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| 7913431517 | Hershey-Chase Experiment | Experiment that showed that only the DNA enters a bacterial cell during infection, not protein by using radioactive S and P. |  | 0 |
| 7913431518 | Frederick Griffith | This person discovered transformation during an experiment that involved injecting mice with smooth S cells, rough R cells, heat-killed S cells, and heat-killed S cells with living R cells. |  | 1 |
| 7913431519 | Erwin Chargaff | Discovered that DNA composition varies, but the amount of adenine is always the same as thymine and the amount of cytosine is always the same as guanine. |  | 2 |
| 7913431520 | Avery, MacLeod, McCarty | Determined that DNA was Griffith's "Transforming Factor." |  | 3 |
| 7913431521 | Rosalind Franklin | Used X-ray diffraction to discover the double-helical structure of DNA. |  | 4 |
| 7913431522 | Watson and Crick | Developed the double helix model of DNA. |  | 5 |
| 7913431523 | nucleic acid | An organic compound, either RNA or DNA, whose molecules are made up of one or two chains of nucleotides and carry genetic information. |  | 6 |
| 7913431524 | nucleotide | Monomer of nucleic acids made up of a sugar, phosphate, base |  | 7 |
| 7913431525 | purines | Nitrogenous bases that have a double ring structure (AG) |  | 8 |
| 7913431526 | pyrimidines | Nitrogenous bases that have a single ring structure (CT) |  | 9 |
| 7913431527 | antiparallel | The opposite arrangement of the sugar-phosphate backbones in a DNA double helix. |  | 10 |
| 7913431528 | phosphodiester bond | Strong covalent bond linking the sugar in one nucleotide to the phosphate of another. (BACKBONE SEALER!) |  | 11 |
| 7913431529 | DNA replication | The process whereby DNA makes a copy of itself prior to cell division. |  | 12 |
| 7913431530 | 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. |  | 13 |
| 7913431531 | DNA polymerase | DNA replication enzyme that adds nucleotides in the 5 to 3 (as it reads in the 3 to 5) |  | 14 |
| 7913431532 | transcription | Synthesis of an RNA molecule from a DNA template. |  | 15 |
| 7913431533 | lagging strand | A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork. |  | 16 |
| 7913431534 | leading strand | The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction. |  | 17 |
| 7913431535 | primase | An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template. |  | 18 |
| 7913431536 | messenger RNA (mRNA) | Carries genetic message from the DNA to he protein-synthesizing machinery of the cell. |  | 19 |
| 7913431537 | Okazaki fragments | Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand. |  | 20 |
| 7913431538 | DNA helicase | An enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands. |  | 21 |
| 7913431539 | translation | The synthesis of a polypeptide, which occurs under the direction of mRNA. |  | 22 |
| 7913431540 | RNA editing | The modification of mRNA before it leaves the nucleus that is unique to eukaryotes. |  | 23 |
| 7913431541 | codons | mRNA base triplets. |  | 24 |
| 7913431542 | RNA polymerase | Enzyme that links together the growing chain of ribonucleotides during transcription. |  | 25 |
| 7913431543 | promoter | A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing mRNA. |  | 26 |
| 7913431544 | TATA box | Crucial promoter DNA sequence. |  | 27 |
| 7913431545 | RNA splicing | Process by which the introns are removed from RNA transcripts and the remaining exons are joined together. |  | 28 |
| 7913431546 | introns | Noncoding segments of nucleic acid that lie between coding sequences. |  | 29 |
| 7913431547 | exons | Coding segments of eukaryotic DNA. |  | 30 |
| 7913431548 | transfer RNA (tRNA) | Interpreter of a series of codons along a mRNA molecule. |  | 31 |
| 7913431549 | ribosomal RNA (rRNA) | RNA molecules that construct ribosomal subunits. |  | 32 |
| 7913431550 | ribosomal P site | Site that holds tRNA carrying the growing polypeptide chain. (PEPTIDE) |  | 33 |
| 7913431551 | ribosomal A site | Site that holds the tRNA carrying the next amino acid to be added to the chain. (ADD) |  | 34 |
| 7913431552 | ribosomal E site | Site where discharged tRNAs leave the ribosome. (EXIT) |  | 35 |
| 7913431553 | transformation | A change in genotype and phenotype due to the assimilation of external DNA by a cell. |  | 36 |
