1 / 13

11-2 Probability and PunneTt Squares

11-2 Probability and PunneTt Squares. 1. Genetics & Probability. Probability can be used to predict the results of genetic crosses. Probability- the likelihood that something is going to happen. In genetics expressed as a ratio or percentage.

platt
Download Presentation

11-2 Probability and PunneTt Squares

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. 11-2 Probability and PunneTt Squares

  2. 1. Genetics & Probability

  3. Probability can be used to predict the results of genetic crosses. • Probability- the likelihood that something is going to happen. • In genetics expressed as a ratio or percentage. • Ex: the probability that it will snow in March is 50:50

  4. Punnett Squares- A tool used to determine the gene combinations that might result from a genetic cross • A capital letter is used to represent the dominant allele • A lower case letter is used to represent the recessive allele.

  5. The principles of probability can be used to predict the outcomes of genetic crosses • This Punnett square shows the probability of each possible outcome of a cross between hybrid tall (Tt) pea plants.

  6. Homozygous- Organisms that have two identical alleles for a particular trait • organisms are true-breeding for a particular trait. • Two alleles for black fur • Heterozygous- Organisms that have two different alleles for the same trait • organisms are hybrid for a particular trait. • One allele for black fur and one allele for white fur

  7. Genotype- genetic make up of the organism • Ex: genes for black fur and white fur • Ex: Tall (T) allele and short (t) allele • Phenotype- the physical characteristics or what the organisms looks like. • Ex: the mouse has black fur. • Ex: all plants appear tall

  8. The plants have different genotypes (TT and Tt), but they have the same phenotype (tall).

  9. 3. Probability and Segregation

  10. Genotypic Ratios • 25% or 1:3 (TT to Tt or tt) likelihood the offspring will be TT • 50% or 2:2 likelihood the offspring will be Tt • 25% or 1:3 likelihood the offspring will be tt • Phenotypic Ratios • 75% or 3:1 (tall to short) likelihood the offspring will appear Tall • 25% or 1:3 likelihood the offspring will appear short

  11. In the F2 generation; the ratio of tall plants (TT or Tt) to short (tt) plants is 3:1. • The predicted ratio showed up in Mendel’s experiments indicating that segregation of gametes did occur.

  12. 4. Probabilities and Averages

  13. Probabilities predict the average outcome of a large number of events. • Probability cannot predict the exact outcome of an individual event • In genetics, the larger the number of offspring, the closer the resulting numbers will get to the expected values.

More Related