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UltimateAP6
Term | Definition |
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Rh factor | Refers to the presence or absence of the Rh antigen on red blood cells. |
ribosomal A site | Site that holds the tRNA carrying the next amino acid to be added to the chain. |
Ribosomal E site | Site where discharged tRNAs leave the ribosome. |
ribosomal P site | Site that holds tRNA carrying the growing polypeptide chain. |
ribosomal RNA (rRNA) | RNA molecules that construct ribosomal subunits. |
ribosomes | Complex particles that facilitate the orderly linking of amino acids into polypeptide chains. |
ribozymes . | RNA molecules that function as enzymes |
RNA interference | Blocking gene expression by means of an miRNA silencing complex. |
RNA polymerase | Enzyme that links together the growing chain of ribonucleotides during transcription. |
RNA processing | The modification of mRNA before it leaves the nucleus that is unique to eukaryotes. |
RNA splicing | Process by which the introns are removed from RNA transcripts and the remaining exons are joined together. |
rough ER | A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; covered with ribosomes that make membrane proteins and secretory proteins. |
rubisco | The most abundant protein on earth. Performs Carbon Fixation in the Calvin Cycle. |
S phase | The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated. |
salicylic acid | A plant hormone that may be partially responsible for activating systemic acquired resistance to pathogens. |
scaffolding proteins | A type of large relay protein to which several other relay proteins are simultaneously attached to increase the efficiency of signal transduction. |
Schwann cells | Type of glia in the PNS, Supporting cells of the peripheral nervous system responsible for the formation of myelin. |
second law of thermodynamics | Every energy transfer or transformation increases the entropy of the universe. |
second messengers | Small, non-protein water soluble molecules or ions that send messages throughout the cells by diffusion. |
secondary consumer | Carnivore that eats herbivores. |
secondary immune response | Immune response after the body has already been exposed to a specific antigen. Response is faster, of greater magnitude, and more prolonged. |
secondary production | Amount of chemical energy in consumers' food that is converted to new biomass. |
secondary structure . | Either an alpha helix or beta pleated sheet |
secondary succession | Succession when an existing community has been cleared, but soil left intact. |
seed coat | A tough outer covering of a seed, formed from the outer coat of an ovule. |
selective permeability | A property of a plasma membrane that allows some substances to cross more easily than others. |
self-incompatibility | The ability of a seed plant to reject its own pollen and sometimes the pollen of closely related individuals. |
semelparity | Big-bang reproduction. |
semiconservative model | Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand. |
sensitive period | A limited phase in an animal's development that is the only time when certain behaviors can be learned. |
sensory neurons | Neurons that carry incoming information from the sense receptors to the central nervous system. |
sepal | A modified leaf in angiosperms that helps enclose and protect a flower bud before it opens. |
serial endosymbiosis | Sequence of endosymbiotic events that led to an ancestral eukaryote. |
serotonin | A neurotransmitter that affects hunger,sleep, arousal, and mood. |
sex chromosomes | X and Y chromosomes. |
sex linked genes | Genes located on the sex chromosomes. |
sexual dimorphism | Differences between the sexes in secondary sexual characteristics. |
sexual recombination | Crossing over and shuffling of genes during meiosis. |
sexual reproduction | When two parents give unique combination of genes to offspring. |
sexual selection | Natural selection for mating success. |
shared derived character | Evolutionary novelty unique to that clade. |
shared primitive character | Trait shared beyond the taxon. |
short-day plant | A plant that flowers only when the light period is shorter than a critical length. Usually fall or winter. |
sickle-cell disease | Genetic disorder in which red blood cells have abnormal hemoglobin molecules and take on an abnormal shape. |
sign stimulus | External sensory stimulus that triggers a fixed action pattern. |
signal | A behavior that causes change in another's behavior. |
signal peptide | A stretch of amino acids on a polypeptide that targets the protein to a specific destination in a eukaryotic cell. |
signal transduction | A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell. |
signal transduction pathway | The process by which a signal on a cell's surface is converted into a specific cellular response. |
signal-recognition particle | A protein-RNA complex that recognizes a signal peptide as it emerges from the ribosome. |
simple epithelium | Single layer of cells. |
simple fruit | A fruit derived from a single carpel or several fused carpels. |
single-strand binding protein (SSB) | Binds to and stabilizes single-stranded DNA until it can be used as a template. |
siRNAs (small interfering RNAs) | RNAs of similar size and functions as miRNAs that inhibit gene expression. |
sister chromatids | Identical copies of a chromosome; full sets of these are created during the S subphase of interphase. |
skeletal muscle | Muscle that is striated, multinucleated. |
smooth ER | Synthesis of lipids, phospholipids and steroid sex hormones-help detoxify drugs and poisons (liver cells). |
smooth muscle | Muscle that is not striated, is single nucleated. |
social learning | Learning through observing others. |
solute | Something dissolved in a solution. |
solute potential | This measurement has a maximum value of 0; it decreases as the concentration of a solute increases. |
solvent | Dissolving agent of a solution. |
somatic cell | Any of the cells of a plant or animal except the reproductive cells. |
Southern blotting | A hybridization technique that enables researchers to determine the presence of certain nucleotide sequences in a sample of DNA. |
spatial learning | The modification of behavior based on experience with the spatial structure of the environment. |
speciation | Origin of new species and the source of biological diversity. |
species diversity | Variety of different kinds of organisms that make up a community. |
species richness | Total number of different species. |
species transplant | Movement of a species to areas where it was previously absent. |
