algae: Single-celled organisms, once considered plants (they aren’t). As aquatic organisms, they grow in water. Like green plants, they depend on sunlight to make their food.
base pair: (in genetics) (in genetics) Two nucleotides pair up to form each rung in DNA’s or RNA’s ladder-like structure. In DNA, each nucleotide contains a base — either adenine (A), cytosine (C), guanine (G) or thymine (T) — together with a phosphate group and a sugar molecule (deoxyribose). In RNA, the bases are A, C, G and uracil, or U (and the nucleotide’s sugar is ribose). Bases link into pairs. And they’re picky. In DNA, A only pairs with T; G only pairs with C. In RNA, A always pairs with U and G only pairs with C. Base pair may also be a term for how many of these combos make up a particular string of nucleotides (such as one might be described as 8 base pairs long).
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
chromosome: A single threadlike piece of coiled DNA found in a cell’s nucleus. A chromosome is generally X-shaped in animals and plants. Some segments of DNA in a chromosome are genes. Other segments of DNA in a chromosome are landing pads for proteins. The function of other segments of DNA in chromosomes is still not fully understood by scientists.
deletion: (v. to delete) The process of removing some specific part or detail; or a reference to the things that has been removed.
DNA: (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.
egg: A reproductive cell that contains half of the genetic information necessary to form a complete organism. In humans and in many other animals, ovaries produce eggs. When an egg fuses with a sperm, they combine to produce a new cell, called a zygote. This is the first step in the development of a new organism.”
function: The specific role some structure or device plays.
gene: (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
genetic: Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.
genome: The complete set of genes or genetic material in a cell or an organism. The study of this genetic inheritance housed within cells is known as genomics.
molecule: A group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in air is made of two bound oxygen atoms (O2). Water is made of two hydrogen atoms and one oxygen atom (H2O).
organism: Any living thing, from elephants and plants to bacteria and other types of single-celled life.
protein: A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Antibodies, hemoglobin and enzymes are all examples of proteins. Medicines frequently work by latching onto proteins.
red blood cell: Colored red by hemoglobin, these cells move oxygen from the lungs to all tissues of the body. Red blood cells are too small to be seen by the unaided eye.
species: A group of similar organisms capable of producing offspring that can survive and reproduce.
sperm: A reproductive cell that contains half of the genetic information necessary to form a complete organism. In humans and in many other animals, testes produce sperm. When a sperm fuses with an egg, the two combine to produce a new cell, called a zygote. This is the first step in the development of a new organism.”
virus: Tiny infectious particles consisting of genetic material (RNA or DNA) surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as alive or dead, in fact many scientists agree that viruses are not truly alive. They don’t eat as animals do or make their own food as plants do. A virus must hijack the cellular machinery of a living cell to survive.