| DNA | a nucleic acid which stores all the genetic information for an organism |
| nucleotide | the building block of DNA |
| nucleic acid | a molecule which consists of nucleotides (e.g. DNA or RNA) |
| ribose | the sugar that makes up the backbone of DNA |
| base | a nitrogen-based molecule that forms the 'rungs' of the DNA 'ladder' (e.g. A, T, C, G) |
| A | the DNA base that pairs with T |
| T | the DNA base that pairs with A |
| C | the DNA base that pairs with G |
| G | the DNA base that pairs with C |
| antiparallel | running parallel, but in opposite directions (like the two sides of a DNA molecule) |
| complementary | (adj) describes the two bases that pair together in DNA (e.g. A and T, or C and G) |
| double helix | the shape of DNA: like a twisted ladder |
| hydrogen bond | a type of weak bond which holds together the bases in a DNA molecule |
| chromatin | a loose combination of DNA and proteins in a cell |
| gene | a section of DNA that has the directions for making a single polypeptide chain |
| chromosome | a large, single molecule of DNA |
| centromere | the area where two sister chromatids join together |
| chromatid | after DNA is copied, this term refers to each of the two copies, which remain joined together |
| replication | copying DNA |
| semi-conservative | describes how each new molecule of DNA contains one old strand joined to one new strand |
| DNA Polymerase | the enzyme responsible for building the new strands of DNA in replication |
| helicase | the enzyme responsible for splitting the two strands of DNA in replication |
| sexual | (adj.) reproduction in which the genes from two parents join to make an offspring |
| asexual | (adj.) reproduction in which a single parent makes an offspring whose DNA is identical to the parent |
| meiosis | a type of cell division in which gametes are made |
| gamete | a sex cell (e.g. sperm or egg) |
| sperm | the male gamete |
| egg | the female gamete |
| fertilization | the process in which a male and female gamete join together |
| zygote | a result of fertilization; a single-celled offspring, before development |
| homologous | (adj.) refers to a pair of chromosomes which contain the same genes, but one came from mom and one from dad |
| allele | a specific version of a gene |
| diploid | (adj.) a cell which contains 2 copies of each chromosome |
| haploid | (adj.) a cell which contains 1 copy of each chromosome |
| crossing over | the step in meiosis when sections of homologous chromosomes are exchanged |
| independent assortment | the idea that chromosomes separate randomly in meiosis |