Details Title: 151 Test 2 Description: just some vocab from book Total Flash Cards: 182 Created: 03/31/2009 16:30:16		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Biology Flashcards
Cards in this set: Term somatic cells Definition all cells except reproductive cells Term gamete Definition sperm or egg - haploid Term sister chromatids Definition contain exact same genetic info Term centromere Definition special region where cromatids are closely attached Term Mitosis Definition division of nucleus Term cytokinesis Definition division of cytoplasm Term meiosis Definition yields nonidentical haploid daughter cells Term mitotic (M) phase Definition includes mitosis and cytokinesis, shortest part of cell cycle Term interphase Definition 90% of cycle, longer stage, cell grows and cpis chromosomes Term G1 Definition cell growth Term S phase Definition copies chromosomes Term g2 Definition prepares for division Term centrosome Definition a subcellular region containing material that functions though-out the cell cycle to organize the cell's microtubules. Term aster Definition radical array of short microtubules that extends from each centrosome Term kinetochore Definition structural protein at centromere, used to pull apart Term cleavage Definition process by which cytokinesis occurs Term cleavage furrow Definition shallow groove in the cell surface near old metaphase plate Term cell cycle control system Definition cyclically operating set of molecules in the cell that both trigger and coordinate key events in the cell cycle Term checkpoint Definition control point where stop and go-ahead signals can regulate the cycle (G1, G2 and M) Term growth factor Definition a protein released by certain cells that stimulates other cells to divide Term transformation Definition process that converts normal cells to cancer cells Term benign tumors Definition lump of normal cells Term malignant tumor Definition invasive tumors that impair the function of one of more organs Term genes Definition unit of hereditary info coding for specific animo acid sequence Term locus Definition genes location along length of chromosome Term homologous chromosome Definition pair carrying genes controlling the same inherited characters Term autosomes Definition all chromosomes besides sex Term diploid Definition any cell with two chromosome sets Term haploid Definition has haploid number of chromosome Term zygote Definition fertilized egg Term alternation of generations Definition both diploid and haploid stages that are multicellular Term synapsis Definition homologous pairs line up and connected allowing crossing over Term chaisma Definition x-shaped region holding homologous together and limit crossing over Term recombinant chromosomes Definition indiviguals that carry genes from two different parents Term character Definition heritable feature that varies among individuals Term each variant for a character Definition Term hybridization Definition the mating of two true-breeding varieties Term p generation Definition parent generation Term F1 generation Definition first filial generation Term alleles Definition alternate versions of genes Term test cross Definition breeding of an unknown by an homo recessive Term mono hybrid Definition heterozygous for one character Term dihybrid Definition individuals heter for two characters Term incomplete dominance Definition offspring show a mixture of the two parent traits Term codominance Definition both alleles effect and are 'expressed' Term pleiotropy Definition have multiple phenotypic effects Term epistasis Definition gene at one locus alters phenotypic expression of a gene at second locus Term polygenic inheritance Definition effect of two or more genes on single phenotypic character Term multifactorial Definition environmental influence phenotypically Term wild type Definition most often observed in the natural population Term sex-linked gene Definition located on either sex chromosomes Term barr body Definition inactive X in females that lies along the inside of the nuclear envelope Term linked genes Definition genes located on the same chromosome Term genetic recombination Definition production of offspring with traits that different from parents Term linkage map Definition genetic map based on recombination frequencies Term map units Definition one recombination frequency Term nondisjunction Definition members of homologous pair do not move apart properly during meiosis 1 or 2 Term monosomic Definition 2n-1 Term trisomic Definition 2n+1 Term polyploidy Definition chromosome alteration Term deletion of chromosome Definition part of chromosome fragment is lost Term duplication Definition deletion added to another chromosome causing repeat in sequence Term inversion Definition chromosome fragment