Chapter 3: Mendelian Genetics Flashcards
In this approach, a scientist uses an organism that is easy to grow, and exhibits general characteristics that are applicable to other, higher forms of specimens.
Model Experimental Approach
What were the reasons for choosing pea plant as specimens of Mendel?
- Pea plant is self-fertilizing in nature, but it is easy to hybridize artificially.
- Reproduces well and grows to maturity in a single season.
These strains have traits that appear unchanged generation after generation in self-fertilizing plants.
True-breeding strain
The simplest crosses that involved only one pair of contrasting traits.
Monohybrid cross
How is monohybrid crossing done?
Made by mating two true-breeding individuals each exhibiting one of the two contrasting forms of the character under study.
It describes the original parents.
P1 or Parental generation
Describes the individuals resulting from the parental generation cross.
First filial generation (F1)
Describes the individuals resulting from self-fertilizing F1 offspring.
Second filial generation (F2)
Crosses could be made in either – pollination of dwarf plants by tall plants, or vice versa
Reciprocal crosses
Genetic characters are controlled by unit factors existing in pairs in individual organisms.
Law of Unit Factors in Pairs
True or False. In Mendelian genetics, each individual may have one of the three combinations: AA, aa, Aa where A is a dominant allele, and a is a recessive allele for the same trait. Each of the alleles comes from each parent.
True.
When two unlike unit factors responsible for a single character are present in a single individual, one factor is dominant to the other, which is said to be recessive.
Law of Dominance and Recessivity
During the formation of gametes, the paired unit factors separate, or segregate, randomly so that each gamete receives one or the other with equal likelihood.
Law of Segregation
True or False. In Mendelian genetics, if an individual contains a pair of like unit factors each of the gametes formed contain like unit factors. But if an individual contains a pair of unlike unit factors, then each of the gametes has a 50 percent chance of acquiring either one of the gametes.
True. According to the law of segregation. AA and aa individuals produce gametes having A, and a, respectively. However, an Aa individual produces gametes with an A and a in equal amounts.
The physical expression of a trait.
Phenotype
Alternative form of the gene which determines the phenotype.
Allele
The modern equivalent of unit factors.
Genes
Set of all alleles for a specific trait.
Genotype
When both alleles are present in an individual, the individual is said to be?
Homozygous or Homozygote
When the alleles are different, then the individual is said to be?
Heterozygous or Heterozygote