Gene and Chromosome Basics

These flashcards cover fundamental concepts related to genes, chromosomes, meiosis, and hereditary principles.

Gene

A region of DNA that is a unit of heredity and encodes polypeptides or other functional molecules.

DNA

Deoxyribonucleic acid, a self-replicating material that comprises chromosomes and carries genetic information.

Chromosome

A threadlike structure of nucleic acids and proteins found in the nucleus, carrying genetic information in the form of genes.

Chromatid

One of the two identical halves of a duplicated chromosome, which is joined at the centromere.

Autosome

A chromosome that is not a sex chromosome.

Diploid

A cell or organism with two sets of chromosomes (2n), one from each parent.

Haploid

A cell or organism with one set of chromosomes (n), as seen in gametes.

Sister Chromatids

Identical copies of a chromatid, attached at a centromere, formed by DNA replication.

Homologous Chromosomes

A pair of chromosomes of the same length and centromere position; carry genes for the same traits at corresponding loci.

Meiosis

A special type of cell division that reduces the chromosome number by half, producing gametes.

Independent Assortment

The principle that alleles of different genes assort independently of one another during gamete formation.

Crossing Over

The exchange of corresponding segments of DNA between non-sister chromatids during meiosis, leading to genetic diversity.

Phenotype

The outward appearance of an organism, which is influenced by its genotype.

Genotype

The genetic constitution of an organism; the set of alleles present.

Homozygous

Having two identical alleles for a particular trait.

Heterozygous

Having two different alleles for a particular trait.

Allele

Different versions of a gene that determine specific traits.

Law of Segregation

The principle stating that the two alleles for each trait separate during gamete formation, so each gamete receives only one allele.

Sex-linked trait

A trait associated with a gene located on a sex chromosome.

Drosophila Melanogaster

A commonly used model organism in genetic studies, known as the fruit fly.

Testcross

Breeding of an organism with an unknown genotype with a recessive homozygous individual to determine the unknown genotype.

Monohybrid cross

A genetic cross between parents that differ in one trait.

Dihybrid cross

A genetic cross between parents that differ in two traits.