Bio Exam 3 Study Guide
Bio Exam 3 Study Guide BSC 2010
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This 6 page Study Guide was uploaded by Curt on Monday March 28, 2016. The Study Guide belongs to BSC 2010 at Florida State University taught by Dr. Steven Marks in Fall 2015. Since its upload, it has received 68 views. For similar materials see Biological Science in Biological Sciences at Florida State University.
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Date Created: 03/28/16
Unit 3 Study Guide Chapter 5 Structure & Function of Large Biological Molecules >DNA is the material inherited from one generation to the next (within chromosomes) >Chromosomes are made of Proteins & DNA >Fredrick Griffith created an experiment using bacterium to see if DNA or Proteins are molecules of heredity >Used S cells (Pathogenic Strain) & R cells (Non Pathogenic Strain) >Injects S cells into mousemouse dies >Injects R cells into mousemouse lives >Takes S cellsheat kills theminjects into mousemouse lives >Heat kills S cellsmixes them with living R cellsmouse dies >Something was passed from killed S cells to living R cells >Converting R cells into S cells >This is called Transformation: change in genotype & phenotype due to assimilation of foreign DNA >In Griffith’s experiment DNA was transformed not Protein >*Heat disrupts hydrogen bonds within macromolecules* >Secondary & Tertiary structure of proteins are held together by hydrogen bonds >More evidence for DNA being the molecule of heredity came from studying viruses (bacteriophages) >Viruses are made up of DNA & Proteins, like chromosomes >DNA was labeled with P (phosphorus) >DNA has no sulfur 35 >Protein was labeled with S (sulfur) >Proteins have no phosphorus >Phages infected bacterial cells while marked >When centrifuged radioactive DNA was in the bottom pellet, meaning DNA was molecule of heredity >Erwin Chargaff studied the composition of DNA and came up with two rules: >The base composition of DNA varies between species >In any species, the number of A & T bases are equal and the number of C & G bases are equal. >Rosalind Franklin used Xray crystallographic images to find DNA has a double helix structure >Watson & Crick found DNA’s backbones run antiparallel, subunits run in opposite directions >DNA (Deoxyribonucleic acid) >3’ end is a hydroxyl group (OH) >5’ end is a phosphate group (PO 4 >Deoxy: means one less oxygen >oxygen is missing from 2’ carbon >Doublestranded (ds), consist of many genes >Doublestrand produces a double helix around imaginary axis >RNA (Ribonucleic Acid) >Contains no T bases, instead it uses U >Singlestranded (ss), dsRNA is very rare >Each gene in DNA produces separate RNA molecules >Nucleoside = nitrogenous base + sugar >Nitrogenous bases >A & G are Purines (larger) >T, C, & U are Pyrimidines (smaller) >Base pairs require one Purine & one Pyrimidines >Nucleotide = nucleoside + phosphate group Chapter 16 The Molecular Basis of Inheritance >DNA is the only biological molecule that can copy itself >DNA contains more information than RNA & Protein >DNA follows semiconservative replication: the new replicated strand is half old DNA & half new DNA >Meselson & Franklin came up with a model supporting semiconservative model >Labeled original DNA with heavy nitrogen (N ), then transferred it into a medium with light 14 nitrogen (N ), and finally centrifuged >Resulted in one band composed of 50% old DNA & 50% new DNA and one band of all new DNA >Each cell has a specific amount of DNA and they do not tolerate more or less DNA >Cells form Diploid cells, a cell with two copies of chromosomes instead of one, in preparation for division >Cells only replicate their DNA in preparation for cell division >Initiation: when DNA begins to separate into separate strands to replicate >Begins at the origin of replication where Helicase unzips DNA’s hydrogen bonds >Single Strand Binding Proteins help keep DNA strands from rejoining (stabilizes strands) >Primase adds a short RNA primer to both ssDNA to begin replication >Eukaryotic cells have no mechanism for adding DNA nucleotides to a naked ssDNA >As long as there is a portion that is double stranded DNA can be added (RNA or DNA) >As DNA is unzipped Topoisomerase travels ahead of the replication fork making () supercoils to counter act the (+) supercoils induced by unwinding the DNA >DNA polymerase adds new DNA nucleotides to the growing DNA strands >DNA polymerase can only add nucleotides to the 3’ end >New strand that is continuous from 5’ to 3’ direction is called the leading strand (needs one primer) >Lagging strands are created to complete the rest of the strand (needs multiple primers) >Primase assembles new primers >Lagging strands are synthesized by DNA polymerase III >Forms a series of segments called Okazaki fragments >DNA polymerase I