Presentation on theme: "Designer Genes (C) National Bio Rules Committee Chairman"— Presentation transcript:
1Designer Genes (C) National Bio Rules Committee Chairman KAREN LANCOURNational Bio RulesCommittee Chairman
2Event Rules DISCLAIMER This presentation was prepared using draft rules. There may be some changes in the final copy of the rules. The rules which will be in your Coaches Manual and Student Manuals will be the official rules.
3Event RulesBE SURE TO CHECK THE CURRENT YEAR EVENT RULES FOR EVENT PARAMETERS AND TOPICS FOR EACH COMPETITION LEVEL
4TRAINING MATERIALS Training Power Point – content overview Training Handout - content informationSample Tournament – sample problems with keyEvent Supervisor Guide – prep tips, event needs, and scoring tipsInternet Resource & Training CD’s – on the Science Olympiad website at under Event InformationBiology-Earth Science CD, new Genetics CD as well as the Division B and Division C Test Packets are available from SO store at
5Designer Genes (C)Content – General Principles plus Molecular Genetics and BiotechnologyDNA structure, function and replicationTypes of RNA, transcription and post-transcription modificationsTranslation and Universal CodeControl of Gene ExpressionDNA technologies such as cloning, sequencing, analysis, fingerprinting, and PCR, gene therapymitochondrial inheritancetrinucleotide repeats and other disordersBioethicsEpigeneticsProcess Skills - observations, inferences, predictions, data analysis, and calculationsEvent ParametersNon programmable calculatorNo other resources
6GENERAL PRINCIPLES OF GENETICS for Designer Genes Students need to review the general principles of geneticsThese areas are covered in the Heredity event in Division B so these event materials are a good reviewMost event supervisors include some general principles and problems on their competitions for Designer Genes
7Emphasis Scheme - General Principles plus Regional & StateNational (all topics)DNA structure & functionLac & Trp OperonsRestriction mappingDNA Semi-conservativeReplicationDNA Fingerprinting/RFLPMitochondrial DNAGene Expression (transcription and translationDNA SequencingDNA RepairControl and detection of gene expressionPlasmid selection and isolationPost- transcriptional modificationMutationsPCRTrinucleotide repeatsGene TherapyEpigenetics
8CENTRAL DOGMA OF MOLECULAR GENETICS DNA ---- RNA --- PROTEIN SYNTHESISREPLICATION TRANSCRIPTION TRANSLATIONExceptions among viruses – RNA to DNA(retroviruses)
12Nuclear vs Cytoplasmic DNA in Eukaryotic Cells Nuclear DNA – in chromosomes within the nucleus of the cellCytoplasmic DNA – in chloroplasts and mitochondria• Chloroplast DNA (cpDNA)• Mitochondrial DNA (mtDNA)Features:• Maternal inheritance• Resemble prokaryotic DNA• Slow accumulation of mutations
13Types of RNA Differences between RNA & DNA RNA is single strand - DNA is double strandRNA has Ribose – DNA has DeoxyriboseRNA has Uracil – DNA has ThymineMessenger RNA – carries blueprint from nucleus to cytoplasmTransfer RNA – brings amino acidsRibosomal RNA – reads code and allows M-RNA and T-RNA to connect
14Transcription Making RNA from DNA template Transcription takes place in the nucleus
15Post-transcription Modifications Introns and exons at transcriptionIntrons removedExons are coding pieces for proteinsynthesisCap and PolyA tail are added
16Gene ExpressionTranscription – DNA is template for making RNA (in nucleus)Translation (protein synthesis) - in cytoplasm at the ribosome. M-RNA has blueprint, T-RNA transfers amino acids, and Ribosome (R-RNA) allows T-RNA to attach to M-RNA at appropriate site.
19Translation (Protein Synthesis) The steps of translation:1. Initiation: mRNA enters the cytoplasm and becomes associated with ribosomes (rRNA + proteins). tRNAs, each carrying a specific amino acid, pair up with the mRNA codons inside the ribosomes. Base pairing (A-U, G-C) between mRNA codons and tRNA anticodons determines the order of amino acids in a protein.2. Elongation: addition of amino acids one-by-one: As the ribosome moves along the mRNA, each tRNA transfers its amino acid to the growing protein chain, producing the protein3. Termination: when the ribosomes hits a stop codon - UAA, UGA, or UAG - the ribosome falls apartNote: The same mRNA may be used hundreds of times during translation by many ribosomes before it is degraded (broken down) by the cell
20Control of Gene Expression Transcriptional ControlPost transcriptional Control – assembling proteinsCell differentiation and specializationTurning genes “on” and “off”Chemical Signals – HormonesChemical ModificationsRelocation of DNA – transposonsAbnormal Expression of Genes
21MutationsMutation – any change in the DNA blueprint for making protein or RNAGene mutationChromosomal mutationAgents causing mutations – radiation, chemicals, excess heat
22Genetic DisordersNondisjunction – extra or missing chromosomes as Down’s SyndromeTrinucleotide repeats – triplet nucleotidesrepeated too often as Huntington’sDefective genes – does not produce correct protein as sickle cell anemia (A & T traded places)
23MITOCHONDRIAL INHERITANCE The inheritance of a trait encoded in the mitochondrial genomeMitochondrial DNA or mtDNA is inherited from the motherThe mtDNA is circular and resembles prokaryotic DNAThe mitochondria are responsible for energy production
24Trp OperonThe genes for the five enzymes in the Trp synthesis pathway are clustered on the same chromosome in what is called the Trp OperonIf the amino acid tryptophan (Trp) is added to a culture of E coli , the bacteria soon stop producing the five enzymes needed to synthesize Trp from intermediates produced during the respiration of glucose so the presence of the products of enzyme action represses enzyme synthesisThis is a repressable operon where the operon are turned off in the presence of a substance
