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Designer Genes (C)-2014 PowerPoint Presentation
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Designer Genes (C)-2014

Designer Genes (C)-2014

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Designer Genes (C)-2014

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  1. Designer Genes (C)-2014 KAREN LANCOUR National Bio Rules Committee Chairman

  2. Event Rules – 2014 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.


  4. TRAINING MATERIALS • Training Power Point – content overview • Training Handout - content information • Sample Tournament – sample problems with key • Event Supervisor Guide – prep tips, event needs, and scoring tips • Internet Resource & Training CD’s – on the Science Olympiad website at under Event Information • Biology-Earth Science CD, Genetics CD as well as the Division B and Division C Test Packetsare available from SO store at

  5. Designer Genes (C) • Content – Molecular Genetics, Biotechnology • DNA structure, function and replication • Types of RNA, transcription and post-transcription modifications • Translation and Universal Code • Control of Gene Expression • Organelle DNA - mitochondrial inheritance • DNA technologies such as cloning, sequencing, analysis, fingerprinting, and PCR, gene therapy • Trinucleotide repeats and other disorders • Gene Therapy, Bioethics, and Epigenetics • Next Generation Sequencing Platform • Process Skills - observations, inferences, predictions, data analysis, and calculations

  6. GENERAL PRINCIPLES OF GENETICS for Designer Genes • Students need to review the general principles of genetics • These areas are covered in the Heredityevent in Division B so these event materials are a good review • Most event supervisors include some general principles and problems on their competitions for Designer Genes

  7. Emphasis Scheme - General Principles plus

  8. PRINCIPLES OF GENETICS • GENES– come in pairs • Section of DNA – codes protein or part of protein • One from each parent • ALLELE– different forms of a gene • MULTIPLE ALLELES – more than 2 forms of a gene • HOMOZYGOUS– same alleles • HETEROZYGOUS– different alleles

  9. Dominant vs. Recessive • Dominant –always expressed • Capital letters – N • Homozygous - NN • Heterozygous - Nn • Recessive –prevented by dominant • Lower case letters – n • Homozygous – nn Punnett Square – Box showing allele combinations

  10. Dominant and Recessive • Autosomal Dominant Dominant gene on an autosome • Autosomal Recessive Recessive gene on an autosome • Sex-linked Dominant Dominant gene on a sex chromosome • Sex-linked Recessive Recessive gene on a sex chromosome

  11. Monohybrid Cross Hybrid– SsX Ss One Trait– Smooth vs wrinkled Two gametes per parent S and s Punnett Squarewith 4 boxes – 4 offspring

  12. Genotype & Phenotype GenotypePhenotype SS or Ss Round ss Wrinkled Genotype frequency 1:2:1 Phenotype frequency 3:1

  13. Dihybrid Cross Dihybrid – 2 traits Gametes per parent = 4 Punnett Square – 16 boxes Genotype ratio 1:2:1:2:4:2:1:2:1 Phenotype ratio 9:3:3:1

  14. Trihybrid Cross

  15. Incomplete Dominance • Hybridis a blend of two traits • Genotype frequency 1:2:1 • Phenotype frequency 1:2:1 • Examples: Flowers, Animal fur

  16. Co-dominance • More than one dominant allele • Blood types – A,B,O alleles • Phenotypes Genotypes A I AI A or I Ai B IBIB or IBi AB I AIB O ii

  17. Co-dominance • co-dominance– both dominant alleles (genes) in an individual are expressed as blood types • A and B genes are co-dominant and both dominant over the O gene which is recessive

  18. ABO Blood System

  19. Independent Assortment vs. Linkage • Independent Assortment– genes on different chromosomes separate independently during meiosis • Linkage– genes on the same chromosome are inherited as a group • Autosomal linkage– on autosomes • Sex-linked– on sex chromosomes

  20. Linkage – Sex Linkage • Linkage– genes on the same chromosome inherited as a group • Sex-linkage– genes on sex chromosomes (esp. X) • Y-chromosome shorter – some genes from X missing • X-linked traits more common in men • Men get X-chromosome from mom • Red-green colorblindness, hemophilia

  21. Environmental influence on genes expression • Gene function is influenced by environment as with identical twins • Genes have blueprint for proteins or parts of proteins • Proteins can be structural proteins (parts of body) or functional proteins (hormones/enzymes)

  22. Epistasis and Multifactorial Inheritance • Epistasis- the interaction between two or more genes to control a single phenotype • Multifactorial inheritance- many factors (multifactorial) both genetic and environmental are involved in producing the trait or condition. Examples: height, weight, cleft palate, spina bifida

  23. Pedigree Symbols • Generations= I – Original Parents, II- F1 (children), III – F2 (grandchildren)

  24. Pedigree – Curly vs Straight Hair Types of Analysis • Relationships • Dominant Gene – H Curly • Recessive Gene – h Straight • Genotypes • Phenotypes

  25. Karyotypes • Pairs 1-22=Autosomes • XY= Sex chromosomes • Male= X & Y • Female= only X • Nondisjunction • Extra chromosomes (Trisomy) • Missing chromosomes (Monosomy)

