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| 283175398 | ecology | study of distribution and abundance of organisms & interaction with environment | |
| 283175399 | divisions of ecology | organismal, population, community, ecosystem | |
| 283175400 | population | a group of interbreeding organisms | |
| 283175401 | community | a group that cannot interbreed, different species interacting | |
| 283175402 | ecosystem | living and nonliving things interacting | |
| 283175403 | biotic factors | something living (e.g. animals, plants) | |
| 283175404 | abiotic factors | something not living (e.g. rocks, sunlight, weather) | |
| 283175405 | aquatic biomes | organisms dependent on light and temperature (usually stable); provides most of earth's food & oxygen; salt or fresh water/light/depth all impact organisms | |
| 283175406 | terrestrial biomes | organisms dependent on rainfall and temperature | |
| 283175407 | tropical forests | near equator (77-84ºF) tropical rain forest: constant rain tropical dry forest: seasonal rain plants: intense competition for light (canopy); plenty of water; diverse organisms | |
| 283175408 | savanna | equatorial and subequatorial: temps 77-84ºF rainy seasons & dry seasons; occasional fires and droughts; grassland with scattered trees; large herbivores (zebra, bison); and carnivores (lions) | |
| 283175409 | desert | 30º N & S latitude from equator; sparse rainfall; temps -22-122ºF (vary daily) plants: low & scattered; cacti, small shrubs animals: snakes, lizards, beetles, etc. (exothermic animals) | |
| 283175410 | chaparral | mid-latitude, coastal regions; temps 50-104ºF; seasonal rains, fires; not a lot of rainfall; lots of shrubs and small trees; deer, goats, reptiles, birds, etc. | |
| 283175411 | temperate grassland | cold, dry winters; hot, wet summers; tall grasses; large mammals/herbivores; lots of farming | |
| 283175412 | temperate deciduous(broadleaf) forest | mid-latitude in north; cold winters; hot summers; moderate rain/snow; deciduous trees (drop leaves); mammals hibernate | |
| 283175413 | coniferous forest/taiga | northern NA and Eurasia; harsh winters - heavy snowfall; periodic droughts; cone-bearing trees; moose, brown bears, etc. | |
| 283175414 | tundra | long, cold winters; short, cool summers; permafrost (prevent tree growth) - ground is frozen; very little precipitation (like a desert); mosses, grasses, small trees, etc.; oxen, foxes, bears, etc. | |
| 283175415 | oligotrophic lakes | deep, nutrient poor, clear (little photosynthesis); O2 rich waters supporting fish; very few plants | |
| 283175416 | eutrophic lakes | shallow; high nutrient content; murky (LOTS of photosynthesis); potentially low O2, may not support fish; lots of plant growth | |
| 283175417 | wetland | has water at least some of the time; support wide variety of life | |
| 283175418 | estuary | transition area between river and sea; very productive biologically; supports wide variety of life | |
| 283175419 | intertidal zones | exposed to tide fluctuations; adaptations to waves, tides, and fluctuating temperatures | |
| 283175420 | pelagic zone | open water of any depth | |
| 283175421 | coral reef | formed by calcium carbonate exoskeletons of corals | |
| 283175422 | benthic zone | neritic and abyssal zones | |
| 283175423 | neritic zone | seafloor below coastal waters | |
| 283175424 | abyssal zone | deep ocean floor; hydrothermal vents; extremeophiles | |
| 283175425 | ethology | study of animal behavior | |
| 283175426 | proximate question | what caused, produced or has modified the behavior? | |
| 283175427 | ultimate question | how is the behavior beneficial? | |
| 283175428 | evolution of behavior | selection of behaviors that increase survival and reproduction | |
| 283175429 | innate | instinctive or inherited behaviors | |
| 283175430 | kinesis | change in activity due to stimulus | |
| 283175431 | taxis | directed movement to or from stimulus | |
| 283175432 | phototaxis | movement toward light | |
| 283175433 | rheotaxis | movement against the current | |
| 283175434 | fixed action patterns (FAP) | innate behaviors triggered by sign stimuli; follow a regular, unvarying pattern | |
| 283175435 | migration | long distance, seasonal movement of animals | |
| 283175436 | imprinting | uses learned and innate behavior; during sensitive period offspring imprints on parent and learns behavior | |
| 283175437 | associative learning | linking one environmental feature with another | |
| 283175438 | classical conditioning | stimulus associated with particular outcome (Pavlov's dogs) | |
| 283175439 | operant conditioning | trial and error, reward and punishment (Skinner box, water maze) | |
| 283175440 | habituation | ignore persistent stimuli | |
