Study Guide II
Study Guide II BISC 1111
Popular in Introductory Biology: Cells and Molecules
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This 29 page Study Guide was uploaded by Rosa Mas Volpe on Tuesday September 22, 2015. The Study Guide belongs to BISC 1111 at George Washington University taught by Doebel, H in Fall 2015. Since its upload, it has received 34 views. For similar materials see Introductory Biology: Cells and Molecules in Biological Sciences at George Washington University.
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Date Created: 09/22/15
Bio Study Guide Part II 161 DNA is genetic material Evidence that DNA can transform bacteria Transformation 0 Change in genotype and phenotype due to assimulation of external DNA of another cell Evidence that Viral DNA can program cells Bacteripohages Bacteria eater phages for short 0 viruses that infect bacteria Virus 0 DNA enclosed in by protective coat usualy protein 0 to produce more viruses a cell must infect a cell and take over it metabolic machinery Herhey chase Experiment 0 Proved that nucleic acis not proteins are herditary material for viruses DNA is the a ploymer of nucleotids 0 made of a nitogenous base ATCG 0 phosphate group 0 Deoxiribose pentose sugar Doube helix 0 Rosalind Franklind s Xray diffraction photopgrapof DNA allow Watson and Crick to deduce the double helix structure Thymine T a o hAdenine A Q I 3E3 t a is f z a I lt7 c 39 quot quot CytosunejC 0 O Law 6quot mi 5 39 HGuan1ne G t c quotD I 39 Hquot a quot G39 quot u M if c Q 39 quot o U 2 D on o39 lt3 g K k 2 9 p o l V H 01 if in quot l m o In l a 3 0quot a i thII I g I 6 r l Extmu I 0 quot o In E or Hydrogen bond 0 Antiparallel backbone 39 back bone run in opp directions 53 and 35 0 Nitorgenous bases 39 complimentarty Purines Adenine A Thymine T 0 2 organic rings Pyradines Cytosine C Guinine G 0 1 organic ring 162 Proteins with with DNA to repair and replicate Model of DNA replication Basic concept 0 a Each nitrogen base has a compmentary pain int eh double helix 0 b The two DNA strands seperate and each single stand serves as a template for a new complimnetary strand 0 c Complimentary nucliotides connect to form sugar phosphate backbone Conservative model 0 Two parent strands reassociate after acting as templates from new strands and restore parent helix 0 AKA seperate but Remarry each other Semiconservative model 0 Two strands of the parent molecule seperate and each function as template for synthesis of new model 0 AKA Divorce and marry new people Dispersive model 0 Each strand of of both daughter molecues contains both new and old DNA 0 Open relationship Replication of Chromosomes Origins of replication 39 Sites of replication chromosom replication which are short streches od DNA with a speci c sequence of nucliotids Back to DNA replication 0 Replication bubbles 39 When DNA seperated it opens a replication bubble Replication fork 39 At the end of each reblication bubble Y shaped region where parental strands are unwound Helicases 39 Enzymes that twist double helix at at rep forms seperating the 2 parent strands and making them available as templates Single strand building blocks 39 Bind unpaired DNA strands keeping them from reforming 0 Topoisomerase Regulates rewinding of double helix 39 breaks swivels and rejoins parent DNA ahead of replication fork 39 RNA replication 0 Primer RNA chain synthesized by enzyme primerase 510 nucliotids long 0 Primase Starts as a compliment to RNA nucliotides one at a time using parental DNA strand as a template 39 Synthezing a new DNA strand DNA polymerase catalyze synthesis of new DNA by adding nucliotids to preeXisiting chain locamotive moving along DNA like railroad track DNA polymerase I and III Big trains Maj or Roles gt details on pg 325 each nucliotide added cosist of sugar attached toa base and 3 phosphate groups dATP adenine nucliotide used to make DNA Chemically reactive becasue of triphosphate tail Unstable neg charge monomer joins relocating DNA 2 phosphate groups are lost as molecules of pryophosphate Hydrosyis of Pryophosphate to 2 molecules of inorganic phosphate is coupled ny exergonic reaction Antiparallel elongation Singlestrand binding protein Leading strand 0 DNA strand made by pol III in the replication fork contiually adding nucliotids Lagging strand 0 DNA strand elongated away from replication fork Okazaki fragments Segments of lagging strands synthezised discontinually DNA polymerase DNA ligase b lidlv lntll luf d n DNA polymerase dimers synthesizing DNA Lagging strand template Primer Helicaseprimase complex Pr39mer Old Okazaki fragment DNA gyrase Newly synthesized Leadingstrand template leading strand Sliding clamp ot the subunit 39 DNA replication complex 0 Proofreading and Repainring Cells 39 DNA polymers proofread to make sure nucliotids fit in DNA bt sometimes their are erros 39 Mismatch repair 0 Enxymers repair and replace incorrecly paired nucliotides mutations permanent changes in DNA 39 Nuclease 0 DNA cutting enzyme gets ride of damaged strands of DNA 39 Nucleotide excision repoair 0 DNA polymerase and DNA ligase repair gap made by nuclease and re ll it with nucleotides Replicating ends of DNA molecules 0 prokayrotes