| 556682684 | Heredity | Transmission of traits from one generation to the next | |
| 556682685 | Variation | Differences between members of the same species | |
| 556682686 | Genetics | Scientific study of heredity and heredity variation | |
| 556682687 | Genes | Coded information in the from of hereditary units | |
| 556682688 | Gametes | Things that transmit genes from one generation to the next | |
| 556682689 | Locus | Gene's specific location along the length of a chromosome | |
| 556682690 | Asexual reproduction | Single individual is the sole parent and passes copies of all genes to offspring without fusion of gametes | |
| 556682691 | Clone | Asexual reproduction; a group of genetically identical individuals | |
| 556682692 | Sexual Reproduction | 2 parents give rise to offspring that have unique combinations of genes inherited from the two parents | |
| 556682693 | Life Cycle | Generation to generation sequence of stages in the reproductive history of an organism from conception to production of its own offspring | |
| 556682694 | Karyotype | A display of the chromosome pairs of a cell arranged by size and shape | |
| 556682695 | Homologous chromosomes | 2 chromosomes consisting a pair of karyotypes of the same length, centromere position, and staining pattern | |
| 556682696 | Sex chromosomes | X and Y chromosomes | |
| 556682697 | Autosomes | Chromosomes that are not sex related | |
| 556682698 | Diploid cell | Any cell with two chromosome sets; 2n; body cells | |
| 556682699 | Haploid cell | Sex cells in gametes. Single set of chromosomes | |
| 556682700 | Fertilization | union of gametes, culminating in fusion of nuclei | |
| 556682701 | Zygote | Fertilized egg- diploid, 2 hapolid sets of chromosomes | |
| 556682702 | Meiosis | Cell division for sex cells (gametes) | |
| 556682703 | Alternation of generations | A life cycle in there is both a multicellular diploid form, the sporophyte and a multicellular haploid form, the gametophyte; characteristic of plants and some algea | |
| 556682704 | Meiosis I | First division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets | |
| 556682705 | Meiosis II | The second division of a two stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets | |
| 556682706 | Prophase I | Chromosomes condense.
Homologs loosely pair along lengths, aligned gene to gene.
Paired homologs go through synapsis.
Crossing over begins during pairing and synapotonemal complex formation, and is completed while homologs are in synapsis. | |
| 556682707 | Synapsis | Paired homologs become physically connected to each other along their lengths by a zipper-like protein structure. | |
| 556682708 | Later in Prophase 1 | Synapsis ends with disassembly of the synaptonmal complex in mid-prophase.
Chromosomes in each pair move slightly apart.
Each homologous pair has one or more chiasmata that exists the point where a crossover occured.
It appears as a cross because sister chromatid cohesion still holds the two original sister chromatids together, even in regions beyond the crossover point, where one chromatid is now pat of the other homolog. | |
| 556682709 | Latest in Prophase 1 | Microtubules from one pole or the other attach to two kinetochores, protein structures at the centromeres of the two homologs.
Homologous pairs move toward metaphase plate | |
| 556682710 | Metaphase 1 | Pairs of homologous chromosomes are now arranged at metaphase plate, with one chromosome in each pair facing each pole.
Both chromatids are attached to kinetochore microtubules from one pole; those of the other homolog are attached to microtubules from the opposite pole | |
| 556682711 | Crossing over | A genetic rearrangement from non sister chromatids involving the exchange of corresponding segments of DNA molecules | |
| 556682712 | Chiasmata | X-shaped region, that exists where crossovers occur | |
| 556682713 | Anaphase I | Breakdown of proteins responsible for sister chromatid cohesion along chromatid arms allows homologs to separate.
Homologs move toward opposite poles, guided by the spindle apparatus
Sister chromatid cohesion persists at the centromere, chromatids move as a unit toward the same pole | |
| 556682714 | Telophase 1 and Cytokinesis | At the beginning, each half of the cell has a complete haploid set of duplicated chromosomes.
Each chromosome is composed of two sister chromatids
One or both chromatids include regions of nonsister chromatid DNA
Cytokinesis occurs with telophase 1, forming two haploid daughter cells
In animal cells like these, a cleavage furrow forms (animal cells) cell plate forms (plant cells)
Chromosomes decondense and nuclear envelope forms
No chromosome duplication occurs between meiosis I and meiosis II | |
| 556682715 | Prophase II | Spindle Apparatus forms
In late Prophase II, chromosomes each still composed of 2 chromatids associated at centromere, more toward the metaphase II plate | |
| 556682716 | Metaphase II | Chromosome are positioned at the metaphase plate as in mitosis.
