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Chapter 4: Genetics and Cellular Function Flashcards

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7350505137DNA-deoxyribonucleic acid -long, threadlike molecule with a uniform diameter but varied length -46 DNA molecules in the average nucleus -DNA and other nucleic acids are polymers of nucleotides0
7482638082Law of complementary base pairingOne strand determines base sequence of other1
7482728182Discovery of Double Helix1900:components of DNA(sugar,phosphate base) known 1953: X ray determined geometry of DNA Nobel prize 1962 to Watson, Crick, Wilkins Rosalind Franklin: discover DNA shape didn't get credit due to her gender2
7350505138nucleotideconsists of one sugar (deoxyribose), one phosphate group, one nitrogenous base -either a pyrimidine (single carbon-nitrogen ring) -or a purine (double ring)3
7350505139purinesdouble ring -adenine (A) -guanine (G)4
7350505140pyrimidinessingle ring -cytosine (C) -thymine (T) -uracil (U)5
7350505141DNA strucutre-molecular shape is a double helix (spiral staircase) -sidepiece- backbone composed of phosphate groups alternating with sugar -"steps" are nitrogenous bases6
7350505142nitrogenous basesheld together by hydrogen bonds -purine on one backbone and pyrimidine on the other - A-T two hydrogen bonds - G-C three hydrogen bonds (stronger)7
7350505143genesgenetic instructions for synthesis of proteins8
7350505144genean information-containing segment of DNA that codes for the production of a molecule of RNA that plays a role in synthesizing one or more proteins9
7350505145genomeTotal set of genes in 23 pairs of chromosomes. Approx 30K genes(2%DNA) Noncoding DNA (98% of DNA)10
7350505146chromatinfine filamentous DNA material complexed with proteins - occurs as 46 long filaments called chromosomes11
7350505147histonesdisc-shaped cluster of eight proteins -DNA molecule winds around cluster -appears to be divided into repeating segments called nucleosomes12
7350505148nucleosomeconsist of core particle (histones with DNA around them) and linker DNA (short segment of DNA connecting core particles)13
7350505149chomatinFine filamentous DNA material complexed with proteins14
7350505150Chromosomes46 comes in pairs of 23 One from each parent Each pair same gene but diff version (alleles)15
7350505152RNAsmaller cousin of DNA (fewer bases) -mRNA, rRNA, tRNA -one nucleotide chain -sugar is ribose -uracil rather than thymine -function: interpret code in DNA, uses the instructions for protein synthesis, leaves nucleus and functions in cytoplasm16
7350505153human genome projectidentified the nitrogenous base sequences of 99% of the human genome17
7350505154geonomicsstudy of the whole genome and how its genes and non-coding DNA interact to affect the structure and function of the whole organism18
7350505155genetic codea system that enables these four nucleotides to code for the amino acid sequence of all proteins19
7350505156base tripleta sequence of three DNA nucleotides that stands for one amino acid20
7350505157codonthe 3-base sequence in mRNA21
7350505158how many possible codons are available to represent the 20 amino acids?there are 64 possible codons to represent the 20 amino acids but only 61 code for amino acids22
7350505159start codonAUG23
7350505160stop codonsUAG, UGA, UAA24
7350505161mRNA (messenger RNA)a RNA mirror image of the gene is made by the process of transcription25
7350505162ribosomes (rRNA)cytoplasmic granules composed of ribosomal RNA and enzymes26
7350505163tRNA (transfer RNA)delivers amino acids to the ribosome27
7350505164process of protein synthesis:DNA --> mRNA --> protein28
7350505165transcription-step from DNA to mRNA -occurs in nucleus where DNA is located -where it finds A it adds U. where it finds T it adds A, where it finds C it adds G, and where it finds G it adds C29
7350505166RNA polymeraseenzyme that binds to the DNA and assembles mRNA30
7350505167translation overview-step from mRNA to protein -RNA polymerase rewinds the DNA helix behind it 15-20% proteins synthesized in the nucleus31
7350505168terminatorbase sequence at the end of a gene which signals polymerase to stop32
7350505169pre-mRNAimmature RNa produced by transcription33
7350505170exons"sense" portions of the immature RNA -will be translated to protein34
7350505171introns"nonsense" portions of the immature RNA -must be removed by translation35
7350505172alternative splicingremoving the introns by enzymes and splicing the exons together into a functional RNA molecule -one gene can code for more than one protein36
7350505173translation process3 steps: initiation, elongation, termination37
7350505174intitiation-leader sequence mRNA binds to small ribosomal subunit -initiator tRNA pairs with start codon -large ribosomal subunit joins the complex and the now fully formed ribosome begins reading bases38
7350505175elongation-next tRNA binds to ribosome while its anticodon pairs with next codon of mRNA -peptide bond forms between start codon and second amino acid -ribosome slides to read next codon and releases next initiator tRNA -next tRNA with appropriate anticodon brings its amino acid to ribosome -another peptide bond forms -process repeats39
7350505176termination-when ribosome reaches stop codon a release factor binds to it -finished protein breaks away from ribosome -ribosome dissociates into two subunits40
7350505177polyribosomeone mRNA holding multiple ribosomes41