| 283175441 | spatial learning | memory of environment's spatial structure | |
| 283175442 | observational learning | copying a behavior | |
| 283175443 | insight | new situation emits behavior that generates desirable outcome | |
| 283175444 | releaser pheromones | cause immediate/specific behavior change | |
| 283175445 | primer pheromones | cause physiological changes | |
| 283175446 | dispersion | distribution of individuals in a population | |
| 283175447 | demographics | statistical analysis of populations and how they change over time | |
| 283175448 | survivorship curve | type 1 curve: most reach middle age (ex. human); type 2 curve: random survival (ex. rodents); type 3 curve: most die young (ex. oysters) | |
| 283175449 | biotic potential | maximum growth rate of a population under ideal conditions (unlimited resources and growth) | |
| 283175450 | exponential growth | unlimited growth of individual | |
| 283175451 | carrying capacity | growth of individuals limited to what environment can sustain | |
| 283175452 | limiting factors | prevent population from reaching biotic potential; affect the carrying capacity (K) | |
| 283175453 | density dependent factors | limiting factors become more intense as population density increases | |
| 283175454 | density independent factors | limiting factors are independent of population density | |
| 283175455 | logistic growth | limiting factor restricts size of population to carrying capacity | |
| 283175456 | r-selected species | opportunistic; rapid growth (J-shaped curve); quickly reproduce, then die; many offspring; little or no parenting; first to colonize | |
| 283175457 | k-selected species | relatively constant population (at carrying capacity); reproduce many times, live long; few offspring; intensive parenting; replace r-selected species | |
| 283175458 | interspecific competition | competition between different species (-/-) | |
| 283175459 | predation | organism totally or partly consume another organism (+/-) | |
| 283175461 | symbiosis | two species in contact during some or all of their lives(+/0, +/+, +/-) | |
| 283175463 | niche | sum of all biotic and abiotic resources used by a species | |
| 283175465 | competitive exclusion principle (Gause's principle) | no two species can occupy the same niche; one species outcompetes and eliminates another | |
| 283175467 | resource partitioning | divide resources among competing species; slightly different resources or get resources another way | |
| 283175469 | fundamental niche | niche potentially occupied by species | |
| 283175471 | realized niche | niche that it actually occupies | |
| 283175473 | character displacement (niche shift) | some characteristics help obtain better resources; reduces competition and leads to divergence of features | |
| 283175474 | coevolution | evolution in one species in response to a new adaptation of another | |
| 283175476 | aposematic coloration | coloration warns prey | |
| 283175478 | mimicry | species resemble one another | |
| 283175480 | mullerian mimicry | animals with special defenses share coloration | |
| 283175482 | batesian mimicry | animals without defense mimics animals with special defenses | |
| 283175484 | mutalism | both species benefit | |
| 283175486 | commensalism | one species benefits, second species isn't helped nor harmed | |
| 283175488 | parasitism | parasites benefit, host is harmed | |
| 283175490 | dominant species | large biomass; big influence on other species | |
| 283175492 | invasive species | no predators/pathogens; rapid growth/large biomass | |
| 283175494 | keystone species | large impact due to ecological role | |
| 283175496 | succession | change in composition of terrestrial species over time | |
| 283175498 | primary succession | occurs where life never existed | |
| 283175500 | secondary succession | occurs on habitat destroyed by fire, flood, etc.; soil and seed bank already present | |
| 283175502 | energy flow | energy can be neither created nor destroyed, only transferred and transformed | |
| 283175504 | chemical cycling | matter cannot be created nor destroyed | |
| 283175506 | herbivore | eats mainly autotrophs | |
| 283175508 | carnivore | eats mainly animals | |
| 283175510 | omnivore | eat animals and autotrophs | |
| 283175512 | net primary production | gross primary production - energy lost to respiration | |
| 283175515 | trophic efficiency | percent energy transferred from one trophic level to the next; typically about 10% | |
| 283175517 | biogeochemical cycles | flow of essential elements between biotic and abiotic factors | |
| 283175519 | reservoirs | major storage locations for essential elements | |
| 283175521 | assimilation | process of incorporating elements into terrestrial | |
