Biology: Genetics Key Terms
allele
Any of the alternative forms of a gene that may occur at a given point on a chromosome.
asexual reproduction
Any type of reproduction that produces offspring without mating or fertilization.
chromosome
A DNA-containing structure that forms by the joining of two identical chromatids during cell division.
clone
An organism that is genetically identical to its parent and siblings.
deoxyribonucleic acid (DNA)
A molecule that contains the genetic code for all cellular (nonvirus) organisms.
diploid
A cell or organism that contains two sets of chromosomes.
dominant allele
An allele that is always expressed regardless of the nature of the other allele in a pair.
exon
A section of DNA that codes for proteins (as opposed to an intron, a noncoding DNA section).
fertilization
The fusion of a male sex cell (sperm) and female sex cell (egg).
gene
The basic unit of heredity; a section of DNA that codes for the structure of a protein.
genome
All the genes present inside an organism.
genotype
The genes in an organism that code for a certain phenotype.
haploid
A cell that contains one set of chromosomes, such as a sex cell.
heredity
The passing of genetic factors from parent to offspring.
heterozygous pair
When two alleles in a pair are different (one is dominant, and one is recessive).
homozygous pair
When two alleles in a pair are the same (both dominant or recessive).
incomplete dominance
A form of inheritance where a copy of a dominant allele cannot produce a complete phenotype.
inheritance
The receiving of genes and their associated characteristics by young from their parents.
intron
A section of noncoding DNA that separates exons.
karyotype
A visual profile of an organism’s chromosomes, arranged in order of size.
meiosis
The process of cell division that produces sex cells.
mitosis
The process of cell division that leads to the production of body cells.
nucleotide
Part of a DNA molecule, comprising a sugar, a phosphate group, and a base.
phenotype
The expression of a particular trait according to an organism’s genes; a feature coded for by a gene.
polyploid
An organism that contains more than two sets of chromosomes.
recessive allele
An allele that is only expressed when paired with an identical allele (not when paired with a dominant one).
ribonucleic acid (RNA)
A chemical similar to DNA involved in protein production.
sexual reproduction
Any type of reproduction that involves mating, fertilization, and the mixing of parental genes.
transcription
The process of converting the coding sections of a DNA molecule into RNA.
zygote
An egg that has been fertilized by a sperm.