Chapter 10 Sexual Reproduction and Genetics Section 1

Chapter 10 Sexual Reproduction and Genetics Section 1: Meiosis Section 2: Mendelian Genetics Section 3: Gene Linkage and Polyploidy Click on a lesson name to select.

Vocabulary *Gene - segments of DNA located on chromosomes that control inherited traits; passed on from one generation to another generation Gene Click on a lesson name to select.

*Chromosome - DNA containing structure that carries genetic material from one generation to another Click on a lesson name to select.

Homologous chromosomes - One of two paired chromosomes, one from each parent, that carries genes for a specific trait at the same location Click on a lesson name to select.

*Synapsis - the pairing of homologous chromosomes during meiosis Click on a lesson name to select.

*Crossing over - Exchange of chromosomal segments between a pair of homologous chromosomes during prophase 1 of meiosis Click on a lesson name to select.

*Gamete - A haploid sex cell, formed during meiosis, that can combine with another haploid sex cell and produce a diploid fertilized egg; egg or sperm *Haploid - Cell with half the number of chromosomes (n) as a diploid (2 n) cell n - Used to represent the number of chromosomes in a gamete; haploid Click on a lesson name to select.

*Meiosis - Reduction division process, occurring only in reproductive cells, in which one diploid (2 n) cell produces four haploid (n) cells that are not genetically identical Click on a lesson name to select.

*Fertilization Process by which haploid gametes combine, forming a diploid cell with 2 n chromosomes, with n chromosomes from the female parent and n chromosomes from the male parent Click on a lesson name to select.

*diploid - A cell that contains both sets of homologous chromosomes; represented by 2 n 2 n - Results after fertilization; n chromosomes from female parent and n chromosomes from the male parent; diploid Click on a lesson name to select.

Asexual reproduction - Organism inherits all of its genes from a single parent Click on a lesson name to select.

Genetic variation Different form of a gene results in different expression in the form of genetic makeup and outward appearance Click on a lesson name to select.

Sexual Reproduction Organism inherits all of its genes from two parents Click on a lesson name to select.

Chapter 10 section 1 Meiosis Main Idea: Meiosis produces haploid gametes. Click on a lesson name to select.

1. Human body cells have 46 chromosomes. 2. Each parent contributes 23 chromosomes, resulting in 23 pairs of chromosomes.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis 3. The chromosomes that make up a pair, one chromosome from each parent, are called homologous chromosomes. 4. Homologous chromosomes in body cells have the same length and the same centromere position and they carry genes that control the same inherited traits.

5. In order to maintain the same chromosome number from generation to generation, an organism produces gametes, which are sex cells that have half the number of chromosomes.

Meiosis • Reduces the genetic material by half • Why is this necessary? from mother from father child too much! meiosis reduces genetic content

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis Haploid and Diploid Cells 6. In humans, each gamete contain 23 chromosomes.

• ploidy - how many times each chromosome is present in a cell. • Diploid – 2 copies of each chromosome • Triploid – 3 copies of each chromosome • Haploid – half the number of each chromosome

7. A cell with n chromosomes is called a haploid cell. 8. A cell that contains 2 n chromosomes is called a diploid cell.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis 9. Gametes are formed during a process called meiosis, which is a type of cell division that reduces the number of chromosomes; therefore, it is referred to as reduction division.

10. Meiosis occurs in the reproductive structures of organisms that reproduce sexually.

11. Meiosis reduces the chromosome number by half through the separation of homologous chromosomes.

12. A cell with 2 n number of chromosomes will have gametes with n number of chromosomes after meiosis. Fertilization. Process by which one Haploid gamete combines With another haploid gamete

13. Meiosis involves two consecutive cell divisions called meiosis I and meiosis II.

14. Mitosis consists of only one set of division phases and produces two identical diploid daughter cells. Meiosis consists of two sets of divisions and produces four haploid daughter cells that are not identical.

