many people get this disease? Any other important information people need to know
about the disease. Pictures
40
Holiday Science
Friday December 19, 2008 Bring some food to share with the class.
It can be anything you enjoy!
If you don’t bring something you can’t eat anything!
41