7350505178protein synthesis is not complete until ____.it coils or folds into precise secondary and tertiary structure and may require post-translational modificatio42
7350505179DNA helicasean enzyme, opens one short segment of helix at a time ezposing its nitrogenous bases43
7350505180replication forkpoint where the DNA is opened up (like two separated halves of a zipper)44
7350505181DNA polymerasemolecules move along each strand, read exposed bases, match the complementary free nucleotides, two separated strands of DNA are copied by separate polymerase molecules proceeding in opposite directions45
7350505182mutationschanges in DNA structure due to replication errors or environmental factors46
7350505183cell cycleextends from one division to the next47
7350505184interphase includesG1 phase S phase G2 phase48
7350505185G1 phase-first gap phase -interval between cell birth from division and DNA replication -carries our normal tasks and accumulates materials needed to replicate DNA49
7350505186S phasesynthesis phase where DNA replication occurs50
7350505187G2 phase-second gap phase -interval between DNA replication and cell division -synthesizes enzymes that control cell division -repairs DNA replication errors51
7350505188M phase-miotic phase -cell replicates its nucleus in 4 phases -pinches in two to form new daughter cells (cytokinesis)52
7350505189G0 phasecells that have left cycle for a "rest" temporarily or permanently53
7350505190mitosiscell division in all body cells except the eggs and sperm; results in 2 genetically identical daughter cells54
7350505191four phases of mitosisprophase, metaphase, anaphase, telophase55
7350505192prophasechromosomes shorten and thicken, coiling into two compact rods56
7350505193metaphasechromosomes are aligned on cell equator57
7350505194anaphaseactivation of enzyme that leaves two sister chromatids apart at centromere58
7350505195telophasechromatids cluster on each side of the cell59
7350505196when do cells divide?-have enough cytoplasm for two daughter cells -have replicated their DNA -have adequate supply of nutrients -stimulated by growth factors -neighboring cells die, opening up space in a tissue to be occupied by new cells60
7350505197when do cells stop dividing?-snugly contact neighboring cells -nutrients or growth factors are withdrawn -undergo contact inhibition- cessation of cell division in response to contact with other cells61
7350505198hereditytransmission of genetic characteristics from parent to offspring62
7350505199karyotypechart of 46 chromosomes laid out in order by size and other physical characteristics63
7350505200homologous chromosomesthe two members of each pair (23 pairs)64
7350505201diploidany cell with 23 pairs of chromosomes (somatic cells)65
7350505202haploidcontain half as many chromosomes as somatic cells: sperm and egg cells (germ cells)66
7350505203fertilizationrestores diploid number to the fertilized egg and the somatic cells rise from it67
7350505204locuslocation of particular gene on a chromosome68
7350505205allelesdifferent forms of a gene at same locus on two homologus chromosomes69
7350505206dominant allele(capital letter) -masks effect of recessive allele that may be present -produces protein responsible for visible trait70
7350505207recessive allele(lowercase) -expressed only when present on both of the homologous chromosomes -no dominant alleles at that locus -often codes for nonfunctional variant of the protein71
7350505208geneotypealleles that an individual possesses for a particular trait -homozygous -heterozygous72
7350505209homozygoustwo identical alleles for a trait73
7350505210heterozygousdifferent alleles for that gene74
7350505211phenotypeobservable trait75
7350505212gene poolcollective genetic makeup of population as a whole76
7350505213multiple allelesmore than two allelic forms for a trait77
7350505214codominantboth alleles are equally dominant78
7350505215incomplete dominancephenotype intermediate between traits each allele would have produced alone79
7350505216polygeneic inheritancegenes at two or more loci, or even different chromosomes, contribute to a single phenotypic trait ( skin/eye color, alcoholism,mental illness,cancer,heart disease)80
7350505217pleiotrpyone gene produces multiple phenotypic effects81
7350505218sex linked traitscarried on the X or Y chromosome, and therefore tend to be inherited by one gender more than the other82
7482728183PleitropyOne gene produces multiple phenotypic effects (sickle cell, Marian's syndrome, Alkaptonuria)83
7350505219penetrancepercentage of a population with a given genotype that actually exhibits the predicted phenotype84
7350505220epigeneticsfield examining nongenetic changes that alter gene expression and can be passed to offspring85
7350505221DNA methylationmechanism or epigenetic change in which methyl groups are added to DNA86
7350505222benign tumorslow growth; usually easy to treat87
7350505223malignant tumorcance; fast growing88
7350505224metastisizegive off cells that seed the growth of multiple tumors elsewhere (malignant tumor)89
7350505225carcinogenenvironmental cancer-causing agent- they typically mutate DNA90
7350505226tumor angiogenesisin-growth of blood vessels stimulated by energy-hungry tumors91
7350505227oncogenescause cell division to accelerate out of control92
7350505228tumor suppressor genesinhibit development of cancer when functional93

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