| 283175523 | molecule | two or more atoms bonded together | |
| 283175525 | compound | two or more different atoms bonded together | |
| 283175528 | element | pure substance that can't be changed into a simpler substance | |
| 283175530 | atom | smallest unit of an element | |
| 283175532 | sub-atomic particles | protons, neutrons and electrons | |
| 283175534 | isotopes | same element, different # of neutrons, so atomic mass is different | |
| 283175537 | atomic mass | # of protons + # of neutrons | |
| 283175539 | atomic number | # of protons | |
| 283175541 | electro-negativity | the ability of an atom to attract electrons | |
| 283175543 | ionic bond | involves gain and loss of electrons; occurs when there's a big difference in electro-negativity of atoms | |
| 283175546 | covalent bond | involves the sharing of electrons | |
| 283175548 | non-polar covalent bonds | atoms have similar electro-negativities; share electrons equally | |
| 283175550 | polar covalent bonds | atoms have different electro-negativities; share electrons unequally; electrons concentrate near more electronegative atom = negative pole; less electrons around less electronegative atom = positive pole | |
| 283175552 | hydrogen bonds | hydrogen in one molecule has a positive charge and is attracted to the negative charge of an atom in another molecule; this is not a covalent bond - it's much weaker; very important biologically - easy to make and break | |
| 283175555 | cohesion | attraction between like substances; under tension, stretch but do not break; helps pull water up plants (xylem); creates high surface tension (forms smooth, round surface) | |
| 283175557 | adhesion | attraction of unlike substances; water adheres and rises up objects | |
| 283175559 | buffers | minimize changes in H+ and OH- in a solution; accept or donate H+ to maintain pH | |
| 283175562 | organic molecule | contains carbon and hydrogen | |
| 283175564 | hydrocarbons | long chains of hydrogen and carbon | |
| 283175566 | functional groups | groups of atoms that predict molecular properties | |
| 283175568 | macromolecules | organic molecules consisting of hundreds or thousands of atoms | |
| 283175570 | polymers | macromolecules of a single unit (monomer) repeated many times | |
| 283175573 | primary structure | unique sequence of amino acids | |
| 283175575 | secondary structure | due to hydrogen bonding; alpha-helix or beta-pleated sheet | |
| 283175577 | prions | proteins that affect folding of other proteins | |
| 283175579 | tertiary structure | irregular contortions; hydrogen bonds and/or ionic bonds form between R groups; hydrophobic R groups clump away from water | |
| 283175582 | disulfide bridge | sulfur in cys bonds to sulfur in another cys; stabilizes turns in peptide | |
| 283175584 | quaternary structure | protein assembled from 2 or more separate peptide chains | |
| 283175586 | chaperonins | enzymes and special proteins the "chaperone" the protein folding | |
| 283175589 | metabolism | chemical reactions that occur in biological systems | |
| 283175591 | catabolism | breaks apart substance | |
| 283175593 | anabolism | builds up substance | |
| 283175596 | first law of thermodynamics | energy is neither created nor destroyed, it only changes form | |
| 283175598 | second law of thermodynamics | disorder in the universe always decreases; for any process, energy available for work decreases - entropy; typically energy is lost as heat | |
| 283175599 | free energy (G) | energy available for work | |
| 283175600 | exergonic reactions | release energy; free energy decreases, so ∆G is negative; reaction will occur spontaneously | |
| 283175601 | endergonic reactions | consume energy; free energy increases, so ∆G is positive; reaction will require energy input | |
| 283175602 | activation energy | minimum energy needed for reaction to occur | |
| 283175603 | catalyst | accelerates rate of reaction by lowering activation energy; remains chemically unaltered; enzyme is a biological catalyst | |
| 283175604 | equilibrium | ∆G = 0; rate of reaction in forward reaction = rate of reaction in reverse direction; no net production of reactant or product | |
| 283175605 | enzymes | proteins that lower activation energy | |
| 283175606 | substrate | what the enzyme acts upon | |
| 283175607 | cofactors | non-protein molecules that help enzymes fit substrates | |
| 283175608 | allosteric enzymes | two binding sites; active site for substrate | |
| 283175609 | allosteric activator | binds to allosteric site, stabilizes active form of enzyme | |
| 283175610 | allosteric inhibitor | binds to allosteric site, stabilizes inactive form of enzyme | |
| 283175611 | coopertivity | substrate primes enzyme to accept more substrate molecules; occurs when enzyme has two or more subunits | |
