110 likes | 379 Views
Work of Gregor Mendel. Section 11-1 Pages 263-266 Standard IV Objective 2a: Explain Mendel’s laws of segregation and independent assortment and their role in genetic inheritance. Genetics Vocabulary. Trait: specific characteristic Gene:
E N D
Work of Gregor Mendel Section 11-1 Pages 263-266 Standard IV Objective 2a: Explain Mendel’s laws of segregation and independent assortment and their role in genetic inheritance.
Genetics Vocabulary • Trait: • specific characteristic • Gene: • sequence of DNA that codes for a protein thus determining a trait • Alleles: • different forms of a gene
Gregor Mendel • Gregor Mendel—father of genetics • Conducted his work in the garden of a monastery—changed biology forever • Worked with true breeding pea plants • True breeding—produce identical offspring if allowed to self-pollinate • He looked at 7 different traits
Alleles • Where do living organisms get alleles from? • Organisms receive one allele for each trait from each parent. • Principle of Dominance: some alleles are dominant and other are recessive • If a dominant allele is present, the organism will take on the characteristic of the dominant allele. • PTC paper
Alleles • Representing different alleles • T (capital letter) = dominant trait • t (lower case) = recessive trait • For each trait there are two alleles (one from each parent) • Example: Plant height • TT and Tt • tt
Probability • Principle of Probability: used to predict outcomes of genetic crosses • Homozygous – 2 identical alleles • Homozygous dominant (TT) • Homozygous recessive (tt) • Heterozygous – 2 different alleles (Tt)
Mendel’s Crosses • Original pair of plants—P (parental) generation • The offspring of the P generation are called the F1 generation • Hybrid—the offspring of crosses between parents with different traits
Genetic Vocabulary • Heterozygous—organisms that have two different alleles for the same trait • Homozygous—organisms that have two identical alleles for a particular trait • Genotype—genetic makeup • Heterozygous (Tt) • Homozygous (TT) or (tt) • Phenotype—physical characteristics • Plant is tall or Plant is short
Mendel’s Crosses • He took pure breeding tall plants (TT) and crossed them with pure breeding short plants (tt). • What is the result of the crosses? Do a Punnett square to show the result. • What is the genotype and phenotype for each of the plants? • Next step: He took two plant from the previous cross and bred them. • What is the result? What are the possible genotypes and phenotypes? Show with a punnett square.
Practice • Dad is heterozygous for a particular trait • Mom is homozygous recessive for the same trait • How do we predict outcomes?
Picture Credits • http://history.nih.gov/exhibits/nirenberg/images/photos/01_mendel_pu.jpg • http://www.jbhs.k12.nf.ca/biology/photos/jillear2.jpg • http://sdmc.lit.org.sg/gedm/imageANDdata/gene.gif • http://www.naturalselectionreptiles.com/Genetics/allele.jpg • http://www.bbc.co.uk/schools/gcsebitesize/img/bipeas.gif • http://psychservices.ucsd.edu/resources_parents_web/resources_parents_images/resources_parents_help.jpg • http://images.google.com/imgres?imgurl=http://i21.photobucket.com/albums/b268/plopperscioly/punnettsquare.jpg&imgrefurl=http:// • http://stavos.homeip.net/detroitarchive/uploadcenter/images/tigon.jpg • http://cricket.biol.sc.edu/herb/CC/Centrosema_virginianum2.jpg • http://users.adelphia.net/~lubehawk/BioHELP!/psquare0.jpg