reattaches to original chromosome but in reverse order Term translocation Definition fragment joins to non-homologous chromosome Term genomic imprinting Definition variation in phenotype depending on who the allele was inherited from Term transformation Definition change in genotype and phenotype due to the assimilation of external DNA by a cell Term chargaffs rule Definition A-T C-G numbers simular Term purines Definition adenine and guanine - two organic rings Term pyrimidines Definition cytosine and thymine - one ring Term origins of replication Definition short stretches of DNA having a specific sequence of nucleotides Term replication fork Definition y-shaped region where the parental strands of of DNA are being unwound Term helicases Definition enzymes that untwist the double helix Term singe strand binding protein Definition bind to unpaired DNA to stabilize Term Topoisomerase Definition relieves winding strain by breaking, swiveling, and rejoining them Term DNA polymerase Definition catalyzes the synthesis of new DNA by adding nucleotides to preexisting chains Term leading strand Definition one primer is needed and then the replication is continuous Term lagging strand Definition moves away from replication fork in small segments Term Okazaki fragments Definition segments of lagging strand Term DNA ligase Definition joins Okazaki fragments Term DNA pol 3 Definition synthesizes new DNA by adding nucleotides to 3' end of pre-existing DNA strand or primer Term DNA pol 1 Definition removes RNA nucleotides of primer from 5' end and replaces them with DNA nucleotides. Term telomeres Definition repetitive sequence at the end of DNA that protects from erosion during rounds of replication Term chromatin Definition DNA combined with large amounts of protein Term heterochromatin Definition tightly packed chromosomes Term euchromatin Definition loosely packed chromosomes Term gene expression Definition process by which DNA directs the synthesis of proteins Term transcription Definition synthesis of RNA under the direction of DNA Term messenger RNA Definition carries genetic messages from DNA to protein-synthesizing machinery Term Translation Definition sisthesis of polypeptide under the direction of mRNA Term ribosomes Definition site of translation Term central dogma Definition DNA --> RNA --> protein Term codon Definition mRNA base triplets written 5' to 3' Term RNA polymerase Definition pulls strands of DNA apart and joins nucleotides as the base pair along Term promotor Definition DNA sequence where RNA polymerase attaches and initiates transcription Term terminator Definition sequence that ends transcription in bac. Term transcription unit Definition stretch of DNA that is transcribed into RNA Term RNA pol 2 Definition used in mRNA synthesis Term transcription factors Definition collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription Term transcription initiation complex Definition whole complex of transcription factors and RNA pol 2 bound to promotor Term TATA box Definition DNA forming initiation complex in eukaryotic promotor Term 5' cap Definition modified form of guanine that reduces degradation Term poly A tail Definition 50-250 A nucleotides that facilitate export, protect from degradation and help ribosomes attach Term RNA splicing Definition removal of introns from mRNA that will then not be translated Term introns Definition noncoding segments Term exons Definition expressed regions Term splicosome Definition several snRNPs joined with additional proteins to form an even larger assembly Term alternative RNA splicing Definition allows for a single gene to code for more than one polypeptide Term transfer RNA Definition transfer amino acids from cytoplasmic pool of amino acids to a ribosome Term anticodon Definition end of tRNA, nucleotide triplet complementary to mRNA Term animoacyl-tRNA synthetases Definition carries out correct matching of tRNA and amino acids Term ribosomal RNA Definition ribosomal subunits constructed of proteins and Rna molecules - most abundant Term polyribosomes Definition string of ribosomes during translation Term base-pair substitution Definition replacement of one nucleotide and its partner with another pair Term missense mutation Definition change one amino acid to another Term insertion Definition addition of nucleotides Term deletion Definition removal of a nucleotide Term frameshift mutation Definition moves reading frame causing false sequence Term mutegens Definition chemical and physical agents that cause mutations Term opetator Definition the switch on a segment of DNA and controls the access of RNA pol to the genes Term operon Definition operator, promotor and the genes they control Term repressor Definition protein that can switch off operon Term regulatory gene