15. Meiosis is important because it results in genetic variation.

16. Pair of homologous chromosomes line up at the equator during metaphase I. How the chromosomes line up is a random process that results in gametes with different combinations of chromosomes.

17. Depending on how the chromosomes line up at the equator, four gametes with four different combinations of chromosomes can result.

18. Genetic variation also is produced during crossing over and fertilization, when gametes randomly combine.

19. During asexual reproduction, the organism inherits all of its chromosomes from a single parent. The new individual is genetically identical to its parent.

10. 2 Vocabulary Mendelian Genetics True breeding - plant consistently produces offspring with only one form of a trait Self fertilization - when a male gamete within a flower combines with a female gamete in the same flower Cross pollination - transferring a male gamete from the flower of one pea plant to the female reproductive organ in a flower of another pea plant

Genetics - Science of heredity P generation - Parent generation; true breeding; Cross between parents with different forms of a trait F 1 generation - The offspring of the P cross are called the first filial (F 1) generation; filius is Latin for son F 2 generation - The offspring of the f 1 generation

Allele - Alternative form that a single gene may have for a particular trait *Traits - Characteristics that are inherited Dominant - Mendel’s name for a specific trait that appeared in the F 1 generation Recessive - Mendel’s name for a specific trait hidden or masked in the F 1 generation

Homozygous - Organism with two of the same alleles for a specific trait; YY or yy Heterozygous - Organism with two different alleles for a specific trait; Yy Hybrid - Organism heterozygous for a specific trait; Yy

Genotype - An organism’s allele pairs; genetic makeup; the letters that represent the genes Phenotype - Observable characteristic that is expressed as a result of an allele pair; physical appearance Law of Segregation - Mendelian law stating that two alleles for each trait separate during meiosis

Monohybrid cross - A cross between hybrids for a single trait; Yy x Yy; Dihybrid cross - A cross between hybrids for 2 traits; Yy. Rr Law of Independent Assortment - Mendelian law stating that a random distribution of alleles occurs during gamete formation; demonstrated in the dihybrid cross by the equal chance that each pair of alleles

*FOIL Method - used to determine gametes in a dihybrid; Punnett Squares - Used to predict the possible ratios of offspring of a cross between two known genotypes; keeps track of possible genotypes involved in a cross *Probability - likelihood that a particular event will occur; helps to predict the average outcome of a large number of events

10. 2 Mendelian Genetics Main Idea - Mendel explained how a dominant allele can mask (hide) the presence of a recessive allele.

Gregor Mendel • 1866 • Austrian monk • Plant breeder Mendel was the first person to succeed in predicting how traits are transferred from one generation to the next.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics How Genetics Began 1. The passing of traits to the next generation is called inheritance, or heredity.

2. Mendel chose to study pea plants. Contrasting characters- green & yellow wrinkled & round Reproduce sexually Crosses can be controlled Short life cycles Produce large number of offspring

In nature the pea plants are true (pure) breeding. 3. True (pure) breeding means that the pea plant consistently produces offspring with only one form of a trait. Short pea plant Tall pea plant 4. Self-fertilization occurs when a male gamete within a flower combines with a female gamete in the same flower. Result: the plant will have characteristics only from 1 parent

5. Mendel performed cross pollination by transferring a male gamete from the flower of one pea plant to the female reproductive organ in a flower of another pea plant.

Mendel was a careful researcher He studied only one trait at a time to control variables, and he analyzed his data mathematically. The tall pea plants he worked with were from populations of plants that had been tall for many generations and had always produced tall offspring.

6. Genetics is the scientific study of heredity.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics 7. The parent generation is also known as the P generation. §Cross between parents with different forms of a trait

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics 8. The offspring of this P cross are called the first filial (F 1) generation. Filius-latin for son

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics 9. The second filial (F 2) generation is the offspring from the F 1 cross.