| 283175612 | competitive inhibition | substance mimics substrate and blocks enzyme's binding site | |
| 283175613 | non-competitve inhibition | substance binds to enzyme at locations other than active site; disables enzyme | |
| 283175614 | cell | basic functional unit of all living things | |
| 283175615 | cell fractionation | homogenize, then centrifuge cells | |
| 283175616 | lipid bilayer | two sheets of phospholipids arranged tail to tail; selectively permeable | |
| 283175617 | outer face | polar hydrophilic head | |
| 283175618 | inner face | nonpolar hydrophobic tails | |
| 283175619 | peripheral proteins | loosely bound to membrane surface | |
| 283175620 | integral proteins | extend into the membrane; must be amphipathic | |
| 283175621 | transmembrane proteins | integral protein that spans the entire membrane | |
| 283175622 | integrins | transmembrane protein binds to extracellular and intercellular areas; transmit signals intra and extracellularly; also provide strength | |
| 283175623 | cholesterol molecules | "temperature buffers"; prevents lipid bilayer from freezing or melting | |
| 283175624 | glycolipids/glycoproteins | attachment to membrane; work as markers for cell-to-cell recognition | |
| 283175625 | passive transport | no energy (ATP) needed to move things around a cell; utilizes concentration gradient; substances diffuse from high to low; selectively permeable membrane | |
| 283175626 | dialysis | diffusion of solutes across a selectively permeable membrane | |
| 283175627 | simple diffusion | movement from high solute to low solute to equilibrium | |
| 283175628 | hypertonic solution | higher concentration of solutes | |
| 283175629 | hypotonic solution | lower concentration of solutes | |
| 283175630 | isotonic solution | equal concentration of solutes | |
| 283175631 | osmotic pressure | pressure created by water as it enters region by osmosis | |
| 283175632 | turgor pressure | large osmotic pressure caused by water entering cells within cell wall | |
| 283175633 | plasmolysis | cells collapse caused by water leaving the cell (especially in plant cells with central vacuoles) | |
| 283175634 | facilitated diffusion | diffusion of solutes through channel or carrier proteins in plasma membrane; no need for energy | |
| 283175635 | vesicular transport | vesicles move macromolecules of large particles across plasma membrane | |
| 283175636 | exocytosis | vesicles fuse with plasma membrane and release contents outside of cell; used when cell produces substances for export | |
| 283175637 | endocytosis | capture substance outside of cell; plasma membrane merges to engulf it; substance enters cytoplasm enclosed in a vesicle | |
| 283175638 | phagocytosis | "cellular eating" of un-dissolved material | |
| 283175639 | pinocytosis | "cellular drinking" of dissolved substances; plasma membrane folds inward and forms vesicle | |
| 283175640 | receptor mediated endocytosis | extracellular molecules bind to specific receptors; occurs in coated pits region of plasma membrane; pits, receptors, and specific molecules (ligands) fold inward; vesicle formed | |
| 283175641 | active transport | needs energy (ATP); usually against concentration gradient (low to high); integral proteins transport solutes (Na+, K+, Cl-, H+), amino acids and monosaccharide's across membrane | |
| 283175642 | cytoplasm | part of the cell outside the nucleus but inside the membrane | |
| 283175643 | cytosol | part of the cytoplasm, not in membrane-enclosed organelle; fluid matrix of H2O and dissolved substances (proteins, nutrients, ect.) | |
| 283175644 | cytoskeleton | protein fiber network: shapes cell, stabilizes organelles and helps cell move | |
| 283175645 | organelles | physically separated to isolate metabolic reactions | |
| 283175646 | nucleus | bound by nuclear envelope (phospholipid bilayer); site of chromosome separated during cell division; contains nucleoli | |
| 283175647 | chromatin | threadlike DNA | |
| 283175648 | chromosome | condensed DNA forms at cell division | |
| 283175649 | histones | coil DNA into nucleosomes - very organized | |
| 283175650 | ribosomes | made in the nucleolus from RNA and proteins; subunits - 60S & 40S move across nuclear envelope into cytoplasm (combine as 80S in cytoplasm) | |
| 283175651 | free ribosomes | found in cytosol; make proteins for use in cytosol | |
| 283175652 | bound ribosomes | on rough ER; make proteins for membranes, organelles, or export | |
| 283175653 | rough endoplasmic reticulum | has ribosomes; makes secretory proteins and membranes components | |
| 283175654 | smooth endoplasmic reticulum | no ribosomes; makes lipids (including steroid hormones); in liver, breakdowns toxins from cell reactions and drugs | |
