MENDEL PPT

• Genetics ● Branch of biology that deals with heredity and variation of organisms.
• Chromosomes ● Carry the hereditary information (genes).
• gene is a coding region of DNA.
• Three reasons why Mendel chose the garden pea plant 1. It was easy to cultivate and had a relatively short life cycle (cross pollination and self-pollination). 2. It had discontinuous characteristics such as flower color and pea texture. 3. Pollination was easy to control.
• Gregor Johann Mendel
• Born in Brunn Austria which is now the Czech Republic

  1822
• Son of a peasant farmer
• Studied Theology

  Joined the St. Augustine Order
• Taught science classes

  Experimented with honeybees and plants
• Starting in 1856, spent a decade studying genetics using pea plants as the model organism
• Went to the University of Vienna, which he studied botany and learned the Scientific Method
• Worked with pure lines of common garden pea plant, Pisum sativum, for eight years
• Prior to Mendel, heredity was regarded as a “blending” process and the offspring were essentially a “dilution” of the different parental characteristics (as it frequently appears to be)
• Man of Science, Man of God
• Mendel looked at seven traits or characteristics of pea plants ○ 7 characteristics ■ Seed shape ■ Seed color ■ Pod shape ■ Pod color ■ Pod location ■ Stem length ■ Flower colo
• 1866 ● Mendel published Experiments in Plant Hybridization, (Versuche über Pflanzen-Hybriden) in which he established his three Principles of Inheritance.
• Work was largely ignored for 34 years, until 1900, when 3 independent botanists rediscovered Mendel’s work.
• Mendel was the first biologist to use Mathematics to explain his results quantitatively
• Genetic Variation and Allele Combination ● Reason why there is a difference in physical traits.
• Stamen = sperm producing ● Carpel = egg producing
• true-breeding (plants that produce off-spring of the same variety when they self-pollinate)
• The true breeding parents are the P generation
• The hybrid offspring of the P generation are called the F1 generation
• F1 individuals self-pollinate or cross-pollinate with other F1 hybrids, the F2 generation is produced
• Gene ● A unit of heredity. ● A section of DNA sequence encoding a single protein.
• Alleles ● Two genes that occupy the same position on homologous chromosomes and that cover the same trait (like “flavors” of a trait”).
• Genome ● The entire set of genes in an organism.
• Locus ● A fixed location on a strand of DNA where a gene or one of its alleles is located.
• Homozygous ● Having identical genes (one from each parent) for a particular characteristic.
• Heterozygous ● Having two different genes for a particular characteristic.
• Dominant and Recessive ● These two terms are used to describe the relationship of Alleles and the Traits they control.
• Dominant (Capital Letters) ● The allele of a gene that masks or suppresses the expression of an alternate allele; the trait appears in the heterozygous condition.
• Recessive (lower case letter) ● An allele that is masked by a dominant allele. ● Does not appear in the heterozygous condition, only in homozygous.
• Genotype ● The genetic makeup of an organism.
• Phenotype ● The physical appearance or observable attribute
• Monohybrid Cross ● A genetic cross involving a single pair of genes (one trait) ● Parents differ by a single trait
• P ○ Parental generation (true-breeding parents
• F1 ○ First filial generation (hybrids); offspring from true-breeding set of parents
• F2 ○ Second filial generation of genetic cross
• Punnett Square ● A useful tool to do genetic crosses. ● For a monohybrid cross, you need a square divided by four. ● Looks like a window pane. ● We use the punnett square to predict the genotypes and phenotypes of an offspring.