Because of crossing over in meiosis I, the 2 sister chromatids of each chromosomes are not genetically identical.
The kinetochores of sister chromatids are attached to microtubules extending from opposite poles. | |
| 556682717 | Anaphase II | Breakdown of proteins holding the sister chromatids together at the centromere allows the chromatids to separate. The chromatids move toward opposite poles as individual chromosomes | |
| 556682718 | Telophase II and Cytokinesis | Nuclei form, the chromosomes begin decondensing, and cytokinesis occurs.
Meiotic division of one parent cell produces four daughter cells, each with a haploid set of (unduplicated) chromosomes.
The four daughter cells are genetically distinct from one another and from the parent cell. | |
| 556682719 | DNA replication occurs... | Mitosis-During interphase before mitosis begins
Meiosis- During interphase before mitosis I begins | |
| 556682720 | Number of divisions... | Mitosis- 1, including prophase, prometaphase, metaphase, anaphase and telophase
Meiosis- 2, each including prophase, metaphase, anaphase and telophase | |
| 556682721 | Synapsis of homologous chromosomes... | Mitosis- Does not occur
Meiosis- Occurs during prophase I along with crossing over between nonsister chromatids; resulting chiasmata hold pairs together due to sister chromatid cohesion | |
| 556682722 | Number of daughter cells and generic composition... | Mitosis- Two, each diploid and genetically identical to the parent cell
Meiosis- Four, each haploid, containing half as many chromosomes as the parent cell;; genetically different from the parent cell and from each other | |
| 556682723 | Role in animal body... | Mitosis- Enables multicelluar adult to arise from zygote; produces cell for growth, repair, and in some species, asexual reproduction
Meiosis- Produces gametes, reduces number of chromosomes sets by half and introduces genetic variability among the gametes | |
| 556682724 | Recombinant chromosomes | individual chromosomes that carry genes (DNA) derived from two different parents | |
| 556682725 | Why do some species employ both mitosis and meiosis, whereas other species use only mitosis? | They need both if they are producing animal gametes. | |
| 556682726 | A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? | 92 | |
| 556682727 | Why is it difficult to observe individual chromosomes with a light microscope during interphase? | They have uncoiled to form long, thin strands. | |
| 556682728 | Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? | 32 | |
| 556682729 | Nucleoli are present during _____. | Interphase | |
| 556682730 | Cytokinesis often, but not always, accompanies _____. | Telophase | |
| 556682731 | Chromosomes become visible during _____. | Prophase | |
| 556682732 | Centromeres divide and sister chromatids become full-fledged chromosomes during _____. | Anaphase | |
| 556682733 | Spindle fibers attach to kinetochores during _____. | Prometaphase | |
| 556682734 | When the separate chromosomes are being pulled from one place to another? This animation illustrates the events of _____. | Anaphase | |
| 556682735 | When the two "circular" cells attached become sister cells? This animation illustrates the events of _____. | Cytokinesis as it occurs in Animal Cells | |
| 556682736 | When the chromosomes become visible? This animation illustrates the events of _____. | Prophase | |
| 556682737 | When chromosomes align laterally (along the metaphase plate: imaginary line located midway between the poles of the duplicated chromosomes and the original chromosomes), before they separate. This animation illustrates the events of _____. | Metaphase | |
| 556682738 | When the chromosomes break the nuclear envelope, and attach to microtubules | Prometaphase | |
| 556682739 | When the two "square" cells attached become sister cells? This animation illustrates the events of _____. | Cytokinesis as it occurs in Plant Cells | |
| 556682740 | When the sister cells are completely divided through Cytokinesis. This animation illustrates the events of _____. | Telophase | |
| 556682741 | During prophase a homologous pair of chromosomes consists of _____. | Two (2) chromosomes and Four (4) Chromatids | |
| 556682742 | Cell division occurs during this short phase, which generally involves two discrete processes: the contents of the nucleus (mainly the duplicated chromosomes) are evenly distributed to two daughter nuclei, and the cytoplasm divides in two. | Mitotic Phase | |
| 556682743 | DNA synthesis (or replication) occurs during this phase. At the beginning of the phase, each chromosome is single. At the end, after DNA replication, each chromosome consists of two sister chromatids. | S Phase | |
| 556682744 | Typically, this phase accounts for 90% of the cell cycle. It is a time of high metabolic activity. The cell grows by producing proteins and organelles, and chromosomes are replicated. | Interphase | |
| 556682745 | This is when division of the nucleus occurs. The chromosomes that have been replicated are distributed to two daughter nuclei. | Mitosis | |
| 556682746 | This third subphase of interphase is a period of metabolic activity and growth. During this phase the cell makes final preparations for division. | G2 Phase | |
