Cell Bio Study Guide PDF

i each division i i i Iii mn Must also repair damage to genetic material 2 Eff.EE iIreplication Repair C G A T T A C G A strand of double helix semiggy Ever...

i each division i i i Iii mn Must also repair damage to genetic material 2 Eff.EE iIreplication Repair C G A T T A C G A strand of double helix semiggy Ever a Parent molecule Ex Replicate Parent  5 3 3 5 of Replication Origin forks yemp Ñ É New DNA Forks The direction of synthesis occurs in 5 to 3 direction for Both strands There are special proteins to help w opening DNA double helix up DNA helicase maintains integrity of genome Single strand DNA Binding proteins SSBproteins DNA Topoisomerase prevent DNA tangling during Replication If there is no precense of Topoisomerase DNA cannot rotate rapidly and torsional stress builds up Can be relieved DNA by supercoiling PNapolymerase Allows for replication of New DNA Enzyme Catalyzes DNA synthesis Works only in one direction Adds only deoxyribosenucleotides only to 3 end of growing DNA chain DNAreplicationmechanisms DNA strands run Anti parallel 5 3 can only synthesize in 5 3 direction needs a free 3 end cannot start from scratch DNA Primase Enzyme that serves as starting point for DNA Replication PrimmerDNA Replication will begin intTmite Replication Fork structure that forms DNA during replication where DNA Polymerase matches É Ég Faggingthan 5 ff.tt F continuous in 5 to 3 fdiscontiniois YYI.FI and results in Okazaki fragments will be later joined together DNA ligase to form  Continuous strand 8 y g Howisleadingstrandsynthesized Proteins at replication fork cooperate to form replication machine Protein InvolvdinDNHReplication NA Polymerase Catalyzed by adding nucleotides to template to make new DNA strands NA helicase Use energy of ATP hydrolysis to unwind DNA before replication fork separate strands SSB protein stabalizes strands and protects from damage also prevents helix from recombining DNA Topoisomerase relieves tension build up and prevents DNA from getting tangled Sliding clamp keeps DNA polymerase attached and prevents from falling off Clamp loader uses from ATP hydrolysis  to look gy y y sliding clamp onto DNA Primase serves as starting point for DNA Replication DNA ligase Bonds the okazaki fragments made on lagging strand to make another continuous strand Replicating endsoflinearchromosomes Telomere structures at end of chromosomes that protect DNA and control cell division problems w Telomeres In the lagging strand the primase adds  g 1 primer towards end of chromosome to The final okazaki fragment is made and primer is removed if there is present DNA no primer Polymerase cannot be added making incomplete strand Telomerase replicates telomeres and adds to ends of chromosomes Germ cell Can be found in Gametes and Stem Cells Somatic cells lack telomerase chromosomes shorten w age Certain length for activity once reached activity shuts down Cancer Cells Active telomerase may result in unlimited cell division DNA polymerase has ability to self correct  has a repair system that removes replications that make it past proofreading Portions of BYfs.luT scribed into RNA 11 S.BE yribose Uracil thymine AC G U AC GT when transcription occurs it produces a strand of RNA complimentary to a strand of DNA Enzyme DNA Dependent RNA polymerases Coding strand DNA 5 3 UUUUUUUUU 3g AM MM MM MMMM Templatestrand Transcription 5 3 UUUUUUUUUU  Three RNA Polymerase in Eukaryotic cells RNH carry instructions to make proteins for regulagting RNApolymerase I Is most rRNA Genes RNA Polymerase II Transcribes DNA into messenger RNA mRNA All protein coding Genes miRNA genes plus genes for other non coding RNAS RNA Polymerase III transcribes noncoding RNAs in Euk cells ERNAgenes 5s rRNA gene genes for many other small RNAs Initiatio T.FI gaYton a t rmination Begins when RNA polymerase binds Promoter sequence RNA polymerase req general transcriptionfactors TF IB TFIID etc Promoteyt.IR PqsmfEE E nso  3 AM mm mm mm 599 Tata Box DNA sequence that signals where genetic sequence can be read decoded followed by2 341 TFIIB recognition element BRE slightly upstream of TATA Box Downstream PromoterElement DPE 30 nucleotides down stream from start General transcriptionfactors TFIID Binds to TATA Box TATA Binding protein subunit TFIIB forms complex w TFIID Rest of GTFs and RNA Pol II TATA Binding Protein gets bound to DNA TFIIH unwinds DNA phosphorylates RNAPol II RNAPol II released Begins transcription FromDNHtoRN Eukaryotic mRNAs are processed in nucleus CAPPING 5 methylated guanosine cap Polyadenylation 3 poly A tail Splicing EE YtiEIEijation coupled to pre mRNA processing RNA pol II phosphorylation RNA.EE nacn G PPP WWW MMMMM MMM AAAAA 150 2503 MRNA LET Tailor Jen  Effributes to mRNA stability protects RNA from Nucleases Plays role in positioning RNA on Ribosome for initiation of translation 27 Poly.AE 