Chapter 12, Patterns of Inheritance Flashcards
Before the 20th century, what were the two concepts that were the basis for ideas about heredity?
- Heredity occurs within species
- Traits are transmitted directly from parent to offspring
___________-1760- crossed tobacco strains to produce hybrids
Josef Kolreuter
What two observations did Josef Kolreuter make about the hybrids?
- hybrid offspring differed from both parents
- additional variation observed in 2nd generation offspring contradicts direct transmission
__________ -1823- crossed two varieties of garden pea, Pisum sativa
T.A Knight
T.A knight crossed two _____-______ strains
true-breeding
What does it mean if a species is true-breeding?
with self-fertilization it produces one type
In T.A knight’s experiment’s 1st generation resembled only 1 ______ strain
parent
In T.A Knight’s experiment’s the 2nd generation resembled ______ strains
both parent
Why did Gregor Mendel use pea plants?
- other research showed that pea bybrids could be produced
- many pea varieties were available
- peas are small plants an easy to grow
- Peas can self-fertilize or be cross-fertilized
What was Mendel’s experimental method?
- Produce true-breeding strains for each trait he was studying
- cross-fertilize true-breeding strains having alternate forms of a trait
- Allow the hybrid offspring to self-fertilize for several generations and count the number of offspring showing each form of the trait
How did Mendel conduct his experiments?
- The anthers are cut away on the purple flower
- pollen is obtained from the white flower
- Pollen is transferred to the purple flower
- All progeny result in purple flowers
________ cross used to study only two variations of single trait
monohybrid
Mendel produced true-breeding pea strains for _____ different traits
seven
What are the seven traits of plants?
flower color, seed color, seed texture, pod color, pod shape, flower position, plant height, plant
F1 generation is also called ____________
first filial generation
For every trait Mendel studied, all F1 plants resembled the same _____
parent
The visible trait is referred to as _____
dominant
In Mendel’s experiments, no ________ inheritance was found
blending
F2 is the second ______ generation
filial
_____ ______ generation was produced from the self-fertilization of F1 plants
second filial
What is the F2 phenotypic ratio?
3:1
What is the genotypic ratio of F2 generation?
1 true-breeding dominant
2 not-true breeding dominant plants
1 true-breeeding recessive plant
What is Mendel’s five-element model?
- parents transmit discrete factors (genes)
- each individual receives one copy of a gene from each parent
- Not all copies of a gene are identical
- alleles remain discrete-no blending
- presence of allele does not guarantee expression
_____ is an alternatve form of a gene
allele
_______- two of the same allele
homozygous
________-different alleles
heterozygous