removes RNA primers & fills gap with DNA nucleotides >DNA ligase joins the 3’ end of lagging strand to the 5’ end of the other DNA molecule >Termination: DNA replication is stopped >Prokaryotes have termination sites & Eukaryotic cells don’t >Telomeres: repetitive DNA sequences at the end of eukaryotic chromosomes that postpone the erosion of molecules >Telomerase: enzyme that catalyzes production of Telomeres (found in germ cells to maintain length in offspring) >In regular somatic cells the length of Telomeres shortens as organism gets older >Both DNA Polymerase I & III have 3’ to 5’ exonuclease activity that can remove wrong nucleotides as soon as they are added (Polymerase I can remove in ahead & behind itself, Polymerase III can only in front) >Humans add nucleotides at 50 per second >Bacteria add nucleotides at 500 per second >Histomes: proteins associated with DNA to build chromosomes (positively charged to bond to negative DNA) >Chromatin: chromosome structure >Hetrochromatin >Tightly packed histomes & DNA aka nucleosomes (at resting state) >No replication or transcription >Euchromatin >loosely packed nucleosomes (during replication or transcription) Chapter 17 From Gene to Protein >DNA is responsible for inheritance & enzyme production and function >Minimal medium has the lowest amount of nutrients required for growth >After being exposed to Xrays damaged cells because they won’t grow on minimal medium after exposer (leads to nonfunctional enzymes) >The mutant cells only grow if you provide arginine to minimal medium >RNA is the bridge from genes to proteins >Prokaryotes >Translation can begin before transcription has finished (due to lack of nucleus) >No processing of RNA before translation >Translation in ribosomes (plasma membrane or free cytoplasm) >Eukaryotes >Translation & Transcription are completely separate >RNA processed in nucleus (must translocate from nucleus to cytoplasm) >Translation in ribosomes (free ribosomes, nuclear envelope, or rough ER) >Transcription >first stage of gene expression >RNA polymerase makes RNA polymers & adds RNA nucleotides to the 3’ end as it grows >RNA is made complementary to DNA template (use same bases except uracil instead of tymine) >Promoters: places where RNA polymerase attaches >piece of DNA that’s transcribed is called transcription unit >Transcription factors bind to DNA forming a transcription initiation factor >TATA Box is a promoter crucial to forming initiation complex in eukaryotes >RNA polymerase II then is recruited to transcript RNA >RNA Processing (Eukaryotes) >Polyadenylation A sequence is released to signal transcription termination >3’ end of mRNA receives polyA tail >5’ end receives modified nucleotide 5’ cap >They facilitate export of RNA into the cytoplasm, protect RNA from hydrolytic enzymes, and help ribosomes attach to 5’ end of mRNA >Introns: noncoding regions of mRNA (not translated into proteins) >Removed in process called splicing >Exons: regions that are translated and expressed >Splicing: removal of introns from mRNA making a mature mRNA strand >Carried out by Spliceosomes that are made of SnRNPs (made of proteins & SnRNA) >SnRNA: recognizes the intron sequences and bring the proteins of the spliceosomes to that position >Proteins: responsible for the cutting & rejoining of the mRNA >Codon: set of 3 RNA nucleotides which code for a specific amino acid >64 unique codons formed in mRNA >Translation >tRNA: non coding RNA that is not translated into proteins >links mRNA to specific amino acids (has 2 different binding sites: 2 steps) >1. Loads tRNA with the proper amino acid >aminoacytltRNA sythetase: enzyme that correctly matches amino acid to tRNA >2. Loaded tRNA binds to the correct codon >wobble groupings are based on size >Ribosomes: translate mRNA into proteins (made of 2 subunits) >Large subunit: made of 3 sites: E (exit), P, A (accepting) each site fits one tRNA >Small subunit: initiates translation (binds to 5’ end of mRNA and scans for start codon AUG) >Uses tRNA with UAC to scan for AUG (always starts with amino acid methinine) >Release factor: protein that binds to stop codon of mRNA and terminates translation >Multiple ribosomes can bind to mRNA forming a polyribosome or polysome >All ribosomes start off as free ribosomes >Signalrecognition particle (SPR) binds to signal peptide that pulls ribosome to translocation proteins in the ER (they become bound ribosomes while proteins translocate into ER) >Mutation: change in one base pair of a gene >Point Mutation: change in one base pair of a gene >Silent: no effect on protein sequence >Missense: changes one codon >Nonsense: changes a codon to a stop codon resulting in a shortened protein >Insertions & Deletions: add or delete nucleotide pairs in a gene >frameshift mutations: addition or lose of a number of nucleotides that