Chapter 10 2 Meiosis and Genetic Variation 1
![Chapter 10. 2 - Meiosis and Genetic Variation 1 Chapter 10. 2 - Meiosis and Genetic Variation 1](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-1.jpg)
![The Human Genome • Genome: Complete complement of an organism’s DNA. – Includes genes The Human Genome • Genome: Complete complement of an organism’s DNA. – Includes genes](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-2.jpg)
![Genes • Eukaryotic DNA is organized in chromosomes. – Genes have specific places on Genes • Eukaryotic DNA is organized in chromosomes. – Genes have specific places on](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-3.jpg)
![Heredity • Heredity – way of transferring genetic information to offspring • Chromosome theory Heredity • Heredity – way of transferring genetic information to offspring • Chromosome theory](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-4.jpg)
![All sexually reproducing organisms have two types of cells in their bodies • Diploid All sexually reproducing organisms have two types of cells in their bodies • Diploid](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-5.jpg)
![Diploid cells A normal diploid human body cell has 46 chromosomes paired together (23 Diploid cells A normal diploid human body cell has 46 chromosomes paired together (23](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-6.jpg)
![Problem-solving Lab 10. 2 on page 264. • • • Answer in your notes Problem-solving Lab 10. 2 on page 264. • • • Answer in your notes](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-7.jpg)
![• Looking at Chromosomes in a cell Karyotype: – ordered display of an • Looking at Chromosomes in a cell Karyotype: – ordered display of an](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-8.jpg)
![Karyotyping • Shows the homologous pairs of chromosomes • Identify sex of offspring • Karyotyping • Shows the homologous pairs of chromosomes • Identify sex of offspring •](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-9.jpg)
![10 10](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-10.jpg)
![Chromosomal disorders • Trisomy - Extra chromosome so 3 instead of 2 • Monosomy Chromosomal disorders • Trisomy - Extra chromosome so 3 instead of 2 • Monosomy](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-11.jpg)
![Genes are passed on through Reproduction • Asexual – Without sex cells – Produces Genes are passed on through Reproduction • Asexual – Without sex cells – Produces](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-12.jpg)
![Asexual Reproduction • single-celled organisms reproduce by splitting, budding, parthenogenesis. • offspring are genetically Asexual Reproduction • single-celled organisms reproduce by splitting, budding, parthenogenesis. • offspring are genetically](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-13.jpg)
![Sexual reproduction • Important vocabulary – Gametes = sex cells (egg and sperm) that Sexual reproduction • Important vocabulary – Gametes = sex cells (egg and sperm) that](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-14.jpg)
![Meiosis (sexual) vs. Mitosis (asexual) • Meiosis reduces the number of chromosomes by half. Meiosis (sexual) vs. Mitosis (asexual) • Meiosis reduces the number of chromosomes by half.](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-15.jpg)
![Sexual Reproduction is Important! • Because a zygote has genes from two different parents…. Sexual Reproduction is Important! • Because a zygote has genes from two different parents….](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-16.jpg)
![Meiosis I - First division of meiosis • Interphase - all chromosomes replicate (just Meiosis I - First division of meiosis • Interphase - all chromosomes replicate (just](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-17.jpg)
![Crossing over - occurs during Prophase I of meiosis Genetic recombination that is an Crossing over - occurs during Prophase I of meiosis Genetic recombination that is an](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-18.jpg)
![Harlequin chromosomes crossing over 19 Harlequin chromosomes crossing over 19](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-19.jpg)
![Meiosis I continued • Metaphase 1: Homologous chromosomes align at the equatorial plate. (in Meiosis I continued • Metaphase 1: Homologous chromosomes align at the equatorial plate. (in](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-20.jpg)
![Meiosis II Second division of meiosis: Gamete formation • Prophase 2: DNA does not Meiosis II Second division of meiosis: Gamete formation • Prophase 2: DNA does not](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-21.jpg)
![Meiosis creates genetic variation • Meiosis results in genetic variation by shuffling of maternal Meiosis creates genetic variation • Meiosis results in genetic variation by shuffling of maternal](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-22.jpg)
![Independent assortment - chromosomes separate randomly during meiosis 23 Independent assortment - chromosomes separate randomly during meiosis 23](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-23.jpg)
