the cell cycles mitosis and meiosis -...
TRANSCRIPT
![Page 1: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/1.jpg)
The Cell Cycles –Mitosis and Meiosis
Essential question:
How do cells reproduce and why?
![Page 2: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/2.jpg)
Objectives – Section 10.1
Explain why cells divide in terms of growth and cell size
![Page 3: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/3.jpg)
Review - Types of Cell Division
• 2 Types of cell division
– Asexual
• Several purposes
– Sexual
• One purpose
![Page 4: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/4.jpg)
Review - Types of Cell Growth
• Individual Cell Size Increase
• Number of Cells Increases
![Page 5: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/5.jpg)
10.1 Why Divide?
![Page 6: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/6.jpg)
10.1 Cell Growth
A set amount of DNA is unable to meet the needs of an ever-growing cell.
Limits to Cell Size:
1. DNA “Overload”
What is the job of the DNA of a cell?
![Page 7: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/7.jpg)
2. Exchange of Materials
How do substances get in and out of a cell?
As a cell grows larger, both the surface area (the cell membrane) and the volume (the cytoplasm and organelles) grow larger, but at different rates!
10.1 Cell Growth
![Page 8: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/8.jpg)
Calculating Surface Area to Volume Ratios
Which cat has the greatest surface area to volume ratio?
10.1 Cell Growth
![Page 9: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/9.jpg)
How do you increase surface area without decreasing overall size of the organism?
Has the volume changed?
![Page 10: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/10.jpg)
2cm
2cm
2cm8cm
8cm
8cm
Surface area = 2cm x 2cm x 6sides =
24 cm2
Volume = 2cm x 2cm x 2cm =
8cm3
SA:V = 24:8 24/8 = 3:1
Surface area = 8x8x6 =
384 cm2
Volume = 8x8x8 =
512cm3
SA:V = 384:512 384/512 = 0.75:1
Which cell has the biggest surface area to volume ratio?
Calculating Surface Area to Volume Ratios
![Page 11: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/11.jpg)
Let’s Practice Calculating Cell Size
1cm 5 cm 10 cm 20 cm 40 cm 80 cm
![Page 12: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/12.jpg)
So as organisms get bigger their surface area/volume ratio gets smaller. It becomes more difficult for them to exchange materials with their surroundings.
If the volume of a cell becomes too big for the surface area to support, substances such as food, O2, and wastes cannot diffuse in and out fast enough.
![Page 13: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/13.jpg)
Objectives – Section 10.1
Explain why cells divide in terms of growth and cell size
![Page 14: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/14.jpg)
10.1 Cell Growth Review
1. Give 2 reasons why cells divide that are not related to growth.
The larger a cell becomes, the more demands the cell places on its DNA and the more trouble the cell has in moving enough nutrients and wastes across the cell membrane.
2. As a cell increases in size, which increases more rapidly, its surface area or its volume?
Its volume.6:1
3:1
![Page 15: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/15.jpg)
3. Calculate the surface area, the volume, and the ratio of surfacearea to volume of an imaginary cubic cell measuring 4 cm on each side.
3 cm
3 cm
3 cm
Surface area: l x w # of sides:
Volume: l x w x h:
SA:V ratio:
3 x 3 x 6 = 54 cm2
3 x 3 x 3 = 27 cm3
54:27 = 6:3 (or 2:1)
![Page 16: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/16.jpg)
How does surface area to volume affect the physiology of organisms?
(Let’s look at a related concept!)
Is it better to be a large animal or a small one in cold climates?
![Page 17: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/17.jpg)
Organisms also exchange heat with their surroundings. Large animals have an advantage in having a small surface
area/volume ratio: they lose less heat than small animals.
Why do penguins huddle?
![Page 18: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/18.jpg)
Which animal has the greatest surface area to volume ratio?
The MOUSE of course!
How might the small surface area to volume ratio help the hippo in its natural environment?
