Ch 11 Flashcards
What did Gregor Mendal study at the University of Vienna?
- Gregory Mendal studied math and science
- 1822-1884
- Worked as a substitute teacher at a local high school
- First scientist to apply math to biology
- he applied statistics and probability to breeding experiments
Describe the blending concept of inheritance.
Mendal theory: particulate theory
- he thought minute particles ( hereditary units) were reshuffled in parents and passed on to offspring
- he proposed the law of segregation
- he proposed the law of independent assortment
- Mendal did not know about DNA or genetic material
Is it the F1 generation or the F2 generation that disproves this theory of inheritance?
F1 generation: this was the offspring from the cross of two true-breeding varieties chosen to be different by only one trait
- blending theory rejected
- when tall plants were crossed with short plants: the offspring were all tall.
What is Mendels Law of segregation?
To test the blended vs particulate nature of inheritance Mendal selected true-breeding pea varieties that differed in only one trait
-tall vs short (everything else is the same)
- red vs white (everything else is the same)
If blended theory was correct: tall crossed with short would give medium offspring and red vs white would give pink offspring
What is Mendals law of independent assortment?
Two or more characteristics are inherited, individuals hereditary factors as sort independently during gamete production, giving different traits an equal opportunity of occurring together
What is a true-breeding organism?
- self-pollination for many plant generations produces offspring plants that look exactly like the parent plant
- tall plants always produce tall offspring
- red plants always produce red offspring
What does the genotype look like or a true-breeding organism and what is the phenotype of an example organism for 1 trait?
Genotype for true-breeding organism is either TT or tt
Phenotype of F1 generation is Tt
What does the genotype look like and what is the phenotype of an example organism for two traits?
F2 generation phenotype: always produces a 3:1 ratio of the true-breeding phenotypes
F2 generation genotype: Ff and Ff produce FF, Ff, Ff, and ff
Why was it necessary for Mendel to remove the anthers from a pea plant in some of his experiments?
For some of the plants to self-pollinate like in F2 generations
Which of the generations could be produced by self-fertilization? Why is this called a monohybrid cross?
F2 generation: generation allowed to self-pollinate
Monohybrid cross: Letting the offspring from the true-breeding cross self-pollinate
Which generation produces a 3:1 ratio of dominant to recessive phenotype so in the offspring?
F2 generation always produces a 3:1 ration of the true-breeding phenotypes
Describe the purpose of a test cross with offspring of the F1 generation of a monohybrid cross. What are the genotype a of both parents for this test cross?
F1 generation: this was the offspring from the cross of two true-breeding varieties chosen to be different by only one trait
Monohybrid cross: letting the offspring from a true-breeding cross self-pollinate
Define locus.
A specific area on a chromosome
Define allele.
- two traits, segregated in gametes, brought together again in offspring
- each trait can be called an allele
Define homozygous.
The alleles are identical
- both dominant: TT
- both recessive: tt