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Mendelian Genetics Father of modern genetics Gregor Mendel.

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Presentation on theme: "Mendelian Genetics Father of modern genetics Gregor Mendel."— Presentation transcript:

1 Mendelian Genetics Father of modern genetics Gregor Mendel

2 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)

3 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.

4 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).

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

6 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.

7 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.

8 Laws of Segregation & Independent assortment Law of Dominance

9 Tools for Genetics Pedigree Karyotype Punnett Squares

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

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

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

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

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

15 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)


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