25Lac OperonThe genes that code for the enzymes needed for lactose catabolism are clustered on the same chromosome in what is called the Lac OperonThe E. coli only express the genes and make these enzymes when lactose is available to be metabolized. This is an inducible operon where genes are expressed in the presence of a substance
26Biotechnology Technology used to manipulate DNA Procedures often called genetic engineeringRecombinant DNA - DNA from two sourcesTransgenic individuals have DNA from another organismOften involve putting genes into viruses or bacteria.Vectors are the pieces of DNA used to transfer genes into a host cell – often plasmids of bacteria
28Basic Tools of DNA Technology Identifying desired DNACutting DNA with Restriction EnzymesInserting DNA into Vector as PlasmidConnecting DNA pieces with LigaseInserting Vector into Host Cell as bacteriumCloning desired DNA and VectorsStoring clones in DNA LibrariesIdentifying cloned genes with Radioactive ProbesAnalyzing DNA by cutting fragments and separating by Electrophoresis
29Basic Tools Gene selection & isolation from Donor Vector - Plasmid selection & isolationRestriction enzyme to cutpiecePutting pieces together(hybridization)DNA ligase to reattach piecesInsert into Host bacteriaClone the bacteria
30cDNA – complementary DNA cDNA- Eukaryotic genes contain introns but bacteria do not contain the necessary enzymes to remove intronsEukaryotic genes that are inserted into bacteria must be inserted without introns.Use reverse transcriptase (from retroviruses) and modified M-RNA to produce cDNA with introns already removed
31Techniques Cloning within cells and with PCR Storing clones in DNA LibrariesIdentifying cloned genes with Radioactive ProbesAnalyzing DNA by cutting fragments and separating by Electrophoresis/nucleic acid hybridization/DNA probesTransferring DNA from gel by BlottingImaging with autoradiographyDNA Sequencing to determine exact sequenceMicroassays to analyze gene function
32DNA Libraries Genomic – normal DNA cDNA – modified to remove introns Fragments storedStored in plasmids or bacteriophages
33Polymerase Chain Reaction (PCR) Technique for quickly making an unlimited number of copies of any piece of DNASometimes called "molecular photocopying"
34Radioactive Probes short, radioactive strands of DNA will pair up with complementing strands of DNAfragments that contain the labeled pieces will show up on an x-ray film
35ElectrophoresisA process in which molecules (such as proteins, DNA, or RNAfragments) can be separated according to size and electricalcharge by applying an electric current to them.
36DNA Hybridization Base pairing of two single strands of DNA or RNA. Can be DNA-DNA, DNA-RNACan be a radioactive probe
38DNA Sequencing Determine the exact nucleotide sequence Columns for A,T,C, and GRead rows from top to bottom
39Restriction MappingDescription of restriction enzyme cleavage sites within a piece of DNAUse of different restriction enzymes to analyze and generate a physical map of genomes, genes, or other segments of DNA
40DNA Microassaystudying how large numbers of genes interact with each otherprecisely apply tiny droplets containing functional DNA to glass slidesattach fluorescent labels to DNA from the cell they are studying.labeled probes are allowed to bind to complementary DNA strands on the slidesslides are put into a scanning microscope that can measure the brightness of each fluorescent dotbrightness reveals how much of a specific DNA fragment is present, an indicator of how active it is.
41DNA Fingerprinting Techniques RFLP – Restriction Fragment Length Polymorphism (original)PCR – Polymerase Chain ReactionVNTRs – Variable Number Tandem RepeatsSTRs - Short Tandem RepeatsRibosomal DNA analysisY-chromosome analysis
42Restriction Fragment Length Polymorphism - RFLP The DNA of an organism is cut up into fragments using restriction enzymes.A large number of short fragments of DNA will be produced. (RFLP’s)Electrophoresis is a technique used to separate the DNA fragments according to their size.Uses- identification of diseased genes including oncogenes, identification of viral infections, determining family relationships among individuals, and identifying tissue found at a crime scene.
43Restriction Fragment Length Polymorphisms (RFLP) Genetic variations at the site where a restriction enzyme cuts a piece of DNA.Such variations affect the size of the resulting fragments.These sequences can be used as markers on physical maps and linkage maps.
44VARIABLE NUMBER TANDAM REPEATS (VNTR’s) Short nucleotidesequencesOrganized in clustersof tandem repeatsVNTR = base pairsSNR = base pairs
45Applications of Biotechnology Techniques Human Genome ProjectDiagnosis of Disease – PCR & DNA probesHuman Gene TherapyVaccines & Pharmaceutical ProductsForensics – DNA Fingerprints (RFLP & VNTR)Environmental – Recycling & detoxificationAgricultural – transgenic organisms
47Epigeneticsthe study of heritable changes in gene activity that occur without a change in the sequence of the genetic material. Epigenetics literally means ‘in addition to genetics’.Epigenetic factors can regulate the amount of gene activity, influencing the growth and appearance of an organismThere are several epigenetic ways in which gene activity can be prevented or controlled, includingmodification of histone proteinsDNA methylationRNA interferenceFor any of these methods of gene regulation, the absence of the protein product of the gene causes a change in the function or development of the cellmalfunctions in epigenetic control of gene activity have been implicated in cancer, cardiovascular disease and several inherited genetic conditions