Absorbance – a measure of the amount of light absorbed by a sample in a colorimeter.

Acute Toxicity – when chemicals cause an adverse reaction in a short period of time.

Agar – a gelatinous substance extracted from seaweed and used to grow different types of cell cultures in science labs.

Antibiotic – a medicine used in inhibit the growth of or to kill microorganisms.

Asexual Reproduction – a mode of reproduction via mitosis, where the daughter cells are genetically identical to the single parental cell.

Bioaccumulation – occurs in an organism when the rate of intake of a substance is greater that the rate at which it’s used or excreted.

Biofilm – a dense community of cells living within a sticky matrix that the cells themselves produce.

Bioinformatics – use of computer technology to store and analyze biological data, particularly in the field of genetics.

Buffer – a solution that prevents rapid changes in PH.

Cannibalism – the act of eating members of your own species.

Chelex – a chemical used in DNA extraction that breaks up cells and inhibits damage to the DNA in the cells. It binds metal ions that are needed by DNA-degrading enzymes. 

Chemotaxis – a change in the direction of movement in response to chemicals in an organism’s environment.

Chronic toxicity – when chemicals accumulate in an organism and cause damage months or years after the initial exposure.

Cilia – “hair-like-structures” found on the outside of some eukaryotic organisms, cilia are used primarily for motion and food consumption in Tetrahymena

Ciliates – a group of protozoans that have cilia.

Clones – a group of identical cells that are derived from the same parent cells by asexual reproduction. 

Colony (bacterial) – a visible accumulation of bacteria on an agar plate, formed when the descendants of a single original bacterial cell pile up in a layer make of millions of bacteria.

Colorimeter – a device that shines a beam of light from an LED through a sample and detects the amount of light that gets through.

Contractile Vacuoles – structures that remove access water and salts from the cytoplasm in protists. 

Control – a portion of the experiment in which the variable being tested ISN’T changed. It allows the scientist to compare the results when the variable IS changed (the experiment). For example, if you wanted to know whether fertilizer makes a plant grow taller then control would be a plant grown with just water and the experiment would be a plant grown with water and fertilizer.

Deoxyribonucleic acid – a molecule that makes up the genes of an organism. It encodes the genetic instructions for how the organism will function.

Dependent Variable – the variable that is measured in the experiment.

DNA – deoxyribonucleic acid, a molecule that makes up the genes of an organism. It encodes the genetic instructions for how that organism will function.

DNA Polymerase – the enzyme that puts nucleotides together to make a DNA molecule.

Enzyme – a substance that acts as a catalyst to speed up a specific reaction (most enzymes are proteins) 

Eukaroyte – an organism that has a membrane-bound nucleus and organelles.

Evolution – a change in the inherited characteristics of biological populations over multiple generations. 

Exocytosis – the process of producing something inside a cell and releasing it for use outside the cell (exo = outside, cyto = cell)

Flagellum – a lash or whip-like appendage found on some prokaryotic and eukaryotic cells; used in movement and in some eukaryotes, may act as a sensory organelle, detecting changes in environment. 

Food Vacuoles – bubble-like sacs created when a cell ingests material from its environment. The material is digested inside the vacuole and the cell absorbs nutrients needed to carry out basic life functions. Indigestible material is released back into the environment when a vacuole fuses to the cell membrane for excretion. 

Growth Rate – the rate at which cells reproduce.

Hydrophilic – attracted to water (hydro=water, philia=loving)

Hydrophobic – repelled by water (hydro=water, phobos=fear)

Hypertonic – having a higher concentration of solutes. The cytoplasm of a cell is hypertonic to distilled water.

Hypothesis – a proposed explanation for a phenomenon that can be tested.

Independent Variable – the variable that you change or manipulate in an experiment.

Index of Biotic Integrity – a scientific tool used to evaluate the quality of the water in a pond or stream by looking at the types of invertebrates that live in it.

Indicator Species – a species whose absence, presence or abundance reflects a specific environmental condition; can be used as an early warning system to assess the overall status of an ecosystem.

Isotonic – having an equal concentration of solutes outside and inside the cell.

LD50 – the dose that kills 50% of a population of test animals (often rats) to whom the chemical bas been given; usually measured in “mg/kg”.

MAC – the macronucleus; the “working nucleus” that is usually larger, contains many copies of the cell’s DNA and directs synthesis of all necessary proteins.

Macroinvertebrates – invertebrates large enough to see with little or no magnification.

Macronucleus – the “working nucleus” that is usually larger, contains many copies of the cell’s DNA and directs synthesis of all necessary proteins.

Macrostome – larger, cannibalistic form of Tetrahymena vorax.

Meiosis – a type of nuclear division in sexual reproduction where the number of sets of chromosomes in the cell is reduced to half the original number (diploid to haploid); the daughter cells are genetically different from the parent cells.

MIC – the micronucleus, a smaller nucleus, has a single copy of the genetic information; used for sexual reproduction in Tetrahymena.

Microcosm – “mini-world”, a small, limited version of a larger, more complicated system; it allows scientists to control variables and look at interactions between some members of the larger system.

Microevolution – changes in allele frequencies in a population over a relatively short period of time. The term “macroevolution” refers to changes in species that have occurred over long (geologic) periods of time.

Microliter – one-millionth of a liter, the symbol is μL.

