high-energy, unstable state (an intermediate form between the substrate and the product) occurring during a chemical reaction

sequence present in protein-coding mRNA after completion of pre-mRNA splicing

describes chemical reactions that release free energy

plant cell organelle that carries out photosynthesis

substance released by an animal that can affect the physiology or behavior of other animals

covalent chemical bond that holds together the polynucleotide chains, with a phosphate group linking two pentose sugars of neighboring nucleotides

(also, binary fission) method by which multicellular organisms increase in size or asexual reproduction in which a unicellular organism splits into two separate organisms by mitosis

occurs because water molecules are attracted to charges on the inner surfaces of narrow tubular structures such as glass tubes, drawing the water molecules to the sides of the tubes

regular structure formed by proteins by intramolecular hydrogen bonding between the oxygen atom of one amino acid residue and the hydrogen attached to the nitrogen atom of another amino acid residue

interaction between two or more of the same or different atoms that results in the formation of molecules

molecule that is capable of absorbing certain wavelengths of light and reflecting others (which accounts for its color)

weakening of a virus during vaccine development

nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division

Y-shaped structure formed during initiation of replication

decrease in activity and metabolism that allows an animal to survive adverse conditions

protein integrated into the membrane structure that interacts extensively with the hydrocarbon chains of membrane lipids and often spans the membrane; these proteins can be removed only by the disruption of the membrane by detergents

structure that extends away from the cell body to receive messages from other neurons

three-nucleotide sequence in a tRNA molecule that corresponds to an mRNA codon

storage carbohydrate in plants

organism that uses resources from another species, the host

selection that favors two or more distinct phenotypes

succession on land that previously has had no life

organism that grows under extreme or harsh conditions

material composed of polysaccharide chains cross-linked to unusual peptides

. (also, karyokinesis) period of the cell cycle during which the duplicated chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase

polyploidy formed within a single species

large molecule necessary for life that is built from smaller organic molecules

speciation that occurs in the same geographic space

weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules

cell-surface receptor that activates membrane-bound G-proteins to transmit a signal from the receptor to nearby membrane components

division of autonomic nervous system that regulates visceral functions during rest and digestion

in a heterozygote, expression of two contrasting alleles such that the individual displays an intermediate phenotype

small, round organelle that contains hydrogen peroxide, oxidizes fatty acids and amino acids, and detoxifies many poisons

termination sequence-dependent termination of prokaryotic mRNA synthesis; caused by hairpin formation in the mRNA that stalls the polymerase

study of the collective genomes of multiple species that grow and interact in an environmental niche

form of reproduction that produces offspring that are genetically identical to the parent

energy content available to the organisms of the next trophic level

avoid detection by blending in with the background.

integral protein and pigment complex in thylakoid membranes that transports electrons from water to the electron transport chain; oxygen is a product of PSII

total weight, at the time of measurement, of living or previously living organisms in a unit area within a trophic level

chemical compound formed when two molecules join together

specific carrier proteins or pumps that facilitate movement

formation of a new species

total number of protons in an atom

process in which the young develop within the female, receiving nourishment from the mother’s blood through a placenta

channel between two adjacent animal cells that allows ions, nutrients, and low molecular weight substances to pass between cells, enabling the cells to communicate

genes do not influence each other with regard to sorting of alleles into gametes; every possible combination of alleles is equally likely to occur

depolarization of a postsynaptic membrane caused by neurotransmitter molecules released from a presynaptic cell

amount of heat required to change the temperature of one gram of water by one degree Celsius

short stretch of nucleotides that is required to initiate replication; in the case of replication, the primer has RNA nucleotides

process that does not use oxygen

measure of the ability of a trophic level to convert the energy it receives from the previous trophic level into biomass

substance capable of dissolving another substance

protein that coats the inward-facing surface of the plasma membrane and assists in the formation of specialized structures, like coated pits, for phagocytosis

detachment, 180° rotation, and reinsertion of a chromosome arm

substance dissolved in a liquid to form a solution

number of organisms added in each reproductive generation

stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by a new nuclear envelope

. apparatus composed of microtubules that orchestrates the movement of chromosomes during mitosis

foreign or “non-self” protein that triggers the immune response

describes chemical reactions that require energy inputprocess during which energy released by one reaction is used to drive another reaction

disc-shaped, membrane-bound structure inside a chloroplast where the light-dependent reactions of photosynthesis take place; stacks of thylakoids are called grana

collection of genes involved in a pathway that are transcribed together as a single mRNA in prokaryotic cells

one of a group of protein kinases that helps to regulate the cell cycle when bound to cyclin; it functions to phosphorylate other proteins that are either activated or inactivated by phosphorylation

biological macromolecule in which the ratio of carbon to hydrogen and to oxygen is 1:2:1; carbohydrates serve as energy sources and structural support in cells and form the a cellular exoskeleton of arthropods

final stage of succession, where a stable community is formed by a characteristic assortment of plant and animal species

refers to organisms that grow without oxygen

position of a species or group of species in a food chain or a food web

process by which a bacteriophage moves DNA from one prokaryote to another

no two species within a habitat can coexist when they compete for the same resources at the same place and time

part of the ocean that is closest to land; parts extend above the water at low tide