10. F 2 generation plants from these crosses showed a 3: 1 ratio. How did green reoccur?

11. Mendel studied 7 different traits in the pea Pod Plant Pod Seed Flower plants he bred. shape color position color shape height Dominant trait round yellow purple axial (side) green inflated tall white terminal (tips) yellow constricted short Recessive trait wrinkled green

The rule of unit factors Mendel concluded that each organism has two factors that control each of its traits. We now know that these factors are genes and that they are located on chromosomes. 12. Allele – an alternative form of a single gene passed from generation to generation. Ex. Pod color in peas – yellow or green

The rule of dominance 13. Dominant – a form of trait that can mask or hide another form of a same trait. Ex. In peas the color yellow pod is dominant—represented by capital letter for allele.

14. Recessive – a form of trait that can be masked or hidden by the dominant form- ex. In peas the color green pod is recessive— represented by lower case letter Mendel concluded that the allele for yellow peas is dominant to the allele for green peas.

The rule of dominance When recording the results of crosses, it is customary to use the same letter for different alleles of the same gene. Short plant Tall plant t T T t t T F 1 All tall plants T t

Phenotypes and Genotypes 15. An organism with two of the same alleles for a particular trait is homozygous. (Ex. YY, yy or RR, rr) 16. An organism with two different alleles for a particular trait is heterozygous (ex. Yy or Rr). When alleles are present in a heterozygous state, the dominant trait will be observed

Phenotypes and Genotypes 17. An organism’s allele pairs are called its genotype. 18. The observable characteristics or outward expression of an allele pair is called the phenotype. An organism’s genotype can’t always be known by its phenotype.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics 19. Mendel’s Law of Segregation states that two alleles for each trait separate during meiosis.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics 20. During fertilization, two alleles for that trait unite.

21. Heterozygous organisms are called hybrids.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics Monohybrid Cross 22. Crosses that study a single trait. Genotypic ratio 1: 2: 1 Phenotypic ratio 3: 1

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics Dihybrid Cross 23. . Crosses that study two or more traits. These F 1 generation plants are called dihybrids because they are heterozygous for each trait

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics 24. Law of Independent Assortment states that a random distribution of alleles occurs during gamete formation. This result in the formation of 4 gametes. 25. Genes on separate chromosomes sort independently during meiosis. 26. Each allele combination is equally likely to occur. 27. These results represent a 9: 3: 3: 1 phenotypic ratio.

Equal chance that each pair of alleles can randomly combine with each other Alleles in parental cell Gamete formation Possible allele combinations in gametes YR Y y R r Yr y. R yr

Punnett Squares In 1905, Reginald Punnett, an English biologist, devised a shorthand way of finding the expected proportions of possible genotypes in the offspring of a cross. This method is called a Punnett squares. 28. Punnett Squares predict the possible offspring or results of a cross between two known genotypes.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics Punnett Squares § Predict the possible offspring of a cross between two known genotypes Punnett Squares

Probability 29. The principles of probability can be used to predict the outcomes of genetic crosses.

Probability r R RR Rr Rr rr R r The Punnett square shows three plants with round seeds out of four total plants, so the probability is 3/4.

Chapter 10 Sexual Reproduction and Genetics 10. 2 Mendelian Genetics Punnett Square— Dihybrid Cross § Four types of alleles from the male gametes and four types of alleles from the female gametes can be produced. § The resulting phenotypic ratio is 9: 3: 3: 1.

“FOIL” Method used to determine gametes in a dihybrid F = first of each pair O = outer two I = inner two L = last of each pair • Bb. Tt = gametes would be BT, Bt, b. T, bt • Remember to keep homologous pairs of chromosomes together when combining gametes to form offspring. Bb. Tt NOT BTbt • Always place the dominant allele first in a homologous pair of chromosomes. Bb. Tt NOT b. Bt. T

P= Phenotype ratio _____________

Dihybrid Cross

10. 3 Gene Linkage and Polyploidy Objectives: 1. Summarize how the process of meiosis produces genetic variation. 2. Explain how gene linkage can be used to create chromosome maps. 3. Analyze why polyploidy is important to the field of agriculture.

