Chapter 3: Basic Principles of Heredity Flashcards

Comprehensive vocabulary flashcards covering Mendel’s principles of heredity, genetic cross terminology, and statistical probability rules as presented in the lecture notes.

Gene

An inherited factor (encoded in the DNA) that helps determine a characteristic

Allele

One of $2$ or more alternative forms of a gene

Locus

Specific place on a chromosome occupied by an allele

Genotype

Set of alleles possessed by an individual organism

Heterozygote

An individual organism possessing $2$ different alleles at a locus

Homozygote

An individual organism possessing $2$ of the same alleles at a locus

Phenotype or trait

The appearance or manifestation of a characteristic

Characteristic or character

An attribute or feature possessed by an organism

Gregor Mendel

A scientist who discovered the basic principles of heredity by using the pea plant ($Pisum\,sativum$) as an experimental model and analyzing results mathematically

Monohybrid cross

A cross between $2$ parents that differ in a single characteristic

Principle of segregation (Mendel's first law)

Each individual diploid organism possesses $2$ alleles for any particular characteristic which separate when gametes are formed, with one allele going into each gamete

Concept of dominance

When $2$ different alleles are present in a genotype, only the trait encoded by one of them—the dominant allele—is observed in the phenotype

Wild type

In animals, the most common trait observed, which is not necessarily dominant and is often symbolized with a $+$ or $R^+$

Chromosomal theory of heredity

A theory developed by Sutton in the early $1900\text{s}$ to explain Mendel's work using chromosomes

Backcross

A cross between an $F_1$ individual and either of the original parental genotypes

Punnett square

A tool used to predict the outcomes of genetic crosses by representing gametes and their potential fusion

Probability

The likelihood of the occurrence of a particular event, ranging from $0$ to $1$ and expressed as a percentage or fraction

Multiplication rule

A rule used to determine the probability of $2$ or more independent events happening together

Addition rule

A rule used to determine the probability of $2$ or more mutually exclusive events occurring

Binomial Expansion

A mathematical tool taking the form $(p + q)^n$ used for complex probability situations to predict the likelihood of specific combinations of events

Testcross

A cross where an unknown genotype is crossed with a homozygous recessive individual to determine the unknown allele

Dihybrid Cross

A genetic cross that examines the inheritance of $2$ traits at one time

Principle of Independent Assortment (Mendel's second law)

Alleles at different loci separate independently during the formation of gametes

Chi-square ($\chi^2$) goodness of fit

A statistical test that indicates the probability that the difference between the observed and expected values is due to chance

Degrees of freedom ($df$)

A value calculated as $n-1$, where $n$ is the number of different expected phenotypes, used in the chi-square test