Chapter 10 Sexual Reproduction and Genetics Section 1: Meiosis Section 2: Mendelian Genetics Section 3: Gene Linkage and Polyploidy

Chromosomes and Chromosome Number Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Chromosomes and Chromosome Number Human body cells have 46 chromosomes Each parent contributes 23 chromosomes Homologous chromosomes—one of two paired chromosomes, one from each parent

We have 46 total chromosomes We have 23 unique chromosomes On each pair of chromosomes are genes for the same traits in the same order Mom’s Chrom. #1 Dad’s Chrom. #1 Gene for hair color Mom’s codes for red Gene for hair color Dad’s codes for brown

Chromosomes and Chromosome Number Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Chromosomes and Chromosome Number Same length Same centromere position Carry genes that control the same inherited traits

Haploid and Diploid Cells Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Haploid and Diploid Cells Sexually reproducing organisms produce gametes to maintain the same number of chromosomes from generation to generation. Human gametes (sperm and egg) contain 23 chromosomes. A cell with n chromosomes is called a haploid cell. (n = 23 in humans) A cell that contains 2n chromosomes is called a diploid cell. (2n = 46 in humans)

The sexual life cycle in animals involves meiosis. Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I The sexual life cycle in animals involves meiosis. Meiosis produces gametes. When gametes combine in fertilization, the number of chromosomes is restored.

Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Stages of Meiosis I Reduces the chromosome number by half through the separation of homologous chromosomes Involves two consecutive cell divisions called meiosis I and meiosis II

Chromosomes replicate. Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I Interphase Chromosomes replicate. Chromatin condenses. Interphase

Pairing of homologous chromosomes occurs. Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I Prophase I Pairing of homologous chromosomes occurs. Each chromosome consists of two chromatids. Prophase I The nuclear envelope breaks down. Spindles form.

Crossing over produces exchange of genetic information. Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I Prophase I Crossing over produces exchange of genetic information. Crossing over—chromosomal segments are exchanged between a pair of homologous chromosomes.

Chromosome centromeres attach to spindle fibers. Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I Metaphase I Chromosome centromeres attach to spindle fibers. Metaphase I Homologous chromosomes line up at the equator.

Homologous chromosomes separate and move Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I Anaphase I Homologous chromosomes separate and move to opposite poles of the cell. Anaphase I

The spindles break down. Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis I Telophase I The spindles break down. Telophase I Chromosomes uncoil and form two nuclei. The cell divides.

A second set of phases begins Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis II Prophase II A second set of phases begins as the spindle apparatus forms and the chromosomes condense. Prophase II

A haploid number of chromosomes Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis II Metaphase II A haploid number of chromosomes line up at the equator. Metaphase II

The sister chromatids are Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis II Anaphase II The sister chromatids are pulled apart at the centromere by spindle fibers and move toward the opposite poles of the cell. Anaphase II

The chromosomes reach the poles, and Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis II Telophase II The chromosomes reach the poles, and the nuclear membrane and nuclei reform. Telophase II

Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis II Cytokinesis results in four haploid cells, each with n number of chromosomes. Cytokinesis

The Importance of Meiosis Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis The Importance of Meiosis Meiosis consists of two sets of divisions Produces four haploid daughter cells that are not identical Results in genetic variation

Meiosis Provides Variation Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Meiosis Provides Variation Depending on how the chromosomes line up at the equator, four gametes with four different combinations of chromosomes can result. Genetic variation also is produced during crossing over and during fertilization, when gametes randomly combine.

Sexual Reproduction v. Asexual Reproduction Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis Sexual Reproduction v. Asexual Reproduction Asexual reproduction (Mitosis) The organism inherits all of its chromosomes from a single parent. The new individual is genetically identical to its parent. Sexual reproduction (Fusion of gametes) Beneficial genes multiply faster over time.