Definition (trp) located far from operon and has own promotor Term corepressor Definition a small molecule that cooperates with a repressor protein to switch an operon off Term inducer Definition inactivated the repressor Term cyclic AMP Definition allosteric regulatory protein Term activator Definition CAP, protein that binds to DNA and stimulates transcription of a gene Term differential gene expression Definition the exxpression of different genes by cells with the same genome Term histone acetylation Definition acetyl groups are added to lysines in histone tails- increase transcription Term epigenetic inheritance Definition inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence Term control elements Definition segments of noncoding DNA that help regulate transcription by binding to certain proteins Term enhancers Definition distal control elements Term proteasomes Definition recognize ubiquitin tagged proteins and degrade them Term microRNA Definition small single stranded RNA molecules that are capable of binding to complementary sequences in mRNA Term RNA interference Definition turn off expression of a gene with same sequence as the RNA Term small interfering RNA Definition small in size and function to miRNA Term oncogenes Definition cancer causing genes Term proto-oncogenes Definition normal versions of the cellular genes that code for normal growth and division Term tumor-suppressor gene Definition help prevent uncontrolled cell growth Term ras gene Definition G protein the relays a signal from a growth factor receptor n plasma membrane to a cascade of protein kinases Term p53 gene Definition coded for specific transcription factor that promotes the synthesis of cell cycle inhibiting proteins Term Frederick Griffith experiment 1920s Definition documented movement of genes from one organism to another (transformation) movement of material can alter the genetic makeup of the recipient cell R and S Term Oswald Theodore Avery, Colin MacLeod, and Maclyn McCarty Definition Only purified DNA from type S could transform type R Purified DNA might still contain traces of contamination that may be the transforming principle Added DNase, RNase and proteases RNase and protease had no effect With DNase no transformation DNA is the genetic material Term Hershey-Chase experiment Definition determined hereditary information was DNA, not protein (phages and tagging) Term Rosalind Franklin Definition x-ray defraction Term Watson & Crick Definition supported semiconservative model Term Meselson-Stahl experiment Definition used centrifuge and label DNA with N 14 and 15 to see how replication occured Term DNA replication is very accurate (reasons) Definition Hydrogen bonding between A and T or G and C more stable than mismatches Active site of DNA polymerase unlikely to form bonds if pairs mismatched DNA polymerase removes mismatched pairs Proofreading results in DNA polymerase backing up and digesting linkages Other DNA repair enzymes Term nuclease Definition cuts error in DNA sequence Term Telomeres Definition Telomeres shorten with each mitotic division too short = no more division Cells typically divide 20-50x Telomere shortening may be the cause of aging Term sigma factor Definition Richard Burgess-The protein that gives promoter-recognition specificity to the RNA polymerase core enzyme of bacteria. Term Direction of transcription and DNA strand used varies among genes Definition In all cases, synthesis of RNA transcript is 5’ to 3’ and DNA template strand reads 3’ to 5’ Term How to build a protein Definition The code: mRNA Adaptors to match codons and amino acids tRNA (+ aminoacyl-tRNA synthetase) An assembler: ribosome Term Stages of Translation Definition Initiation mRNA, first tRNA and ribosomal subunits assemble Elongation Synthesis from start codon to stop codon Termination Complex disassembles at stop codon releasing completed polypeptide Term polypeptide facts Definition Polypeptide chain has directionality Parallels 5’ to 3’ orientation of mRNA N-terminus or amino terminus is first amino acid C-terminus or carboxyl terminus is last amino acid Term Messenger RNA (mRNA) Definition Carries information specifying amino acid sequences of proteins from DNA to ribosomes Term Transfer RNA (tRNA) Definition Serves as adapter molecule in protein synthesis; translates mRNA codons into amino acids Term Ribosomal RNA (rRNA) Definition Plays catalytic (ribozyme) roles and structural roles in ribosomes Term Primary transcript Definition Serves as a precursor to mRNA, rRNA, or tRNA, before being processed by splicing or cleavage Term Small nuclear RNA (snRNA) Definition Plays structural and catalytic roles in spliceosomes Term SRP RNA Definition Is a component of the the signal-recognition particle (SRP) Term Small nucleolar