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Introduction to Genetics

Introduction to Genetics. Genetics. The study of heredity. Heredity . Characteristics that an offspring receives from its parents. Inherited characteristics are called traits. Gregor Mendel – Father of Genetics. Austrian monk in 1860’s

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Introduction to Genetics

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  1. Introduction to Genetics

  2. Genetics • The study of heredity

  3. Heredity • Characteristics that an offspring receives from its parents. • Inherited characteristics are called traits.

  4. Gregor Mendel – Father of Genetics • Austrian monk in 1860’s • Used pea plants to study how traits are passed from one generation to the next

  5. Mendel’s Findings • Individual factors found on chromosomes called GENES control each trait • There are at least 2 forms of each gene, these forms are called ALLELES

  6. Mendel’s Findings • LAW OF DOMINANCE – one allele is dominant or expressed (seen) while the recessive allele is hidden

  7. Mendel’s Findings • Law of Segregation – each pair of genes separates during meiosis

  8. Mendel’s Findings • Law of Independent Assortment – gene pairs separate into gametes randomly and independently of each other With your elbow partner discuss and come up with an answer for- Why is it that you look similar to your parents or siblings but you're not an exact copy?

  9. How are characteristics passed from parents to offspring? • By genes • Gene – segment of DNA that codes for a specific characteristic. • Genes are inherited through the sex cells from the parents

  10. Where are all the genes? • On chromosomes! • Chromosomes are tightly coiled pieces of DNA • Each chromosome has thousands of genes • Every regular body cell has a complete set of chromosomes

  11. …which grows into a DIPLOID fetus HAPLOID gametes join… …to form a DIPLOID zygote Remember, in SEXUAL reproduction…

  12. Diploid zygote Haploid sperm (gamete) Haploid egg (gamete) 1n 1n 2n Sexual Reproduction + =

  13. Genotype • The 2 genes that an organism has for a characteristic • Each gene is usually written as a single letter • Ex. Genotype Rr • Gene from one parent R • Gene from other parent r

  14. Phenotype • How an organisms looks • Ex. Eye color = brown • Ex. Plant height = tall

  15. Dominant • An allele that can hide the effects of a recessive allele • If there are only 2 alleles for a characteristic, the dominant allele is written as an upper case letter • Ex. T is dominant over t - Tt

  16. Recessive • An allele that can be hidden by a dominant allele • Written as lower case letter if there are only 2 alleles for a characteristic • Ex. t is recessive to T

  17. Homozygous • Genotype where the 2 alleles are the same • Also called pure bred • Ex. TT or tt

  18. Heterozygous • A genotype where the 2 alleles are different • Also called hybrid • Ex. Tt

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