Meiosis
VOCAB THAT MUST BE KNOWN
Ploidy:
1n, Haploid
2n, Diploid
Chromatid
Homologous chromsomes
Tetrad
Crossing Over
9.9.Meiosis
10.10.SexualReproduction
11.11.AsexualReproduction
12.12.Chromatid
13.13.Chromosome
14.14.GeneticRecombination
15.15.Fertilization
16.16.IndependentAssortment
Write Down…
ALL THE Key Terms!
1.Prophase I
2.Metaphase I
3.Anaphase I
4.Telophase I
5.Prophase II
6.Metaphase II
7.Anaphase II
8.Telophase II
17.Ploidy
18.Haploid (n)
19.Diploid (2n)
20.Tetrad
21.HomologousPair
22.Crossing Over
23.Somatic Cell
24.Germ Cell
25.Gamete
26.Zygote
nb - You have to actuallydefine them to get credit atthe end of the unit
BellworkObj: Describe the process of meiosis
1.What are the 4 stages of mitosis?
2.Is interphase a part of mitosis?Explain.
3.What is the purpose of mitosis?
4.What is the difference betweensexual reproduction and asexualreproduction? Give an example ofa species for each.
5.Which type of reproduction wouldbe more advantageous in natureand why? Explain in 1-2 completesentences.
On science fair boards:
Each of thenucleus ofyour cellscontains allthis:
Special cellsin yourbody onlyhave ½ thisamount.
Where?
Why?
Long red: mother/chromosome 1
Short red:Mother/chromosome 2
Long blue: father/chromosome 1
Short blue: father/chromosome 2
Each gamete has:
1 MIXED copy of chromosome ONE
1 MIXED copy of chromosome TWO
Each somatic cell has:
2 copies of chromosome ONE
-1 from mom, 1 from dad
2 copies of chromosome TWO
-1 from mom, 1 from dad
How to create a gamete: Meiosis
Or ‘How to create an egg or a sperm’
Make a copy!
•the diploid somatic cells of an individualcontain one copy of the chromosome set fromthe sperm and one copy of the chromosomeset from the egg; that is, the cells of theoffspring have genes expressing characteristicsof both the father and the mother.
•A gamete (from Ancient Greek γαμετή gamete"wife"[1]) is a cell that fuses with another cellduring fertilization (conception) in organismsthat reproduce sexually.
•A gamete's chromosomes are not exactduplicates of either of the sets ofchromosomes carried in the dfschromosomes.
CROSSING
OVER
GAMETES
23=N
HAPLOID
SOMATIC
46=2N
DIPLOID
MITOSIS
MEIOSIS
•In humans, an ovum can carry only an Xchromosome (of the X and Y chromosomes),whereas a sperm may carry either an X or a Y;thus the male sperm determines the sex ofany resulting zygote, if the zygote has two Xchromosomes it will develop into a female, ifit has an X and a Y chromosome, it willdevelop into a male
Long red: mother/chromosome 1
Short red:Mother/chromosome 2
Long blue: father/chromosome 1
Short blue: father/chromosome 2
Each gamete has:
1 MIXED copy of chromosome ONE
1 MIXED copy of chromosome TWO
Each somatic cell has:
2 copies of chromosome ONE
-1 from mom, 1 from dad
2 copies of chromosome TWO
-1 from mom, 1 from dad
How to create a gamete: Meiosis
Or ‘How to create an egg or a sperm’
Make a copy!
Mitosis vs Meiosis
Mitosis Body cell division (cloning)
Mitosis makes “my toes-es”
MeiosisMaking sex cells (halving)
Meiosis makes “my OH…baby!”
Meiosis
•_________________ is theprocess that___________________ cellsundergo when a single cell____________ to make ___unique ________________daughter cells
Meiosis
Somatic (diploid)
divides
4
haploid
Meiosis
Explain to your partner
1.How many original cells were there?
2.How many cells did it divide into?
3.Were all these new cells the same?
4.What do we call the new cells?
How do Organisms Reproduce?
Organisms either reproducesexually or asexually.
•Meiosis only occurs in ____________________species
Sexually reproducing
Asexual reproduction
Asexual reproduction involvesformation of a new individualfrom cells of the parent,without meiosis, gameteformation, or fertilization.
Question????
•So, why, if an animal is reproducingasexually, does meiosis NOT occur?
Asexual reproduction involves formation of a newindividual from cells of the parent, withoutmeiosis, gamete formation, or fertilization.
Sexual Reproduction
In sexual reproduction the ______________________of one parent are _______________ with that of theother parent to produce a ___________________________________ offspring.
chromosomes
combined
genetically
unique
Fill in the diagram as we go
Meiosis I
Meiosis II
Prophase I
__________form and__________________ occurs!
Tetrads
crossing
over
Tetrads & Crossing Over
Tetrads- ______association of sisterchromatids of____________
_____________ (4)
close
homologouschromosomes
Crossing Over:
Homologouschromosomes _________small pieces, resulting in____ chromosomes!
exchange
NEW
Tet Cr-O
1. What are ‘sister chromatids’
–Why did we keep them together in mitosis?
2. What are ‘homologous’ chromosomes?
-Genes for eye color and height are both onchromosome 11 for humans.
Metaphase I
Anaphase I
__________________________occurs creating_____combinations!
Independent
Assortment
new
Independent Assortment
Chromosomesfrom the _____ &_____ _________move to one sideor the other
mom
dad
randomly
Telophase I
(Cytokinesis)
Long red: mother/chromosome 1
Short red:Mother/chromosome 2
Long blue: father/chromosome 1
Short blue: father/chromosome 2
Each gamete has:
1 MIXED copy of chromosome ONE
1 MIXED copy of chromosome TWO
Each somatic cell has:
2 copies of chromosome ONE
-1 from mom, 1 from dad
2 copies of chromosome TWO
-1 from mom, 1 from dad
How to create a gamete: Meiosis
Or ‘How to create an egg or a sperm’
Make a copy!
Prophase II
Metaphase II
Anaphase II
Telophase II
(Cytokinesis)
Summary of ways Meiosis is differentfrom Mitosis
•Involves_________________________________________
2 consecutive cell divisions
Summary of ways Meiosis is differentfrom Mitosis
•Ends with ___ cells that are all _______________(sex cells: _______& ____)
4
haploid
sperm
egg
Summary of ways Meiosis is differentfrom Mitosis
•Makes _____ _________________ combinationsthrough ___________ ______ and_____________ __________
NEW
genetic
crossing
over
independent
assortment
Meiosis Card Sort
Order the 11 cards to show the progress from asingle cell in interphase and progressing to 4haploid sex cells
Slate Quiz!
•Look at the pictures on the following slides &name the stage of meiosis!
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