Mitosis vs Meiosis differences Mitosis Meiosis_______ -one division -2 sets of divisions -creates 2 clones -creates 4 genetically different cells -creates diploid cells -creates haploid cells -for creating body cells -for creating gametes -No crossing over -crossing over occurs Sister chromatids split in Ana -Homolog. pairs sep in Ana1

Mendellian Genetics Mendel grew up on a small farm in what is today the Czech Republic. In 1843, Mendel entered an Augustinian monastery. He studied at the University of Vienna from 1851 to 1853 where he was influenced by two teachers: -a physicist who encouraged experimentation and the application of mathematics to science and a botanist who aroused Mendel’s interest in the causes of variation in plants. These influences gelled in Mendel’s experiments.

Mendel studied seven different traits. Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Mendel studied seven different traits. Seed or pea color Flower color Seed pod color Seed shape or texture Seed pod shape Stem length Flower position

Mendel performed cross-pollination in pea plants. Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics How Genetics Began The passing of traits to the next generation is called inheritance, or heredity. Mendel performed cross-pollination in pea plants. Mendel followed various traits in the pea plants he bred.

The parent generation is also known as the P generation. Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics The parent generation is also known as the P generation.

The second filial (F2) generation is the offspring from the F1 cross. Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics The offspring of this P cross are called the first filial (F1) generation. The second filial (F2) generation is the offspring from the F1 cross.

F2 results were always the same

Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics An organism with two of the same alleles for a particular trait is homozygous. An organism with two different alleles for a particular trait is heterozygous.

Genotype and Phenotype Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Genotype and Phenotype An organism’s allele pairs are called its genotype. The observable characteristic or outward expression of an allele pair is called the phenotype.

Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Genes in Pairs Allele An alternative form of a single gene passed from generation to generation Dominant: an allele that produces the same phenotypic effect whether inherited with a homozygous or heterozygous allele Recessive: A condition that appears only in individuals who have received two copies of a this allele

Mendel developed a hypothesis to explain these results that consisted of four related ideas. 1. Alternative version of genes (different alleles) account for variations in inherited characters. Different alleles vary somewhat in the sequence of nucleotides at the specific locus of a gene. The purple-flower allele and white-flower allele are two DNA variations at the flower-color locus.

Alternatively, the two alleles may differ 2. For each character, an organism inherits two alleles, one from each parent. A diploid organism inherits one set of chromosomes from each parent. Each diploid organism has a pair of homologous chromosomes and therefore two copies of each gene. These two alleles an organism has for a trait may be identical, as in the true-breeding plants of the P generation. Alternatively, the two alleles may differ

3. If two alleles differ, then one, the dominant allele, is fully expressed in the the organism’s appearance. The other, the recessive allele, has no noticeable effect on the organism’s appearance. Mendel’s F1 plants had purple flowers because the purple-flower allele is dominant and the white-flower allele is recessive.

4. The two alleles for each character segregate (separate from each other) during gamete production. The separation of alleles into separate gametes is summarized as Mendel’s law of segregation. ***This happens during Anaphase I of meiosis***

Mendel’s Law of Segregation Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Mendel’s Law of Segregation Two alleles for each trait separate during meiosis. During fertilization, two alleles for that trait unite. Heterozygous organisms are called hybrids.

Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Monohybrid Cross A cross that involves hybrids for a single trait is called a monohybrid cross.

Predict the possible offspring 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

Dihybrids are heterozygous for both traits. Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Dihybrid Cross The simultaneous inheritance of two or more traits in the same plant is a dihybrid cross. Dihybrids are heterozygous for both traits.

Punnett Square—Dihybrid Cross 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.

Ex. Dihybrid cross Ex. Predict how many Tall (T or t), yellow (G or g) would be expected in this cross: TtGg X TtGg

Law of Independent Assortment Chapter 10 Sexual Reproduction and Genetics 10.2 Mendelian Genetics Law of Independent Assortment Random distribution of alleles occurs during gamete formation Genes on separate chromosomes sort independently during meiosis. No 2 traits are tied together Green peas could be in green pods or yellow pods Each allele combination is equally likely to occur.

