Exam of Cell

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Biological Sciences
Connie Zavitz

Biology Exam 3 I Nucleus and Nucleolusa Not the leader of the cell b Recognized in the cell theory c Some cells dont have a nucleus Ex Red Blood Cells Anucleateshorter life d Multi NucleiCoenocyticmany nuclei lg cells i Has a nucleusCytoplasm ratio e Double membrane innerouterf Inside nucleus is nucleolus g If stretched out human DNA would stretch for 6 ft h Major function is DNA storage DNA replication genetic info provided DNA organized for cell division chromosomes i Outer membrane is the ER j Nucleolus produces ribosomes RNA and Protein k Nucleuslots of proteins but no protein assembly all transported in l Can be more than one nucleoli II Organization a DNA is in tight coils b Has cytoskeleton of intermediate filaments called nuclear laminins i Bind to surface of inner membrane for support and shape c Euchromatin genes that are available for cell not bunched up d Heterochromatin genes are not available for cell bunched up shows up as a blotch under the microscope e DNA attached to laminins by proteins i Heterochromatin is nearer to laminin euchromatin is more toward center f On strands of DNA there is a section of genes that code for the function of the nucleolus called NOR nucleorlar organizing region g Each chromosome has its own territory h RNA processing occurs in spaces around chromosomal territories i Gaps thru outerinner membranes called nuclear pores can move place to place where things get inout of nucleus receptor mediatedIII Nuclear Pores a Made up of a rosette of 8 pore proteins around a central pore protein central plug b Cytosolic fibrils are extended into the cytoplasm c Things can only go thru with permission d Things that are bigger than the pore can get thru but no one knows how e Protein has to have a specific amino acid sequence NLS sequence nuclear localization sequence30 amino acids cargo protein f Nuclear Import i Cargo protein encounters alpha importin in cytoplasm binds to NLS ii Beta importin binds to alpha importin iii Receptor for alphabeta importin on cytosolic fibril attach iv ATP and RAN GDP forces complex thru pore v Alpha beta bind to 2 separate RAN GTP molecules to unattach from protein cargo protein is freed g Nuclear Export i Proteins with NES sequence ii Alpha and beta exportin bind to NES iii RAN GTP helps them oiut of nucleus GTPase cuts off RAN GTP from complex h GAPsGEFs proteins i GEFs in nucleus GAPs outside ii GEF 1 GTP exchange factor cuts off GDP replaces with GTP iii GAP 1 GTPase activating protein iv So that GDP that brought things in can become GTP to bring things out and vice versaIV RNA processing and ribosomes a NUCLEOLUS i rRNA is built ii assembles ribosomes iii strands of DNA that come together in nucleoli NOR contains multiple copes for 1 gene 1 there is 400 copies of 1 gene in humans for rRNA iv will need a gene outside nucleolus5S rRNA gene to build rRNA b DNA i Replicates in nucleus ii Contains segments called genes 1 Genes used as templates for RNA called transcription iii Can replicate all strand or transcription certain sections stiv 1 transcript is copied from DNAhas to be changed before can used processed v Ribosomes have small and lg subunitsstrands of rRNA wrapped in proteins c RNA TRANSCRIPT i Contains spacers and 18S RNA and 58S RNA and 28S RNA ii Enzymes come and cut out spacers iii 5S piece built OUTSIDE nucleolus iv 58S and 28S and 5S come together with 49 proteinslarge subunit v 18S32 proteinssmall subunit
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