Mendelian Genetics Gregor Mendel Father of modern genetics

Mendelian Genetics Gregor Mendel Father of modern genetics

Cell Division Review • mitosis produces two daughter cells genetically identical to the original parent cell (diploid) • meiosis produces four daughter cells with exactly half the genetic material of the original parent cell. (haploid)

Gametogenesis-meiosis Creation of the gametes. • Male meiosis generally results in the production of four sperm that are capable of producing offspring. • Female meiosis generally results in the production of ONE viable oocyte plus 3 polar bodies.

• allele: different forms of a gene found in the gene pool – ie: A , B & O alleles for human blood type. • phenotype: the physical trait in an organism – ie: hitchhiker’s thumb • genotype: the actual genes of an organism – ie: homozygous recessive (aa) • dominant allele: if present, determines the phenotype of trait ie: roll tongue • recessive allele: No dominant allele present, trait will be expressed – ie: no tongue roll. • homozygous: the two alleles are the same (dominant – AA or recessive - aa). • heterozygous: the two alleles are different (one big, one small - Aa) • autosomal trait: a gene located on one of the autosomes (any chromosome that is not a sex chromosome). • sex-linked trait: a gene located on one of the sex chromosomes (either the X (X-linked) or Y (Y-linked) chromosome).

Sex chromosomes Karyotype of normal human male & female. 46 chromosomes (23 pair)

• DNA make up your chromosomes. • Chromosomes are where your genes are stored. • Genes determine your traits (proteins). • You inherit 1 allele from each parent for each trait. (total of 2) • Traits have dominant forms and recessive forms. • Your alleles will determine your genotype and phenotype.

Mendel’s Laws worked with pea plants to make observations. • Law of Segregation - The two forms of a gene (now known as alleles) present in each organism segregate into different cells during gamete formation. • Law of Independent Assortment - The (two) alleles of the many different genes present in any given (diploid) organism segregate/assort from one another in a random fashion. • Law of Dominance - alleles can be dominant or recessive. The dominant allele, if present, will always determine the trait.

Laws of Segregation & Independent assortment Law of Dominance

Tools for Genetics Karyotype Pedigree Punnett Squares

Punnett Square Practice!! Cross a male who is heterozygous for tongue rolling (Tt) with a female that is homozygous recessive (tt)

Punnett Square Practice!! T t t Tt Tt t tt tt Cross a male who is heterozygous for tongue rolling (Tt) with a female that is homozygous recessive (tt) Genotypic ratio: _______ TT : Tt : tt Phenotypic ratio: _______ Rolling ; no rolling

Punnett Square Practice!! Cross 2 parents who are heterozygous for freckles (Ff)

Punnett Square Practice!! F F f FF Ff ff Cross 2 parents who are heterozygous for freckles (Ff) Genotypic ratio: _______ FF : Ff : ff Phenotypic ratio: _______ Freckles ; no freckles

Pedigrees A way to trace a specific trait through a family tree!

Patterns of Human Inheritance • Dominance – If dominant allele is present, it is expressed. • Incomplete dominance - Neither allele fully expressed in heterozygote -Aa; looks like a mixture of both (red & white = pink) • Co-dominance – both alleles equally expressed in heterozygote -Aa (AB blood type) • Sex-linked – traits on the sex chromosomes • Polygenic – many genes control ONE trait (height)