have cicular chromosomes 0 Eukaryotes linear 0 Telomers speacialized nucliotid sequence of eukaryotic chomosomes Multiple replitions of one a short nucliotide sequence 131 Offspring and genese 39 Genes herditary units of coded information from parents 39 Gametes 0 sex cells 0 Vehicles that transmit genes from one generation to the next 0 during fetilization egg and sperm gamets unite passing genes to offspring Somatic cell 0 body cells 46 chromosomes locus 0 genes specific location on the lenngth of a chromosome 39 Genome 0 genetic endowment consist of genes and other DNA inherited from parents 39 Assexual reporduction 0 Exact genetic copy Sexual Reproduction 0 two parents make a baby 132 Fertilization of Meiosis Life cycle 0 Generations to generation sequence of stages in reproductive history of an organism Karyotype 0 Display of Chromosomes longest to shortest Karyotypes can show if all of the chromosomes are present and whether an individual is male XY or female XX 0 detect defects such as deletions translocations and inversions 39 homologous chromosomes Homologs 2 chromosomes of a pair that have the same length centosome position and pattern Human seX chromosomes 0 Women XX 0 MEN XY 39 diploid cell 0 two chromosone set 0 somatic 0 2n 46 haploid 0 one chromosone set 0 gametes 0 n 23 Human life cycle 39 Fertilization 0 union of gamates resulting in fusion of nuclei 39 zygoat 0 fertilized egg diploid bc it has two haploid sets Meiosis 0 sex cell diVison 0 reduces of sets of chromosomes from two to one gamate combines two haploid sets of chromosomes 39 alternation of generations 0 eXist for plant cells and some speices of algea sporophymulticelluar stagediploid Plants sexual lifecylce gemetophyte formation of plant gamates 133 39 Meiosis I and II 0 Can only occur in diploid cells 0 interphase 39 chomosones diplicated sister chromatids copied Meiosis I 39 homoologous chromosomes seperate haploid cells with duplicated chromosomes Meiosis II 39 Sister Chromoatids seperate 0 haploid cells with unduplicated chromosomes The stages of Meiosis 39 Pair or homologous chromosomes are both duplicated and then duplicated and into 4 haploid daughter cells 39 sister chromatid cohesion sister chromatids are 2 copy of l chromosome allele homolog that look alike diffrenct version of genese Crossing over and synapsis during prophase of non sister chromatids Cross over DNA molecules of non chromotids are broken by proteins and rejoined to each other 0 Chiasmata X shape of chromatids as a result of cross over Synaptonomel complex 0 Zipper like structure that hold one homolog tightly to thte other Synapsis 0 DNA breaks are closed up so that each broken end is joined to correseponding segment 0 at least one cross over must chromosone in order to pass to metaphase Mitosis vs Miosis Property Mitosis Meiosis 39 i i DNA mutation Occurs during interphase before during nterphase be are mitosis begins meiosis begins Number of divisions One Two 5 quota s of homolo ous Occurs along with crossing over y W 8 Does not occur between nonsister chromatids chromosomes in prophase I 4 haploid n daughter cells each containing half as many 1 Number of daughter cells m plow 2quot new ceus chromosomes as the parent cell and genetic composition that are genetically identical to the parent cell Daughter cells are genetically different from the parent cell and each other Role in the animal body 0 Three event unique to Meiosis l Synapsis and Crossing over Produces cells for growth and repair 2 Homolgous pairs at metaphase plate 3 Seperation of Homologs Produces gametes and assures genetic diversity in sexual reproduction during prophase I duplicated homolog pair up and cross over chromosome pairs in metaphase plane rather then single chromoatids During Anaphase I duplicated chomsomes of each homolog pair move to poles of cell but sister chromatids stay attached due to sister chromatid cohesison rather then serpaerate Meiosis I Reduction division 39 reduces of chromosome sets from two 0 Meiosis II Equational division 39 sister chromatids seperate producing haploid daughters 134 Genetic variation in Evolution Three reasons for Genetic variation 0 Independent assortment of chromosomes Crossing over and Random Fertilization Independent Assortment random orientation of pairs of homolog chromosomes at metaphase I 39 random assortment of chromosomes during the production of gametes the results are genetically unique individual gametes 39 Roughly 84 million combos 223 0 Crossing over Result of independent assortment 39 priduce gametes not exlusivly maratel or paternal recombinant Chromosomes chromosomes that carry genes that derive from two chromosomes Random Fertilization randomness of fusion of egg and sperm 39 creats 7 0 trillion possible combos 223 x 223 Evolutionary signi cance 39 genetic variation is the raw mterial of natural selection mutations are the original source of variationa and diversity 141 Medel experiment 39 Pea breeding experiment 0 Choose peas because of many varieties 0 character a heritable feature that varies among individuals 0 Cross pollination of white and purple ower and performed inheritance test True breeding 0 same variety of parent plant through many