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

Chromosomes and Chromosome Number Section 1 Sexual Reproduction and Genetics I. Meiosis (important characteristics) Chromosomes and Chromosome Number Sketch a chromosome Human body cells have 46 chromosomes Each parent contributes 23 chromosomes Homologous chromosomes—one of two paired chromosomes, one from each parent Use the prefix “homo” to help!

Chromosomes and Chromosome Number cont. Section 1 Sexual Reproduction and Genetics Meiosis Chromosomes and Chromosome Number cont. Same length Same centromere position Carry genes that control the same inherited traits

B. Haploid and Diploid Cells Section 1 Sexual Reproduction and Genetics Meiosis B. Haploid and Diploid Cells An organism produces gametes to maintain the same number of chromosomes from generation to generation. What would happen if you received all of both parents genetic info??? Human gametes contain 23 chromosomes. What is a gamete? Specifically what are they in humans?

A cell with n chromosomes is called a haploid cell. “halved” A cell that contains 2n chromosomes is called a diploid cell. (complete set, all the cells in your body except gametes)

The sexual life cycle in animals involves meiosis. Section 1 Sexual Reproduction and Genetics Meiosis II. Meiosis I The sexual life cycle in animals involves meiosis. Meiosis produces gametes. When gametes combine in fertilization, the number of chromosomes is restored.

Section 1 Sexual Reproduction and Genetics Meiosis A. 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. Section 1 Sexual Reproduction and Genetics Meiosis Meiosis I 1. Interphase Prior to prophase Chromosomes replicate. Chromatin condenses. Interphase

Pairing of homologous chromosomes occurs. *** Section 1 Sexual Reproduction and Genetics Meiosis Meiosis I 2. Prophase I Pairing of homologous chromosomes occurs. *** Each chromosome consists of two chromatids. Prophase I The nuclear envelope breaks down. Spindles form.

Meiosis I 2. Prophase I (cont.) Section 1 Sexual Reproduction and Genetics Meiosis Meiosis I 2. Prophase I (cont.) **Crossing over produces exchange of genetic information. Creates variety! Crossing over—chromosomal segments are exchanged between a pair of homologous chromosomes.

Chromosome centromeres attach to spindle fibers. Section 1 Sexual Reproduction and Genetics Meiosis Meiosis I 3. Metaphase I Chromosome centromeres attach to spindle fibers. Metaphase I Homologous chromosomes line up at the equator.

Homologous chromosomes separate and move Section 1 Sexual Reproduction and Genetics Meiosis Meiosis I 4. Anaphase I Homologous chromosomes separate and move to opposite poles of the cell. **No longer paired Anaphase I

The spindles break down. Section 1 Sexual Reproduction and Genetics Meiosis Meiosis I 5. Telophase I The spindles break down. Telophase I Chromosomes uncoil and form two nuclei. The cell pinches in.

A second set of phases begins Section 1 Sexual Reproduction and Genetics Meiosis B. Stages Meiosis II 1. Prophase II A second set of phases begins as the spindle apparatus forms and the chromosomes condense. *events are very similar to mitosis Prophase II

A haploid number of chromosomes Section 1 Sexual Reproduction and Genetics Meiosis Meiosis II 2. Metaphase II A haploid number of chromosomes line up at the equator. Metaphase II

The sister chromatids are Section 1 Sexual Reproduction and Genetics Meiosis Meiosis II 3. 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 Section 1 Sexual Reproduction and Genetics Meiosis Meiosis II 4. Telophase II The chromosomes reach the poles, and the nuclear membrane and nuclei reform. Telophase II

Section 1 Sexual Reproduction and Genetics Meiosis Meiosis II C. Cytokinesis results in four haploid cells, each with n number of chromosomes. Cytokinesis

III. The Importance of Meiosis Section 1 Sexual Reproduction and Genetics Meiosis III. 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 Section 1 Sexual Reproduction and Genetics 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 Section 1 Sexual Reproduction and Genetics Meiosis Sexual Reproduction v. Asexual Reproduction Asexual reproduction The organism inherits all of its chromosomes from a single parent. The new individual is genetically identical to its parent. Sexual reproduction Beneficial genes multiply faster over time.

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

What is the term for a pair of chromosomes Chapter Sexual Reproduction and Genetics Section 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 A B C D FQ 2

Chapter Sexual Reproduction and Genetics Section 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. Gametes have 1/2 the number of chromosomes. Gametes have the same number of chromosomes. Gametes have twice as many chromosomes. A B C D FQ 3

What type of organisms only reproduce asexually? Chapter Sexual Reproduction and Genetics Section 1 Formative Questions What type of organisms only reproduce asexually? bacteria protists plants simple animals A B C D FQ 4

I. Mendel; How Genetics Began Section 2 Sexual Reproduction and Genetics Mendelian Genetics I. Mendel; How Genetics Began The passing of traits to the next generation is called inheritance, or heredity. Mendel performed cross-pollination in pea plants. The “father of genetics” Mendel followed various traits in the pea plants he bred.

A. The parent generation is also known as the P generation. Section 2 Sexual Reproduction and Genetics Mendelian Genetics A. The parent generation is also known as the P generation.

Section 2 Sexual Reproduction and Genetics Mendelian Genetics B. The offspring of this P cross are called the first filial (F1) generation. C. The second filial (F2) generation is the offspring from the F1 cross.