150 250 nucleotides long Added A polymerase by enzyme poly Protects mRNA from nucleases Req for export of transcript to cytoplasm Protein coding are interrupted genes 68 Informofting exons non coding introns a sequence sequence3 mummammammmmmm 5 mmmmmmmmmmmmmmm DNA 3 Mmmmmmmmmmmmmmmmmmmmmmmmm 5 non coding Fukaryottgne t Et Exons opoteins Introns are then removed from pre mRNAs  by RNA splicing Splicesites Intron 5 endstarts w GV and terminates with AG at 3 end Sequences adjacent to 3 and 5 ends of intron tend to be similiar Branch point near 3 end contains an A residue spliceosome Intron removal is catalyzed by spliceosome 5 types of RNA more than 200 proteins Assemble from SnRNPs small nuclear ribonucleopori complexes n Each contains or 2 SnRNAs small nuclear RNAS  Spliceosomeassembly Sequential Binding of snRNPs to pre mRNA First UI recognizes 5 splice site V2 Binds to branch point sequence 04 46 V5 Bring intron ends together pre mRNA cleaved at 5 splice site joined to branch point A residue Lariat 3 site cleaved splice two ends of exon joined together  Alternativesplicings Introns allow pre mRNA to be spliced in multiple ways Leads to production of multiple protein products Possible via mechanisms allowing certain splice sites to be activated or skipped YpToce RNA synthesis hgIt place in Factories within the nucleus Mature Eukaryotic mRNAs are exported from nucleus mRNA single stranded RNA involved in Protein tf synthesis mRNA molecules are eventually degraded in caff.si 5uetions cytosol cytoplasm MRNA sequence is decoded into sets of three nucleotides tRNA molecules match amino acids to codons in  MRNA Specific enzymes then couple tRNAs to correct Amino Acid FromRNAtoprotein tart and stp Codons start codon AUG stop Codon UAG Proteins are produced polyribosomes on Inhibitors of prokaryotic protein synthesis are used as antibiotics Intracellular compartments and proteintransport main function of Membrane enclosed organelles ofAEuharyotic.CI Cytosol many metabolic pathways protein synthesis the Cytoskeleton  y Nucleus Contains main genome DNA RNA synthesis Endoplasmic Reticulum ER synth of most lipids synth of proteins for distribution to organelles and Plasma membrane Golgi Apparatus modification sorting packing of proteins lipids for secretion or delivery to organelle Lysosomes intracellular degradation Endosomes sorting of endocytosed material Mitochondria ATP synthesis by oxidative phosporylatio Chloroplasts ATP synthesis and carbon fixation by photosynthesis Peroxisomes oxidative breakdown of toxic molecules  Proteinsorting Proteins are transported into organelles by 3 mechanisms Signal sequences direct proteins to Correct compartment Proteins enter nucleus through nuclear pores Signal sequences direct proteins to correct compartment N terminus and or C terminus  Structure of nuclear Envelopet Nuclear envelope Separates nucleus from rest of cell inner outer membrane separated by perinuclear space outer membrane continuous w ER Nuclear lamina Supports nuclear envelope and composed of Lamins Nuclear envelope poriferated w nuclear openings pores specialized channels where inner outer membranes are fused nuclearporecomplex Proteins will then enter nucleus through Nuclear  1 Inbound Traffic nucleoside triphosphate proteins responsible for copying DNA proteins responsible for synthesizing RNAs needed for assembling ribosomes proteins Over 5000 molecules imported through 2000 5000 nuclear pores second every Nuclear localization signals Usually 8 30 amino acids often Contain Proline E basic amino acids Lysine and Arginine Ehydrolysisdrivnucleartransport RAN small GTPase Ran GDP cytoplasm  Ran GTP nucleus GTP bound to Ran hydrolyzed to GDP RAN GAP ran GTPase activatingprotein cytoplasmic GDP bound to Ran exchanged GTP by RAN GEF Ran guanine nucleotide exchange factor trot nuclear transport Ran GDP into out us IPI T ING Cytosol nucleus 380 85 M tp Ran GEP GTP Exchanges Ran GDP GTP  Nuclear localization signals direct cytosolic proteins into the nucleus 5 sneededtransportpok.in tonucleus 1 nuclear localization signal on protein 2 nuclear pore complex 3 Importin proteins receptor proteins 4 Ran GTPase 5 ATP Energy Intracellular Compartments and protein transport Protein synthesis occurs in of on ribosomes cytoplasm Cytosol cytoplasm Transported to nucleus 4g Plastids Mitochondria through nuclear pores Transported to Plastids and Mitochondria through signals The transport of proteins into Mitochondria depends on signal sequences protein translocators Proteins are transported by Tim and Tom complex transported into inner mitochondrial membrane Tim Inner Core mitochondria TOM Outer core mitochondria Hydrolysis of ATP provides energy In chloroplasts two signal sequences direct proteins to thylakoid membrane TIC and TOC handle transportation of proteins TOC outer for chloroplasts core TIC Inner core for chloroplasts