generations of self pollination hybridization Crossing of two true breed parents P generation 0 Parental generation of true breeding F1 generation 0 First Filial generation 0 hybrid offspring of P generation F2 generation 0 second filial generation 0 Offspring of F1 generation 3 1 inheritance model of purple to white ower peas 0 purple dominant white recessive The Law of Segregation 39 dominant and recessive geners heritable factor of recessive trait is not destroyed or blended in F1 generation but merely masked by presence of the the dominant trait Mendels model 0 4 concepts related to law of segregation 1Altemative versions of gene account for variation in inherited character Alleles 0 Alternate versions of a gene 0 chromosome attached to different locus of slightly varies DNA sequence 0 2For each character an organism inherits two copies 2 alleles of a gene on from each parent 39 each somatic cells is diploid and has 2 sets of chromosomes one from each parent 0 3If two alleles at a locus differ then one the dominant allele deters the organisms appearance the other the recessive allele has no effect on appearance 0 4 Two alleles for heritable character segregate from each other during gamete formation and end up in different gamates Punnent square 0 diagram devise for predicting the allele composition of offering from known genetic makeup Genetic vocabulary Homozygous 0 identical alleles Heterozygous 0 different alleles Phenotype 0 organisms observed traits 39 Genotype 0 genetic makeup 39 Testcross 0 breeding an organism with a recessive homozygote to fm out genotype Law of independent assortment Monohybrids heterozygous for one particular character being followed in a cross Dihybrids indivudual heterozygous for the two character being followed in the cross YrRr Law of independent assortment 0 Two or more genes assort independently that is each pair of alleles segregates independently from each other pair of alleles during gamete formation 0 law only apples to genes of different chromosomes 142 Multiplication and addition rules of genetics 0 Multiplication Rule 39 States that to determine probability you multiply the probably of one event by another 0 Addition Rule Probability that 1 or 2 mutually exclusive events will occur is calculated by adding their individual probabilities 39 Solving complex Genetics WRules of probability 0 Probability of YYRR 14prob of YY x 14RR 116 143 Extending Medelian genetics from a single gene Degrees of Dominance 0 Complete Dominance 39 Phenotype of heterozygote and dominant homozygote are indistinguishable 0 Incomplete dominance neither allele is completely dominant hybrid of phenotype are somewhere between parental varieties codominance 39 two alleles each affect the phenotype in separate distinguishable ways 39 For any character the observed dominancerecessive allele depends on level which we examine phenotype 39 TaySachs disease 0 cannot metabolize certain lipids bc certain enzymes do not work properly 0 recessive allele Dominant allele is not always as common and the recessive allele Multiple alleles 0 blood type ABO groups more than 2 alleles Pietropy 0 single gene has multiple phenotypic effects 0 Assosiacted with hereditary diseases such as cyclic fibrosis and sickle cell diseases Epistasis 0 Phenotypic expression for a gene at one locus alters than of a gene at a second locus 0 ex lab hair colors 0 blackgt browngtgolden Polygenetic inheritance additive effect of one or more genes on single phenotype character 0 Exheight affected 180 genes 39 skin color 39 quanitative qualities 0 characteristics that vary in polulation in gradations along a continuum 39 Expression of a genotype can be affected by environmental in uence resulting in a range of many phenotypes Multifactorial characters polygenetic characters that are in uenced by the environment 144 Pedigrees 0 info about the family history of a speci c trait 0 analysis of pedigree s used to reduce possible genotypes and make predictions about offspring Heterozygous carriers 0 Usually genetic disorder phenotype sickle cell persistence bc heterozygotes have an advantage bc one copy of the sickle cell allele reduces the frequency malaria attacks most human genetic disease multifactorial Amniocentesis 0 test in 1416th week of pregnancy 0 used to determine tay sachs Chorionic villus sampling 0 sample tissue from the placenta from a tube injected through cervix other genetic test after birth can be preformed as well 1 5 1 Morgan s choice of experimental Organism Morgan tested fruit y Drosophilia observing genetics in sex cells 0 profile breeders offspring to 100s has only 4 chromosomes Wild type Phonotype most common in natural populations 39 Ex In Drosophilia Mutant Phenotype 39 alternative to phenotypes 0 Morgan concluded that some traits are linked in cell cell Thus supporting the chromosome theory of inheritance Specific genes are carried on specific chromosomes 152 Sex linked gene 0 Sex determined in human is 5050 chance in fertilization 39 Women XX 39 Men XY anatomical signs of sex in humans begin to form in the embryo 2 months old Sexlinked gene 0 Gene located on either sex chromosome 39 SRY 0 gene on y chromosome required for development