| 556682747 | This is the portion of the cell cycle just after division, but before DNA synthesis. During this time the cell grows by producing proteins and organelles. | G1 Phase | |
| 556682748 | This is the step in the cell cycle when the cytoplasm divides in two. | Cytokinesis | |
| 556682749 | During _____ both the contents of the nucleus and the cytoplasm are divided. | The Mitotic Phase: The Mitotic Phase encompasses both Mitosis and Cytokinesis! | |
| 556682750 | During _____ the cell grows and replicates both its organelles and its chromosomes. | Interphase | |
| 556682751 | Which of the following is true of kinetochores? | They are sites at which microtubules attach to chromosomes. | |
| 556682752 | Which of the following correctly matches a phase of the cell cycle with its description? | G1: follows cell division | |
| 556682753 | In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? | Large cells containing many nuclei. | |
| 556682754 | Which of the following is found in binary fission but not in mitosis? | Duplicated chromosomes attach to the plasma membrane. | |
| 556682755 | Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? | cleavage | |
| 556682756 | Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? | G1 | |
| 556682757 | Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? | They remain confined to their original site | |
| 556682758 | Which of the following is a function of the S phase in the cell cycle? | The synthesis of sister chromatids | |
| 556682759 | The copying of chromosomes occurs during which of the following phases of the cell cycle? | S Phase | |
| 556682760 | For the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to M without gaps. Which of the following is likely to be true about dividing cells in early frog embryos? | The cells get smaller with each generation | |
| 556682761 | True or false? The M phase is characterized by the replication and division of a cell's chromosomes. | False: Cells replicate their chromosomes during the S phase and divide partition their chromosomes during the M phase. | |
| 556682762 | If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle? | 34 | |
| 556682763 | Which of the following events would cause the cell cycle to arrest? | Poor nutrition conditions | |
| 556682764 | DNA replication produces two identical DNA molecules called ______, which separates during mitosis. | Sister Chromatids | |
| 556682765 | After chromosomes condense, the ______ is the region where the identical DNA molecules are most tightly attached to each other | Centromere | |
| 556682766 | During Mitosis, microtubules attach to chromosomes at the _______. | Kinetochore | |
| 556682767 | In dividing cells, most of the cell's growth occurs during ______. | Interphase | |
| 556682768 | The ____________ is a cell structure consising of microtubules, which forms during early mitosis and plays a role in cell division | Mitotic Spindle | |
| 556682769 | During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called _______. | Chromatin | |
| 556682770 | In most eukaryotes, division of the nucleus is followed by ________, when the rest of the cell divides. | Cytokinesis | |
| 556682771 | The ________ are the organzing centers for mcrotubules involed in seperatng chromasomes during mitosis | Centrosomes | |
| 556682772 | Which of the following statements are true of cytokinesis in plant cells? Two that apply. | 1. Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
2. The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. | |
| 556682773 | Which species does this apply to? The cells divide by constriction of a ring protein. (2 apply) | Bacteria & Animal | |
| 556682774 | Which species does this apply to? The presence of a cell wall prevents the cell from dividing by constriction. (1 apply) | Plants | |
| 556682775 | Which species does this apply to? Tubulin subunits or tubulin-like molecules function in the division of the cell. (2 apply) | Bacteria & Plants | |
| 556682776 | A mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor's origin. | Benign Tumor | |
| 556682777 | A method of asexual reproduction by "division in half." In prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process. | Binary Fission | |
| 556682778 | (1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer. | Transformation | |
| 556682779 | A cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading and surviving in new sites. Malignant tumors can impair the functions of one or more organs. | Malignant Tumor | |
| 556682780 | An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located. | Metaphase Plate | |
| 556682781 | The spread of cancer cells to locations distant from their original site. | Metastasis | |
| 556682782 | Any cell in a multicellular organism except a sperm or egg or their precursors. | Somatic Cell | |
| 556682783 | One difference between cancer cells and normal cells is that cancer cells.... | continue to divide even when they are tightly packed together. | |
| 556682784 | operator | region of DNA that controls RNA polymerase's access to a set of genes with related functions | |