| 7913431554 | gene expression | Conversion of the information encoded in a gene first into messenger RNA and then to a protein. |  | 37 |
| 7913431555 | recombinant DNA | A DNA molecule made in vitro with segments from different sources. |  | 38 |
| 7913431556 | restriction enzyme | A degradative enzyme that recognizes and cuts up DNA (including that of certain phages) that is foreign to a bacterium. |  | 39 |
| 7913431557 | DNA ligase | A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain. |  | 40 |
| 7913431558 | denaturation | In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix. |  | 41 |
| 7913431559 | polymerase chain reaction (PCR) | A technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and nucleotides. |  | 42 |
| 7913431560 | gel electrophoresis | The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel. |  | 43 |
| 7913431561 | plasmid | Small extra-chromosomal, double-stranded circular DNA molecules. |  | 44 |
| 7913431562 | RNA primer | Short segment of RNA used to initiate synthesis of a new strand of DNA during replication. |  | 45 |
| 7913431563 | reverse transcriptase | A polymerase that catalyzes the formation of DNA using RNA as a template. |  | 46 |
| 7913431564 | somatic cell | Any of the cells of a plant or animal except the reproductive cells. |  | 47 |
| 7913431565 | centromere | The region of the chromosome that holds the two sister chromatids together during mitosis. |  | 48 |
| 7913431566 | mitosis | Cell division in which the nucleus divides into nuclei containing the same number of chromosomes. |  | 49 |
| 7913431567 | interphase | Period of the cell cycle between cell divisions. |  | 50 |
| 7913431568 | S phase | The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated. | 51 | |
| 7913431569 | cancer | Disease that results from disruptions of cell cycle control. |  | 52 |
| 7913431570 | kinetochore microtubules | Connects the centrosome with the kinetochore in the centromere region of the chromosome. |  | 53 |
| 7913431571 | growth factors | Regulatory proteins that ensure that the events of cell division occur in the proper sequence and at the correct rate. |  | 54 |
| 7913431572 | allele | One of the alternative forms of a gene that governs a characteristic, such as hair color. |  | 55 |
| 7913431573 | crossing over | Nonsister chromatids exchanging DNA segments. |  | 56 |
| 7913431574 | diploid cell | Has two sets of chromosomes. |  | 57 |
| 7913431575 | fertilization | Union of gametes. |  | 58 |
| 7913431576 | gametes | A haploid cell such as an egg or sperm that unite during sexual reproduction to produce a diploid zygote. |  | 59 |
| 7913431577 | genes | Units of heredity made up of DNA. |  | 60 |
| 7913431578 | haploid | One set of chromosomes. |  | 61 |
| 7913431579 | homologous chromosomes | Pair of chromosomes that are the same size, same appearance and same genes. |  | 62 |
| 7913431580 | zygote | Fertilized egg; carries one set of chromosomes from each parent. |  | 63 |
| 7913431581 | law of independent assortment | The random distribution of the pairs of genes on different chromosomes to the gametes. |  | 64 |
| 7913431582 | law of segregation | Allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. Due to separation of homologous chromosomes in Meiosis I. | 65 | |
| 7913431583 | true-breeding | Organisms that, when reproducing, create offspring of all the same variety. |  | 66 |
| 7913431584 | hybridization | The crossing of two different true-breeding parents. |  | 67 |
| 7913431585 | dominant allele | An allele whose trait always shows up in the organism when the allele is present. |  | 68 |
| 7913431586 | recessive allele | An allele that is masked when a dominant allele is present |  | 69 |
| 7913431587 | homozygous | An organism having a pair of identical alleles for a character, either dominant or recessive. |  | 70 |
| 7913431588 | phenotype | An organism's traits. |  | 71 |
| 7913431589 | genotype | An organism's genetic makeup. |  | 72 |
| 7913431590 | codominance | When which the phenotypes of both alleles are exhibited in the heterozygote. |  | 73 |
| 7913431591 | incomplete dominance | Creates a blended phenotype; one allele is not completely dominant over the other. |  | 74 |