of testies 0 sex developing region of Y Xlinked genes 0 Genes on the X chromosomes contains about 1000 genes 0 Xlinked disorders colorblindness female can express phenotype if she is homozygous Hemizygous Xlinked traits in hearted by males 0 any male receiving a receive trait from his mother will express it 0 Duchenne muscular dystrophy x linked disorder in dystrophin protein that affects 13500 men in US 39 weakening muscles and loss of coordination 39 affected individuals rarely live past 20s 0 Hemophilia 0 X linked recessive disorder defined by absence of one or more proteins required for blood clotting 0 X inactivation in female mammals Barr body 0 Inactive X in each cell that is condensed along nuclear envelope 0 most genes in barr body X not expressed 0 but in ovaries barr bodies are reactivated in cells that give rise to eggs 0 Eery female egg has an active X 0 barr body chosen Randomly 0 inactivation of X involves modification proteins and DNA attached to it proteinshistone proteins DNA methyl CO4 group to nucleotides 39 mosaic of two types of cells 0 Active X derived from mother 0 Active X derived from father 2 Parts of the X chrome involved in inactive process 0 XIST gene X inactive specific transporter becoems active only on chromosome that will be barr body 153 Linked genes 0 Linked genes genes located near each other inherited together in a genetic cross linked genes deviate from law of independent assortment 0 Genetic recombinations 39 production of offspring with a combination of traits that differ from either found in P generation 0 Recomb in unlinked genes parental types phenotype identical to parent 39 recom type new trait 39 50 recom frequency in testcrosses means the chromosomes are on different genes and cant be cross 0 recomb in Linked genes 39 recom frequency greater than 50 than genes are linked Crossing over 0 set proteins exchange segment of part of the paternal and external chromatid 0 occurs while replicated homologs are paired in meiosis 39 Genetic maps 0 list of genetic loci along a chromosome 0 recombination frequency is proportional to distance between genes on a chromosome 0 further apart more likely they will cross and higher the Recom frequency Linkage map 0 genetic map based on recombination frequency map units 0 distance between genes equivalent to 1 frequency of recombination 39 Cytogentic map 0 locate genes based in chromosome features liner sequence between genetic physical and cytogenic are same but distance is now 1 54 Abnormal Chromosome Number 39 Nondisjunction 0 a pair of homolog chromosomes do not move apart a part properly during meiosis I or sister chromatids fail to move apart separately dying meiosis II 0 once gemate recives 2 of the same or no copy of a chromosome Aneuplodiy abbermt zygote fertilizes with an normal one producing an abnormal number of a particular chromosome 0 Monosomic type anauplodity fertilization involving a gamate that has no copy of a particular chromosome which results in a missing chromosome in the zygote 39 2nl 0 Trisomic Extra copy of a chromosome in zygote 2n 1 0 Polyploidy 39 more than two complete chromosome sets in a in all somatic cells triploid tetraploid examples of polypoidies common in plans bananas are tripoid wheat hexaploid Alterations of chromosome structure most likely occurs during during mieois cross overs 39 Deletion 0 Chromosome fragment is lost Duplication deleted fragment can attached to an extra section of a sister chromatid deleted fragment can also attach to a non sister chromatid of homolog 0 no identical bc carry different alleles Inversion chromosomal fragment reattaches to original chromosome in reverse orientation Translocation 0 fragment joins non homlog chromosomes 0 moves segment from one chromosome to non homologous chromosome and vise versa Human disorders due to alteration Down syndrome Trisomy 21 aneuploid condition as a result of an extra 21 chromosome 0 disordered facial stature increase chance of lukenia and Alzheimers and steril 0 increased chance of having down syndrome is a mother is older Aneuploidy of sex chromosomes 0 Klinefelter syndrome XXY 39 testies abnormally smal 0 Trisomy X XXX 39 slightely taller and at risk for learning disabilities 0 Turners syndrome monosomy X 39 sterile bc sex organs do not mature 39 Disorders called by structurally altered Chromosomes 0 Cri du chat deletion in Chromosome 5 0 severe intellectual disabilities small head unusual facial features and cry that sounds like a cat 0 Chronic myelogenous leukemia CML 39 occurs due to reciprocal translocation during mitosis of White blood cycles on chromosome 22 and chromosome 9 chromosome 22 Philadelphia chromos 39 casues cancer that activated a gene that leads to uncontrolled cell cycle progression 1 55 Genomic imprinting 39 variation in phenotype depending on Whether an allele is inherited from a male or female parent 39 occures during gamete formation and results in silencing a particular allele of certain parents What is a genomic imprint 0 usually consist of methyls CH3 groups that are added to cytosine nucleotides 0 methylation usually silences an allele but in some cases it can activate expression 0 thought to affect a small