  26. Cell Cycle • Interphase • G1 • S – DNA replicates • G2 • Mitosis • Prophase • Metaphase • Anaphase • Telophase

  27. Mitosis vs Meiosis • Mitosis • Growth and Asexual Reproduction • One division – 2 diploid cells • Genetically same as original • Meiosis • Gametes for Sexual Reproduction • 2 divisions – 4 haploid cells


  29. DNA Structure • Double helix • Antiparallel • Nucleotide • Deoxyribose • Phosphate • Nitrogen bases • Adenine • Thymine • Guanine • Cytosine

  30. DNA Replication • Replication(in nucleus) • DNA uncoils & splits • Reads 3’ to 5’ • Assembles 5’ to 3’ • 4 types of nucleotides • Okazaki fragments in lagging strand


  32. DNA Repair • Genes encode proteins that correct mistakes in DNA caused by incorrect copying during replication and environmental factors such as by-products of metabolism, exposure to ultraviolet light or mutagens • The DNA repair process must operate constantly to correct any damage to the DNA as soon as it occurs

  33. Gene Expression • Transcription– 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

  34. TranscriptionMaking RNA from DNA template Transcription takes place in the nucleus

  35. Types of RNA • Differences between RNA & DNA • RNA is single strand - DNA is double strand • RNA has Ribose – DNA has Deoxyribose • RNA has Uracil – DNA has Thymine • Messenger RNA– carries blueprint from nucleus to cytoplasm • Transfer RNA– brings amino acids • Ribosomal RNA– reads codeand allows M-RNA and T-RNA to connect

  36. Promoters • region of DNA that initiatestranscription of a particular gene • located near the genes they transcribe, on the same strand and upstream on the DNA (towards the 3' region of the anti-sense strand • also called template strand and non-coding strand)

  37. RNA Processing • mRNA in prokaryotic cells is to function after transcription but in eukaryotic cells it is modified after transcription • RNA Processing includes 5’ capping for RNA stabilization and ribosome binding; splicing for removing intron sequence and 3’ polyadenylation for protecting mRNA from 3’ exonuclease, extending the half life of mRNA • Eukaryotic pre-mRNA is converted into mature mRNA

  38. Post-transcription Modifications • Intronsandexonsat transcription • Intronsremoved • Exonsare coding pieces for protein synthesis • Cap and PolyA tail are added

  39. Universal Genetic Code • Special start codon (AUG) and three stop codons (UAA, UAG and UGA) • Many codons may code for same amino acid • Third position of the codon, it is more likely the nucleotide is different but it still may code for same amino acid (wobble)

  40. Universal Code (Codon = Amino Acid)

  41. Translation(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 tRNAanticodons 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 protein 3. Termination:when the ribosomes hits a stop codon - UAA, UGA, or UAG - the ribosome falls apart Note: The same mRNA may be used hundreds of times during translation by many ribosomes before it is degraded (broken down) by the cell

  42. Control of Gene Expression in Prokaryotes • Important for single celled organisms who depend on environment for all activities • Bacteria use operons - many functional-related genes are clustered and transcribed under the same types of regulation • Lac & TrpOperons- examples of prokaryotic gene regulation

  43. Lac Operon The genes that code for the enzymes needed for lactose catabolism are clustered on the same chromosome in what is called the Lac Operon The E. coli only express the genes and make these enzymes when lactose is available to be metabolized. This is an inducible operonwhere genes are expressed in the presence of a substance

  44. TrpOperon • The genes for the five enzymes in the Trp synthesis pathway are clustered on the same chromosome in what is called the Trp Operon • This is a repressable operon wherethe operon are turned offin the presence of a substance

  45. Regulatory Components in Eukaryotes • Enhancers - short regions of DNA that can be bound with proteins to promote expression of a distal or a proximal gene. • Promoters - proximal DNA sequences that binds to RNA polymerase for regulating geneexpression. • TATA Box - binds to transcription factor for regulating gene expression, usually within 30bp of the transcription start site.

  46. Control of Gene Expression in Eukaryotes • Transcriptional Control • Post transcriptional Control – assemblingproteins • Cell differentiation and specialization • Turning genes “on” and “off” • Chemical Signals – Hormones • Chemical Modifications • Relocation of DNA– transposons • Abnormal Expression of Genes

  47. Nuclear vsCytoplasmic DNAin Eukaryotic Cells • Nuclear DNA– in chromosomes within the nucleus of the cell • Cytoplasmic or Organelle DNA– in chloroplasts and mitochondria •Chloroplast DNA(cpDNA) •Mitochondrial DNA(mtDNA) Features: •Maternal inheritance •Resemble prokaryotic DNA •Slow accumulation of mutations

  48. Organelle DNA • Mitochondria and Chloroplasts have DNA similar to Prokaryotic cells • It is believed that these organelles were once independent prokaryotes who took up residence and formed a mutualistic relationship • They are involved in energy transfer- photosynthesis & respiration