| 7913431592 | nondisjunction | A failure of paired homologous chromosomes to separate during meiosis which results in an abnormal chromosome number. |  | 75 |
| 7913431593 | linked genes | Genes located on the same chromosome that tend to be inherited together in genetic crosses. |  | 76 |
| 7913431594 | sex linked genes | Genes located on the sex chromosomes. |  | 77 |
| 7913431595 | operon | A unit of genetic function common in bacteria and phages, consisting of coordinately regulated clusters of genes with related functions. |  | 78 |
| 7913431596 | operator | Region of DNA that controls RNA polymerase's access to a set of genes with related functions. |  | 79 |
| 7913431597 | repressor | A protein that suppresses the transcription of a gene. |  | 80 |
| 7913431598 | Trp operon | An example of a repressible operon. |  | 81 |
| 7913431599 | Lac operon | An example of an inducible operon. |  | 82 |
| 7913431600 | transcription factors | Proteins that bind to specific DNA sequences or other regulatory proteins that promote or block RNA polymerase. |  | 83 |
| 7913431601 | hormones | Circulating chemical signals that are formed in specialized cells, travel in body fluids, and act on specific target cells. |  | 84 |
| 7913431602 | ligand | A molecule that specifically binds to another molecule, often a larger one. |  | 85 |
| 7913431603 | protein kinase | The enzyme that transfers phosphate groups from ATP to protein. |  | 86 |
| 7913431604 | reception | The target cell's detection of a signal molecule coming from outside the cell. |  | 87 |
| 7913431605 | transduction | The binding of the signal molecule changes the receptor protein in some way. |  | 88 |
| 7913431606 | response | The transduced signal finally triggers a specific cellular response. |  | 89 |
| 7913431607 | endocrine signaling | Type of cell signalling where signals released by one cell type can travel long distances to target cells of another cell type. |  | 90 |
| 7913431608 | cell body (soma) | Contains most of a neuron's organelles and its nucleus. |  | 91 |
| 7913431609 | dendrites | highly branched extensions that receive signals from other neurons |  | 92 |
| 7913431610 | axon | Long nerve fiber that conducts away from the cell body of the neuron. |  | 93 |
| 7913431611 | synapse | The junction between two neurons or between a neuron and a muscle. |  | 94 |
| 7913431612 | neurotransmitters | Chemical messengers that cross the synaptic gaps between neurons. |  | 95 |
| 7913431613 | membrane potential | The voltage across a cell's plasma membrane. |  | 96 |
| 7913431614 | resting potential | The membrane potential of a neuron that is at rest. |  | 97 |
| 7913431615 | depolarization | The process during the action potential when sodium is rushing into the cell causing the interior to become more positive. |  | 98 |
| 7913431616 | voltage-gated ion channels | Channels that open or close in response to a change in the membrane potential. |  | 99 |
| 7913431617 | action potential | A neural impulse; a brief electrical charge that travels down an axon. |  | 100 |
| 7913431618 | repolarization | Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell. |  | 101 |
| 7913431619 | threshold | The minimum membrane potential that must be reached in order for an action potential to be generated. |  | 102 |
| 7913431620 | myelin sheath | A layer of electrical insulation that surrounds the axon. |  | 103 |
| 7913431621 | sodium-potassium pump | a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell. |  | 104 |
| 7913431622 | point mutation | A mutation that affects a single nucleotide, usually by substituting one nucleotide for another. |  | 105 |
| 7913431623 | frameshift mutation | Mutation that shifts the "reading frame" of the genetic message by the insertion or deletion of a nucleotide. |  | 106 |
| 7913431624 | bacteriophage | A virus that infects and replicates within bacteria. |  | 107 |
| 7913431625 | lytic cycle | Viral life cycle in which the viral DNA exists as a separate molecule within the bacterial cell. Results in the destruction of the infected cell. |  | 108 |
| 7913431626 | lysogenic cycle | Viral life cycle characterized by integration of the viral nucleic acid into the host bacterium's genome. The viral genetic material can be transmitted to daughter cells. |  | 109 |
