mcb 150 week 11
mcb 150 week 11 MCB 244
Popular in Human Anatomy and Physiology I
Popular in Biology
This 12 page Class Notes was uploaded by Laura Kunigonis on Tuesday November 3, 2015. The Class Notes belongs to MCB 244 at University of Illinois at Urbana-Champaign taught by Dr, Chester Brown in Fall 2015. Since its upload, it has received 19 views. For similar materials see Human Anatomy and Physiology I in Biology at University of Illinois at Urbana-Champaign.
Reviews for mcb 150 week 11
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 11/03/15
MCB 150 Exam lll Review The nucleolus is the site for rRNA synthesis rRNA processing assembly of ribosomal subun s Eukaryotic ribosomes consist of 4 types of rRNA 58 588 188 288 and 75 proteins How do mammalian cells meet the 510 million demand for ribosomes We have 28O copies of 588 188 and 28S and 2000 copies of 5S rRNA genes What is processing NOT SPLICING The unwanted parts are taken out but the rest is NOT linked together How do we keep the rRNA genes for 583 183 and 28S stored Tandem arrays which then get transcribed by RNA Polymerase 1 into prerRNAs Where can we find the 583 183 283 gene arrays Called 45S gene arrays can be foundo on 5 different human chromosomes 13 14 15 21 22 Where can we find the 53 gene arrays Chromosome 1 How does the necleolus formed After processing is finsihed the 428 tandem arrays are unbound and bunch together forming the nucleolus NOR What is a snRNP A RNAprotein complexes that combine with unmodified premRNA and various other proteins to form a spliceosome The action ofsnRNPs is essential to the removal of introns from premRNA occurring only in the nucleus of eukaryotic cells What is a snoRNP The processing machinery for rRNA transcription dice up the precursor rRNA and DOES NOT link it back together Are all mutations passed down in singlecell organisms Yes ifa bacteria cell has a mutation every daughter cell that arises with have that mutation Fibrillar Region region of the nucleolus where RNA polymerase trancibes the pre458 rRNA What 3 regions make up the nucleolus Fibrillar CenterRegion Dense Fibrillar REgion and the Granular Zone This is where transcription processing and accembly take place Somatic Cell nonsex cell mutations are passed to the daughter cells in the area Dense Fibillar Region rRNA is being processed so present there are transcription factors RNA polymerase SNORPS and ribosomal proteins laci lnfers this is the wild type of the gene laci lnfers this is the mutated version of the gene Granular Zone of Nucleolus At the periphery and contains the ribosomal precursor particles Why do we not see the nucleolus during Mphase The DNA is inaccessible during M phase because we pack it away What is nucleoplasm The aqueous compartment inside the nuclear envelope that is essentially the nuclear counterpart of the cytoplasm What is the Nuclear Envelope A double lipid bilayer structure that is comprised ofan outer and inner membrane What is the perinuclear space The space between the inner and outer membranes Why is DNA replication the most reliable Mistakes in the replication lead to alterations in the nucleaotide and are passed on to the daughter cells so it cant mess up Why are mistakes in transcription or translation not as critical There are many copies of the RNA produced and they are not heritable over multiple generations DNA sequences can be changed by Uncorrected mistakes in replication chemical mutagens highintensity radiation How often do errors occur in DNA replication e coli 4100 average organism 1 per billion nucleotides How does E coli reduce the frequency With proofreaders which is an example of 339539 exonuclease activity What if proofreading doesnt catch the mistake 1 There is a mismatch repair system in E coli that scans synthesized DNA 2 Then the DNA gets methylated at the adenine residues withing the 539GATC339 3 Mistake is in a new strand 4 Mismatch repair enzymes fic the problem in unmethylated strand What does the methyldirected mismatch repair MMR do in E coli Uses the MutH to cut the nonmethylated strand then an exonuclease removes bases just beyond the mismatch and DNA polymerase III fills in the gap and Ligase seals the nick What are the two broad types of categories Point and Chromosome Base Substitution Replaces one base pair with another GCgtAT Missense A type of base substitution in which a single nucleotide change codes for a different amino acid AACUUGgtLeu AACgtCACGUGgtVal Nonsense A type of base substitution in which a single nucleotide change codes for a stop codon causing premature termination Same sense A base substitution in which a change in nucleotide codes for the same amino acid Examples for Missense mutation Siclecell anemia PKU Frameshift mutations The addition or removal of a small number of bases not divisible by 3 this disrups the reading frame in the mRNA causeing all codons to be changed Usually results in a premature STOP codon Example of frameshift Cystic Fibrosis Different types of chromosomal level mutations Insertion deletion inversion and translocation What keeps cytoplasmic protiens out of the nucleus Nuclear Loocalization