Section 2 Sexual Reproduction and Genetics

Mendel studied seven different traits. Section 2 Sexual Reproduction and Genetics 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

II. Genes in Pairs (language of genetics) Section 2 Sexual Reproduction and Genetics Mendelian Genetics II. Genes in Pairs (language of genetics) A. Allele An alternative form of a single gene passed from generation to generation (2 alleles for each trait)(expressed by using letters) B. Dominant: masks recessive; capital letter C. Recessive: shown only if both alleles are recessive; uses a lower case letter

Section 2 Sexual Reproduction and Genetics Mendelian Genetics Dominance D. An organism with two of the same alleles for a particular trait is homozygous. E. An organism with two different alleles for a particular trait is heterozygous. Practice: AA, Aa, aa

Genotype and Phenotype Section 2 Sexual Reproduction and Genetics Mendelian Genetics Genotype and Phenotype F. An organism’s allele pairs are called its genotype. G. The observable characteristic or outward expression of an allele pair is called the phenotype.

A. Mendel’s Law of Segregation Section 2 Sexual Reproduction and Genetics Mendelian Genetics III. Mendel’s laws A. 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.

Section 2 Sexual Reproduction and Genetics Mendelian Genetics Monohybrid Cross A cross that involves hybrids for a single trait is called a monohybrid cross.

Dihybrids are heterozygous for both traits. Section 2 Sexual Reproduction and Genetics 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.

B. Law of Independent Assortment Section 2 Sexual Reproduction and Genetics Mendelian Genetics B. Law of Independent Assortment Random distribution of alleles occurs during gamete formation Genes on separate chromosomes sort independently during meiosis. Each allele combination is equally likely to occur.

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

Punnett Square—Dihybrid Cross Section 2 Sexual Reproduction and Genetics 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.

What is the name for different forms of a Chapter Sexual Reproduction and Genetics Section 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 A B C D FQ 5

Which pair of alleles is heterozygous? Chapter Sexual Reproduction and Genetics Section 2 Formative Questions Which pair of alleles is heterozygous? RR Rr rr yR A B C D FQ 6

In rabbits, gray fur (G) is dominant to black Chapter Sexual Reproduction and Genetics Section 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 A B C D FQ 7

Section 3 I. Gene Linkage Chromosomes contain genes that code for proteins. Genes close together on a chromosome are “linked” and travel together *Genes that are farther apart cross over more frequently than if closer together.

Genetic Recombination Section 3 Sexual Reproduction and Genetics 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.

Gene Linkage and Polyploidy Section 3 Sexual Reproduction and Genetics 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.

Section 3 Sexual Reproduction and Genetics Gene Linkage and Polyploidy II. Polyploidy Polyploidy is the occurrence of one or more extra sets of all chromosomes in an organism. (rarely occurs in animals, in humans it is always lethal!) A triploid organism, for instance, would be designated 3n, which means that it has three complete sets of chromosomes.

1 in 3 species of flowering plants is polyploid. Increases size and vigor Ex: strawberries, oats, wheat, sugarcane

Which explains how the shuffling of genes Chapter Sexual Reproduction and Genetics Section 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 A B C D FQ 8

Two genes on the same chromosome may become separated during meiosis. Chapter Sexual Reproduction and Genetics Section 3 Formative Questions Two genes on the same chromosome may become separated during meiosis. true false A B FQ 9

What is the term for an organism that has one Chapter Sexual Reproduction and Genetics Section 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 A B C D FQ 10

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 connected.mcgraw-hill.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding feature.

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

Name the person known as the father of genetics. Chapter 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 A B C D CDQ 2

Which term refers to the outward expression of an allele pair? Chapter Sexual Reproduction and Genetics Chapter Diagnostic Questions Which term refers to the outward expression of an allele pair? gamete hybrid phenotype genotype A B C D CDQ 3

How many chromosomes would a cell have Chapter 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 A B C D CAQ 1

Which stage of meiosis is illustrated? Chapter Sexual Reproduction and Genetics Chapter Assessment Questions Which stage of meiosis is illustrated? prophase I interphase anaphase I anaphase II A B C D CAQ 2

What is the next step for the chromosomes illustrated? Chapter Sexual Reproduction and Genetics Chapter Assessment Questions What is the next step for the chromosomes illustrated? Chromosomes replicate. Chromosomes move to opposite poles. Chromosomes uncoil and form two nuclei. Chromosomes line up at the equator. A B C D CAQ 3

What is this process called? Chapter Sexual Reproduction and Genetics Standardized Test Practice What is this process called? fertilization gamete formation inheritance reproduction A B C D STP 1

Standardized Test Practice Chapter 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 A B C D STP 2

At what stage is the chromosome number reduced from 2n to n? Chapter 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 A B C D STP 3

To which step in this process does the law of segregation apply? Chapter 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 A B C D STP 4

1/4 1/2 1 For human eye color, brown is dominant and Chapter 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 A B C D STP 5

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Chapter Sexual Reproduction and Genetics Image Bank

Chapter Sexual Reproduction and Genetics Image Bank

Section 1 Vocabulary gene homologous chromosome gamete haploid 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 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 Section 3 Sexual Reproduction and Genetics Vocabulary Section 3 genetic recombination polyploidy

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

Chapter Sexual Reproduction and Genetics

Chapter Sexual Reproduction and Genetics