Micronucleus – smaller nucleus, has a single copy of the genetic information; used for sexual reproduction in Tetrahymena.

Micropipette – a tool used to measure small volumes of liquid in science labs; measurements are in microliters μL.

Microstome – small-mouthed version of Tetrahymena vorax.

Microtubules – tiny tubes that make up cilia; they are made of a protein called tubulin.

Milliliter – one-millionth of a liter, the symbol is ml.

Mitosis – a form of nuclear division in which a cell replicates its chromosomes and provides a copy of each to the daughter cells; the daughter cells are genetically identical to the parent cells. 

Model Organism – one that is used in science to study how it works. The information learned is often used to compare similar organisms or similar structures in other organisms; rats are common model organisms used in science to understand human biology.

Morphology – shape and structure of an organism.

Motility – the ability to move.

Mucocyst – structure just under the cell membrane of Tetrahymena that stores a protein called mucus. 

Mutation – a permanent change to an organisms’ DNA.

Natural Selection – the process whereby organisms better adapted to their environment tend to survive and produce more offspring than other members of the population.

Neff – a mixture of protein and yeast extract with added sugar and iron chloride; a solution of Neff is used to grow Tetrahymena in a lab environment.

Niche – the specific type of habitat an organism inhabits and its role or function in an ecosystem.

Nopathogenic – an organism that does not cause disease.

Nucleotides – the A,C,G and T building blocks of DNA.

Oral Groove – the mouth-like opening in a ciliate where food particles are collected and transported through the organism’s gullet into food vacuoles for digestion. 

Organelle – an organelle is a specialized subunit within a cell that has a specific function, which is vital for the cell to live.

Osmoregulation – the process by which animals regulate the amount of water in their bodies and the concentration of various solutes and ions in their body fluids. 

Osmoregulators – organisms that spend energy to maintain water balance with an environment that has a water and salt concentration that is different from their cytoplasm; Tetrahymena is an osmoregulatory. 

Osmosis – refers to the movement of water across a membrane.

PCR – polymerase chain reaction.

Pellet – the dense collection of particles at the bottom of a tube caused by spinning a sample culture in a centrifuge.

Permissive temperature – the temperature at which a temperature sensitive mutant gene product takes on a normal, functional phenotype.

Phagocytosis – the process of engulfing a particle for the purpose of obtaining food.

Polymerase Chain Reaction – a laboratory technique used to make many copies of DNA from living organisms (PCR).

Predator – an organism that preys on and consumes another organism; ex. Tetrahymena are predators of bacteria.

Primers – a short piece of nucleic acid that serves as a starting point for DNA synthesis.

Protozoan – animal-like organisms in Kingdom Protista that are single-celled and microscopic; these include ciliates, amoebae, flagellates and sporozoans. 

Pseudomonas fluorescens – a rod-shaped, flagellated bacteria that lives in water films in the soil and in association with plant roots; it does not cause disease in healthy people and is used frequently in lab activities. 

Restrictive or nonpermissive temperature – the temperature at which a temperature sensitive mutant gene product takes on its abnormal phenotype.

Ribonucleic acid – a large molecule whose main function is to transfer information coded in a cell’s DNA to the ribosomes, where the information is used to make proteins.

RNA – ribonucleic acid.

Selectively Permeable Membrane– a membrane that allows some substances to pass through while other substances are blocked.

Serial Dilution – a stepwise dilution of a substance where the dilution factor is known at each step.

Sexual Reproduction – a mode of reproduction involving meiosis, where the daughter cells are genetically different from the parental cells.

Solute – a substance dissolved in a solvent; in cells, the solvent is water.

Spread Plate – a technique used to distribute diluted bacterial cells across a large area of an agar plate so you can see individual colonies; a small volume of liquid culture is transferred to the plate and then spread to cover the entire plate. 

Standard Curve – a graph of the relationship between two variables based on many actual measurements. For example, it could be a graph of the relationship between the concentration of a solute and the amount of light a solution absorbs. Once graphed, the concentration of an unknown solution can be determined by measuring the solution’s absorbance and finding that point on the curve. 

Stock Culture – a culture that is used to grow more cultures. It may also be a back-up sample in case your working cultures become contaminated. 

Stomatin – a mixture composed of hypoxanthine and urcil, which are metabolic products of the breakdown of nucleic acids; it is secreted by prey organisms and triggers the change from normal to “cannibal” in Tetrahymena vorax.

Streak Plate – a technique used to distribute an originally dense sample of bacterial culture across an agar plate; sterile loops are used to streak bacteria into uncontaminated areas of the plate, diluting the total number with each successive streak so that individual colonies can grow.

Synchronous – going on at the same rate and exactly together; recurring together.

Temperature sensitive mutation – a conditional mutation that produces the mutant phenotype in one temperature range and the wild-type phenotype in another temperature range.

Tetrahymena – single-celled protist, measuring only about 50 μm, that lives in fresh water environments and consumes mostly bacteria that decompose dead animal or plant matter.

Traits- inherited characteristics of an organism that are the product of genes, like height or flower color.

Tris – an isotonic mixture of salts without any carbon source or amino acids, used to starve Tetrahymena

Turbidity – cloudiness of a solution.

Working culture – larger volume of cells prepared for the whole class to use in experiments.