| 556682785 | operon | a unit of genetic function found in bacteria and phages, consisting of a promoter, an operator, and a coordinately regulated cluster of genes whose products function in a common pathway. | |
| 556682786 | repressor | protein that binds to the operator in an operon to switch off transcription | |
| 556682787 | corepressor | a small molecule that cooperates with a repressor protein to switch an operon off | |
| 556682788 | regulatory gene | A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes. | |
| 556682789 | inducer | A specific small molecule that inactivates the repressor in an operon. | |
| 556682790 | cAMP | is a second messenger important in many biological processes. is derived from adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway. | |
| 556682791 | activator | A protein that binds to DNA and stimulates transcription of a specific gene. | |
| 556682792 | lac operon | a gene system whose operator gene and three structural genes control lactose metabolism in E. coli | |
| 556682793 | differential gene expression | The expression of different sets of genes by cells with the same genome. | |
| 556682794 | histone acetylation | the attachment of acetyl groups (-COCH3) to certain amino acids of histone proteins, the chromatin becomes less compact, and the DNA is accessible for transcription | |
| 556682795 | DNA methylation | The addition of methyl groups (—CH3) to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression. | |
| 556682796 | epigenetic inheritance | Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence. | |
| 556682797 | control elements | segments of noncoding DNA that help regulate transcription by binding certain proteins | |
| 556682798 | enhancers | A DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes. | |
| 556682799 | alternative RNA splicing | in which different mRNA molecules
are produced from the same primary transcript, depending
on which RNA segments are treated as exons and
which as introns | |
| 556682800 | proteasomes | a giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin | |
| 556682801 | miRNA | a class of functional RNA that regulates the amount of protein produced by a eukaryotic gene | |
| 556682802 | RNAi | a way of assessing the function of a gene by introducing special transgenic constructs to inactivate its mRNA | |
| 556682803 | siRNA | class of double-stranded RNAs about 23 nucleotides in length that silence gene expression; act by either promoting the degradation of mRNAs with precisely complementary sequences or by inhibiting the transcription of genes containing precisely complementary sequences | |
| 556682804 | cytoplasmic determinants | The maternal substances in the egg that influence the course of early development by regulating the expression of genes that affect the developmental fate of cells. | |
| 556682805 | differentiation | change in structure and function of a cell as it matures; specialization | |
| 556682806 | morphogen | A substance governing the pattern of tissue development and, in particular, the positions of the various specialized cell types within a tissue. It spreads from a localized source and forms a concentration gradient across a developing tissue. | |
| 556682807 | induction | The process in which one group of embryonic cells influences the development of another, usually by causing changes in gene expression. | |
| 556682808 | determination | The point during development at which a cell becomes committed to a particular fate (sensory, other, etc.). Note that the cell is not differentiated at this point; determination comes before differentiation. Determination can be due to cytoplasmic effects or to induction by neighboring cells. | |
| 556682809 | pattern formation | The development of a multicellular organism's spatial organization, the arrangement of organs and tissues in their characteristic places in three-dimensional space. | |
| 556682810 | positional information | Signals to which genes regulating development respond, indicating a cell's location relative to other cells in an embryonic structure. | |
| 556682811 | embryonic lethals | Mutations with phenotypes leading to death at the embryo or larval stage. | |
| 556682812 | homeotic genes | Any of the genes that control the overall body plan of animals by controlling the developmental fate of groups of cells. | |
| 556682813 | maternal effect genes | A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the genotype. | |
| 556682814 | bicoid | A maternal effect gene that codes for a protein responsible for specifying the anterior end in Drosophila. | |
| 556682815 | egg polarity genes | Another name for maternal effect genes, these genes control the orientation (polarity) of the egg, one group sets up the anterior posterior axis, while the other sets up the dorsal ventrtal axis. | |
| 556682816 | morphogenesis | development of body form and organization | |
| 556682817 | oncogenes | genes that cause cancer by blocking the normal controls on cell reproduction | |
| 556682818 | proto-oncogenes | normal cellular genes that are important regulators of normal cellular processes, they promote growth. alterations in the expression of these cells resulr in oncogenes | |
