Presentation on theme: "Chapter Menu Lesson 1:Foundations of GeneticsFoundations of Genetics Lesson 2:Understanding InheritanceUnderstanding Inheritance Click on a hyperlink."— Presentation transcript:
Chapter Menu Lesson 1:Foundations of GeneticsFoundations of Genetics Lesson 2:Understanding InheritanceUnderstanding Inheritance Click on a hyperlink to view the corresponding lesson.
heredity genetics dominant recessive gene law of segregation law of independent assortment 4.1 Foundations of Genetics allele phenotype genotype homozygous heterozygous
Early Ideas About Heredity Combined genetic material from a sperm and an egg determines the traits or features of an offspring. 4.1 Foundations of Genetics Heredity is the passing of traits from parents to offspring.
Early Ideas About Heredity (cont.) The idea of blending inheritance is offspring are a blend of genetic material from both parents. 4.1 Foundations of Genetics –The genetic material mixed or blended like colors of paint. –Over many generations, populations would eventually look alike. –Blending inheritance cannot explain why some traits skip a generation.
Gregor Mendel and His Experiments Gregor Mendel was the first to record evidence that traits are determined by factors passed from parents to offspring. Mendel established the basic laws of heredity. Genetics is the study of how traits of organisms are passed from parents to offspring. 4.1 Foundations of Genetics
Mendels Experimental Methods Mendel conducted breeding experiments by studying seven traits of pea plants and each traits had only two variations. 4.1 Foundations of Genetics
Controlled Experiments Mendel controlled fertilization in the pea plants, allowing him to see how traits pass from one generation to another. 4.1 Foundations of Genetics Mendel allowed some flowers to self-fertilize. He also performed cross-fertilization by transferring pollen from one pea flower to another.
Mendels Unique Methods Used true-breeding plants for each trait plants that always produce offspring with that trait when they self-pollinate 4.1 Foundations of Genetics Recorded the inheritance of traits for several generations Used a mathematical approach
Mendels Experimental Results Mendel concluded that two factors control each inherited trait. 4.1 Foundations of Genetics When organisms reproduce, each gamete sperm or eggcontributes one factor for each trait.
Dominant Factors A genetic factor that blocks another genetic factor is called dominant. 4.1 Foundations of Genetics A dominant trait is observed when offspring have one or two dominant factors.
Recessive Factors A genetic factor that is hidden by the presence of a dominant factor is recessive. 4.1 Foundations of Genetics A recessive trait can be observed only when two recessive genetic factors are present in offspring.
Mendels Laws of Heredity Law of segregation: the two factors for each trait segregateseparate from each otherduring meiosis when gametes form 4.1 Foundations of Genetics Law of independent assortment: the factors for one trait separate independently of how factors for other traits separate
Modern Definitions of Mendels Ideas Mendel did not know about DNA or how cells reproduce, but his ideas about inheritance are still true today. 4.1 Foundations of Genetics
Genes and Alleles A gene is a section of DNA that has information about a trait in an organism. 4.1 Foundations of Genetics Each form of a gene with different information is called an allele.
Genes and Alleles (cont.) 4.1 Foundations of Genetics
Phenotype and Genotype The observable traits and all characteristics of an organism make up the organisms phenotype. 4.1 Foundations of Genetics The alleles that make up an organism is the organisms genotype. The alleles of a particular gene is that genes genotype.
Homozygous and Heterozygous Genotypes Because eukaryotes have pairs of chromosomes, a genotype for a gene has two alleles. 4.1 Foundations of Genetics If the two alleles have the same information, the genotype is homozygous. If the two alleles have different information, the genotype is heterozygous.
Homozygous and Heterozygous Genotypes (cont.) 4.1 Foundations of Genetics
Law of Segregation Explained The movement of chromosomes during meiosis explains Mendels law of segregation. –Each set of chromatids separates into different gametes during meiosis II. –Each gamete receives only one allele. 4.1 Foundations of Genetics
Law of Segregation Explained (cont.) 4.1 Foundations of Genetics
Law of Independent Assortment Explained The daughter cells produced by meiosis receive only one chromosome from each pair of homologous chromosomes. –A daughter cell might receive the A or a chromosome from pair 1 and the B or b chromosome from pair 2. –This results in four possible allele combinations for two homologous pairs of chromosomes. 4.1 Foundations of Genetics
Law of Independent Assortment Explained (cont.) 4.1 Foundations of Genetics
Importance of Mendels Genetic Studies In the 1860s, no one knew about chromosomes or meiosis so it was hard to understand Mendels discoveries. All the research of modern genetics is based on Mendels conclusions from his work with pea plants. 4.1 Foundations of Genetics
Lesson 1 Review What is the passing of traits from parents to offspring called? Ainheritance Bgenetics Cheredity Dallele 4.1 Foundations of Genetics
Lesson 1 Review What are the alleles that make up an organism called? Agenes Bgenotype Cphenotype Dfactors 4.1 Foundations of Genetics
Lesson 1 Review If two alleles for a gene have the same information, what kind of genotype does that gene have? Ahomologous Brecessive Cheterozygous Dhomozygous 4.1 Foundations of Genetics
Modeling Inheritance –Punnett square –pedigree Two tools can be used to identify and predict traits among genetically related individuals. 4.2 Understanding Inheritance Heredity
Punnett Squares If the genotypes of the parents are known, the genotypes and phenotypes of the offspring can be predicted. A Punnett square is a model used to predict possible genotypes and phenotypes of offspring. 4.2 Understanding Inheritance
One-Trait Model The Punnett square shows the possible offspring of a cross between two true- breeding pea plantsone with yellow seeds and one with green. 4.2 Understanding Inheritance
One-Trait Model (cont.) –The phenotype will be yellow seeds because Y is dominant to y. –The only possible genotype for hybrid offspring is heterozygousYy. 4.2 Understanding Inheritance
One-Trait Model (cont.) 4.2 Understanding Inheritance
Two-Trait Model The possible offspring of two heterozygous genotypesYy and Yywould have three different genotypes and two phenotypes. 4.2 Understanding Inheritance
Pedigrees All the genetically related members of a family are part of a family tree. 4.2 Understanding Inheritance A pedigree shows genetic traits that were inherited by members of a family tree. Pedigrees are important tools for tracking complex pattern of inheritance and genetic disorders in families.
