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Introduction to Genetics

Introduction to Genetics. Ms. Lazzaro. Heredity. passing characteristics from parent to offspring (children) Fertilization-male and female gametes combine to form new offspring Pollination – (in plants) pollen grains fertilize female gamete. Genetics. study of heredity. Gregor Mendel.

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Introduction to Genetics

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  1. Introduction to Genetics Ms. Lazzaro

  2. Heredity • passing characteristics from parent to offspring (children) • Fertilization-male and female gametes combine to form new offspring • Pollination – (in plants) pollen grains fertilize female gamete

  3. Genetics • study of heredity

  4. Gregor Mendel • in charge of monastery garden, • Father of genetics • studied characteristics of peas and how characteristics are passed on • Normally peas self –pollinate = males fertilize female’s egg of same flower • He would cause cross-polination = offspring (seeds) of 2 different parents • Studied 7 characteristics – study a few or else too many

  5. Mendel’s Findings • Due to his observations, Mendel decided that there must be two factors controlling each trait. He concluded that there was a dominant (A) and a recessive (a) form of each trait and that presence of the dominant form masked the recessive form. Each of these forms is now called an allele. • Mendel’s law of segregation says that a pair of factors is separated or segregated during the formation of gametes (meiosis). • Mendel’s law of independent assortment says that factors for different traits are distributed to gametes independently from one another.

  6. Trait • Characteristic • example: eye color or hair color or height

  7. Genes • Factors or piece of DNA that determines a characteristic • for example a piece of DNA codes for a protein or product which determines these characteristics

  8. Alleles • different forms or versions of a gene • Example: blue, brown, green eye color • Example: Gene: height; alleles = tall short; • Organisms have 2 alleles for each gene (1 on each chromosome) • Gametes have 1 allele because haploid • Let Y = yellow and y = green since same gene & (only 2 alleles) lets use the same letter

  9. Dominant • seen even if other versions are present ex: Yy and YY both appear yellow no blending • designated with a capital letter • usually more common but not always Recessive • NOT seen if other versions are present • Only if homozygous recessive yy • designated with a lower case letter

  10. Geneotype • Genetic make-up • the alleles you have • Homozygous = have the same alleles for a particular gene example: YY or yy • Heterozygous = have different alleles for a particular gene example: Yy

  11. Pheneotype • Physical appearance • characteristics we see • If YY or Yy = appears yellow (so phenotype = yellow) • If yy = green • Why is Yy yellow not green?

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