partition of genes in mammals Oregenelle genese 39 some genes in mitochondria or cytoplasmic mutations in these genes generally not lethal 1 8 2 Bacteria adapt to environment through transcription Regulation of metabolic pathway 0 feedback inhibition typical in anabolic pathways allows a cell to adapt to short term functions in supply of substance it needs 0 Cells adjust the production of enzymes 39 Operon models regalatm gene promote operator sttuctwal genes r I ll 1 1 1 DNA RNA potymerase l 5 3 1 1 MM If m l 1 l 1 enzymes d a Tryptophan about Enzymes needed to symnesae tryptopnan are produced 7 RNA potymerase cannot bcnd to promoter actrve repressm Q mmphan inactive tepressor An operon 0 is a group of structural and regulatory genes that function as a single unit it includes the following A regulator gene 0 located outside the operon codes for a repressor protein molecule that controls whether the operon is active or not Apromotor 0 sequence of DNA where RNA polymerase attaches when a gene is to b transcribed An operator 0 is a short sequence of DNA where an active repressor binds preventing RNA polymerase from attaching to the promotortranscription therefore does not occur 0 Consist of Operator promoter and the genes they control 0 basic mechanism that bacteria uses to control gene expression 0 three step pathway catalyzed by a speci c enzyme 39 controls enzxyme activity and regulates enzyme production 0 Operator 39 Segment of DNA that can controls access of RNA polymerase to the genes 39 on and off switch 39 positioned near the promotor and enzyme controlling genes 0 repressor protein that can switches off operon 39 repressor binds to operator and blocks attachment of RNA polyermase to promoter preventing transcription go genes 39 product of regulatory gene 39 alternates between two states 0 bound and not bound to repressor 0 duration of repressor state increases when their are more active repressor molecules 0 Corepromotor 39 small molecule that cooperates with repressor protein to switch on operon off 0 Repressible operon EX trp operon 39 transcription is usually on but can be inhibited when a small molecule binds to a regulatory protein 0 Inducable operon EX lac operon 39 usually off but can be stimulated with a regulatory protein inducer activated the repressor inactivates the repressor 39 Negative control of genes 0 Trp and lac operons are negative bc operons are switched off by active form of repressor gene 39 Positive gene regulation 0 Positive is regulatory protein interacts with the genome to switch transcription 0 Ecoli energy supply 39 glucose and lactose 39 perfers glucose and glucose is broken down through gycolsis 39 but when when glusose is low it will use lactose for energy 39 Cyclic AMP 0 small organic molecule which accumulates when glucose is scarce to let Ecoli know it has to use lac operon 39 Activator protein 0 regulatory protein 0 in Ecoli regulatory protein is catabolic activator protein 0 binds to DNA and stimulates transcription of a gene 0 as glucose increases cAMP decreases and CAP detaches from operon 0 RNA polymerase then binds less efficiently to promotes and lac operon is SLOW CYTOPLASM O nucleosome NUCLEUS Translationl 6 mRNA 4 Protein negative and positive 1 8 2 39Differential Gene expression Expression of genes in a different genes by cells in the same genome highly differential cells muscle or nerve cells express less than 20 of protein gene expression at a time lt Gene expression in Eukaryotic cells 39Regulation of Chromatin structure Chromatin 39carries DNA and proteins basic unit of 39 packages DNA into a compact form that can fit into nucleus 39 helps regulate gene expression 0 Heterochromatin highly condensed 39 genes usuaully nor expressed Histone Modifcations and DNA Methylation in uence chromatin structure and gene expression Histone acetylation promotes transcription by opening up chromatin structure DNA methylation 0 Addition of Menthyl groups 0 leads to condensation of chromatin and reduced transcription 0 once methylated genes usually stay the way that way through cell division 0 methylation patterns are passed on 0 accounts for genomic imprinting in mammals Epigentic Inheritance Inheritance of traits transmitted by mechanism not involving nucleotide sequence 0 can be reversible 0 Ex methylation patterns are often reestablished during gamete formation 0 Helps explain why one identical twin can have schizophrenia and the other would not 39 same DNA but one was altered 39 Regulation of Transcription Initiation 0 Proteins or DNA help or hurt RNA polymerase 39 Eukaryotic Gene transcription Addition of Menthyl groups Enhancer Proximal PolyA signal Termination distal control elements control elements sequence region Exon lntron Exon lntron Exon r DNA 1 1 UDS feam p t Downstream romo er Transcription PolyA signal pnmary RNA Exon lntron Exon lntron Exon Cleaved 3 em a transcript 5 of primary EMFquotW wwl preOmFlNA transcript v RNA processing Cap and tail added introns excised and quotmoquot RNA exons spliced together 3ffn quot quotW39quot Coding segment 39 I A pquot39quot ti i mRNA G 9 F 339 v W W4 Start Stop W 539 Cap 539 UTR codon codon 339 UTR PolyA untranslated untranslated tail 0 leads