| 283175655 | golgi bodies | flattened sacs arranged like bowls; make polysaccharides; modify and package proteins, lipids & polysaccharides into vesicles | |
| 283175656 | lysosome | membranous sac of hydrolytic enzymes; break down food, cellular debris & foreign invaders; recycle organelles; numerous in single cell eukaryotes and white blood cells; membrane prevents cell from digesting itself | |
| 283175657 | peroxisomes | enzymatically transfers H from toxins to oxygen forming H2O2; enzymatically converts H2O2 (toxic)→ H2O; found in liver & kidney (both break down toxins); split in two when get too large | |
| 283175658 | microtubules | tubulin (protein) polymers; in spindle apparatus (guides chromosomes during cell division); in flagella and cilia (locomotion) | |
| 283175659 | intermediate filaments | support cell shape | |
| 283175660 | microfilaments | actin (protein); cell motility; for phagocytes, cleavage furrows, and muscle cell contraction | |
| 283175661 | mitochondria | carry out cellular (aerobic) respiration; two membranes; folded inner membrane (cristae); contains own DNA and ribosomes & can self-replicate | |
| 283175662 | endosymbiotic theory | large eukaryote or prokaryote engulfed small prokaryotes; small prokaryotes became mitochondria and/or chloroplasts | |
| 283175663 | flagella | long and few microtubules in 9 + 2 array | |
| 283175664 | cilia | short and many microtubules in 9 + 2 array | |
| 283175665 | thylakoid | interconnected internal sacs stacked into grana | |
| 283175666 | stroma | fluid outside thylakoid but inside inner membrane | |
| 283175667 | chloroplast | carries out photosynthesis; has its own DNA and ribosomes and can self replicate | |
| 283175668 | centrosome | just outside the nuclear envelope; microtubules of spindle apparatus form here during cell division; centrioles located here may play a role in organizing microtubules | |
| 283175669 | basal bodies | at base of each flagellum and cilium; appear to organize development of flagellum and cilium | |
| 283175670 | cell wall | found in plants, fungi, protists and bacteria; develop in plasma membrane; supports cell | |
| 283175671 | food vacuoles | receptacles of nutrients | |
| 283175672 | central vacuoles | large bodies in plant cells; decreases the volume of cytoplasm; increases surface to cytosol ration; when filled, exert turgor pressure on cell walls; mainly cell rigidity; stores nutrients, pigments, inorganic ions; carry out similar functions of lysosomes in animal cells | |
| 283175673 | contractile vacuoles | in single celled organisms; pump water in and out to maintain water balance | |
| 283175674 | plasmodesmata | cell connection in plants; channels that perforate cell walls; cytosol contents pass from one cell to next; creates one living continuum in plant | |
| 283175675 | desmosomes | cell connection in animals; protein (keratin) attachment between adjacent animal cells; function like rivets, holds tissues that are stressed together | |
| 283175676 | tight junctions | tightly stitch adjacent cells together; prevent fluid from leaking between cells | |
| 283175677 | gap junctions | narrow tunnels between cells; allow communication between cells through material exchange or electrical impulses | |
| 283175678 | photosynthesis | purpose: converting light energy to chemical bond energy; light + 6H2O + 6 CO2 -> C6H12O6 + 6 O2 | |
| 283175679 | chloroplast | absorbs sunlight for photosynthesis; found in mesophyll cells in interior of leaf; contain chlorophyll | |
| 283175680 | chlorophyll | pigment molecules; absorbs every light wavelength except the color you can see; made of chlorophyll a, chlorphyll b, and carotenoids | |
| 283175681 | thylakoids | contain light-absorbing pigments and enzymes for light-dependant rxn; stack forms a granum | |
| 283175682 | stomata | microscopic pores in leaf where CO2 and O2 are exchanged | |
| 283175683 | photophosphorylation | using photons to phosphorylate ADP into ATP via proton gradient | |
| 283175684 | photorespiration | occurs when O2 is too high and CO2 is too low | |
| 283175685 | respiration | extracting energy from glucose to form ATP; C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy | |
| 283175686 | oxidative phosphorylation | using oxygen to phosphoralate ADP into ATP | |
| 283175687 | cristae | inner foldings of inner mitochondrial membrane; increase surface area; separate matrix from intermembrane space of mitochondria | |
| 283175688 | genome | genetic material in nucleus | |
| 283175689 | interphase | DNA replicates; cell growth after mitotic phase - accounts for 90% of cell cycle; chromatin enclosed in nuclear envelope; within nucleus, one or more nucleoli visible; outside nucleus, centrosomes replicate | |