species-area curve | The larger the geographic area, the greater the number of species. |
specific epithet | Second part of scientific name. |
spirilla | Spiral bacteria. |
splicosome | Different particles that recognize splice sites are compiled in a large assembly. A complex of RNA and protein subunits. Removes introns from a transcribed pre-RNA segments. |
spores | Produced by meiosis. Grow into haploid organisms by mitosis. |
sporophyte | Diploid, or spore-producing, phase of an organism. Makes haploid spores by meiosis. |
squamous epithelium | Cells that look like floor tiles. |
stabilizing selection | Shift that favors the mean. |
stamen | The pollen-producing reproductive organ of a flower, consisting of an anther and a filament. |
standard metabolic rate (SMR) | The metabolic rate of a resting, fasting, nonstressed ectotherm. |
starch | Storage polysaccharide of plants. |
stem cell | Unspecialized cell that can both reproduce itself indefinitely and differentiate into specialized cells of one or more types. |
steroids | Made of four rings of carbon. |
sticky end | A single-stranded end of a double-stranded DNA restriction fragment. |
stigma | The sticky part of a flower's carpel, which receives pollen grain. |
stomata | Microscopic pores in the leaf which lets CO2 in and O2 out. Also where water is lost. |
stratified epithelium | Multiples tiers of cells. |
stroma | Fluid inside the chloroplast where the Calvin Cycle happens. |
stroma | The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water. |
stromatolites | Oldest known fossils formed from many layers of bacteria and sediment. |
structural isomers | Differ in arrangement of atoms. |
style | The stalk of a flower's carpel, with the ovary at the base and the stigma at the top. |
substrate-level phosphorylation | When an enzyme transfers a phosphate group from a substrate molecule. |
survivorship curves | Graph of the proportion of a cohort still alive at each age. |
sympathetic division | The part of the autonomic nervous system that arouses the body to deal with perceived threats. |
sympatric speciation | Speciation without a divided population. |
synapse | The junction between two neurons or between a neuron and a muscle. |
synapsis | Homologous chromosomes pair up, aligned gene by gene. |
synaptic cleft | The narrow gap that separates the presynaptic neuron from the postsynaptic cell. |
synaptic terminal | A bulb at the end of an axon in which neurotransmitter molecules are stored and released. |
synaptic vesicles | Membrane-bounded compartments in which synthesized neurotransmitters are kept. |
synthesis | To put together. |
systematics | Analytical approach to understanding the diversity and relationships of present and past organisms. |
systemic acquired resistance (SAR) | A defensive response in infected plants that helps protect healthy tissue from pathogenic invasion. |
T cell receptor | Antigen receptors on a T cell. Unlike antibodies, T cell receptors are never produced in a secreted form. |
T lymphocytes (T cells) | Lymphocyte that matures in the thymus and acts directly against antigens in cell-mediated immune responses. |
TATA box | A promoter DNA sequence crucial in forming the transcription initiation complex. |
taxis | Automatic, oriented movement toward or away from some stimuli. |
taxonomy | A classification of organisms into groups based on similarities. |
Tay-Sachs disease | A human genetic disease caused by a recessive allele that leads to the accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and mental performance usually become manifest a few months after birth. |
telomerase | An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells. |
telomeres | Repeated DNA sequences at the ends of eukaryotic chromosomes. |
temperate phage | A phage that is capable of reproducing by either the lytic or lysogenic cycle. |
template strand | The DNA strand that provides the template for ordering the sequence of nucleotides in an mRNA transcript. |
temporal isolation | When two species breed at different times of day, season, or years. |
tendons | Attach muscles to bones. |
terminator | In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene. |
territoriality | Defense of a space against encroachment by other individuals. |
tertiary consumer | Carnivore that eats carnivores. |
tertiary structure | Results from interactions between side chains. |
testcross | The result of breeding a recessive homozygote with an organism of dominant phenotype but unknown genotype. |
tetrad | A pair of chromosomes form tetrads made up of four chromatids. |
thalamus | Major input center for sensory information going to the cerebrum and the main output center for motor information leaving the cerebrum. |
The Law of Segregation | Two alleles separate during gamete formation and end up in different gametes because they are on on homologous chromosomes. |
the three-domain system | Domains Bacteria, Archae, and Eukarya. |
therapeutic cloning | The cloning of human cells by nuclear transplantation for therapeutic purposes, such as the generation of embryonic stem cells to treat disease. |
thermal energy | Kinetic energy associated with the random movement of molecules or atoms. |
thermophiles | Archaea that thrive in very hot environments, such as volcanic springs. |
thermoregulation | Process of maintaining an internal temperature within a tolerable range. |
thoracic cavity | cavity housing lungs and heart |
threatened species | Species that is likely to become endangered. |
threshold potential | The minimum membrane potential that must be reached in order for an action potential to be generated. |
thylakoid | Flattened membranes in the chloroplast where the light reactions take place. |
thylakoids | Membranous structures within a chloroplast that serve as the site for light harvesting in photosynthesis. |
thymus | Gland in the thoracic cavity above the heart where T lymphocytes mature. |
tissues | Groups of cells with a common structure and function. |
tonicity | The ability of a solution to cause a cell to gain or lose water; depends partly on concentration of nonpenetrating solutes relative to inside of cell. |
top-down model I | nfluence moves from top trophic levels to bottom. |
topoisomerase | Enzyme that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork. |
torpor | Physiological state in which activity is low and metabolism decreases. |
totipotent | Cells that are able to develop into any type of cell found in the body. |
totipotent | Stem cells with the potential to differentiate into any type of cell. |
trait | Each variant of a character. |