Term | Definition |
DNA | molecule in the nucleus of a cell that contains instructions for how to make proteins (and how to run the cell) (DNA is the abbreviation for deoxyribonucleic acid) |
code | information that has to be translated to find its meaning |
double helix | a twisted spiral staircase…the shape of DNA |
nitrogen bases (nucleotides) | molecules that make up the “steps” in the DNA “ladder;” there are four: adenine paired with thymine, and cytosine paired with guanine |
triplet | a group of three nitrogen bases that are the code for a specific amino acid |
gene | a sequence of triplets which all together are the code for one protein |
mutation | a permanent change in a gene that causes a protein to be made incorrectly |
chromosome | structure made of DNA in the cell nucleus that becomes visible when the cell divides, it contains hundreds or thousands of genes |
genome | all the DNA in the nucleus of an organism’s cell(s) |
genetics | the study of how traits are inherited |
heredity | passing of traits from parents to offspring |
trait | a characteristic that is caused by genes |
allele | different versions of a gene that cause the variations of a trait |
dominant | the form of a gene that covers up (dominates) the weaker form of the gene |
recessive | the form of a gene that gets covered up if the dominant form of the gene is present |
Punnett Square | a tool to predict possible offspring’s genes based on parents’ genes (invented by Reginald Punnett 50 years after Mendel’s studies) |
homozygous | when both alleles in a pair are the same (both dominant or both recessive) |
heterozygous | when the two alleles in a pair are different (one is dominant and one is recessive) |
genotype | a pair of capital and/or lower case letters to represent an organism’s genetic makeup |
phenotype | the physical trait that shows up because of an organism’s genotype |
probability | a measurement of the chance (likelihood) of an event happening |
independent | when the chance of one event happening does not affect the chance of another event happening |