Signal NLS which is a very BASIC molecule Bipartite NLS An NLS that is seperated into 2 parts Nuclear Pore Complex Gets to decide what comes in and out of the cell lmportin Helps the NPC recognize all the NLSs by pairing to cargo proteins and brings it into the nucleus Steps of Nuclear Import 1 lmportin bnds to cargo and bring it into the nucleus 2 RanGTP forces the the cargo to get released 3 The Ran GTP and cargo then go through to the cytoplaasm 4 RanGTP fets hydrolyzed to GDP P relasing the importin 5 GEF bringd the RanGDP back into the nucleus What keeps the nuclear proteins out of the cytoplasm NES which is rich in Leu39s Exportin Recognizes NES39s Steps of nuclear Export 1Ran GTP connects the Exportin and Cargo 2 Cross to the cytoplasm 3 RanGTP is hydrolyzes and relases cargo 4 Exportin is brouhgt back into the nucleus and GEF brings RanGDP back How are RNA molecules brought through the become bound by shuttle proteins which display a NES and exportin with attatch to it Where did Mitochondria come from Endosymbinic theory that a small prokaryote was engolfed by a larger one How much DNA does a human Mitochondria have 165 kb of DNA How many proteincoding genes does a mitochondira have 13 all translated and transcribed in house How many rRNA genes does a human mitochondria have 2 How many tRNA genes does a human mitochondria have 22 Electrochemical gradient The cytosol and intermembrane space are more positively charged acidic and the matrix is more megatively charged Most mitochondrial protiens are not codded for by genes on the mitochondrial genome Where are the mitochondrial protiens transcribed The nucleus Where are the mitochondrial protiens translated The cytoplasm How are the mitochondrial protiens transported Mitochondrial Presequence or Transit Sequence Steps to mitochondrial protein import 1 Protein is translated by a free cytosolic ribosome 2 Attatched to a transit sequence and chaperones so it does not fold 3 TOM recognizes the transit sequence 4 Once fed through the chaperones are pulled off via ATP 5 The protein is pulled into the matrix bc of the Electon Gradient 6 Transit peptidase pulls of the transit sequence 7 Chaperone in TIM pulls the protein through 8 Chaperones are pulled off via ATP and pulled into the chaperonin complex Amino terminal peptide Nterminal A signal peptide found at the amino terminal that gets you to the ER and causes theh Nterminal in the lumen and the Cterminal in the cytoplasm Stop transfer sequence Tells translocon to eject the protein Internal signal sequence A singal peptide found somewhere otherthan the amino terminal not allowing the signal to get cut off because the aminos before it is needed and allows the rest of the protein continues to be threaded through so the Nteminus is left in the cytoplasm and the Cterminus is left in the lumen Who is responsible for protein processing and folding Proteins native to the ER lumen Bip a chaperone that assists in protein folding Disulfide bond Wass formed in the ER Nlinked glycosylation The addition ofoligosaccharides to asparagine N residues this happens when 3 amino acids is presented Nearly every protein that goes through the ER gets this happened to them in one or more places doHchol an oddly shaped lipid that gets phosophorilated a few times 14mer a oligosaccaride tree make up of 14 sugars on the dolichol platform which is then trimmed down into an 11mer GPI anchoring accures in the ER Recongizes and cuts off cterminal tail and links it covalently to an Ethanolamine which is connected to the Phosphatidyl lnositol SER purposes lipid bilayer synthesis and detoxification Pulsechase experiment An experiment designed by Palase figuring out if you mark a molecule in a way that it can be deteected but nothing else can you can see where it originates and where it goes Before the pulse the protein molecules are being synthesized at a steady state through translation of mRNA by membranebound ribosomes The pulse this begins when a large dose of radioactive amino acid is added The chase This begins when a very large amount of nonradioactive amino acid is added and no more radioactive proteins are made The Secretory Pathway Rough ERgtGolgigtSecretory VesiclesgtExterior RER purposes Protein secretion synthesis of membrane proteins and protein processing What starts cytosolic stays cytocolic Traffic through the endomembrane system Bulk flow goes through the cis side of the golgi and retrieval goes through the trans side of the golgi Zip codes Different sugars and modifications Golgi purpose Does additional processing forthe proteins and lipids Using lysosomes for autophagy 1 Damaged organelle surronded by membrane 2 Delivery to lysosome 3 Small molecules are recycled Using lysosomes for phagocytosis 1 Detection of smaller cell orfood particle 2 Phagosome formation 3 Delivery to lysosome and digestion 4 Small molecules recycled Why do plant cells lack lysosomes They have vacuoles which work as lysosomes in addition to roles in osmotic balance and storage Disorders caused by translocations lymphoma and leukemia What can a deficiency in Glucocerebrosidase lead to A lysosomal