to condensation of chromatin and reduced transcription 0 Roles of Transcription Factors 39 general transcription 0 required for all protein coding genes 39 speci c transcription factors 0 high levels of transcription of particular genes dependent on control elements 0 proximal control elements 39 control elements close to the promoter Distal control elements distant to the promoter Enhancers 0 1000s of nucleotides upstream and downstream an intron Rate of gene expression dependent on binding of transcription factors Mediator proteins 39 bends DNA and interacts proteins and promoter Silencing phenomenon 39 Repressors recruit proteins that remove acetyl groups from histones leading to reduced transcription 39 Combinatorial Control of Gene activation 0 Combo of enhancers rather than single enhancer that is importing in regulating a gene 39 Coordinate control Coexpressed Eukaryote genes 0 Genes that encode enzymes for metabolic pathways are often dispersed coordinate control occurs in response to chemical signals outside of the cells Ex steroid hormone and estrogen 0 Nuclear Architecture and gene Expression 39 loops of chromatin extend from chromosomes into speci c sited in nucleus Transcription factories 0 loops congregate specialized for common function Mechanism of Post transcriptional Regulation 0 RNA processing 39 alternative RNA slicing 0 different molecules are produced from the same primary transcription 0 Ex T gene Which encodes two different proteins Initiation of Translation and mRNA degradation 0 during intimation stage translation can be blocked by regulatory proteins 0 they can also be regulated 0 Ex hemoglobin polypeptides in developing red blood cells are usually uncuttable and these long love mRNAs translated repeatedly in red blood cells Protein Processing and Degradation 0 after translation genes regulated by modifying r transporting a protein or in selective degradation 171 39 Geneone enzyme hypothesis 0 Genes dictate phenotype through enzymes that catalyze speci c chemical reactions in a cell Ex Alkaptonuria A disorder in Which someone s urine is black because it contains alkapton because they have inherited an inability to metabolize 39 The products of Gene Expression 0 One Gene One polypeptide hypothesis 39 Not accutare 39 Eukaryotic genes code for a set of related polypeptides via alternative splicing 39 Many genes code for RNA molecules that have important functions in cell that are never translated into proteins But their are many codes that do polypeptide 39 Basic Principals of Transcription and Translation 0 Genes give the instruction for making specific proteins but not directly 0 DNA gt nucleic acid gt RNA 0 RNA Chemically similar to DNA except 0 it contains ribose instead of dioxiribose 0 it has a nitrogenous base urcaril rather than thymine 0 It consist of a single strand 0 Transcription 39 synthesis of RNA using the info in the DNA info transcribes rewritten from DNA to RNA mRNA 0 messanger RNA carries a genetic message from DNA to the protein synthesizing material Translation 39 synthesis of a polypeptide using info from mRNA 39 Cell must translate the nucleotide sequence of an mRNA molecule into an amino acid sequence of a polypeptide 39 Ribosomes Site of Translation 0 molecular complexes that facilitate the orderly linking of amino acids into polypeptide chains 0 Transcription and Translation in Bacteria 39 No nuclei in bacteria no separation by nuclear membranes of ribosomes Lack of compartmentalization allows transcription and translation to occur at the same time Transcription occurs in the nucleus and mRNA is transported to cytoplasm Where translation occurs Gene Programs are governed by the Central Dogma m DNA fr a 39 dv7 Nucleus J a Sip Processing 5 Cytoplasm Ribosome Rlbosome Nascent protein PROKARYOTE EUKARYOTE Figure 2921 iiochcmistry Smnlh Edition w T Rl w n 1m mu nlnnum Nascent protein 39 DNA gt RNA gt Protein 174 39 Molecular Components Translation 0 Translation the Basic Concept 39 mRNA is moved through ribosome and codons are translated into amino acids 39 interpreters tRNA with a speci c nucleotide triplet called Anticodons at one end of a corresponding amino acids 39 anticodons add its aa cargo to the end of the polypeptide chain When the anticodon hydrogen bonds on the complementary codon go the mRNA Transfer RNA 39 Series of codons along an mRNA molecule and the translator 39 Function transfer amino acids from the cytoplasmic pool of amino acids to a growing polypeptide Cell cytoplasm 39 stocked with all 20 amino acids either by synthesis from other compounds of by taking them up from surrounding solution Ribosome 39 Structure made of proteins and RNA s 39 Function add each aa brought by tRNA to the growing end of the polypeptide chain Structure and Function of Transfer RNA Function of tRNA 0 Each tRNA molecule translates a given mRNA codon into certain aa s 0 Possible bc tRNA has the speci c aa sequence at one end and the nucliotode triplet that can basepair with a complementary codon on mRNA 39 Structure of tRNA 0 Consist of single RNA strand that is a about 80 nucleotides long 0 Strand can fold on itself b of hydrogen bonding of complementary pairs and make a 3 d structure