1 / 7

Genetics

Genetics. The study of inherited characteristics. Monohybrid inheritance. Let the allele for round seeds be: R (dominant allele) Let the allele for wrinkled seeds be: r (recessive allele) Parents phenotype round seeds x wrinkled seeds genotype RR rr Gametes

finna
Télécharger la présentation

Genetics

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. Genetics The study of inherited characteristics

  2. Monohybrid inheritance Let the allele for round seeds be: R (dominant allele) Let the allele for wrinkled seeds be: r (recessive allele) Parents phenotyperound seeds x wrinkled seeds genotype RRrr Gametes F1 generation R R r r F1 phenotypes 100% plants producing round seeds F1 genotypes 100% heterozygotes Rr

  3. F1 intercross • Parents phenotyperound seeds x round seeds genotype RrRr • Gametes • F2 generation R r R r Phenotype 75% plants producing round seeds 25% plants producing wrinkled seeds Genotype25% RR 50% Rr 25% rr Ratio 3:1 Round seeds: wrinkled seeds

  4. Does the observed ratio match the theoretical ratio? • The theoretical or expected ratio of plants producing round or wrinkled seeds is 3 round :1 wrinkled • Mendel’s observed ratio was 2.96:1 • The discrepancy is due to statistical error • The observed ratio is very rarely the same as the expected ratio • The larger the sample the more nearly the results approximate to the theoretical ratio • Statistical tests such as the chi-squared test can be used to test the closeness of fit of the observed and theoretical ratios

  5. What if the parents are not homozygous? • The use of the term F1 generation is limited to the offspring of two homozygous parents • The use of the term F2 is limited to the offspring of intercrossing the F1 generation • In all other cases the terms offspring (1) and offspring (2) should be used • The complete set of headings will be: Parents phenotypes Parents genotypes Gametes Offspring (1) genotypes Offspring (1) phenotypes Gametes Offspring (2) phenotypes Offspring (2) genotypes

  6. If plant is homozygous dominant RR Parents phenotype round x wrinkled genotype RR rr gametes Offspring If plant is heterozygous Rr Parents phenotype round x wrinkled genotype Rr rr gametes Offspring BackcrossTo test whether a plant producing round seeds is homozygous RR or heterozygous Rr it can be crossed with a homozygous rr plant R r r r R R r r Offspring phenotype 100% round Genotype 100% Rr Offspring phenotype 50% round 50% wrinkled genotype 50% Rr 50% rr

  7. This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.

More Related