Cells Terms
Get down with the lingo
ATP
Adenosine triphosphate. An adenine molecule, or a nucleotide, attached to three linearly connected phosphate groups (–H2PO4R, where R is a functional group). The breaking of chemical bonds between the 2nd and 3rd phosphate groups provides most of the chemical energy used by a cell. Most of the ATP in a cell is made in the mitochondria, the cell's powerhouse. ATP is a coenzyme (the -ase in the name gives it away) and a strong reducing agent, or electron donor, that acts as the principal energy carrier in the cell. Donating the terminal phosphate group, or the phosphate group on the end, from ATP causes the release of a large amount of energy. ATP basically shuffles energy around to support metabolism and a bunch of super important cellular processes, like photosynthesis.Cell Theory
The scientifically supported idea that the basic structural unit of life is the cell and that all cells arise from other cells. Remember that a "theory" in biology is equivalent to a "law" in physics: neither of which are very likely to be refuted by further observations or experiments. This theory is here to stay.Cell Wall
A rigid, but often flexible, layer containing cellulose or chitin, pectin, and other polymers. The cell wall is the outermost structure of plant, algal, fungal, and some prokaryotic cells.Centriole
A tubular structure that is made of protein and found only in animal cells. It is involved in cell division and the formation of flagella and cilia (types of pointy things that assist cells in what they do).Chloroplast
The organelle (see definition; think "mini organ") in plant cells, and a few other eukaryotic cells, that contains chlorophyll, the magical green pigment, and carries out the process of photosynthesis, aka the conversion of sunlight into food.Cholesterol
A carbon-based steroid molecule that provides permeability and fluidity to plasma membranes. Cholesterol gets a bad rap for clogging arteries and causing heart attacks when present in the body in excessive amounts.Chromosome
A single piece of wound (as in, "twisted," not "injury") DNA bound to other "stuff" like proteins and nucleotides.Chromatin
A condensed package of DNA and proteins in the nucleus of a cell.Cilium (plural cilia)
A projection of a cell membrane sticking out from the main cell body. Cilia are used for locomotion (choo choo) in some unicellular, aka one-celled, organisms, and for movement of matter past a group of cells in some multicellular, aka more-than-one-celled, organisms. For example, cilia move the mucus and debris past the mucosal cells lining the tracheae in some animals.Cytoplasm
The cytosol (fluid inside cells), organelles (except the nucleus), and other particles enclosed within the cell membrane. The cytoplasm is the site of most cellular activities, including glycolysis, aka the production of energy from carbohydrates, and cell division, or the way cells reproduce.Cytosis
The process by which cells bring in or release very large particles and quantities of fluid. Exocytosis is the general term for cell release, endocytosis is the general term for cell consumption, and pinocytosis and phagocytosis are specific types of endocytosis. Enough -cytosis for you? Pinocytosis refers to the cellular uptake of fluid, or "cell drinking," while phagocytosis refers to the cellular uptake of solid matter, or "cell eating." Not like cookie eating.Cytoskeleton
The complex structure of protein filaments within the cytosol (fluid inside cells) that maintains cell shape and structure, controls cellular locomotion and cytosis (see the definition before this one), provides scaffolding for intracellular transport, and controls cell division. A cytoskeleton is found in all types of both eukaryotic and prokaryotic cells.Cytosol
The fluid component of the cytoplasm (collective name for the stuff within the boundaries of the cell membrane) composed of cytoskeleton filaments, dissolved molecules, and water. The cytosol is the part of the cytoplasm between the cell membrane and organelle membranes. Membrane = thin encasing layer.DNA
Deoxyribonucleic acid. DNA is a macromolecule ("macro" = big) also known as a nucleic acid that is composed of phosphate groups, deoxyribose sugar groups, and the nucleotides adenine, guanine, cytosine, and thymine. DNA contains the genetic code needed by all cells to produce proteins and other molecules necessary to sustain life. He seems to make into every one of Shmoop's Biology glossaries.Endosymbiosis
The condition of living within the body or cells of another organism. Sounds weird, and it is. There is evidence that millions of years ago, the ancestors of mitochondria and chloroplasts, two organelles ("mini organs") were actually prokaryotic organisms that entered into endosymbiotic relationships with eukaryotic cells. We know; that is some wild and crazy talk right there.Enzymes
A protein that catalyzes, or increases the rate of, a chemical reaction in a cell. Most enzyme-catalyzed reactions in the cell take place within the cytosol (fluid inside cells), but many others take place within the nucleus and within certain organelles ("mini organs") like lysosomes, mitochondria, and chloroplasts (the green organelle in plants).Eukaryote
An organism whose cells contain a membrane-bound nucleus. Many eukaryotic cells also possess other membrane-bound organelles. All eukaryotes are more closely related to each other than they are to prokaryotes. Apples and oranges you might say, except apples and oranges are both eukaryotes so…that analogy doesn't work. Scratch that.Flagellum
A protrusion of the cell membrane in some eukaryotic and prokaryotic cells that spins or lashes back and forth to aid in cellular locomotion. We say whip it; whip it good! There are significant differences among bacterial, Archaean, and eukaryotic flagella structure and movement.Genome
All of an organism's heredity information encoded in either DNA or RNA. You may have heard of the Human Genome Project.Golgi Body
An organelle ("mini organ") in eukaryotic cells containing between three and seven flattened membrane disks called cisternae. The Golgi body packages and processes proteins and lipids, and is also called the "Golgi apparatus." Stack of pancakes, anyone?Histone
Large protein complexes that control the messages sent from the DNA to the rest of the cell.Hydrophilic
The physical property of being attracted to water, or "water-loving." Phosphate ions (PO43-) and other ions are notoriously hydrophilic. They have an unhealthy obsession with water.Hydrophobic
The physical property of being repelled by water, or "water-fearing." Lipids (fatty fat fats) are notoriously hydrophobic. Living in fear is no fun, so hydrophobic things like to cling to each other like white on rice when water is nearby.Lysosome
A spherical, membrane-bound organelle ("mini organ") in eukaryotic cells (membrane-bound-nucleus-containing) that contains enzymes (catalysts) and other proteins that digest, or break down, substances that have been taken into a cell by phagocytosis (swallowing them up).Membrane Protein
Any of several types of proteins embedded in the plasma membrane (the lipid bilayer that encapsulates the cell). Here are the heavier details:- Receptor proteins perform cell communication.
- Transport proteins move materials into and out of the cell.
- Surface (or peripheral) proteins do not penetrate the membrane but can be found on the inside or outside of the cell and are usually involved in cell communication.
- Transmembrane (or integral) proteins completely traverse the lipid bilayer and are usually involved in transport of materials into and out of the cell, and they are also sometimes in cell communication. Phew.