![In humans e. g. 23 chromosomes in haploid 2 n = 46; n = In humans e. g. 23 chromosomes in haploid 2 n = 46; n =](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-24.jpg)
![Random fertilization At least 8 million combinations from Mom, and another 8 million from Random fertilization At least 8 million combinations from Mom, and another 8 million from](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-25.jpg)
![Meiosis & sexual life cycles • Life cycle = sequence of stages in organisms Meiosis & sexual life cycles • Life cycle = sequence of stages in organisms](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-26.jpg)
![Sex is costly! • Large amounts of energy required to find a mate and Sex is costly! • Large amounts of energy required to find a mate and](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-27.jpg)
![But … • More genetic diversity: more potential for survival of species when environmental But … • More genetic diversity: more potential for survival of species when environmental](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-28.jpg)
![Study Questions • 1. What happens as homologous chromosomes pair up during prophase I Study Questions • 1. What happens as homologous chromosomes pair up during prophase I](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-29.jpg)
![• • • 5. Compare mitosis and meiosis on the following points: a. • • • 5. Compare mitosis and meiosis on the following points: a.](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-30.jpg)
![Meiosis – key differences from mitosis • Meiosis reduces the number of chromosomes by Meiosis – key differences from mitosis • Meiosis reduces the number of chromosomes by](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-31.jpg)
- Slides: 31
![Chapter 10 2 Meiosis and Genetic Variation 1 Chapter 10. 2 - Meiosis and Genetic Variation 1](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-1.jpg)
Chapter 10. 2 - Meiosis and Genetic Variation 1
![The Human Genome Genome Complete complement of an organisms DNA Includes genes The Human Genome • Genome: Complete complement of an organism’s DNA. – Includes genes](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-2.jpg)
The Human Genome • Genome: Complete complement of an organism’s DNA. – Includes genes (control traits) and non -coding DNA organized into chromosomes. 2
![Genes Eukaryotic DNA is organized in chromosomes Genes have specific places on Genes • Eukaryotic DNA is organized in chromosomes. – Genes have specific places on](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-3.jpg)
Genes • Eukaryotic DNA is organized in chromosomes. – Genes have specific places on chromosomes. 3
![Heredity Heredity way of transferring genetic information to offspring Chromosome theory Heredity • Heredity – way of transferring genetic information to offspring • Chromosome theory](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-4.jpg)
Heredity • Heredity – way of transferring genetic information to offspring • Chromosome theory of heredity: chromosomes carry genes. • Gene – “unit of heredity”. 4
![All sexually reproducing organisms have two types of cells in their bodies Diploid All sexually reproducing organisms have two types of cells in their bodies • Diploid](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-5.jpg)
All sexually reproducing organisms have two types of cells in their bodies • Diploid cells • – Normal body cells – Produced during mitosis – 2 sets of chromosomes paired together (2 n) Haploid Cells – Sex cells (gametes) – Produced during meiosis – Only 1 set of chromosomes (n) 5
![Diploid cells A normal diploid human body cell has 46 chromosomes paired together 23 Diploid cells A normal diploid human body cell has 46 chromosomes paired together (23](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-6.jpg)
Diploid cells A normal diploid human body cell has 46 chromosomes paired together (23 pairs) • The paired chromosomes match each other in gene type and location • They are called homologous pairs 6
![Problemsolving Lab 10 2 on page 264 Answer in your notes Problem-solving Lab 10. 2 on page 264. • • • Answer in your notes](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-7.jpg)
Problem-solving Lab 10. 2 on page 264. • • • Answer in your notes 1) 2) 3) 4) 7
![Looking at Chromosomes in a cell Karyotype ordered display of an • Looking at Chromosomes in a cell Karyotype: – ordered display of an](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-8.jpg)
• Looking at Chromosomes in a cell Karyotype: – ordered display of an individual’s chromosomes – Chromosomes are stained to reveal visible band patterns and major abnormalities. 8
![Karyotyping Shows the homologous pairs of chromosomes Identify sex of offspring Karyotyping • Shows the homologous pairs of chromosomes • Identify sex of offspring •](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-9.jpg)
Karyotyping • Shows the homologous pairs of chromosomes • Identify sex of offspring • Identify extra or missing chromosomal disorders 9
