Ongoing 3-1: Genes

Gene

A heritable factor of DNA that influences a specific characteristic.

Allele

A specific or alternate form of a gene.

Genome

All the genetic information of an organism, including all genes and non-coding DNA.

Gene Mutation

A permanent change in the nucleotide sequence of a section of DNA.

Substitution Mutation

A mutation where a base is changed for another base, affecting only a single codon.

Silent Mutation

A mutation that doesn’t change the resulting amino acid.

Missense Mutation

A mutation where the DNA change alters a single amino acid in the polypeptide chain.

Nonsense Mutation

A mutation that creates a premature stop codon, shortening the polypeptide.

Frameshift Mutation

A mutation caused by insertion or deletion of bases that changes the reading frame of the mRNA.

Mutagen

Any agent that causes mutation, which can increase the likelihood of genetic changes.

Germline Mutation

A mutation that occurs in a gamete that can be passed onto offspring.

Somatic Mutation

A mutation occurring in somatic cells that cannot be passed on to the next generation.

Degeneracy of the Genetic Code

The redundancy of the code, where multiple codons can code for the same amino acid.

Single Nucleotide Polymorphism (SNP)

A genomic variant at a single base position.

Sickle Cell Anemia

A disorder caused by a missense mutation on hemoglobin, altering the protein structure.

Natural Selection

The process by which traits that enhance survival and reproduction become more common in a population.

Chromosome

A structure made of DNA and proteins that contains genetic information.

Homozygous

An organism with two identical alleles for a specific trait.

Heterozygous

An organism with two different alleles for a specific trait.

Phenotype

The observable characteristics or traits of an organism.

Genotype

The genetic makeup of an organism that determines a specific characteristic.

Dihybrid Cross

A genetic cross between parents that differ in two traits.

Law of Segregation

During gamete formation, the alleles for each gene separate from each other.

Law of Independent Assortment

Genes for different traits are inherited independently of each other.

Polygenic Trait

A trait controlled by two or more genes, resulting in a wide range of phenotypes.

Incomplete Dominance

A genetic situation where one allele does not completely dominate another, resulting in a blend of traits.