is not multiple of 3 (breaks up a codon) Chapter 18 Regulation of Gene Expression >Prokaryotes & Eukaryotes alter gene expression in response to their changing environment >In eukaryotes gene expression regulates development & responsible for differences in cells >Genes are activated separately allowing processing at every step >Differential gene expression: expression of different genes by cells of same genome >Causes differences between cells (abnormalities can lead to diseases) >To find the function of a single gene use protein as an output for gene activity (use antibody to measure amounts of proteins) >RNA Sequencing: isolate all RNA in a cell (separate mRNA from other RNA & count mRNA for each gene) >Separate mRNA using string of T nucleotides >Cell types are organized successively into tissues, organs, organ systems, and the whole organism >The uneven inheritance of RNA & proteins causes differences during asymmetric division >Developmental control of cell function >Cytoplasmic determinants: material substances in an egg that influence early development >As the zygote divides the cells contain different cytoplasmic determinants >Induction: signal molecules from embryotic cells cause transcriptional changes in nearby target cells >Pattern formation: the development of a spatial organization of tissues and organs >Positional information: molecular cues that control pattern formation >Tell a cell its location relative to the body axis and neighboring cells >Bicoid gene: a maternal effect gene that is responsible for the development of the front half of an embryo >Cancer: division of cells when they shouldn’t divide & continue to divide >Two different cancerpromoting genes >Oncogenes: promote cell division (expression is high in cancer) >Protooncogenes: when they are responsible for normal cell division >Mutation in ras gene leads to production of hyperactive Ras protein that increases cell division >Amplification & Point mutation convert protooncogenes to oncogenes >Tumorsuppressor genes: regulate cell division (expression is low in cancer) >Mutation in p53 gene disrupt cell cycle checkpoint allowing unhealthy cell division >Gene Regulation >Eukaryotes >Chromatin modification: DNA unpacking >Genes within highly packed heterochromatin are usually not expressed >Chemical modifications to either histones or DNA can influence both chromatin structure and gene expression >Histone modification >In histone acetylation, acetyl groups are attached to positively charged lysines in histone tails (loosens chromatin structure promoting initiation of transcription) >Addition of methyl groups (methylation) condenses chromatin: adding phosphate groups (phosphorylation) next to methylated amino acid loosen chromatin >DNA methylation: addition of methyl group to certain DNA bases (can cause longterm inactivation of genes in differentiation) >Epigenetic inheritance: inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence >Pregnant mice exposed to nicotine passed on traits that were retained for generations >Transcription >Levels of transcription of genes depend on control elements interacting with specific transcription factors >Proximal control elements: located close to the promoter >Distal control elements (enhancers): located far from promoters (composed of about 10 control elements) >Degradation of mRNA >Eukaryotic mRNA is longer lived than in prokaryotic mRNA (influenced by 3’ UTR) >Translation >The initiation of translation of selected mRNAs can be blocked by regulatory proteins that bind to sequences or structures of the mRNA >Translation of all mRNAs in a cell may be regulated simultaneously >Degradation of protein >After translation protein processing >Proteasomes: giant protein complexes that bind protein molecules and degrade them >Prokaryotes >Bacteria respond to environmental change by regulating transcription of gene clusters >Cell can regulate the production of enzymes by feedback inhibition or by gene regulation >Operon: stretch of DNA composed of operator, promoter, and the genes they control >Operator: regulatory on/off switch usually positioned in the promoter (proteins can bind to them to switch them on/off) >Repressors: turn off operator function (repress transcription of operon’s genes) >Compressors: active repressors of operon genes >Inducers: repress the repressors activating transcription of operon genes Helpful Quizlets & Notecards https://quizlet.com/18540992/melbio16flashcards/ http://www.easynotecards.com/notecard_set/31948 http://www.easynotecards.com/notecard_set/7768 https://quizlet.com/45103687/biosci97geneticsproblemset1flashcards/ https://quizlet.com/48196876/biologychapter4flashcards/ http://www.easynotecards.com/notecard_set/32349 https://quizlet.com/78769929/bioch17flashcards/
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