![10 10](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-10.jpg)
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![Chromosomal disorders Trisomy Extra chromosome so 3 instead of 2 Monosomy Chromosomal disorders • Trisomy - Extra chromosome so 3 instead of 2 • Monosomy](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-11.jpg)
Chromosomal disorders • Trisomy - Extra chromosome so 3 instead of 2 • Monosomy - Missing a chromosome so 1 instead of 2 Down’s Syndrome (trisomy 21) 11
![Genes are passed on through Reproduction Asexual Without sex cells Produces Genes are passed on through Reproduction • Asexual – Without sex cells – Produces](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-12.jpg)
Genes are passed on through Reproduction • Asexual – Without sex cells – Produces identical copies of parent (clones) – Mitosis is asexual reproduction • Sexual – With sex cells – Produces genetically variable offspring • This is good for survival! – Meiosis is sexual reproduction 12
![Asexual Reproduction singlecelled organisms reproduce by splitting budding parthenogenesis offspring are genetically Asexual Reproduction • single-celled organisms reproduce by splitting, budding, parthenogenesis. • offspring are genetically](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-13.jpg)
Asexual Reproduction • single-celled organisms reproduce by splitting, budding, parthenogenesis. • offspring are genetically identical to parent. 13
![Sexual reproduction Important vocabulary Gametes sex cells egg and sperm that Sexual reproduction • Important vocabulary – Gametes = sex cells (egg and sperm) that](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-14.jpg)
Sexual reproduction • Important vocabulary – Gametes = sex cells (egg and sperm) that are haploid – Haploid = one set of chromosomes – Diploid = two sets of chromosomes – Zygote = fertilized egg • Fusion of two gametes to produce a single fertilized egg (zygote). 14
![Meiosis sexual vs Mitosis asexual Meiosis reduces the number of chromosomes by half Meiosis (sexual) vs. Mitosis (asexual) • Meiosis reduces the number of chromosomes by half.](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-15.jpg)
Meiosis (sexual) vs. Mitosis (asexual) • Meiosis reduces the number of chromosomes by half. – Produces 4 haploid cells • Daughter cells differ from parent cell • Meiosis involves two divisions • Mitosis keeps the same number of chromosomes – Produces 2 diploid cells • Daughter cells identical to parent (clones) • Mitosis involves only one division 15
![Sexual Reproduction is Important Because a zygote has genes from two different parents Sexual Reproduction is Important! • Because a zygote has genes from two different parents….](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-16.jpg)
Sexual Reproduction is Important! • Because a zygote has genes from two different parents…. . – Introduces greater genetic variation for a species – Allows for genetic recombination – Increase species survival! 16
![Meiosis I First division of meiosis Interphase all chromosomes replicate just Meiosis I - First division of meiosis • Interphase - all chromosomes replicate (just](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-17.jpg)
Meiosis I - First division of meiosis • Interphase - all chromosomes replicate (just like in mitosis) • Prophase 1: Homologous chromosomes begin to pair up. Crossing-over can occur during the latter part of this stage. 17
![Crossing over occurs during Prophase I of meiosis Genetic recombination that is an Crossing over - occurs during Prophase I of meiosis Genetic recombination that is an](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-18.jpg)
Crossing over - occurs during Prophase I of meiosis Genetic recombination that is an exchange of genetic material between homologous chromosomes Crossing over produces recombinant chromosomes and increases genetic variation! 18
![Harlequin chromosomes crossing over 19 Harlequin chromosomes crossing over 19](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-19.jpg)
Harlequin chromosomes crossing over 19
![Meiosis I continued Metaphase 1 Homologous chromosomes align at the equatorial plate in Meiosis I continued • Metaphase 1: Homologous chromosomes align at the equatorial plate. (in](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-20.jpg)
Meiosis I continued • Metaphase 1: Homologous chromosomes align at the equatorial plate. (in pairs next to each other) • Anaphase 1: Homologous pairs separate with sister chromatids remaining together. • Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair. 20
![Meiosis II Second division of meiosis Gamete formation Prophase 2 DNA does not Meiosis II Second division of meiosis: Gamete formation • Prophase 2: DNA does not](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-21.jpg)
Meiosis II Second division of meiosis: Gamete formation • Prophase 2: DNA does not replicate again. • Metaphase 2: Chromosomes align at the equatorial plate. • Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four haploid daughter cells are obtained. 21
