Inheritance and Genetic Variation

Flashcards covering Mendelian inheritance, complex inheritance patterns, and genetic variation.

What is inheritance?

The passing of traits from parents to offspring, closely linked to evolution.

What is Darwin's theory of natural selection?

Natural variation exists within a population, giving some individuals a fitness advantage.

Who was Gregor Mendel?

A priest and biologist who developed the concept of Mendelian inheritance through his work with pea plants.

What are the advantages of using pea plants for inheritance studies?

Variability in easily scorable characters, large family sizes, short generation times, and suitability for controlled matings.

What is a character?

An observable physical feature (e.g., seed shape).

What is a trait?

A particular form of a character (e.g., round versus wrinkled seeds).

What are the key generations in genetic crosses?

Parental generation, F1 (first filial) generation, and F2 (second filial) generation.

What is a monohybrid cross?

A cross analyzing a single character.

What is a dominant trait?

The trait that appears in the F1 generation and is more abundant in the F2 generation.

What is a recessive trait?

The trait that is less commonly expressed.

What characterizes genes?

Genes can exist as variants, and we have two copies of each gene.

What are alleles?

Different versions of the same gene.

What is the Law of Segregation?

When an individual produces gametes, the two copies of a gene separate, with half the gametes receiving one copy and half the other.

What is a monogenic condition?

A disease caused by variants in a single gene.

What is dominant inheritance?

Requires only one copy of a disease-causing allele for the condition to be expressed.

What is recessive inheritance?

Requires two copies of the disease-causing allele for the condition to be expressed.

What is the Law of Independent Assortment?

Copies of different genes assort independently.

When do genes not sort independently?

When genes are located on the same chromosome.

What are some complexities beyond Mendelian inheritance?

More than two alleles for a given gene, incomplete dominance, codominance, pleiotropy, and interactions between multiple genes and the environment.

What is incomplete dominance?

Heterozygotes display an intermediate phenotype.

What is codominance?

Phenotypes for both alleles are fully expressed in the heterozygote.

What is a pleiotropic effect?

An allele that influences multiple traits.

What is epistasis?

One gene depends on the action of another gene for its function to be seen.

What are polygenic traits?

Traits controlled by multiple genes.

What is penetrance?

The probability that a specific genotype will lead to expression of the associated phenotype or trait.

What are mutations?

Changes in the genome; the preferred term is "variants."

How does genetic variation arise?

Arises through recombination during meiosis and accumulation of small changes.

What is a single nucleotide variation?

A change in a single nucleotide in the DNA.

What is a silent variant?

A variant that does not impact the amino acid composition of the protein.

What is a missense variant?

A nucleotide change in the DNA results in a different amino acid being incorporated into the protein.

What is a nonsense variant?

A nucleotide in the DNA creates a premature stop codon, resulting in no functional protein being generated.

What is an insertion or deletion (frameshift variant)?

Addition or loss of a nucleotide, which changes the DNA reading frame.

What are chromosomal variations?

The number or structure of the chromosomes is altered.

What is a benign genetic variant?

A genetic variant that does not cause disease or increase disease risk.

What is a beneficial genetic variant?

A genetic variant that gives a protective advantage, such as protection against disease.

What is a pathogenic genetic variant?

A genetic variant that causes or increases the risk of a genetic condition.