Background Teaching Resources for Genetics and DNA


There are many Technical Terms used in this Field.

To help in learning the material, I have put in a glossary for many of the Biology Terms we use.


One of the four bases in DNA that make up the letters ATGC, adenine is the "A". The others are guanine, cytosine, and thymine. Adenine always pairs with thymine.  Adenine is a purine. 


One of the variant forms of a gene at a particular locus, or location, on a chromosome. Different alleles produce variation in inherited characteristics such as hair color or blood type. In an individual, one form of the allele (the dominant one) may be expressed more than another form (the recessive one).

Base Pair:

Two bases which form a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.


One of the threadlike "packages" of genes and other DNA in the nucleus of a cell. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes. Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their fathers.


Three bases in a DNA or RNA sequence which specify a single amino acid.


One of the four bases in DNA that make up the letters ATGC, cytosine is the "C". The others are adenine, guanine, and thymine. Cytosine always pairs with guanine.  Cytosine is a pyrimidine.


Deoxyribonucleic Acid: The chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms.

DNA Replication

The process by which the DNA double helix unwinds and makes an exact copy of itself.

Genetic Code

The instructions in a gene that tell the cell how to make a specific protein. A, T, G, and C are the "letters" of the DNA code; they stand for the chemicals adenine, thymine, guanine, and cytosine, respectively, that make up the nucleotide bases of DNA. Each gene's code combines the four chemicals in various ways to spell out 3-letter "words" that specify which amino acid is needed at every step in making a protein.


The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

Gene Pool

The sum total of genes, with all their variations, possessed by a particular species at a particular time.


All the DNA contained in an organism or a cell, which includes both the chromosomes within the nucleus and the DNA in mitochondria.


The genetic identity of an individual with respect to a particular gene is determined by which specific alleles they received from their parents.  . 


One of the four bases in DNA that make up the letters ATGC, guanine is the "G". The others are adenine, cytosine, and thymine. Guanine always pairs with cytosine.  Guanine is a purine.

Hardy Weinberg Equilibrium

The Hardy–Weinberg principle states that the genotype frequencies in a large, randomly mating population remain constant (in equilibrium) from generation to generation.  Hardy Weinberg Equilibrium can be disrupted with big changes in the genotype frequencies if there is natural selection, small populations, or migration of new individuals into the population.


Base pairing of two single strands of DNA or RNA.

Junk DNA

Non-coding repetitive DNA dispersed throughout the genome.


The place on a chromosome where a specific gene is located, a kind of address for the gene. The plural is "loci," not "locuses."

The energy producing organelle in the cytoplasm.  The mitochondria have small circular chromosomes made of DNA which can differ from person to person.

Non-coding DNA

The strand of DNA that does not carry the information necessary to make a protein. The non-coding strand is the mirror image of the coding strand and is also known as the antisense strand.


The central cell structure that contains the chromosomes.


One of the structural components, or building blocks, of DNA and RNA. A nucleotide consists of a base (one of four chemicals: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid.

PCR (Polymerase Chain Reaction)

A fast, inexpensive technique for making an unlimited number of copies of any piece of DNA. Sometimes called "molecular photocopying," PCR has had an immense impact on biology and medicine, especially genetic research.


A short oligonucleotide sequence used in a polymerase chain reaction to start specific DNA replication.  A primer must be the mirror image of the DNA and have a free 3’ end to build new DNA onto.


A piece of labeled DNA or RNA or an antibody used to detect the presence of a gene or protein.


A large complex molecule made up of one or more chains of amino acids. Proteins perform a wide variety of activities in the cell.


A substance used in a chemical reaction to detect, measure, examine, or produce other substances. Many chemical companies refer to chemicals as "reagent grade" meaning they are of suitable purity to use in experiments. The materials made for an experiment (solutions, enzyme mixtures) can be referred to as reagents as well as purchased materials..

Restriction Enzymes

Enzymes that recognize a specific sequence of double-stranded DNA and cut the DNA at that site. Restriction enzymes are often referred to as molecular scissors.

RFLP (Restriction Fragment Length Polymorphism)

Genetic variations at the site where a restriction enzyme cuts a piece of DNA. Such variations affect the size of the resulting fragments. These sequences can be used as markers on physical maps and linkage maps. RFLP is also pronounced "rif" lip.

Ribonucleic Acid

A chemical similar to a single strand of DNA. In RNA, the letter U, which stands for uracil, is substituted for T in the genetic code. RNA delivers DNA's genetic message to the cytoplasm of a cell where proteins are made.

Southern Blot

A technique used to identify and locate DNA sequences which are complementary to another piece of DNA called a probe.

STR (Short Tandem Repeat)
STRs are locations on a chromosome that contain short sequences that repeat themselves within the DNA molecule.   The number of repeats can be determined by amplifying the DNA using specific sequences or primers located to the left and right of the repeating region.


One of the four bases in DNA that make up the letters ATGC, Thymine is the "T". The others are adenine, guanine, and cytosine. Thymine always pairs with adenine.

Genetics Tutorials

There are many excellent Genetics Tutorials. One of my favorites comes from the Dolan DNA Learning Center and is called DNA from the Beginning

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