Chapter 2 Flashcards
(19 cards)
Law of Segregation
During gamete formation, alleles separate so each gamete receives one allele.
Punnett Square
A tool used to predict the outcome of genetic crosses by simulating meiosis and fertilization.
Test Cross
Used to determine whether an organism with a dominant phenotype is homozygous dominant (TT) or heterozygous (Tt).
Dihybrid Cross
Crosses involving two traits at once
Recessive disorders
like cystic fibrosis and sickle-cell anemia are common examples of single-gene traits.
Dominant diseases
Rare, but include Huntington’s disease and Achondroplasia (a form of dwarfism).
F1 Generation
The first filial generation (f1) always displayed the dominant trait, rejecting the blending theory of inheritance.
Dominance
In a cross between two pure-bred parents (e.g., tall and short plants), only one trait (the dominant one) appears in the F1 generation.
Recessive
Hidden Trait
Alleles
Different versions of a gene.
Dominant Allele
An allele that masks the effect of a recessive allele in heterozygotes.
Recessive Allele
An allele that is masked by a dominant allele; only expressed when two copies are present.
Homozygous
Having two identical alleles for a gene (e.g., TT or tt).
Heterozygous
Having two different alleles for a gene (e.g., Tt).
Monohybrid Cross
A genetic cross involving a single trait.
Dihybrid Cross
A genetic cross involving two traits.
Law of Segregation
Two alleles for a trait separate during the formation of gametes, and each gamete gets one allele.
Law of Independent Assortment
Alleles of different genes assort independently of each other during gamete formation.
Testcross
A cross between an individual with a dominant phenotype but unknown genotype and a homozygous recessive individual to determine the unknown genotype.