structure formed when cells in the mammalian blastula separate into an inner and outer layer

division of class in the taxonomic classification system

biological macromolecule that carries the genetic blueprint of a cell and carries instructions for the functioning of the cell

type of strong bond formed between two atoms of the same or different elements; forms when electrons are shared between atoms

signaling molecule secreted by bacteria to communicate with other bacteria of its kind and others

hydrocarbon consisting of a linear chain of carbon atoms

exchange of genetic material between non-sister chromatids resulting in chromosomes that incorporate genes from both parents of the organism

enzyme that catalyzes the transfer of a phosphate group from ATP to another molecule

rigid cell covering made of various molecules that protects the cell, provides structural support, and gives shape to the cell

study of life on island chains and how their geography interacts with the diversity of species found there

speciation when one species radiates out to form several other species

biological substance that, in low concentration, is antagonistic to the growth of prokaryotes

space between the presynaptic and postsynaptic membranes

widespread, usually worldwide, epidemic disease

strand of DNA that is not used to transcribe mRNA; this strand is identical to the mRNA except that T nucleotides in the DNA are replaced by U nucleotides in the mRNA

the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius

ability of an organism to be unaffected by the actions of an antibiotic

study of the geographic distribution of living things and the abiotic factors that affect their distribution

reaction center of photosystem I

combination of carbohydrates and lipids

inheritance pattern in which a character shows a range of trait values with small gradations rather than large gaps between them

animal that consumes strictly plant diet

differences in breeding schedules that can act as a form of prezygotic barrier leading to reproductive isolation

attraction between water molecules and other molecules

process by which homologous chromosomes undergo reciprocal physical exchanges at their arms, also known as crossing over

similarity in characteristics resulting from a shared ancestry

study of energy flowing through living systems

any molecule containing carbon (except carbon dioxide)

distribution of phenotypes in a population

organism with optimal growth pH of nine or above

any gene on a sex chromosome

large molecule, typically formed by the joining of smaller molecules

single DNA molecule of two strands of duplicated DNA and associated proteins held together at the centromere

number of population members in a habitat at the same time

ordered series of events involving cell growth and cell division

mechanism that monitors the preparedness of a eukaryotic cell to advance through the various cell cycle stages

organelle in an animal cell that functions as the cell’s digestive component; it breaks down proteins, polysaccharides, lipids, nucleic acids, and even worn-out organelles

molecule found on the left side of a chemical equation

chemical signaling molecule, usually protein or steroid, secreted by endocrine cells that act to control or regulate specific physiological processes

group of atoms that provides or imparts a specific function to a carbon skeleton

organism with cells that have nuclei and membrane-bound organelles

energy transfer efficiency between two successive trophic levels

(also, species distribution pattern) spatial location of individuals of a given species within a habitat at a particular point in time

section of a scientific paper that includes a complete description of the substances, methods, and techniques used by the researchers to gather data

fraction of population variation that can be attributed to its genetic variance

(also, gene frequency) rate at which a specific allele appears within a population

species whose presence is key to maintaining biodiversity in an ecosystem and to upholding an ecological community’s structure

bacterium that contains mainly peptidoglycan in its cell walls

individuals that are members of the same species

combination of DNA fragments generated by molecular cloning that does not exist in nature; also known as a chimeric molecule

polysaccharide that makes up the cell wall of plants; provides structural support to the cell

one of 118 unique substances that cannot be broken down into smaller substances; each element has unique properties and a specified number of protons

organism that can build organic molecules using energy derived from inorganic chemicals instead of sunlight

a stable, non-evolving state of a population in which allelic frequencies are stable over time

competition between members of the same species

usually a carnivore that eat primary consumers

the simplest, most straightforward way of constructing phylogenetic and evolutionary relationships between organisms

carnivore that eat other carnivores

species suited to stable environments that produce a few, relatively large offspring and provide parental care

channel that passes between the cell walls of adjacent plant cells, connects their cytoplasm, and allows materials to be transported from cell to cell

external structure that enables a prokaryote to attach to surfaces and protects it from dehydration

tension at the surface of a body of liquid that prevents the molecules from separating; created by the attractive cohesive forces between the molecules of the liquid

adaptive immune response that is carried out by T cells

part of the ocean where no light penetrates

use of microbial metabolism to remove pollutants

disease making an initial appearance in a population or that is increasing in incidence or geographic range

increasing concentrations of persistent, toxic substances in organisms at each trophic level, from the primary producers to the apex consumers

division of domain in the taxonomic classification system

physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor

small organic molecule, such as a vitamin or its derivative, which is required to enhance the activity of an enzyme

branches and foliage of trees that form a layer of overhead coverage in a forest

structure within the nucleus that is made up of chromatin that contains DNA, the hereditary material

animal capable of maintaining a relatively constant internal body temperature

when individuals tend to mate with those who are phenotypically similar to themselves

second round of meiotic cell division following meiosis I; sister chromatids are separated into individual chromosomes, and the result is four unique haploid cells

spherical structure that contains a neurotransmitter

light-independent reactions of photosynthesis that convert carbon dioxide from the atmosphere into carbohydrates using the energy and reducing power of ATP and NADPH

study of the chemistry of biological organisms