RNA (snoRNA) Definition Aids in processing pre-rRNA transcripts for ribosome subunit formation in the nucleolus Term Small interfering RNA (siRNA) and microRNA (miRNA) Definition Are involved in regulation of gene expression Term Bacterial gene regulation Definition Most commonly occurs at the level of transcription Or control rate mRNA translated Or regulated at protein or post-translation Term Transcriptional regulation in bacteria Definition Involves regulatory transcription factors Bind to DNA in the vicinity of a promoter and affect transcription of one or more nearby genes Repressors inhibit transcription Negative control Activators increase the rate of transcription Positive control Term cAMP in Lac Definition Lactose present, glucose scarce (cAMP level high): abundant lac mRNA synthesized Term Genes involved with breaking down lactose Definition (lac operon) Negative regulation – because the repressor protein shuts down gene expression Positive regulation – because Catabolite Activator Protein (CAP) turns gene expression up Inducible – because the target of the gene products (lactose/allolactose) turns gene expression on Term Histones Definition = proteins used to pack DNA Term Chromatin Definition = DNA-histone complex Term Methylation can inhibit transcription in 2 general ways Definition Methylation of CpG islands may prevent an activator from binding to an enhancer element Converting chromatin from an open to a closed conformation Methyl-CpG-binding proteins bind to methylated sequences and recruit proteins that condense the chromatin Term 3 features found in most promoters Definition Transcriptional start site Where transcription begins With TATA box forms core promoter By itself results in low level basal transcription TATA box 5’ – TATAAAA – 3’ 25 base pairs upstream from transcriptional start site Determines precise starting point for transcription Response elements Recognized by regulatory proteins that control initiation of transcription Enhancers and silencers Term The Roles of Transcription Factors Definition To initiate transcription, eukaryotic RNA polymerase requires the assistance of proteins called transcription factors General transcription factors are essential for the transcription of all protein-coding genes In eukaryotes, high levels of transcription of particular genes depend on control elements interacting with specific transcription factors Term Alternative splicing of pre-mRNAs Definition In eukaryotes, a pre-mRNA transcript is processed before it becomes a mature mRNA When a pre-mRNA has multiple introns and exons, splicing may occur in more than one way Alternative splicing causes mRNAs to contain different patterns of exons. Allows same gene to make different proteins At different stages of development In different cells types In response to a change in the environmental conditions Term MicroRNAs Definition miRNAs are small RNA molecules that silence the expression of specific mRNAs Widely found in animals and plants Important mechanism of mRNA silencing Effect also called RNA interference (RNAi Term MicroRNAs Definition First synthesized as pre-miRNA Cut by Dicer to release miRNA Associates with cellular proteins to become RNA-induced silencing complex (RISC) Directs RISC to specific mRNAs In some cases binding inhibits translation Or RISC degrades mRNA Term The 5 “superpowers” of cancer Definition Growth stimulatory signals −Growth inhibitory signals −Apoptosis resistance −Infinite proliferative capacity −Angiogenic potential Term p53 Definition p53 is a G1 checkpoint protein Expression of the p53 gene is induced when DNA is damaged Then, a cell cannot progress from G1 to the S, or synthesis, phase of the cell cycle If DNA is repaired, a cell may later proceed through the cell cycle Term Chromosomal mutations Definition Deletion- Segment missing  Duplications Section occurs 2 or more times in a row Inversions -Change in direction along a single chromosome Translocations- One segment becomes attached to another chromosome Term Polyploid Definition – 3 or more sets of chromosomes Term pleiotropy Definition Most genes have multiple phenotypic effects, a property called Term amniocentesis Definition In amniocentesis, the liquid that bathes the fetus is removed and tested Term chorionic villus sampling (CVS) Definition In chorionic villus sampling (CVS), a sample of the placenta is removed and tested Term Epigenetic inheritance Definition Modification of a gene or chromosome during egg formation, sperm formation, or early stages of embryo growth alters gene expression in a way that is fixed during an individual’s lifetime Permanently affect the phenotype of the individual, but they are not permanent over the course of many generations and they do not change the actual DNA sequence