If attened it looks like a cloverleaf 0 3D it looks like an L 0 5 end of the loop extending from L anticodon 39 Speci c nucleotide triplet sequence that base pairs to speci c mRNA codon 3 end of tRNA attachment site for aa s Molecular recognition for translation 0 l tRNA binds to mRNA codon for a particular aa and carries it to the ribosome 39 Endergonic process Which occurs at eXpense of ATP Which loses 2 phosphate groups becoming AMP 39 Aminoacyl tRNA synthetases Enzyme that carries out correct matching of tRNA and aa 0 20 synthetases for each aa 0 catalyze attachment of aa s to tRNAs in a process by driven by hydrolysis of ATP 0 Resulting aminoacyl tRNA aka charge tRNA is released from enzyme and able to deliver aa s from polypeptide chain on ribosome 0 2 Matching tRNA anticodon with mRNA codon 39 Rules of base pairing in 3rd nucleotide base of a codon and the corresponding tRNA anticodon 39 Wobble Flexible base pairing at codon Ribosomes 0 Function Facilitate the coupling of tRNA anticodons with mRNA codons during protein synthesis 0 Structure Large subunit and small subunit made up of ribosomal RNAs 0 In both pro and Euks a large and small subunit join to form a functional ribosome only When attached to a small mRNA molecules 0 Mass of ribosomal make up 39 13 mass made from proteins 39 the rest rRNA 3 molecules in bacteria 0 4 molecules in Eukaryotes rRNA is the most abundant cell type of RNA 0 Eukaryotic ribosomes V Prokaryotic Ribosome39s Similar in structure and function 39 Eukaryotic39s are larger and certain antibacterial drugs can inactivate bacterial ribosomes Without affecting eukaryotic ribosomes 0 Structure of bacterial ribosomes 3 binding sites 0 P site peptidyltRNA site holds tRNA carrying the polypeptide chain 0 A site aminoacyltRNAholds tRNA carrying the next aa to be added to the chain 0 E site Exit site where discharged tRNAs leave the ribosome 39 tRNA and mRNA held closely together so it can be added to carboxyl end of the growing polypeptide the polypeptide chain is then catalyzed to form a peptide bond and passes through eXit tunnel in ribosomal subunit when complete rRNA hypothesis 0 RNA not protein is primarily responsible for structure and function of a ribosome Building a Polypeptide 0 Translation the synthesis of a polypeptide diVided in 3 stages 0 Initiation Elongation and Termination Initiation Stage Brings together mRNA a tRNA with the 1st aa of the polypeptide 2 subunits of the Ribosome Followed by the attachment of a large ribosomal subunit completing the transition initiation complex Initiation factor proteins bring all the components together Cell eXpends energy from hydrolysis of GTP molecule to form initiation compleX Polypeptide is always synthesized in one direction from the initial methionine at the aa end 2 ends N terminius and Cterminius carboyl end 0 Elongations stage aa s are added to one by one to preVious aa at the Cterminous of the growing chain Aided by elongation factor proteins Occurs in a three step cycle 0 lcodon recognition 39 Via aminoacyl tRNA base pairs with mRNA Hydrolysis of GTP increase and accuracy of this step 0 2 Peptide bond formation 39MA CKILNDH JMV Ribosome mady tor next aminoacyl tRNA 5 3translocation 0 Termination 39 Release factors protein binds to stop codon in A site 39 Causes the addition of water instead of an aa to polypetide chain 39 reaction hydrolyzes and breaks the bond Polypeptide chain eXits Via the P site 39 Polypeptide after translation 0 Folding and other modi cations coils to form primary structure ribosomes alternate from being free and bound to the next Signal peptide 0 Mark polypeptides of proteins destined for endomembrane system and targets proteins to ER Signalrecognition particle SPR 0 protein RNA complex 0 Making multiple polypeptides in Bacteria and Eukaryotes 39 single mRNA is used to make many copies for a polypeptide chain Polyribosomes polysome 0 multiple ribosomes trailing on mRNA Summery of Transcription and translation in Eukaryotic cell DNA 394 quotI39m1 V I I an mull Exon 175 Mutations of nucleotide affecting protein structure and function 0 Mutations 39 sources of diversity in genes 0 long scale mutations changes in chromosomal arrangement 0 Point mutation 39 Small scale mutations that occur on single nucleotide pair in a gene 0 Genetic disease hereditary disorder point mutation is on gametes and passed down to offspring EX Sickle Cell disease 0 mutation of nucleotide pair in the gene that encoded Betaglobin polypeptide of hemoglobin Leads to the formation of abnormal protein 39 homozygous for mutant allele have a sickle shaped red blood cells caused by alter hemoglobin produced from the altered nucleotide sequence Ex 11 Familial cardiomyopathy 0 heart condition caused by point mutation responsible for sudden death of you athletes Substitutes 39 Nucleotidepair substitute 0 replacement of one nucleotide pair for another 0 Silent mutation 39 No effect on aa sequence 39 When a mutation has no affect on the outcome of the protein 39 EX CCG and CCA both make glycine so if one is substituted for the the other it will still make the same protein 0 Missence mutations Range of effects depending on location within protein and the