Chapter 10 Sexual Reproduction and Genetics 10. 3 Gene Linkage and Polyploidy 1. Genetic Recombination is the new combination of genes produced by crossing over and independent assortment 2. Combinations of genes due to independent assortment can be calculated using the formula n 2 , where n is the number of chromosome pairs.

3. Genes that are located close together on the same chromosome are said to be linked and usually travel together during gamete formation.

Chapter 10 Sexual Reproduction and Genetics 10. 3 Gene Linkage and Polyploidy Gene Linkage 4. The linkage of genes on a chromosome results in an exception to Mendel’s law of independent assortment because linked genes usually do not segregate independently.

5. Crossing over occurs more frequently between genes that are far apart than those that are close together. 6. 1 st chromosome maps were constructed on data from fruit fly crosses.

7. Chromosome map percentages represent relative positions on the genes. 8. The higher the crossover frequency, the farther apart the two genes are.

Chapter 10 Sexual Reproduction and Genetics 10. 3 Gene Linkage and Polyploidy 1. Polyploidy is the occurrence of one or more extra sets of all chromosomes in an organism. 2. A triploid organism, for instance, would be designated 3 n, which means that it has 3 complete sets of chromosomes.

3. Polyploidy rarely occurs in animals. In humans, polyploidy is always lethal. 4. Roughly one in three species of known flowering plants are polyploidy. Often they have increased vigor and size. Vigor -active healthy wellbalanced growth especially of plants

Chapter 10 Sexual Reproduction and Genetics Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh. com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding lesson.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis I § Interphase § Chromosomes replicate. § Chromatin condenses. Interphase

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis I § Prophase I § Pairing of homologous chromosomes occurs. § Each chromosome consists of two chromatids. § The nuclear envelope breaks down. § Spindles form. Prophase I

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis I § Prophase I § Crossing over produces exchange of genetic information. § Crossing over—chromosomal segments are exchanged between a pair of homologous chromosomes.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis I § Metaphase I § Chromosome centromeres attach to spindle fibers. Metaphase I § Homologous chromosomes line up at the equator.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis I § Anaphase I § Homologous chromosomes separate and move to opposite poles of the cell. Anaphase I

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis I § Telophase I § The spindles break down. Telophase I § Chromosomes uncoil and form two nuclei. § The cell divides.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis II § Prophase II § A second set of Prophase II phases begins as the spindle apparatus forms and the chromosomes condense.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis II § Metaphase II § A haploid number of chromosomes line up at the equator. Metaphase II

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis II § Anaphase II § The sister Anaphase II chromatids are pulled apart at the centromere by spindle fibers and move toward the opposite poles of the cell.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis II § Telophase II § The chromosomes Telophase II reach the poles, and the nuclear membrane and nuclei reform.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Meiosis II § Cytokinesis results in four haploid cells, each with n number of chromosomes. Cytokinesis Visualizing Meiosis I and Meiosis II

Chapter 10 Sexual Reproduction and Genetics Chapter Diagnostic Questions 1. Which symbol is used to represent the number of chromosomes in a gamete? A. # B. x C. r D. n

Chapter 10 Sexual Reproduction and Genetics 10. 1 Formative Questions 2. Segments of DNA that control the production of proteins are called _______. A. chromatids B. chromosomes C. genes D. traits

Chapter 10 Sexual Reproduction and Genetics 10. 1 Formative Questions 3. What is the term for a pair of chromosomes that have the same length, same centromere position, and carry genes that control the same traits? A. diploid B. heterozygous C. homozygous D. homologous

Chapter 10 Sexual Reproduction and Genetics 10. 1 Formative Questions 4. How does the number of chromosomes in gametes compare with the number of chromosomes in body cells? A. Gametes have 1/4 the number of chromosomes. B. Gametes have 1/2 the number of chromosomes. C. Gametes have the same number of chromosomes. D. Gametes have twice as many chromosomes

Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions 5. Which stage of meiosis is illustrated? A. prophase I B. interphase C. anaphase I D. anaphase II

Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions 6. What is the next step for the chromosomes illustrated? A. Chromosomes replicate. B. Chromosomes move to opposite poles. C. Chromosomes uncoil and form two nuclei. D. Chromosomes line up at the equator.

Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice 7. Before meiosis I, the sister chromatids of this chromosome were identical. What process caused a change in a section of one chromatid? A. DNA replication B. crossing over C. synapsis D. telophase

Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice 8. At what stage is the chromosome number reduced from 2 n to n? A. prophase I B. metaphase I C. anaphase I D. meiosis II

Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice 9. What is this process called? A. fertilization B. gamete formation C. inheritance D. reproduction

Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions 10. How many chromosomes would a cell have during metaphase I of meiosis if it has 12 chromosomes during interphase? A. 6 B. 12 C. 24 D. 36

Chapter 10 Sexual Reproduction and Genetics 10. 3 Formative Questions True or False 11. Two genes on the same chromosome may become separated during meiosis.

Chapter 10 Sexual Reproduction and Genetics 10. 1 Formative Questions 12. What type of organisms only reproduce asexually? A. bacteria B. protists C. plants D. simple animals

Chapter 10 Sexual Reproduction and Genetics 10. 2 13. Name the person known as the father of genetics. A. Felix Mendelssohn B. Gregor Mendel C. Dr. Reginald Punnett D. Albert Einstein

Chapter 10 Sexual Reproduction and Genetics Chapter Diagnostic Questions 14. Which term refers to the outward expression of an allele pair? A. gamete B. hybrid C. phenotype D. genotype

Chapter 10 Sexual Reproduction and Genetics 10. 2 Formative Questions 15. What is the name for different forms of a single gene that are passed from generation to generation? A. alleles B. genotypes C. phenotypes D. traits

Chapter 10 Sexual Reproduction and Genetics 10. 2 Formative Questions 16. Which pair of alleles is heterozygous? A. RR B. Rr C. rr D. y. R

Chapter 10 Sexual Reproduction and Genetics 17. To which step in this process does the law of segregation apply? A. grows into plant B. gamete formation C. fertilization D. seed development

Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice 18. For human eye color, brown is dominant and blue is recessive. If a husband is heterozygous and his wife has blue eyes, what is the probability that their child will have blue eyes? A. 0 B. 1/4 C. 1/2 D. 1

Chapter 10 Sexual Reproduction and Genetics 10. 2 Formative Questions 19. . In rabbits, gray fur (G) is dominant to black fur (g). If a heterozygous male is crossed with a heterozygous female, What is the phenotypic ratio of the possible offspring? A. 1: 1 B. 1: 2: 1 C. 2: 1 D. 3: 1

Chapter 10 Sexual Reproduction and Genetics 10. 3 20. Which explains how the shuffling of genes during meiosis results in billions of possible combinations? A. crossing over B. gene linkage C. genetic recombination D. independent segregation

Chapter 10 Sexual Reproduction and Genetics 10. 3 Formative Questions 21. What is the term for an organism that has one or more sets of extra chromosomes in its cells? A. diploid B. gamete C. hybrid D. polyploid

Chapter 10 Sexual Reproduction and Genetics Glencoe Biology Transparencies

Chapter 10 Sexual Reproduction and Genetics Image Bank

Chapter 10 Sexual Reproduction and Genetics Image Bank

Chapter 10 Sexual Reproduction and Genetics Vocabulary Section 1 gene meiosis homologous chromosome gamete haploid fertilization diploid crossing over

Chapter 10 Sexual Reproduction and Genetics Vocabulary Section 2 genetics phenotype allele dominant recessive homozygous heterozygous genotype law of segregation hybrid law of independent assortment

Chapter 10 Sexual Reproduction and Genetics Vocabulary Section 3 genetic recombination polyploidy

Chapter 10 Sexual Reproduction and Genetics Animation § Visualizing Meiosis I and Meiosis II § Generations