![Meiosis creates genetic variation Meiosis results in genetic variation by shuffling of maternal Meiosis creates genetic variation • Meiosis results in genetic variation by shuffling of maternal](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-22.jpg)
Meiosis creates genetic variation • Meiosis results in genetic variation by shuffling of maternal and paternal chromosomes and crossing over. *No daughter cells formed during meiosis are genetically identical to either mother or father *During sexual reproduction, fusion of the unique haploid gametes produces truly unique offspring. 22
![Independent assortment chromosomes separate randomly during meiosis 23 Independent assortment - chromosomes separate randomly during meiosis 23](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-23.jpg)
Independent assortment - chromosomes separate randomly during meiosis 23
![In humans e g 23 chromosomes in haploid 2 n 46 n In humans e. g. 23 chromosomes in haploid 2 n = 46; n =](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-24.jpg)
In humans e. g. 23 chromosomes in haploid 2 n = 46; n = 23 2 n = 223 = ~ 8 million possible combinations! 24
![Random fertilization At least 8 million combinations from Mom and another 8 million from Random fertilization At least 8 million combinations from Mom, and another 8 million from](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-25.jpg)
Random fertilization At least 8 million combinations from Mom, and another 8 million from Dad … >64 trillion combinations for a diploid zygote!!! 25
![Meiosis sexual life cycles Life cycle sequence of stages in organisms Meiosis & sexual life cycles • Life cycle = sequence of stages in organisms](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-26.jpg)
Meiosis & sexual life cycles • Life cycle = sequence of stages in organisms reproductive history; conception to reproduction. • Somatic cells = any cell other than gametes, most of the cells in the body. • Gametes produced by Generalized animal life cycle meiosis. 26
![Sex is costly Large amounts of energy required to find a mate and Sex is costly! • Large amounts of energy required to find a mate and](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-27.jpg)
Sex is costly! • Large amounts of energy required to find a mate and do the mating: specialized structures and behavior required • Intimate contact provides route for infection by parasites (AIDS, syphillis, etc. ) • Genetic costs: in sex, we pass on only half of genes to offspring. • Males are an expensive luxury - in most species they contribute little to rearing offspring. 27
![But More genetic diversity more potential for survival of species when environmental But … • More genetic diversity: more potential for survival of species when environmental](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-28.jpg)
But … • More genetic diversity: more potential for survival of species when environmental conditions change. – Shuffling of genes in meiosis – Crossing-over in meiosis – Fertilization: combines genes from 2 separate individuals • DNA back-up and repair. – Asexual organisms don't have back-up copies of genes, sexual organisms have 2 sets of chromosomes and one can act as a back-up if the other is damaged. – Sexual mechanisms, especially recombination, are used to repair damaged DNA - the undamaged chromosome acts as a template and eventually both chromosomes end up with the correct gene. 28
![Study Questions 1 What happens as homologous chromosomes pair up during prophase I Study Questions • 1. What happens as homologous chromosomes pair up during prophase I](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-29.jpg)
Study Questions • 1. What happens as homologous chromosomes pair up during prophase I of meiosis? • 2. How does metaphase of mitosis differ from metaphase I of meiosis? • 3. What is the sole purpose of meiosis? • 4. What specific activities, involving DNA, occur during interphase prior to both mitosis and meiosis? 29
![5 Compare mitosis and meiosis on the following points a • • • 5. Compare mitosis and meiosis on the following points: a.](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-30.jpg)
• • • 5. Compare mitosis and meiosis on the following points: a. number of daughter cells produced. b. the amount of DNA in the daughter cells in contrast to the original cell. c. mechanism for introducing genetic variation. 6. What is a zygote and how is it formed? 7. What is the main advantage of sexual reproduction? 30
![Meiosis key differences from mitosis Meiosis reduces the number of chromosomes by Meiosis – key differences from mitosis • Meiosis reduces the number of chromosomes by](https://slidetodoc.com/presentation_image_h/1ac5b16ac65d6c8e2b6a2dbff51b74ff/image-31.jpg)
Meiosis – key differences from mitosis • Meiosis reduces the number of chromosomes by half (haploid cells). • Daughter cells differ from parent cell and each other. • Meiosis involves two divisions, Mitosis only one. • Meiosis produces 4 haploid cells, Mitosis produces 2 diploid cells. 31
Crossing over occurs during:
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