1 / 12

Mendel I Notes

Mendel I Notes. CP Biology Ms. Morrison. Genetics: scientific study of heredity. Gregor Mendel. Austrian monk – in mid 1800s taught high school and took care of the monastery gardens Garden stocked with true breeding pea plants True-breeding = always have identical offspring

Télécharger la présentation

Mendel I Notes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Mendel I Notes CP Biology Ms. Morrison

  2. Genetics: scientific study of heredity

  3. Gregor Mendel • Austrian monk – in mid 1800s taught high school and took care of the monastery gardens • Garden stocked with true breeding pea plants • True-breeding = always have identical offspring • Ex. Tall plants always produce more tall plants • Controlled how plants pollinated • Did not allow self-pollination • Cross pollinated between different pea plants

  4. Mendel’s Pea Plant Experiments • Studied 7 pea plant traits • Trait = specific characteristic, ex. Plant height • Crossed two true-breeding pea plants • Starting plants = P (parental) generation, one tall and one short • All offspring = hybrids (offspring of parents with different traits) • Offspring generation = F1 (first filial) • Had expected blend of parents’ traits – thought plants would have medium height • Actual results – all plants tall, short trait disappeared

  5. Mendel’s Conclusions • First – biological inheritance is determined by factors passed from one generation to the next • Genes = chemical factors that determine traits • Genes have two contrasting forms (tall, short) • Alleles = different forms of a gene

  6. Mendel’s Conclusions • Second – principle of dominance: some alleles are dominant and some are recessive • Dominant allele always shows • Recessive allele only shows when not dominant allele present • Tall = dominant, short = recessive

  7. Mendel’s Further Experiments • Crossed F1 hybrid offspring to determine if recessive allele still present • Offspring = F2 generation • 75% tall • 25% short – recessive allele reappeared

  8. Mendel’s Final Conclusions • At some point recessive allele was separated from the dominant allele in F1 = segregation of alleles • Suggested that segregation of alleles occurred during formation of gametes – meiosis • Gametes only carry single copy of each gene • Offspring inherit one allele from each parent (so they have two alleles total)

  9. Probability • Is likelihood that an event will occur • Mendel realized outcomes of genetic crosses could be predicted using probability • Punnett square – diagram that shows the genetic combinations that might result from a genetic cross • Dominant alleles are capitals, ex. Tall, T • Recessive alleles are lowercase, ex. Short, t

  10. Genetics Terms • Homozygous (true-breeding): have two identical alleles, ex. TT or tt • Heterozygous (hybrid): have 2 different alleles, ex. Tt • Phenotype = physical appearance (what organism looks like) • Genotype = genetic makeup (organism’s actual alleles) • NOTE – can have same phenotype but different gentotype, ex. TT and Tt both look tall

  11. Punnett Square Example 1 • F1 results: • Phenotype: 100% tall • Genotype: 100% Tt

  12. Punnett Square Example 2 • F2 results: • Phenotype: (3:1) • 75% tall • 25% short • Genotype: (1:2:1) • 25% TT • 50% Tt • 25% tt

More Related