Mendelian Genetics, Patterns of Inheritance

A set of flashcards covering key vocabulary and concepts from Mendelian genetics and patterns of inheritance.

Gene

A segment of DNA that codes for a protein, determining a trait.

Allele

Different forms of a trait (gene).

Dominant Allele

An allele that is always expressed if present and can mask other alleles.

Recessive Allele

An allele that can be masked by another and needs two copies to be expressed.

Homozygous

Having two of the same alleles (e.g., BB or bb).

Heterozygous

Having two different alleles (e.g., Bb).

Genotype

Genetic makeup of an organism, written as letters.

Phenotype

Physical expression of the gene; what you see (e.g., size, shape, color).

Law of Segregation

States that during meiosis genes will separate into different cells so each cell has one allele.

Law of Independent Assortment

States that the separation of alleles is at random.

Punnett Square

A diagram showing the results of genetic crosses based on parental genotypes.

Monohybrid Cross

A cross looking at one trait.

Dihybrid Cross

A cross looking at two pairs of traits.

Complete Dominance

Occurs when one allele completely masks the other.

Incomplete Dominance

Both alleles influence phenotype, resulting in blending.

Co-dominance

Both alleles are fully expressed for a trait.

Polygenic Inheritance

Traits controlled by more than two genes.

Gene Linkage

Genes that are close on a chromosome usually travel together.

Polyploidy

Presence of an extra set of chromosomes.

Nondisjunction

Error in meiosis in which chromosomes fail to separate.

Karyotype

Picture of chromosomes paired with its homologous chromosome.

Sex-Linked Traits

Disorder found on X or Y chromosome.

Pedigree

Chart used to determine inheritance patterns within a family.

Autosomal Dominant

If present, will be expressed; only need one bad copy to be expressed.

Autosomal Recessive

Can be masked; must have two bad copies to be expressed.

Gene Therapy

Treatment for genetic disorders in which a faulty gene is replaced with a normal gene.