Meiosis and Sexual Reproduction Notes To be used with Meiosis and Sexual Reproduction Guided Notes.
Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.
-
Upload
harvey-hood -
Category
Documents
-
view
217 -
download
0
Transcript of Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.
![Page 1: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/1.jpg)
Meiosis and Sexual Reproduction
Ch. 7
Biology
Ms. Haut
![Page 2: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/2.jpg)
Introduction to Heredity
• Offspring acquire genes from parents by inheriting chromosomes
• Inheritance is possible because:
– Sperm and ova carrying each parent’s genes are combined in the nucleus of the fertilized egg
![Page 3: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/3.jpg)
Actual transmission of genes depends on the behavior of chromosomes
•Chromosomes-organizational unit of hereditary material in the nucleus of eukaryotic organisms•Contain hundreds of thousands of genes, each of
which is a specific region of the DNA molecule, or locus
![Page 4: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/4.jpg)
Meiosis
• Reduces chromosome number from diploid to haploid• Increases genetic variation among offspring• Steps resemble steps in mitosis• Single replication of DNA is followed by 2
consecutive cell divisions – Meiosis I– Meiosis II
• Produces 4 different daughter cells which have half the number of chromosomes as the original cell
![Page 5: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/5.jpg)
Interphase I
• Chromosomes replicate (still as chromatin)• Duplicated chromosomes consist of 2 identical sister chromatids attached by centromere• Centriole pairs replicate
![Page 6: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/6.jpg)
Meiosis I
• This cell division separates the 2 chromosomes of each homologous pair and reduce the chromosome number by one-half
![Page 7: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/7.jpg)
Prophase I• Chromosomes condense• Synapsis occurs
(homologues pair)• Chromosomes seen as
distinct structures; each chromosome has 2 chromatids, so each synapsis forms a tetrad
![Page 8: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/8.jpg)
Prophase I
• Sister chromatids held together by centromeres; non-sister chromatids held together by chiasmata where crossing-over occurs (exchange of DNA)
![Page 9: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/9.jpg)
![Page 10: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/10.jpg)
![Page 11: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/11.jpg)
Late Prophase I
• Centriole pairs move apart and spindle fibers form
• Nuclear envelope disappears and nucleoli disperse
![Page 12: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/12.jpg)
Prophase I
![Page 13: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/13.jpg)
Metaphase I
• Homologous chromosomes line up along metaphase plate
![Page 14: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/14.jpg)
Metaphase I
![Page 15: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/15.jpg)
Anaphase I
• Homologous chromosomes separate, independently from others
![Page 16: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/16.jpg)
Anaphase I
![Page 17: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/17.jpg)
Telophase I and Cytokinesis
• Each pole now has a haploid set of chromosomes (each with 2 sister chromatids)
• Usually, cytokinesis occurs simultaneously with telophase I, forming 2 haploid daughter cells (cleavage furrow forms in animals; cell plate forms in plants)
![Page 18: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/18.jpg)
Telophase I
![Page 19: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/19.jpg)
Meiosis II
• This cell division separates the 2 sister chromatids of each chromosome
![Page 20: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/20.jpg)
Prophase II
• Spindle apparatus forms and chromosomes move toward metaphase II plate
![Page 21: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/21.jpg)
Prophase II
![Page 22: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/22.jpg)
Metaphase II
• Chromosomes align singly on the metaphase plate
![Page 23: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/23.jpg)
Metaphase II
![Page 24: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/24.jpg)
Anaphase II
• Sister chromatids of each pair (now individual chromosomes) separate and move toward opposite poles of the cell
![Page 25: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/25.jpg)
Anaphase II
![Page 26: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/26.jpg)
Anaphase II
![Page 27: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/27.jpg)
Telophase II and Cytokinesis
• Nuclei form at opposite poles of the cell
• Cytokinesis occurs producing 4 haploid daughter cells (each genetically different)
![Page 28: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/28.jpg)
Telophase II
![Page 29: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/29.jpg)
Telophase II
![Page 30: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/30.jpg)
Key Differences Between Mitosis and Meiosis
• Meiosis is a reduction division
– Mitotic cells produce clones (same xsome #)
– Meiosis produces haploid cells
• Meiosis creates genetic variation
– Mitosis produces 2 identical daughter cells
– Meiosis produces 4 genetically different daughter cells
• Meiosis is 2 successive nuclear divisions
– Mitosis has one division
![Page 31: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/31.jpg)
Mechanisms of Genetic Variation
1. Independent assortment—each pair of homologous chromosomes separate independently
– Results in gametes with different gene combinations
2. Crossing-over—exchange of genetic material between non-sister chromatids
– Results in genetic recombination
3. Random fertilization—random joining of two gametes
![Page 32: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/32.jpg)
Importance of Genetic variation
• Essential to evolution (change over time)
• Variation can cause changes that leads to different traits– Some favorable– Some unfavorable
![Page 33: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/33.jpg)
Spermatogenesis
• Process of sperm production
• Results in 4 viable sperm
![Page 34: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/34.jpg)
![Page 35: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/35.jpg)
Oogenesis
• Process of egg (ova) production
• Results in 1 viable egg and 3 polar bodies that will not survive
• Polar bodies result from an uneven division of cytoplasm
![Page 36: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/36.jpg)
![Page 37: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/37.jpg)
Asexual Reproduction
• Prokaryotes—binary fission
• Eukaryotes—2 mechanisms– Fission—separation of a
parent into two or more individuals of identical size
– Budding—new individuals split off from existing ones
![Page 38: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/38.jpg)
Asexual Reproduction
Sexual Reproduction
Advantages
•Produce offspring in short time•Uses no energy
•Genetic diversity•Allows adaptation to changing environment
Disadvantages
•No genetic diversity•Harder to adapt to changing environment
•Uses energy
![Page 39: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/39.jpg)
Eukaryotic Sexual Life Cycles
• Life cycle—entire span in the life of an organism from one generation to the next
• All sexually reproducing organisms follow a basic pattern– Alteration between diploid and haploid
chromosome numbers
![Page 40: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/40.jpg)
Haploid Life Cycles
![Page 41: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/41.jpg)
n
n
nFresh water green algae
![Page 42: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/42.jpg)
Diploid Life Cycles
![Page 43: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/43.jpg)
Alternation of Generations Life Cycles
![Page 44: Meiosis and Sexual Reproduction Ch. 7 Biology Ms. Haut.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649ee05503460f94bf0ee5/html5/thumbnails/44.jpg)
Parthenogenesis
• New individual develops from an unfertilized egg
• Offspring is a clone of the mother
• Occurs in long absences of male companionship