Aim: Why is meiosis important?
description
Transcript of Aim: Why is meiosis important?
![Page 1: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/1.jpg)
Aim:Why is meiosis important?
• Do Now: Label each phase of cell division (IPMATC)
![Page 2: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/2.jpg)
So, what is the difference between
mitosis and meiosis?
![Page 3: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/3.jpg)
Mitosis• 2 identically
diploid cells (same as parent)
• Makes cells used for growth, repair, development & asexual development
Meiosis - 4
genetically different haploid cells
- Makes cells for Sexual reproduction
- Genetic info is exchanged/rearranged.
![Page 4: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/4.jpg)
Meiosis I
• Contains all phases of mitosis
• Homologous chromosomes separatedI P M A T CI
PrayMoreAt The Church
![Page 5: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/5.jpg)
![Page 6: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/6.jpg)
![Page 7: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/7.jpg)
Interphase I• This is where
the chromosomes are duplicated, replicated, or copied.
![Page 8: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/8.jpg)
Eukaryotic Cell Cycle
![Page 9: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/9.jpg)
Prophase I• Chromosomes
condense. The nuclear envelope breaks down.
“Crossing Over” occurs.
![Page 10: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/10.jpg)
• “Crossing Over”-Chromatids exchange genetic material
![Page 11: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/11.jpg)
Metaphase I• Pairs of
homologous chromosomes move to the cell’s middle.
Metaphase = Move Middle
![Page 12: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/12.jpg)
Anaphase I• Homologous
chromosomes move to the cell’s opposite poles.
![Page 13: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/13.jpg)
Telophase I• Chromosomes
gather at the poles.
• The cytoplasm divides.
![Page 14: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/14.jpg)
What about cytokinesis?• In cytokinesis, the nuclear membrane is
reforming around each new cell.
Cytokinesis happens after the division of
chromosomes and cells are made.
![Page 15: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/15.jpg)
Meiosis IINO
INTERPHASE and NO
REPLICATION of
chromosomes!!
P M A T
![Page 16: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/16.jpg)
Prophase II• A new
spindle forms around the chromosomes.
![Page 17: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/17.jpg)
Metaphase II• Chromosomes
line up at the middle.
![Page 18: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/18.jpg)
Anaphase II• Centromeres
divide, and chromatids move to opposite poles.
![Page 19: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/19.jpg)
Telophase II• A nuclear
envelope forms around each set of chromosomes. The cells divide.
![Page 20: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/20.jpg)
What do we end up with at the end of meiosis?
• 4 haploid cells
![Page 21: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/21.jpg)
Answer to Aim:Why is meiosis important?
• Allows genetic information from 2 parents to combine to form offspring that are different from both parents.
![Page 22: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/22.jpg)
Aim: Why is genetic variation so important?
Do Now: Copy the chart on the side board. Fill
in the blank areas about Mitosis and Meiosis.
![Page 23: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/23.jpg)
• Mitosis vs Meiosis
![Page 24: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/24.jpg)
What is a homologous chromosome?
Chromosomes that have the same sequence of genes, that have the
same structure, and that pair during meiosis.
![Page 25: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/25.jpg)
Chromatid is a single strand of chromosomes.
Chromosomes are 2 chromatids together, made of condensed chromatin.
Centromere is where the two chromatids meet.
![Page 26: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/26.jpg)
Chromatin are ribbon-liked structures of DNA and histone proteins.
![Page 27: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/27.jpg)
Label the chromosome
![Page 28: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/28.jpg)
• “Crossing Over”-Chromatids exchange genetic material(Occurs during Prophase I in Meiosis.)
![Page 29: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/29.jpg)
Why is crossing over important?
• With out it, every one will look the same!
• New combinations of genetics
• Variety
Crossing Over Video
![Page 30: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/30.jpg)
• Crossing over is one of the several processes that lead to genetic variation. • The
rearranging of genetic info leads to genetic variation in offspring.
![Page 31: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/31.jpg)
Genetic Variability• Natural
Selection• Allows for
adaptation and ultimate survival of certain organisms when the environment changes.
![Page 32: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/32.jpg)
3 Ways to Promote Genetic Variation
• 1. Crossing over• 2. Independent
Assortment• 3. Random Union of
sperm and egg
![Page 33: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/33.jpg)
![Page 34: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/34.jpg)
• Tetrad- a pair of homologous chromosomes.As the tetrads
form, the chromosomes exchange parts of their chromatids during the process of crossing over.
![Page 35: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/35.jpg)
DisjunctionTetrads separate equally as a result of a process known as disjunction.
During what phase does this
occur?
Anaphase
![Page 36: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/36.jpg)
Non-disjunctionTetrads separate UNEQUALLY.
• Uneven # of chromosomes will result in the gametes.
If these gametes are fertilized, the offspring will have either 1 too many chromosomes or 1 too few chromosomes.
Example of Result of non-disjunction: Down’s Syndrome
![Page 37: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/37.jpg)
Down’s Syndrome• The non-
disjunction of the 21st chromosome.• Occurrence: One in every 700 American children.
![Page 38: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/38.jpg)
Answer to Aim:So why is genetic
variability so important???
![Page 39: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/39.jpg)
AlleleDifferent forms of the same gene. For example,
humans have genes for eye color. However, there exists an allele for brown eyes and an allele for blue eyes.
Responsible for Dominant or Recessive
Traits
![Page 40: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/40.jpg)
• Each individual has 2 allele’s, one on each chromatid.
• You can have 2 of the same alleles or 2 different alleles.
• The dominant allele will determine what trait you have.
![Page 41: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/41.jpg)
• Dominant Traits:
The traits that come out in the individual.* Only 1 dominant trait is needed.
Expressed as the capital letter.
• Recessive Traits:The “weaker” trait that we do not see unless there are 2 of them.
Expressed as the lower case letter.AA, Aa, aA aa
![Page 42: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/42.jpg)
What color eyes does each individual have?
![Page 43: Aim: Why is meiosis important?](https://reader030.fdocuments.us/reader030/viewer/2022012911/56816598550346895dd8718d/html5/thumbnails/43.jpg)
Activity in text page 253 on crossing over.