identity of the new aa 39 substitutions that change one amino acid for another 39 still codes for an aaeven though its the wrong one its the right sense 0 Nonsense mutations 39 effect depende on how close the mutation is to the wildtype stop codon 39 can cause termination to be terminated prematurely resulting in a short polypeptide Usually lead to nonf1ctional proteins Insertion and Deletions 0 addition or losses of nucleotide pairs in a gene 81 39 Metabolism 0 Total Chemical reactions of an organism manages energy and material 39 Metabolic pathway Thousands chem reactions 39 Catabolic pathways 0 Release energy by breaking down compounds into smaller ones 0 Release C02 and H20 39 EX Cellular respiration Catabolic pathway Sugar and glucose break down 2 H20 and C02 Anabolic pathways 0 Consume energy to build complicated molecules from smaller ones AKA biosynthetic pathways EX Synthesis of amino acids from simple molecules Synthesis of protein from amino acids Bioenergetics 39 Study of energy ow through living organisms 39 Energy 39 Capacity to cause change used for work 39 Kinetic Energy 0 Energy associated w mvmt 0 Thermal Energy KE associated w random mvmt of atoms 0 Transfer of thermal energy to another object HEAT 39 Potential Energy 0 Energy matter posses bc of location and structure EX Energy bc of arrangement electrons in a molecule 0 Chemical Energy PE available for release in chem raction Glucose high in PE Law of Thermodynamics 0 Thermodynamics 39 Study of energy transformation 0 1st Law of Thermodynamics Energy can be transferred and transformed it cannot be created or destroyed 0 2nd Law Of Thermodynamics Every energy transfer increases entropy 0 Entropy 39 Measure of disorder 0 Spontaneous process 39 Process that occurs wo energy energetically favorable 8 2 39 Free Energy 0 Energy that can perform work when temp and pressure are uniform in a system Delta G DeltaH TDelta S 0 G Free energy H Enthalpy 0 S Entropy 0 T Temp in K 39 Spontaneous Less energy less likey to change More stable Higher G Less stable more free energy more ablilty to do work 39 Lower G More stable Less FE Less able to do work 39 A process is spontatoeu and can perform work only when moving toward equilibrium Exeronic reaction 0 Chem reaction that has a net release of free energy 0 Delta G is Energonic reaction 0 Chemreaction that absorbs free energy 0 Delta G is 39 If a cell is at metabolic equilibrium it will die 84 Enzyme Macromolecule tht acts as a catylast 0 Catalyst chem agent that speeds up a reaction wo being consumed by the reaction 39 Activation Energy 0 Highly unstable state in chemical reaction need to reach the controlled product 0 activation Energy is supplied by heat in the form of thermal energy Transition State 0 MaX top of the hill 0 When energy has been absorbed that bonds can break 0 reactions unstable 39 How to enzymes work 0 Lower EA barrion 0 hasten chem reaction process 0 Substrate 39 Reactant an enzyme acts on 0 Enzyme substrate compleX where enzyme binds to substrate Enzymes are mostly proteins that catalyze When they t into a substrate 0 Active site 39 Site that the substrate attached to the substrate enzyme complex 0 Induced Fit no set in stone shape but general Wiggile room for the substrate to n in substrate enxyme compleX Substrate sucrosel n Enzyme is available with empty active site Active site 7 Enzyme sucrase o Substrate binds to enzyme W a Water Fructose 0 Products e Substrate is are released converted to products Saturated enzyme highest concentration of substrate All sightes active Effects of Emp and pH on Enzyme 39 Optimal temp and Presure for each enzyme most human enzyme opt temp 3540 C 39 Optimal pH for mist human enzymes in 68 0 Exception pepcin digestiv enzyme 2 Cofactos 39 Non protein helpers for catabolic activity Non organic 39 Coenzyme 0 Organic Cofactor Enzyme inhibitors irreversable inhibitors attach to enzyme by covalent bonds Compettive enzymes 0 mimic substrates and compete for active site inhibit substrates from entering 39 Noncompetative inhibitors 0 Impede enzyme reaction by attaching part of enzyme 0 Cause enzyme to change shape and active sites become less effective 91 Cells break down glucose and other organic fuels to yield chemical energy in the form of ATP 39 Fermentation 0 Process that results in the particle degradation of glucose Without the use of oxygen 0 anaerobic process 39 Cellular respiration 0 Complete breakdown of glucose Aerobic respiration 0 O is used as a reactant Glucose C6H1206 is oxidize to C2 and 02 is reduced to H20 Redox reactions 0 Process in Which one substance partially or totally shifts electrons to another 0 Taps energy stored in food molecules Oxidation 0 Loss of electrons from one substance 39 Reduction 0 Addition of electrons Electrons lose potential energy in the transfer of glucose to other organic compounds to O 39 Electrons are usually passed 1st to NAD reducing it to NADH to electron transport chain Electron transport chain 0 conducts electron to 02 in energy releasing steps and the energy is good to make ATP Anaerobic respiration occurs in three steeps 0 l glycosis 0 2 Citrid acid cycle 0 3 Phosphoylation
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