Genetics

Genetics: Study of genes and how genes cause characteristics to be passed from parent to offspring.

Characteristics: Characteristic: a trait, ex. Height or color

Genes: Genes: a section of DNA that has info for a certain trait. an area on a chromosome that has directions for how a trait should look When DNA of a chromosome is copied the trait s copied

Alleles: Alleles: different versions of the same gene Each gene may have several different versions Gene for height: tall, short Color gene: yellow, green

Gregor Mendel: 1842 became an Austrian Monk Studied at the University of Vienna Taught physics and local history Worked with pea plants to study heredity Use mathematics to interpret his results 1865 presented his findings to the Brunn Society of Natural History 1900 his findings were determined to be significant

Why Pea Plants? Regenerate/grow quickly in a small garden Produce many seeds Pollinate easily Easily manipulated due to their ability to self pollinate

Pea Plant Anatomy:

Mendel’s Experiments: He used true breeding strains that self pollinated. He cross-pollinated his true breeding plants by removing the reproductive parts of the flowers. He was very methodical and used math and ratios to explain his findings.

Dominant allele: Version of the gene that the organism will look like ________________________________________________________________ Shown by upper case letters Examples:

Recessive allele: Version of the gene that the organism looks like ________________________________________________________________ Show by two lower case letters: Example:

Example: T= dominant t= recessive Gene= Tt= tt= TT=

Genotype: The specific alleles (genes) an organism has _____________________ ____________ Dominant: TT (________________) Homozygous _____________: tt (_________________________) __________: Tt (1 upper , 1 lower case)

Phenotype: What the organism actually looks like TT= Tt= tt=

Punnett Squares: A diagram used for ____________________________________________ involved in a genetic cross. Each side of the square is ______________________________________________ allele combinations. Each allele _____________ therefore each letter is placed in its own row/column (monohybrid crosses)

______________ ___________

Mendel’s Crosses: Rr P1 Generation Cross R R r r F1 Generation: Genotypes: Phenotypes:

Mendel’s Crosses: RR Rr rr F1 Generation Cross r R R r F2 Generation: Genotypes: Phenotypes:

Mendel’s Crosses: F2 Generation Cross r R r r F3 Generation: Genotypes: Phenotypes:

Law of Independent Assortment: During gamete formation, each parents allele combination is distributed randomly to form different gamete combinations. Use FOIL YyRr: YR, Yr, yR, yr

DiHybrid Crosses: A punnett square showing the possible gamete combinations for more than one trait Each trait is represented by a different letter Genotypic and Phenotypic ratios include both traits

Dihybrid Crosses: YR Yr yR yr

Incomplete Dominance: A combination of alleles where the heterozygous genotype has a phenotype that is a mix of the homogeneous phenotypes Neither of the alleles are the dominant allele. Example: Rr Rr=red, Rw Rw=white, Rr Rw= pink

Incomplete Dominance Example: P1 Cross: Cross red with a white: F1 Generation: Genotypes: 4: RR Rw Phenotypes: 4 Pink RR Rw RR Rw

Incomplete Dominance: F1 Cross RR Rw RR RR RR Rw RW RW Rw

Co-Dominance: A combination of alleles where the dominant forms of both are evident when heterozygous. Example: Blood Type: Alleles IA, IB, Io (recessive) IAIA or IA IO: Type A blood IA IB: Type AB blood IB IB or IBIO: Type B blood IOIO: Type O blood

Sex Linked Traits: Traits that are controlled by genes on the X chromosome. Recessive sex-linked traits are more likely to effect males because of the one x chromosome Red-Green Colorblindness: recessive x linked trait Hemophilia: recessive x linked trait