Download Chapter 10 Notes Gregor Mendel Austrian monk who is known for

Chapter 10 Notes Gregor Mendel ● Austrian monk who is known for his ​
experiments with garden peas​
. ● He was the first person to successfully predict how traits would be expressed from one generation to the next by studying 7 characteristics of the plants. These characteristics were: plant height, seed shape, seed color, pod shape, pod color, flower position and flower color. ● Founder of the science we know today as ​
genetics ○ genetics​
­ branch of science concerned with genes, heredity, and variation in living organisms ■ heredity​
­ passing of traits from parents to their offspring through asexual or sexual reproduction ● traits​
­ characteristics that are passed from parent to offspring (inherited characteristics or qualities) Why did Mendel choose to use the garden pea? ● sexual reproduction (must have male and female ​
gametes​
­ sex cells) ○ garden peas produce both male and female gametes ■ male gametes form in pollen grains that are made in the ​
anther ● the ​
anther​
is the male reproductive organ in a flower ■ female gametes (eggs) are found in the ​
pistil​
and are reached by pollen grains attaching to the ​
stigma,​
move through the ​
style​
to the ovary ● the ​
pistil​
is the female reproductive organ in plants ● the ​
stigma​
is the opening to the female reproductive organ in a flower and it is covered with a sticky substance to which the pollen grains attach. ● the ​
style​
provides a pathway to the ​
ovary ​
where the eggs are stored in ovules ■ pollination​
occurs when a pollen grain is introduced into the pistil ● In some plants, including pea plants, this can happen in a single flower resulting in self­pollination ● It is possible to cross­pollinate where pollen grains from one plant are introduced into the pistil of a different plant ○ Mendel often removed the stamen and anther from a flower if he was going to cross­pollinate. This would ensure that he knew exactly which plants were the “parent plants” ■ fertilization​
is the process in which the male and female gametes unite and result in a ​
zygote ● a ​
zygote​
is a fertilized cell that will develop into a seed ○ Mendel carefully chose his plants (tall and short that had been true bred for many generations) Mendel’s Monohybrid Crosses ● Mendel crossed the tall plants with the short plants to produce ​
hybrids ○ hybrid​
­­ offspring formed by parents having different forms of a trait ■ monohybrid​
­ only one trait is varied ● In Mendel’s first experiments the single trait that varied was the height of the plants ■ Original Parent Plants (P​
) 1​
■ First Generation (F​
) 1​
■ Second Generation (F​
) 2​
● traits that seem to have “disappeared” from the P​
to F​
1​
1 sometimes reappear ● RULE OF UNIT FACTORS ○ alleles​
­ alternative forms of a gene for each variation of a trait of an organism (one inherited from the female parent and one inherited from the male parent) ○ most genes have 2 alleles ○ ​
heterozygous ​
­­ the two alleles for a trait differ from each other ○ homozygous​
­­ both alleles for a trait are the same ● RULE OF DOMINANCE ○ dominant​
(will be demonstrated if heterozygous representation) ­ represented with a capital letter and written first if present ○ recessive​
(must be homozygous for the trait to show up) ­ represented with a lowercase letter Mendel’s 2 laws of heredity 1. Law of Segregation a. Mendelian principle explaining that because each plant has two different alleles, it can produce two different types of gametes. During fertilization, male and female gametes randomly pair to produce four combinations of alleles. ● phenotype​
­­ outward appearance of an organism, regardless of its genes ○ observable traits ■ height ■ eye color ■ hair color ■ ● genotype​
­­ combination of genes in an organism ○ “type of genes” Genotype or Phenotype???? LL Blonde Hair Dimpled Chin Blue Eyes Dd ss White and Green Leaves For each of the following: 1. Write the genotype 2. Determine if homozygous or heterozygous G = green pea pod g = yellow pea pod Gg GG gg Punnett Squares for Monohybrid Crosses Di​
hybrid Crosses ● Instead of manipulating one trait, Mendel began manipulating ​
two traits ● This raises a new question: Will the two traits stay together or be inherited independent of each other? ○ Mendel crossed true­bred plants ■ RRYY (round, yellow seeds) ■ rryy (wrinkled, green seeds) ■ F​
yielded: 1​
■ F​
yielded: 2​
Mendel’s Second Law of Heredity ● Law of Independent Assortment ○ genes for different traits are inherited independently of each other PRACTICE PRACTICE PRACTICE