![Page 19: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/19.jpg)
Chapter 10.2
The Cell Cycle and Mitosis
![Page 20: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/20.jpg)
Objectives
• Describe the main events of the cell cycle
• Explain each of the four phases of mitosis
![Page 21: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/21.jpg)
Some Cell Division Terminology
Don’t panic…
Just sharpen your pencil!
![Page 22: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/22.jpg)
• Each of the time periods of a cell’s life are referred to as phases
• This is similar to the way you can breakdown your life into phases
• Certain events are associated with each phase and can be used for identification of the phase
Phases
![Page 23: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/23.jpg)
Chromosomes• Chromosomes are made up of DNA wound tightly
around proteins called histones
• Histones + DNA = chromatin
• When a cell prepares for division it duplicates its DNA and condenses the chromatin into neat packages called chromosomes
![Page 24: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/24.jpg)
Chromosomes
• Exist in homologous pairs– One from mom
– One from dad
• Humans have 23 pairs– 22 autosome pairs
– 1 sex pair (these determine the sex of the organism)
![Page 25: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/25.jpg)
Sister Chromatids
• During replication (S phase) a pair of sister chromatids are made for each homolog of a chromosome pair
![Page 26: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/26.jpg)
Chromosomes
• Are generally represented in their duplicated form
• A single duplicated chromosome has two parts, each called a chromatid
• Each chromatid is referred to as a “sister” and is attached at a centromere
![Page 27: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/27.jpg)
Cell Cycle
• During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each of which then begins the cycle again.
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html
![Page 28: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/28.jpg)
Cell Cycle• It includes two major stages
1) Interphase• G1, S, G2
2) M phase (nuclear and cellular division)• Mitosis (division of the
nucleus)
• Cytokinesis (division the cell)
![Page 29: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/29.jpg)
Stage 1 - Interphase – “In Between”
• Interphase
G1= cell grows
S =chromosomes duplicate
G2= organelles duplicate, DNA checked
![Page 30: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/30.jpg)
Stage 2 – Mitosis – Nuclear Division
• First part of M Phase• The division of the
nucleus of somatic (body) cells during the cell cycle.
• Its divided into 4 phases.• Remember Interphase
and Cytokinesis are NOT part of Mitosis.
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
![Page 31: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/31.jpg)
KEY CONCEPT
• The phases of the M Phase of the cell cycle do not occur in isolation
• The are a continuum starting with prophase and proceeding sequentially through metaphase, anaphase and finally telophase
• Sometimes it can be difficult to determine the phase a cell is in because it will appear to be transitioning from one phase to another
![Page 32: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/32.jpg)
Prophase
• First stage of Mitosis
• Nuclear membrane breaks down
• Chromatin condenses into chromosomes
• Centrioles (animal cells only) separate and a spindle apparatus begins to form a cage like structure across the cell
![Page 33: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/33.jpg)
Prophase
![Page 34: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/34.jpg)
Metaphase
• Second Phase of Mitosis
• Each chromosome is connected to a spindle fiber at an area called the kinetochore on the centromere.
• the chromosomes line up in the middle of the spindle (called the metaphase plate)
![Page 35: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/35.jpg)
Metaphase
![Page 36: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/36.jpg)
Anaphase
• Third Phase of Mitosis
• The sister chromatids separate at the centromere into individual chromosomes and move apart to opposite ends of the cell.
• the spindle fibers shorten and pull the chromosomes to each end (aster)
![Page 37: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/37.jpg)
Anaphase
![Page 38: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/38.jpg)
Telophase
• Fourth and Final Stage of Mitosis
• Nuclear envelopes reform around each complete set of chromosomes
• Chromosomes unwind back into chromatin losing their distinct shape
![Page 39: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/39.jpg)
Telophase
![Page 40: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/40.jpg)
Final Step - Cytokinesis• The last step of M phase
• The equatorial belt pinches cytoplasm in half
• Each daughter cell has an identical set of chromosomes
![Page 41: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/41.jpg)
The Whole Cell Cycle – Putting it all together!
![Page 42: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/42.jpg)
So what is the END RESULT?
One Parent Cell
DIVIDES INTO
Two identical Daughter Cells
![Page 43: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/43.jpg)
Regulating the Cycle
• Proteins called cyclin help regulate the cell cycle in eukaryotic cells.
