Mendelian Genetics Flashcards
Monohybrid Cross
The parent individuals varied from each other in only one traits
Dominant
Traits that prevailed
Recessive
Traits that disappeared
Name of Mendel’s First Law of Inheritance
The Law of Segragation
The Law of Segregation
Various expressions of a trait were controlled by discrete units
What process explains the Law of Segregation
Meiosis
___ and ____ maintain variation that Natural Selection can act upon
Masked variation and law of Segregation
What does it mean for a trait to be masked?
It could not be expressed
Phenotype
Observable physical feature of an organism
Genotype
Genetic makeup of an individual
Homozygous
Individuals with 2 copies of the same allele
Heterozygous
Individuals with 2 different alleles for a gene
The recessive allele in a heterozygous individual will be:
masked
Punnett Square Diagram
Used to represent the different ways that alleles can be combined during any specific cross
Punnett squares can be used to predict the:
proportion of genotypes
Dihybrid Cross
A cross between individuals who differ with respect to 2 gene pairs
ex: cross between hair color and eye color
In a Dihybrid cross:
Each characteristic (trait) must segregate ____
independently
Law of Independent Assortment
The expressions and segregation of one trait is not influenced by the expression of the other trait
Recombination
The alleles that code for diffferent traits assort ***
Linkage
When alleles are on the same chromosome and so are inherited together
Mendelian Traits
Traits influenced by a single genetic locus and follow a simple pattern of inheritance
Co-dominance
When different alleles occur in heterozygous condition and the product of BOTH alleles are expressed
Ex: Red and yellow spots on a flower
Incomplete Dominance
When a heterozygote has. aphenotype which is intermediate to those of homozygous parents
Ex: Red and white dlower make a pink flower
Pedigrees
(mating charts)
An indirect approach used to demonstrate patterns of inheritance
Pedigrees help determine if a trait is ____
Mendelian
Autosomal dominant traits
Traits equally present in males and females that are located on non-sex chromosomes
Autosomal recessive traits
Traits that skip a generation that create carriers
also located on non-sex chromosomes and equally present in both males an
X-linked dominant traits
Dominant traits that are located on female sex chromosome
Females affected twice as often as males
X-linked recessive traits
Recessive traits that are located on the female sex chromosome
males affected more than females
Y-linked Traits
Located on male sex chromosome
Located ONLY in males
Sex-linked traits are found on:
sex chromosomes
almost all are found on the X chromosome
Patriline
Tracing male parenage via the Y-chromosome
Pleiotropic Effect
A single gene having multiple effects
Polygenic Traits
Multiple genes producing one single effect
Quantitative Inheritance
Distribution fllows a normal, bell-shaped curve, and most people have phenotypes between the extremese
Regression to the mean
Most offspring individuals at the extremes of a polygenic distribution are less extreme than their parents
Heritability
A measure of the proportion of the total observed variation that can be attrivuted to genetics rather than environment
The 3 Types of Selection of Continuous Characters
- Stabilizing
- Directional
- Disruptive
Stabilizing Characteristics
Selects against the extremes
Directional Characteristics
Selects against ONE extreme
Disruptive Characteristics
Selects against the mean (for both extremes)