storage disorder called Gaucher39s disease Disorders caused by duplications Fragile X Syndrome Huntington39s disease activation of oncogenes Disorders caused by insertions Haemophilia A Disorders caused by deletion Duchenne39s Muscular Dystrophy Types of lysosomal acid hydrolases Proteases amp Peptidases Nucleases Glycosidases Lipases Phosphatases Sulfatases Vesicle traffic tolfrom early endosomes Receptors and macromolecules come from the outside of the cell through an endocytic vesicle gt Macromols stay in the early endosome while receptors go to the recycling endosome and get recycled back out Maturationformation of an active lysosome After an endosome39s pH is lowered it undergoes a series of processing steps that causes it to mature into a late endosome A prelysosomal compartment introduced earlier where the acid hydrolases from the Golgi apparatus are dropped off The emptied cargo receptors transported from the Golgi are removed from the late endosome as it matures into a fully active lysosome Has a lower pH than an early endsosome bc proton pumps have had more time to work The cytoskeleton Dynamic system of protein fibers of various sizes and can be reorganized as needed Examples of physical support and allows for movement phagocytosis organelle positioning mitosis G actin 43 kDa protein 375 amino acids has nucleotide binding site that can accommodate ATP Polar conserved abundant Factin ls made up of Gactin and has a barbed end and pointed end thin filaments withing a myofibril structure Progerin shortens the telomere aging the cell Myosin a molecular motor that converts chem energy ATP into mechanical energy generating force and movement thick filaments within a myofibril structure Myosin and Actin are responsible for cell divesion crawling some vesicle movement and muscle contraction Class 2 Myosin move toward the barbed end Filament sliding When 2 myosin II are connected and moving in opposite directions so they are playing tugawar forcing the actin inwards Why does rigor mortis happen The body stops producing ATP which myosins need to let go of the actin so the myosins and actin are stuck together How does myosin make its way down the actin toward the barbed end When the ATP binds to the nuclear head group it allows the myosin to let go the ATP hydrolyzes ADPP this moves the position of the myosin to a part closerthe barded end then the P from ADP is ejected causing the myosin to move back into the previous position Why is myosin able to move down the actin the way it does ATP has no affinity for actin filaments but ADPP has some affinity for it Power Strobe caused by the P from ADP being ejected moving the myosin part back into the previous position Steps of Cell Crawling 1 Extension of leading edge 2 Attatches to substration 3 Myosins attatch and begin to contract pulling everything with it 4 Detatch in back so it doesnt stretch out Conventional Myosin forming think filament not actually attatched to myosin Uncoventional Myosin Not capable of forming thick filaments heads spend a lot of the cycle bound to actin Do myosins ever move toward the pointed end Yes there 1 or2 that move in the opposite direction but majority move to the barbed end What is different about muscle cells compaired to normal cells They are long and cylendrical and have numerous nuclei of which and other organelles have been pushed to the periphery Myofibril Small fibers of repeating actin and myosin that make up most of the interior of the muscle fiber many sarcomeres Sarcomeres functional unit of contraction in a myofibril spans the dark line of one light band to the other dark line of the other light band LBand a light band within a sarcomere where actin is present but there is no overlapping myosin Zdisc The dark line within a lband light band within the sarcomere a collection of proteins that allow forthe anchoring of the barbed ends of the actin What is exactly is the contraction of the myofibril structure Myosin motors pulling actin filaments into the middle ofa sarcomere and increasing the overlap between thin and thick filaments Mline The middle of the sarcomere which is found in the middle of the Aband and HZone where the tail end fibers of the myosins are anchored Aband The length of the myosis which do not change There will also be regions within it that with have overlapping actin filaments HZone a subregion of the Aband where there is myosin but no actin also does not change size the brighter part within the Aband What is the only thing to change within a sarcomere The amount of overlap between the Actin and the myosins The length of the myosins and the length of the actin do not change though Sarcomere contraction Each of the myosins head groups anchored to the actin will move closerto the barbed end of those actins since the myosins cant move and the barbed ends of the actins are anchored into the zdiscs the zdiscs will be moved in towards the mline How does the Aband stay the same size while the Hzone disappears The myosin head groupsjust moved not change their lengths Disorders caused by duplications Fragile X Syndrome Huntington39s disease activation of oncogenes