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AP Biology Chapter 17: Protein Synthesis Flashcards

From Gene to Protein

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8429426442Gene Expressionprocess by which DNA directs synthesis of proteins0
8429426443Transcription-synthesis of RNA under direction of DNA -DNA serves as template for assembling complementary RNA molecule -resulting RNA molecule faithful transcript of gene's protein-building instructions -occurs in nucleus1
8429426444Messenger RNA (mRNA)RNA molecule that carries genetic message from DNA to protein synthesizing machinery of cell2
8429426445Translation-synthesis of polypeptide -occurs under direction of mRNA -change in language-cell must translate base sequence of mRnA molecule into amino acid sequence of polypeptide -occurs in cytoplasm3
8429426446Ribosomes-sites of translation -complex particles that facilitate orderly linking of amino acids into polypeptide chains4
8429426447Primary Transcriptinitial RNA transcript from any gene, including those coding for RNA that is not translated into protein5
8429426448Triplet Codegenetic instructions for polypeptide chain written in DNA as series of non-overlapping, 3 nucleotide words6
8429426449Template StrandDNA strand that provides pattern/template for sequence of nucleotides in RNA transcript7
8429426450CodonsmRNA base triplets written 5'-3' direction8
8429426451Reading Framegrapings w/ symbols w/ message that needs to be translated to written language9
8429426452RNA Polymerase-pries 2 strands of DNA apart -joins RNA nucleotides as they base pair along DNA template -assemble polynucleotides 5' -> 3' -can start chain from scratch-no primer needed10
8429426453PromoterDNA sequence where RNA polymerase attaches and initiates transcription11
8429426454Terminatorsequence that signals end of transcription in bacteria12
8429426455Transcription Unitstretch of DNA transcribed into RNA molecule13
8429426456Transcription Factorsproteins that mediate binding of RNA polymerase and initiation of transcription14
8429426457Transcription Initiation Complexcomplex of transcription factors and RNA polymerase II bound to promoter15
8429426458TATA Boxcrucial promoter DNA sequence16
8429426459RNA Processingenzymes in eukaryotic nucleus modify pre-mRNA in specific ways before genetic messages dispatched to cytoplasm17
84294264605' Capmodified form of guanine added onto 5' end after transcription 1. facilitates export of mature mRNA from nucleus 2. helps protect mRNA from degradation by hydrolytic enzymes 3. helps ribosomes attach to 5' end of mRNA once mRNA reaches cytoplasm18
8429426461poly-A Tail-50-250 more A nucleotides added to 3' end by enzyme 1. facilitates export of mature mRNA from nucleus 2. helps protect mRNA from degradation by hydrolytic enzymes 3. helps ribosomes attach to 5' end of mRNA once mRNA reaches cytoplasm19
8429426462RNA splicingremoval of large portions of RNA molecule initially synthesized20
8429426463Intronsnoncoding segments of nucleic acid that lie between coding regions21
8429426464Exonsnucleotide regions that are expressed, usually translated into amino acid sequences22
8429426465Spliceosomeinteracts w/ certain sites along introns, releasing intron and joining together 2 exons that flanked intron23
8429426466RibozymesRNA molecules that function as enzymes, can b/c: 1. RNA single stranded, region of RNA molecule may base-pair w/ complementary region elsewhere in same molecule-gives molecule particular 3D structure-essential to catalytic function of ribozymes, just like in enzymatic proteins 2. some RNA bases have functional groups that may participate in catalysis 3. ability of RNA to hydrogen bond w/ other nucleic acid molecules-adds specificity to catalytic activity24
8429426467Alternative RNA Splicingmany genes can give rise to 2+ polypeptides, depending on which segments are treated as exons during RNA processing -# different protein products > # genes25
8429426468Domainsfunctional regions part of protein architecture26
8429426469Transfer RNA (tRNA)transfer amino acids from cytoplasmic pool of AA to ribosome27
8429426470Anticodonnucleotide triplet that base pairs of complementary codon of mRNA28
8429426471Aminoacyl tRNA Synthetases-able to bind to different tRNAs that code for specific amino acid -catalyzes covalent attachment to tRNA -> aminoacyl tRNA released from enzyme -available to deliver AA to growing polypeptide chain of ribosome29
8429426472Wobbleflexible base pairing at codon position30
8429426473Ribosomal RNA (rRNA)made in nucleolus, make up ribosomal subunits31
8429426474P Site (peptidyl-tRNA site)holds tRNA carrying growing polypeptide chain32
8429426475A Site (aminoacyl-tRNA site)holds tRNA carrying next AA to be added in chain33
8429426476E Site (exit site)where discharged tRNAs leave ribosome34
8429426477Release Factorprotein that binds to stop codon @ A site35
8429426478Polyribosomes-strings of ribosomes trailing along mRNA -enables cells to make many copies of polypeptide quickly36
8429426479Signal Peptide-targets protein to ER -marks if polypeptide of proteins destined for endomembrane system or for secretion37
8429426480Signal Recognition Particle (SRP)brings ribosome to receptor protein into ER membrane38
8429426481Signal Mechanism for Targeting Proteins to ER1. polypeptide synthesis begins on free ribosome in cytosol 2. SRP binds to signal peptide, halting synthesis momentarily 3. SRP binds to receptor proteins in ER membrane (receptor is part of protein complex w/ membrane and signal cleaving enzyme) 4. SRP leaves, and polypeptide synthesis resumes w/ simultaneous translocation across membrane (signal peptide stays attached to translocation complex) 5. signal cleaving enzyme cuts off signal peptide 6. rest of complexed polypeptide leaves ribosome and folds into final conformation39
8429426482Mutations-change into genetic information of cell -responsible for huge diversity of genes found along organisms40
8429426483Point Mutations-chemical changes in a single base pair of a gene -if occurs in a gamete, can be transmitted to offspring and future generations41
8429426484Base Pair Substitutionsreplacement of one nucleotide and its partner w/ another pair of nucleotides42
8429426485Missense Mutations-change one amino acid to another -new amino acid may have properties similar to replaced amino acid, or may be in region where exact sequence of amino acids not essential to proteins functions43
8429426486Nonsense Mutation-change codon for amino acid into stop codon -causes translation to be terminated prematurely -resulting polypeptide shorter than polypeptide encoded by normal gene44
8429426487Insertionsadditions of nucleotide pairs in gene45
8429426488Deletionlosses of nucleotide pairs in gene46
8429426489Frameshift Mutations-# nucleotides inserted/deleted NOT multiple of 3 -may alter reading frame of genetic message47
8429426490Mutagenphysical and chemical agents that interact w/ DNA that cause mutations48
8429426491rRNAmakes up 60% of the ribosome; site of protein synthesis49
8429426492geneequals one RNA molecule50
8429426493snRNAsmall nuclear RNA51
8429426494srpRNAsignal recognition particle that binds to signal peptides52
8429426495RNAiInterference RNA53
8429426496ribozymeRNA molecule that functions as an enzyme54

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