Pedigrees (cont.) 4.2 Understanding Inheritance A pedigree chart that shows three generations of a family.
Types of Dominance Alleles show incomplete dominance when they produce a phenotype that is a blend of the parents phenotypes. When both alleles can be observed in the phenotype, the interaction is called codominance. 4.2 Understanding Inheritance –The human blood type AB is an example of codominance.
Multiple Alleles Some genes have more than two alleles, or multiple alleles. The human ABO blood group is determined by multiple alleles as well as codominance. There are three different alleles for the ABO blood typeIA, IB, and i. 4.2 Understanding Inheritance
Sex-Linked Inheritance Chromosomes X and Y are the sex chromosomesthey contain the genes that determine gender or sex. 4.2 Understanding Inheritance Except for sperm and eggs, each cell in a male has an X and a Y chromosome, and each cell in a female has two X chromosomes. A recessive phenotype is observed in a male when a one-allele gene on his X chromosome has a recessive allele.
Sex-Linked Inheritance (cont.) 4.2 Understanding Inheritance In this family, the grandmothers genome included the color blindness allele.
Polygenic Inheritance Polygenic inheritance is when multiple genes determine the phenotype of a trait. 4.2 Understanding Inheritance Many phenotypes are possible when possible when polygenic inheritance determines a trait.
Maternal Inheritance Humans inherit mitochondrial genes only from their mothers. 4.2 Understanding Inheritance Inheritance of traits related to the mitochondria can be traced from grandmother to grandchildren. How are the traits of parents inherited and expressed in offspring?
Human Genetic Disorders If a change occurs in a gene, the organism with the mutation may not be able to function as it should. 4.2 Understanding Inheritance An inherited mutation can result in a phenotype called a genetic disorder.
Human Genetic Disorders (cont.) 4.2 Understanding Inheritance
Genes and the Environment An organisms environment can affect its phenotype. –Genes affect heart disease, but so do diet and exercise. –Genes affect skin color, but so does exposure to sunlight. 4.2 Understanding Inheritance
Lesson 2 Review Punnett squares model the ____ of offspring. Agenotypes Bphenotypes Cgenotypes and phenotypes Dgenes 4.2 Understanding Inheritance
Lesson 2 Review What is the term for when alleles produce a phenotype that is a blend of the parents phenotypes? Aincomplete dominance Bcodominance Cmultiple alleles Dpolygenic inheritance 4.2 Understanding Inheritance
Lesson 2 Review How many Y chromosomes do females have? A0A0 B1B1 C2C2 D4D4 4.2 Understanding Inheritance
End of Lesson 2
Chapter Assessment California Standards Practice Concepts in Motion Image Bank Science Online Chapter Resources Menu Click on a hyperlink to view the corresponding feature.
What is the term for the idea that offspring are a blend of genetic material from both parents? Apolygenic inheritance Bsex-linked inheritance Cmaternal inheritance Dblending inheritance Chapter Assessment 1
What type of alleles can only be observed in the phenotype when they are present as a homozygous genotype? Adominant Brecessive Cinherited Dheterozygous Chapter Assessment 2
What is the term for the idea that inheritance of one trait is not influenced by inheritance of another trait? Alaw of independent assortment Blaw of heredity Claw of segregation Dmaternal inheritance Chapter Assessment 3
What is a good example of a trait that is determined by multiple alleles? Acolor of camellia flowers Bhuman AB blood type Ccolor blindness Dhuman ABO blood group Chapter Assessment 4
Why are male humans more likely to be color-blind than females? Amaternal inheritance Bsex-linked inheritance Cpolygenic inheritance Dincomplete dominance Chapter Assessment 5
Which pea trait did Mendel not study? Aseed color Bpod color Cflower position Dflower shape CA Standards Practice 1 SCI 2.c
If two plants with genotypes Mm are crossed, what percent of the offspring will have phenotype M? A0% B25% C75% D100% CA Standards Practice 2 SCI 2.d
What is the term for when more than one gene determine a trait? Aincomplete dominance Bmultiple alleles Cpolygenic inheritance Dsex-linked inheritance CA Standards Practice 3 SCI 2.c, 2.d
Which does NOT describe Mendels experiments? AMendel observed several generations of plants. BMendel chose pea plants because they reproduce quickly. CMendel counted small numbers of offspring. DMendel used true-breeding plants. CA Standards Practice 4 SCI 2.d
What type of genetic disorder is hemophilia? Adominant BX-linked recessive Ccodominant Drecessive CA Standards Practice 5 SCI 2.d