| 556682819 | ras gene | This gene codes for Ras protein, a G protein that relays a growth signal from a growth-factor receptor on the plasma membrane to a cascade of protein kinases that ultimately results in the stimulation of the cell cycle. Many ras oncogenes have a point mutation that leads to a hyperactive version of the Ras protein that can lead to excessive cell division. | |
| 556682820 | p53 gene | The "guardian angel of the genome," p53 is expressed when a cell's DNA is damaged. Its product, p53 protein, functions as a transcription factor for several genes. | |
| 556682821 | tumor suppressor genes | Genes which code for proteins that suppress tumor formation by applying brakes on cell proliferation. (mutation that creates a deficiency would contribute to carcinogenesis) | |
| 556682822 | gene expression | the process by which DNA directs the synthesis of proteins
(or, in some cases, just RNAs) | |
| 556682823 | transcription | synthesis of an RNA molecule from a DNA template | |
| 556682824 | primary transcript | the initial RNA transcript from any gene, including those specifying RNA that is not translated into protein | |
| 556682825 | mRNA | messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome | |
| 556682826 | translation | The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule | |
| 556682827 | ribosomes | The sites of translation, complex particles that facilitate the orderly linking of amino acids into polypeptide chains. | |
| 556682828 | triplet code | 3 bases of DNA that code for a single amino acid | |
| 556682829 | codons | mRNA base triplets | |
| 556682830 | template strand | The DNA strand that provides the template for ordering the sequence of nucleotides in an RNA transcript. | |
| 556682831 | reading frame | the way a cell's mRNA-translating machinery groups the mRNA nucleotides into codons | |
| 556682832 | RNA polymerase | pries the two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand, thus elongating the RNA polynucleotide | |
| 556682833 | promoter | The DNA sequence where RNA polymerase attaches and initiates transcription | |
| 556682834 | terminator | In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene. It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene. | |
| 556682835 | transcription unit | the stretch of DNA that is transcribed into an RNA molecule | |
| 556682836 | start point | nucleotide where RNA synthesis actually begins | |
| 556682837 | transcription factors | in eukaryotes, a collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription | |
| 556682838 | transcription initiation complex | the whole complex of transcription factors and RNA polymerase II bound to the promoter | |
| 556682839 | TATA box | A promoter DNA sequence crucial in forming the transcription initiation complex., a DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex (the transcription factors recognize this); "tells RNA pol where to land" | |
| 556682840 | 5' cap | a methylated guanine nucleotide added to the 5' end of eukaryotic mRNA | |
| 556682841 | poly-A tail | The modified end of the 3' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides. | |
| 556682842 | RNA splicing | process by which the introns are removed from RNA transcripts and the remaining exons are joined together | |
| 556682843 | introns | a non-coding, intervening sequence within a eukaryotic gene | |
| 556682844 | exons | expressed sequence of DNA; codes for a protein | |
| 556682845 | spliceosome | A complex assembly that interacts with the ends of an RNA intron in splicing RNA, releasing the intron and joining the two adjacent exons. | |
| 556682846 | ribozymes | An enzymatic RNA molecule that catalyzes reactions during RNA splicing. | |
| 556682847 | domains | modular architecture on proteins consisting of discrete structural and functional regions | |
| 556682848 | alternative RNA splicing | A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns | |
| 556682849 | aminoacyl-tRNA synthetases | an enzyme that joins each amino acid to the appropriate tRNA | |
| 556682850 | tRNA | short-chain RNA molecules present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesized at the ribosome of the cell (according | |
| 556682851 | anticodon | group of three bases on a tRNA molecule that are complementary to an mRNA codon | |
| 556682852 | wobble | flexibility in the base-pairing rules in which the nucleotide at the 5' end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3' end) of a codon | |
| 556682853 | rRNA | The most abundant type of RNA, which together with proteins froms the structure of ribosomes. Ribosomes coordinate the sequential coupling of tRNA molecules to mRNA codons | |
| 556682854 | P site | holds the tRNA carrying the growing polypeptide chain. | |
| 556682855 | A site | holds the tRNA carrying the next amino acid to be added to the chain | |
| 556682856 | E site | This site is the place where discharged tRNAs leave the ribosome. | |
| 556682857 | polyribosomes | An aggregation of several ribosomes attached to one messenger RNA molecule. | |
