12-13-Heredity-1.pptx - Heredity Ch12 \u2013 Mendelian Heredity Ch13 \u2013 Modern Heredity Heredity Genetics \u2022 Heredity = transmission of genetic info from

12-13-Heredity-1.pptx - Heredity Ch12 u2013 Mendelian...

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Heredity Ch12 – Mendelian Heredity Ch13 – Modern Heredity
Heredity & Genetics Heredity = transmission of genetic info from parent to offspring; follows predictable patterns Genetics = study of heredity; similarities and variation between and among generations or among individuals in a population
Principles of Inheritance True breeding = offspring always have same traits as parents Hybrid = offspring of different true breeding parents (don’t breed true) Character vs. Trait Character = seed color Trait = yellow seed
Principles of Inheritance Mendel recognized a pattern in the way parental traits reappear in offspring of hybrid garden peas Parental generation (P) First filial generation (F 1 ) Second filial generation (F 2 ) Dominant & Recessive traits Dominant – trait expressed in F 1 (ex. purple flower) Recessive – trait masked in F 1 (ex. white flower)
P generaton F 1 generaton 3 tall: 1 short All tall plants F 2 generaton
Mendel’s Model of Inheritance 1. Alternative forms of a “factor” account for variations in inherited traits 2. Inherited traits pass from parents to offspring as unmodified factors 3. Each individual has two sets of factors, one of each pair inherited from the mother and one from the father. 4. The paired factors separate prior to the formation of reproductive cells (the principle of segregation) 5. Factors may be expressed or hidden in a given generation, but they are never lost 6. Each factor is passed to the next generation independently from all other factors (the principle of independent assortment)
Modern Terminology Characters = genes = parts of DNA code for protein with a specific function Trait = alleles = different forms of gene on corresponding loci on homologs Locus: the site a gene occupies in the chromosome Phenotype: the physical appearance of an organism Genotype: the genetic makeup of an organism Homozygous: two identical alleles Heterozygous: two different alleles Genes Alleles parts of DNA code for protein with a specific function different forms of gene on corresponding loci on homologs Homozygous Heterozygous
Alleles Occupy Corresponding Loci On Homologous Chromosomes Gene loci A pair of alleles These genes are not allelic to one another Alleles controlling fur color: Alleles controlling fur length: Black Brown Long Short
The Principle of Segregation During meiosis, alleles for each locus segregate from each other When haploid gametes are formed, each contains only one allele for each locus Note that half the haploid cells carry T and half carry t METAPHASE I METAPHASE II Homologous chromosomes t -carrying haploid cells T -carrying haploid cells
Monohybrid Crosses & Punnett Squares Monohybrid cross: a cross between homozygous parents w/ different alleles

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