What is meiosis You have 15 minutes Use your Chromebook amp Biology books Turn something in that answers these six questions What is the purpose of meiosis What does it look like Why is it called reduction division ID: 759188
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Slide1
Bell Ringer
Objective:Question: Page 7 of POD
Slide2What is meiosis?
You have 15 minutes. Use your Chromebook & Biology books.Turn something in that answers these six questions:What is the purpose of meiosis?What does it look like?Why is it called reduction division?Define diploid and haploid. Provide examples of each.Explain crossing over.How does this relate to content we have already learned in this year?
Slide3MEIOSIS
(making sperm and egg cells)
Slide4DNA Passes from Parent to Offspring
What are the two types of reproduction?
http://artfiles.art.com/images/-/Oxford-Scientific/Green-Hydra-Budding-Photographic-Print-C12940880.jpeg
http://lifeboat.com/images/bacteria.jpg
Slide5Review of Chromosomes
Chromosome
→ ______________________________________________________Normal cells = diploid (2n) → 2 copies of each chromosome In diploid cells, 1 copy came from each parent (people: 1 from mom, 1 from dad)
Slide6What is meiosis?
Meiosis
→ special cell division for sexual reproductionProduces haploid (1n) cells → 1 copy of each chromosomeHaploid cells = gametes (sperm/eggs) Human gametes:In ♂, meiosis produces (in testes) 4 sperm cellsIn ♀, meiosis produces (in ovaries) 1 egg cell and 3 polar bodies (that later disintegrate)
Mitosis: cells divide once
Meiosis: cells divide
twice
Slide7Why do meiosis?
Meiosis is
“reduction division.” It reduces the chromosome number in the gametes by one half. From diploid (2n) to haploid (n).
Why do ovary and testes cells go through meiosis?
Slide8Chromosome numbers…
In humans, 2n = 46A normal body cell has 46 chromosomes → 23 came from mom, 23 from dad; each set of 23 from mom is similar to the set of 23 from dadIn humans, n = 23A normal gamete has half the normal chromosome number (n) → just one set
Slide9Chromosome number questions
If a horse retina cell has 36 chromosomes, how many chromosomes does a horse sperm cell have?
If n= 4 for fruit flies, how many chromosomes does a wing cell have?
If the 2n number of a pine tree is 86, how many chromosomes would be found in a pine ovum?
If n = 16 for goldfish, how many chromosomes are in a fin cell?
Slide10Homologous Pairs
Homologous pairs Pairs of chromosomes with the same sequence of genesOne is from mom, one is from dadGenes are in the same order, but not identical
Slide11Phases of Meiosis
Remember mitosis? (I)PMAT…
In meiosis, each phase occurs
twice
Meiosis I: Prophase I, Metaphase I, Anaphase I,
Telophase
I,
Cytokinesis
I
Meiosis II: Prophase II, Metaphase II, Anaphase II, and
Telophase
II,
Cytokinesis
II
Slide12Meiosis I
In Prophase I, homologous chromosomes pair up in a tetrad (group of four)same gene sequences, same banding pattern, same position of centromereCrossing-over takes place
Slide13A Sketch of Chromosomes Crossing Over (Prophase I)
http://images.google.com/imgres?imgurl=http://www.phschool.com/science/biology_place/labbench/lab3/images/crossovr.gif&imgrefurl=http://www.phschool.com/science/biology_place/labbench/lab3/crossovr.html&h=320&w=240&sz=3&hl=en&start=11&tbnid=GqFKVxw1ZWYopM:&tbnh=118&tbnw=89&prev=/images%3Fq%3Dcrossing%2Bover%2Bchromosomes%26gbv%3D2%26svnum%3D10%26hl%3Den%26safe%3Dactive%26sa%3DG
During
crossing-over,
homologous
chromosomes*
exchange pieces of
DNA.
Wwwhhhyyy
?
**What does homologous chromosome mean?
Same size and similar structure.
Slide14Meiosis and Sexual Reproduction: Practice
Which of the following types of cells would experience mitosis, meiosis, or both? Write ME for meiosis, MI for mitosis.
____A pollen cell of a plant
____A leaf cell of a plant
____A root cell of a plant
____The cells in the petal of a flower
____Stem cells
____Kidney cells
____Liver cells
____Testes cells
____Ovary cells
____Tree bark cells
Slide15Task #1-3
Slide16Closure
What is the difference between a gene, chromosome, and DNA?What cells are considered haploid?What is the 10% rule?Which macromolecule is responsible for long term energy storage?What type of cells are pictured below?
Slide17Slide18Bell Ringer
Which word do we use to describe a cell that has a single set of chromosomes?
How would you describe diploid?
What is a somatic cell? Give examples.
If an eye cell in a monkey has 20 chromosomes, how many chromosomes will be found in its sperm cell?
What is the difference between meiosis and mitosis?
Slide19Meiosis I
Meiosis I results in 2 haploid daughter cells
Slide20Meiosis II
Each of the haploid daughter cells from meiosis I divide again to make 4 haploid cells.
Meiosis
Slide21Comparing Mitosis and Meiosis
The processes of mitosis and meiosis are very similar, but with some important differences:
MeiosisIncludes 2 cycles of cell division (meiosis I and meiosis II)Occurs only in sex cells (gametes)Chromosomes cross over in Prophase IResults in four genetically different haploid cellsMetaphase I: 2 duplicated chromosomes per spindle fiber
Mitosis
Includes only 1 cycle of cell division
Occurs in body cells (somatic cells)
No crossing over of chromosomes
Results in two genetically identical diploid cells
Metaphase: 1 duplicated chromosome per spindle fiber
Slide22Slide23Interphase
DNA replication occursDNA is in chromatin form (unwound, like spaghetti)
Slide24Prophase I
DNA condenses to form chromosomesHomologous chromosomes pair up to form tetradsCrossing over takes place
Slide25Metaphase I
Homologous pairs line up along center of cell1 homologous chromosome and its duplicate are attached to each spindle fiber
Slide26Anaphase I
Homologous pairs separate, move to opposite ends of the cell
Slide27Telophase I
Nuclear membrane reappearsSpindle fibers disappear
Slide28Cytokinesis
Cytoplasm of the two cells separateMeiosis I results in 2 haploid cells that are genetically different
Slide29Prophase II
The 2 haploid cells from Meiosis I will divide again
Slide30Metaphase II
Chromosomes (set of sister chromatids) line up along the center of the cell1 sister chromatid attaches to each spindle fiber
Slide31Anaphase II
Centromeres split, sister chromatids are pulled apart
Slide32Telophase II and Cytokinesis
Cytoplasm divides, resulting in 4 genetically different haploid cells
Slide33Bell Ringer
Go to weebly under the meiosis tab Read the kidsahead.com Live Science Reading. Answer questions based on reading.
Slide34The Creation of Life
https://www.youtube.com/watch?v=GZk4hT7ncv0
Slide35Create a child
Definitions on the back side FIRST if you don’t do this you will be STUCK on the front. Show me to get your penny.EVERYONE WILL NAME THEIR BABY ARDREY. If you don’t enjoy your zero.Draw baby under vocabWhen finished hand in & you may begin your homework.
Slide36Closure
What is a genotype?
What type of cell undergoes meiosis?
Is a liver cell said to be haploid or diploid?
How many times does a cell divide during meiosis?
What is a chromosome?
What are the 6
kingdoms?
Slide37Homeroom: Door Decorating Challenge
Guys vs Girls: Winner gets candy on Friday.
Choose your door.
Voted on by the biology teachers.
M
ay use any resources from station #7.
If you don’t participate. No candy for you.