Bio 181 terms exam 1

Archaea

Single-celled prokaryotes that are genetically distinct from bacteria.

ATP (adenosine triphosphate)

The main molecule cells use to store and transfer usable energy.

Cell

The basic unit of life.

Cell theory

The theory that all living things are made of cells, cells are the basic unit of life, and cells come from preexisting cells.

Central dogma

The flow of genetic information: DNA → RNA → protein.

Chromosome

A DNA-containing structure that carries genes.

Chromosome theory of inheritance

The theory that genes are located on chromosomes.

Control group

The group in an experiment that does not receive the experimental treatment.

DNA

The molecule that stores hereditary genetic information.

Domain

The broadest major category of biological classification.

Double helix

The twisted-ladder shape of DNA.

Energy

The ability to do work or cause change.

Eukaryote

An organism whose cells contain a nucleus and membrane-bound organelles.

Evolution

Change in inherited characteristics of populations over generations.

Experiment

A scientific test in which variables are deliberately manipulated.

Genes

Segments of DNA that contain instructions for traits or functional products.

Genus

A taxonomic group containing closely related species.

Heritable trait

A characteristic that can be passed genetically from parents to offspring.

Hypothesis

A testable proposed explanation for an observation.

Hypothesis testing

Using evidence or experiments to determine whether a hypothesis is supported.

Inheritance

The passing of genetic information from parents to offspring.

Kingdom

A taxonomic category below domain and above phylum.

Microscope

An instrument used to view objects too small to see with the naked eye.

Natural selection

The process by which organisms with advantageous heritable traits reproduce more successfully.

Observational study

A study in which researchers observe without deliberately changing conditions.

Organism

An individual living thing.

Phylogenetic tree

A diagram showing evolutionary relationships among organisms.

Phylogeny

The evolutionary history and relationships of an organism or group.

Phylum

A taxonomic category below kingdom and above class.

Population

Members of the same species living in the same area.

Prediction

A specific expected result based on a hypothesis.

Prokaryote

An organism whose cells lack a nucleus.

Protein

A molecule made of amino acids that performs many cellular functions.

Replication

The process of copying DNA.

RNA

A nucleic acid involved in using genetic information to make proteins.

Scientific name

The two-part name of a species: genus and specific epithet.

Species

A group of organisms that can generally reproduce and produce fertile offspring.

Spontaneous generation

The disproven idea that living organisms arise from nonliving matter.

Taxon

A named group in biological classification; plural is taxa.

Taxonomy

The science of naming and classifying organisms.

Theory

A well-supported explanation based on extensive scientific evidence.

Tree of life

A representation of evolutionary relationships among living organisms.

Amino group

A functional group containing nitrogen; written as –NH₂.

Anion

A negatively charged ion.

Aqueous

Dissolved in or containing water.

Atom

The smallest unit of an element that retains its properties.

Atomic number

The number of protons in an atom.

Atomic weight

The average mass of an element's naturally occurring isotopes.

Base

A substance that accepts hydrogen ions or increases hydroxide ions in solution.

Buffer

A substance that resists changes in pH.

Carbon

A chemical element that forms the backbone of many biological molecules.

Carboxyl group

A functional group containing carbon, oxygen, and hydrogen; –COOH.

Cation

A positively charged ion.

Covalent bond

A bond formed when atoms share electrons.

Double bond

A covalent bond in which two pairs of electrons are shared.

Electron

A negatively charged subatomic particle.

Electron shell

A region around the nucleus where electrons are found.

Electronegativity

An atom's ability to attract electrons in a bond.

Element

A substance made of atoms with the same number of protons.

Functional groups

Specific groups of atoms that give molecules characteristic properties.

Hydrogen

A chemical element with one proton and usually one electron.

Hydrogen bond

A weak attraction between a partially positive hydrogen and an electronegative atom.

Hydrogen ion

A positively charged hydrogen atom, H⁺.

Hydrophilic

Attracted to water; usually polar or charged.

Hydrophobic

Repelled by water; usually nonpolar.

Hydrophobic interactions

The tendency of nonpolar molecules or regions to cluster away from water.

Hydroxide ion

A negatively charged ion, OH⁻.

Hydroxyl group

A functional group containing oxygen and hydrogen; –OH.

Ion

An atom or molecule with an electrical charge.

Ionic bond

An attraction between oppositely charged ions.

Isotope

Atoms of the same element with different numbers of neutrons.

Kinetic energy

The energy of motion.

Mass number

The total number of protons and neutrons in an atom.

Molecule

Two or more atoms held together by chemical bonds.

Neutron

A neutral subatomic particle in the nucleus.

Nitrogen

A chemical element commonly found in proteins and nucleic acids.

Nonpolar covalent bond

A covalent bond in which electrons are shared relatively equally.

Nucleus

The positively charged center of an atom containing protons and neutrons.

Organic compounds

Carbon-containing compounds, especially those associated with living organisms.

Oxygen

A chemical element important in water, respiration, and many biological molecules.

pH

A measure of hydrogen ion concentration in a solution.

pH scale

A scale from about 0–14 that measures acidity and basicity.

Phosphate group

A functional group containing phosphorus and oxygen; important in ATP and nucleic acids.

Polar covalent bond

A covalent bond in which electrons are shared unequally.

Polarity

Unequal distribution of electrical charge in a molecule.

Proton

A positively charged subatomic particle in the nucleus.

Single bond

A covalent bond in which one pair of electrons is shared.

Solute

A substance dissolved in a solution.

Solution

A homogeneous mixture of a solute and solvent.

Solvent

The substance that dissolves the solute.

Space-filling model

A molecular model showing atoms as overlapping spheres sized according to their relative sizes.

Triple bond

A covalent bond in which three pairs of electrons are shared.

Valence

The bonding capacity of an atom.

Valence electron

An electron in an atom's outermost shell.

Valence shell

The outermost electron shell of an atom.

α-helix

A coiled form of protein secondary structure.

β-pleated sheet

A folded sheet form of protein secondary structure.

Active site

The region of an enzyme where the substrate binds and the reaction occurs.