• They respond to internal and external events. These proteins are regulators.
![Page 44: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/44.jpg)
When Things Go Wrong
• Some cells begin to grow without regulation• They produce a mass of cells called a tumor
– Benign tumors do not cause damage to surrounding tissues
– Malignant tumors DO cause damage to tissues and may become cancerous
• Cancer cells do not respond to the signals that regulate the growth of most cells.
• As a result, they form masses of cells called tumors that can damage surrounding tissues.
• Brief animation!
![Page 45: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/45.jpg)
11-4 Meiosis
Cell Division for Sexual Reproduction
![Page 46: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/46.jpg)
Homologous Chromosomes
• All sexually reproducing organisms inherit one set of
chromosomes from each parent
• Each parental set contains exactly the same number of
chromosomes
• The corresponding chromosome from each parent is called
a homolog
• 2 homologs make a homologous pair
![Page 47: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/47.jpg)
![Page 48: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/48.jpg)
Chromosome Pair 1
Chromosome Pair 2
Chromosome Pair 3
![Page 49: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/49.jpg)
Chromosome Number
• Diploid (2 N)
– Cells with a complete set of homologous pairs
• Haploid (N)
– Cells with one half the homologous chromosomes in a diploid cell
Let’s do a quick activity to investigate this.
![Page 50: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/50.jpg)
What is Meiosis?
• A cell division cycle which reduces the number
of chromosomes in new cells by half
• Diploid (2N) somatic (body) cells are reduced
to haploid (N) gamete (sex) cells
• Chromosome reduction occurs by separation
of homologous chromosomes
![Page 51: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/51.jpg)
![Page 52: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/52.jpg)
Meiotic Cell Division – the Basics
• Meiosis involves 2 distinct phases
– Meiosis I
• Homologous pairs are separated
• 2 haploid cells are formed
– Meiosis II
• Sister chromatids are separated
• 4 haploid cells are formed
• End result is 4 genetically distinct haploid cells
![Page 53: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/53.jpg)
Meiotic Cell Division – the Basics
Start with Interphase
• Meiosis I– Prophase I
– Metaphase I
– Anaphase I
– Telophase I
– Cytokinesis
• 2 daughter cells result
• Meiosis II– Prophase II
– Metaphase II
– Anaphase II
– Telophase II
– Cytokinesis
• Each daughter cells divides into 2 new daughter cells
• 4 daughter cells in total
![Page 54: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/54.jpg)
A Closer Look at Meiosis I
• Meiosis I involves a special step that leads to genetic changes in duplicate sister chromatids
• During PROPHASE I– Homologous
chromosomes join together in a structure called a TETRAD
![Page 55: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/55.jpg)
Tetrads and Crossing Over
• TETRAD formation (synapsis),
– the arms of one chromatid of each
homolog CROSSOVER one another
– a gene segment from one parent
chromosome is exchanged with an
equal gene segment from the
other parent chromosome
![Page 56: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/56.jpg)
![Page 57: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/57.jpg)
![Page 58: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/58.jpg)
Cytoplasm distribution in human gamete formation
Males Females
• Cytoplasm distribution is even
• Meiosis results in – Four equal sperm cells
– Occurs in the testes
• Cytoplasm distribution is uneven
• Meiosis results in – One large egg
– Three smaller polar bodies
– Occurs in the ovaries
![Page 59: The Cell Cycles Mitosis and Meiosis - Introductionfriedsci.weebly.com/uploads/2/1/7/9/21791640/chapter_10_and_11.4.pdf · The Cell Cycles – Mitosis and Meiosis ... Organisms also](https://reader031.vdocuments.us/reader031/viewer/2022020214/5ac835437f8b9aa3298bdd2d/html5/thumbnails/59.jpg)
Zygote Formation
• Fertilization
– The joining of a haploid egg and a haploid sperm cell
– Results in the formation of a ZYGOTE (a fertilized egg)
• What is the chromosome number of a zygote?
– Haploid or Diploid?