| 556682858 | signal recognition particle | binds to the signal sequence and the ribosomal subunits and transports the complex to the ER | |
| 556682859 | signal peptide | A stretch of amino acids on a polypeptide that targets the protein to a specific destination in a eukaryotic cell. | |
| 556682860 | nucleotide-pair substitution | A type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides. | |
| 556682861 | mutation | change in a DNA sequence that affects genetic information | |
| 556682862 | silent mutation | A mutation that changes a single nucleotide, but does not change the amino acid created. | |
| 556682863 | nonsense mutation | A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein. | |
| 556682864 | missense mutation | The most common type of mutation, a base-pair substitution in which the new codon makes sense in that it still codes for an amino acid. | |
| 556682865 | point mutation | mutation that affects a single nucleotide, usually by substituting one nucleotide for another | |
| 556682866 | insertion | A mutation involving the addition of one or more nucleotide pairs to a gene. | |
| 556682867 | deletion | The loss of one or more nucleotides from a gene by mutation; the loss of a fragment of a chromosome | |
| 556682868 | frameshift mutation | mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide | |
| 556682869 | mutagen | any agent (physical or environmental) that can induce a genetic mutation or can increase the rate of mutation | |
| 556682870 | DNA replication | the process of making a copy of DNA | |
| 556682871 | transformation | the transfer of genetic material in the form of DNA fragments from one cell to another or from one organism to another | |
| 556682872 | bacteriophage | a virus that infects bacteria | |
| 556682873 | virus | ultramicroscopic infectious agent that replicates itself only within cells of living hosts | |
| 556682874 | double helix | two strands of nucleotides wound about each other; structure of DNA | |
| 556682875 | antiparallel | The opposite arrangement of the sugar-phosphate backbones in a DNA double helix. | |
| 556682876 | semiconservative | method of replication that implies that each new strand of DNA is half original and half new | |
| 556682877 | origin of replication | Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides. | |
| 556682878 | replication fork | A Y-shaped region on a replicating DNA molecule where new strands are growing. | |
| 556682879 | helicase | an enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands | |
| 556682880 | single strand binding proteins | Proteins that bind to and stabilize the signle strands of DNA exposed when helicase unwinds the double helix in preparation for replication. | |
| 556682881 | topoisomerase | A protein that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork. | |
| 556682882 | primer | An already existing RNA chain bound to template DNA to which DNA nucleotides are added during DNA synthesis., a short segment of DNA that serves as the starting point for DNA synthesis | |
| 556682883 | primase | An enzyme that joins RNA nucleotides to make the primer. | |
| 556682884 | DNA polymerase | enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule | |
| 556682885 | leading strand | the new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' --> 3' direction | |
| 556682886 | lagging strand | A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork. | |
| 556682887 | okazaki fragments | Short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication. | |
| 556682888 | DNA ligase | an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments | |
| 556682889 | mismatch repair | The cellular process that uses special enzymes to fix incorrectly paired nucleotides. | |
| 556682890 | nuclease | An enzyme that hydrolyzes DNA and RNA into their component nucleotides. | |
| 556682891 | nucleotide excision repair | The process of removing and then correctly replacing a damaged segment of DNA using the undamaged strand as a guide. | |
| 556682892 | telomeres | Repeated DNA sequences at the ends of eukaryotic chromosomes. | |
| 556682893 | telomerase | An enzyme that catalyzes the lengthening of telomeres. The enzyme includes a molecule of RNA that serves as a template for new telomere segments. | |
| 556682894 | histones | protein molecules around which DNA is tightly coiled in chromatin | |
| 556682895 | nucleosomes | bead-like structures formed by histones and DNA, 10nm | |
| 556682896 | nucleoid | A dense region of DNA in a prokaryotic cell. | |
| 556682897 | chromatin | long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes | |
| 556682898 | 30nm fiber | nucleosomes associate with each other to form a more compact structure - results from interactions between adjacent histone H1 proteins | |
| 556682899 | looped domains | 30-nm fiber forms loops that attach to a protein chromosome scaffold, making up a 300-nm fiber | |
| 556682900 | heterochromatin | Nontranscribed eukaryotic chromatin that is so highly compacted that it is visible with a light microscope during interphase | |
| 556682901 | euchromatin | a region of DNA that is uncoiled and undergoing active transcription into RNA | |