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

Observable Mendellian Traits in Humans Widows peak = Dom Tongue rolling = Dom Dimples = Dom Cleft in chin = Rec Free earlobe = Dom Hitchhikers thumb= Dom PTC tasting = Dom

Genetic Recombination Chapter 10 Sexual Reproduction and Genetics 10.3 Gene Linkage and Polyploidy Genetic Recombination The new combination of genes produced by crossing over and independent assortment Combinations of genes due to independent assortment can be calculated using the formula 2n, where n is the number of chromosome pairs.

10.3 Gene Linkage and Polyploidy Chapter 10 Sexual Reproduction and Genetics 10.3 Gene Linkage and Polyploidy Gene Linkage 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.

Polyploidy is the occurrence of one or more extra sets of all Chapter 10 Sexual Reproduction and Genetics 10.3 Gene Linkage and Polyploidy Polyploidy Polyploidy is the occurrence of one or more extra sets of all chromosomes in an organism. A triploid organism, for instance, would be designated 3n, which means that it has three complete sets of chromosomes.

Chapter Resource Menu Chapter Diagnostic Questions 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.

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

Name the person known as the father of genetics. Chapter 10 Sexual Reproduction and Genetics Chapter Diagnostic Questions Name the person known as the father of genetics. Felix Mendelssohn Gregor Mendel Dr. Reginald Punnett Albert Einstein

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

Segments of DNA that control the production Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions Segments of DNA that control the production of proteins are called _______. chromatids chromosomes genes traits

What is the term for a pair of chromosomes Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions 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? diploid heterozygous homozygous homologous

How does the number of chromosomes Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions How does the number of chromosomes in gametes compare with the number of chromosomes in body cells?

Gametes have 1/4 the number of chromosomes. Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions Gametes have 1/4 the number of chromosomes. Gametes have 1/2 the number of chromosomes. Gametes have the same number of chromosomes. Gametes have twice as many chromosomes.

What type of organisms only reproduce asexually? Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions What type of organisms only reproduce asexually? bacteria protists plants simple animals

What is the name for different forms of a Chapter 10 Sexual Reproduction and Genetics 10.2 Formative Questions What is the name for different forms of a single gene that are passed from generation to generation? alleles genotypes phenotypes traits

Which pair of alleles is heterozygous? Chapter 10 Sexual Reproduction and Genetics 10.2 Formative Questions Which pair of alleles is heterozygous? RR Rr rr yR

In rabbits, gray fur (G) is dominant to black Chapter 10 Sexual Reproduction and Genetics 10.2 Formative Questions 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? 1:1 1:2:1 2:1 3:1

Which explains how the shuffling of genes Chapter 10 Sexual Reproduction and Genetics 10.3 Formative Questions Which explains how the shuffling of genes during meiosis results in billions of possible combinations? crossing over gene linkage genetic recombination independent segregation

Two genes on the same chromosome may become separated during meiosis. Chapter 10 Sexual Reproduction and Genetics 10.3 Formative Questions True or False Two genes on the same chromosome may become separated during meiosis.

What is the term for an organism that has one Chapter 10 Sexual Reproduction and Genetics 10.3 Formative Questions What is the term for an organism that has one or more sets of extra chromosomes in its cells? diploid gamete hybrid polyploid

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

Which stage of meiosis is illustrated? Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions Which stage of meiosis is illustrated? prophase I interphase anaphase I anaphase II

What is the next step for the chromosomes illustrated? Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions What is the next step for the chromosomes illustrated?

Chromosomes replicate. Chromosomes move to opposite poles. Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions Chromosomes replicate. Chromosomes move to opposite poles. Chromosomes uncoil and form two nuclei. Chromosomes line up at the equator.

What is this process called? Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice What is this process called? fertilization gamete formation inheritance reproduction

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

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

To which step in this process does the law of segregation apply? Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice To which step in this process does the law of segregation apply?

grows into plant gamete formation fertilization seed development Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice grows into plant gamete formation fertilization seed development

1/4 1/2 1 For human eye color, brown is dominant and Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice 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? 1/4 1/2 1

Glencoe Biology Transparencies 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

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

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

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

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