Understanding genetics can be challenging. Below is a list of common terminology.
1. DNA (deoxyribonucleic acid): A complex organic molecule made of two polynucleotide chains. Polynucleotide chains consist of nucleotides – monomers built from three components: nitrogen-containing nucleobases (A, G, C, T), deoxyribose (sugar) and a phosphate group. The order of these nucleotides in the DNA determines the coding information for the synthesis of every gene product in the body.
2. RNA (ribonucleic acid): An organic molecule composed of one polynucleotide chain. There are many different types of RNAs in the cell. One such type is mRNA (messenger RNA). mRNA is a DNA transcript, and it serves as an intermediate product between a gene (within the DNA) and protein (a gene product). The flow of genetic information within a cell is explained in the Central dogma of molecular biology. The central dogma states that DNA produces RNA (in a process called transcription). While all cells in the same organism have the same DNA, each cell type decides which genes to transcribe into RNA and when to do so. This is how different cell types emerge. The RNA is subsequently translated into proteins.
3. Proteins: Complex organic molecules which serve as the main structural and functional molecules in the body. The genes in the DNA encode the synthesis of many different kinds of proteins. These are subsequently modified and differentiated into molecules which carry out every single function in the body, thus playing a crucial role in health, disease, physical traits, etc.
4. Genome: The entire genetic information of one cell. Every cell in the body contains the same genetic information
5. Chromosome: A DNA molecules which carries a part (or all) of the genetic material in a cell. Cats have 38 chromosomes in each cell, while we have 46.
6. Gene: A sequence of nucleotides in the DNA which encodes the synthesis of a gene product (RNA or protein).
7. Allele: Different variant of the genes gene. For example, a nucleotide at a specific position in gene 1 can be either an A or a T.
8. Dominant alleles: Alleles which are always expressed.
9. Recessive alleles: Alleles which are expressed only in the absence of dominant alleles.
10. Genotype: One part of the genome which determines a certain trait (phenotype).
11. Phenotype: The expressed trait of an organism determined by the genotype. Phenotype is also shaped by environmental factors.
12. Homozygotes: A genotype in which there are two identical alleles for a certain trait.
13. Heterozygotes: A genotype in which there are two different alleles for a certain trait.
Key Genetic Terminology Explained
Genotype: The portion of the genome (set of genes) which encodes a particular trait (i.e. the color of the eyes).
Phenotype: The physical expression of a genetically encoded trait. The expression of a genetic trait is largely impacted by environment. Thus, phenotype comprises of all the observable characteristics of an organism shaped by both the genotype and the environment. It is important to remember that the observable characteristics are not just the physical appearance, but also all the proteins, cells, organs and systems which compose the body.
Genetic marker: Specific sequence of the DNA with a known location in the genome which can be used to identify species, breeds, individuals or characteristics. In our Health Markers report, we are looking for genetic markers associated with different genetic conditions in cats. We are using 39 genetic markers to test 17 different genetic conditions.
Genetic mutation: A permanent alteration to the genetic sequence which results in a novel gene variant. Genetic mutations are important sources of variability among individuals of all species, including cats. While these genetic anomalies can have different impacts - beneficial, neutral or even harmful - their occurrence is very important as it provides the populations with diverse and unique individuals.
Allele: Distinct variant of a gene. Every gene is present in two copies (one inherited from each parent). Genetic mutations create new variants of genes called alleles. Thus, every individual will carry two alleles of each gene.
Homozygote: A carrier for two identical alleles of one gene.
Heterozygote: A carrier for two different alleles of one gene.