| 283175690 | nuclear division | divides genetic material in nucleus | |
| 283175691 | mitosis | divides nucleus so both daughter cells are genetically identical | |
| 283175692 | meiosis | reduction division; produces daughter cells with ½ genetic information of the parent cell | |
| 283175693 | cytokinesis | divides cytoplasm; forms two separate plasma membranes | |
| 283175694 | density dependent inhibition | crowded cells stop dividing; some cells may lose contact inhibition and divide uncontrollably (cancer) | |
| 283175695 | cell senescence | limits the number of times a cell divides | |
| 283175696 | asexual reproduction | uses mitosis to produce clone | |
| 283175697 | sexual reproduction | produces genetically distinct offspring | |
| 283175698 | diploid cell (2n) | two copies of every chromosome - homologous chromosomes; one homologue from maternal parent, one from parental; 46 chromosomes; 23 homologous pairs | |
| 283175699 | synapsis | pairing of homologous chromosomes | |
| 283175700 | tetrad | group of four chromatids | |
| 283175701 | chiasmata | criss crossed chromatids of homologous chromosomes | |
| 283175702 | crossing over | exchange of genetic material at the chiasmata | |
| 283175703 | synaptonemal complex | protein structure that binds homologs together | |
| 283175704 | fertilization | fusion of egg and sperm | |
| 283175705 | zygote | diploid cell, result of fertilization | |
| 283175706 | dominant allele | trait coded is trait expressed | |
| 283175707 | recessive allele | trait coded not always expressed | |
| 283175708 | homozygous recessive | two recessive alleles inherited (pp); recessive trait expressed | |
| 283175709 | heterozygous | two inherited alleles are different (Pp); only dominant allele is expressed | |
| 283175710 | true breeding | plants produce offspring of same variety when self-pollinate; can never be heterozygous | |
| 283175711 | law of segregation | alleles segregate during meiosis | |
| 283175712 | law of independent assortment | homologous chromosomes segregate independently; produces mix of maternal and paternal chromosomes in gametes | |
| 283175713 | monohybrid | heterozygous for only one trait | |
| 283175714 | incomplete dominance | combined expression of two different alleles in heterozygous condition; produce a blending of individual expressions | |
| 283175715 | co-dominance | both inherited alleles are completely expressed | |
| 283175716 | multiple alleles | genes that exist in populations in more than two allelic forms | |
| 283175717 | epistasis | one gene affects phenotypic expression of second gene | |
| 283175718 | pleiotrophy | single gene has more than one phenotypic expression | |
| 283175719 | polygenic inheritance | interaction of many genes shapes a single phenotype | |
| 283175720 | linked genes | genes close together on same chromosome; cannot segregate independently | |
| 283175721 | autosomes | chromosomes not directly involved in determining sex | |
| 283175722 | sex chromosomes | responsible for determining sex | |
| 283175723 | nondisjunction | chromosomes don't separate properly during meiosis; both homologous chromosomes migrate to the same pole; missing a chromosome | |
| 283175724 | deletions | chromosomal segment deleted | |
| 283175725 | duplication | chromosome segment duplicated | |
| 283175726 | translocation | segment moved from one chromosome to another | |
| 283175727 | inversion | segment reverses itself within a chromosome | |
| 283175728 | nucleosome | chromatin (DNA) coiled around 8 or 9 histone proteins | |
| 283175729 | euchromatin | nucleosomes loosely together; DNA is being actively transcribed | |
| 283175730 | heterochromatin | nucleosomes tightly compacted; DNA is inactive | |
| 283175731 | origins of replication | where two DNA strands separate; form replication bubbles; special nucleotide sequences | |
| 283175732 | helicase | enzyme that unwinds the DNA helix | |
| 283175733 | replication fork | the y-shaped region where new DNA strands elongate | |
| 283175734 | topoisomerase | group of enzymes that break and rejoin the double helix; allows twists to unravel; prevents knotting | |
| 283175735 | single stranded DNA binding proteins | stabilize DNA that is unwound and keep them apart | |
| 283175736 | telomerase | enzyme catalyzes lengthening of telomeres in germ (stem) cells | |
| 283175737 | codon | three adjacent nucleotides on mRNA that codes on an amino acid | |
| 283175738 | transcription factors | collection of proteins that recognize the promotor region (TATA box) | |
| 283175739 | exons | sequences that express polypeptide code | |
| 283175740 | introns | non-coding sequences, will be removed | |
| 283175741 | anticodon | triplet of nucleotides; pairs with mRNA codon to attach amino acid |
