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Genetics: The Old and the New (and there is a “Lot” of Newness). Introduction Analogy to an “information broker” Radical transformation of the science (i.e., what is a revolution in the sciences ) Genetics of inheritance - Mendelian genetics ( > 1860)
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Genetics: The Old and the New (and there is a “Lot” of Newness) • Introduction • Analogy to an “information broker” • Radical transformation of the science (i.e., what is a revolution in the sciences) • Genetics of inheritance - Mendelian genetics (> 1860) • Genetics of cell’s operation - molecular genetics (> 1950) • The “Genetic Code” • Genetics “on the cutting edge”: last five years
Introduction • Why is an “information broker” important in living systems? • What constitutes a “revolution” in the sciences?
The Old: Genetics of Inheritance (1860’s) • Classical or Mendelian genetics (Gregory Mendel) • Competing hypotheses • Blended inheritance versus particulate inheritance • Testing the hypotheses (Scientific Method!!) • Flower color in peas (1 parent with red flowers and 2nd parent with white flowers) • Results: two classes of flowers • Red (300 seedlings) • White (100 seedlings) • Pink (0 seedlings) • Conclusion • Hypothesis: Data support the particulate theory Data reject blended theory • Specific quantitative data: 3:1 ratio (strange but revealing quantitative ratio!) 300 100
Rules of Classical Mendelian Genetics (1860’s) • Traits passed from parent to offspring consistent with particulate inheritance model • Mechanism unknown at the time (now we know) • Two “copies” of each trait in each individual (3:1 ratio) • One from each parent • Some “copies” are dominant and some copies are recessive • Dominant traits = expressed • Recessive traits = expressed only if both copies recessive
Mendelian Genetics (1860’s) and Coming Forward • Gene - trait determined by a sequence of DNA • Allele - alternative forms (“copies”) of the same gene (e.g., normal hemoglobin vs sickle cell hemoglobin; blue vs brown eyes) • No longer called “copies” but alleles!!! • Dominant allele (e.g., brown eyes) • Recessive allele (e.g., blue eyes) • Chromosomes - physical packaging of genes in nucleus • Pairs of chromosomes • Genome - all of the genes of an organism in the nucleus • Humans: ~20,000 genes
Question If you were to cross rabbits that were black with rabbits that were white and the offspring were gray, this outcome would supportthe theory of ___________. A particulate inheritance B conspicuous inheritance C Lamarckian inheritance D blended inheritance E None of the above
Question The “unit of inheritance” documented by Mendel is now called the ___. A hybrid B parental strain C gene D dominant allele E the “Mendel”
Question In genetic crosses the re-current quantitative ratio of 3:1 among offspring supports the presence of ____ copy/copies of each gene in an organism of all species of eukaryotes. A four B three C two D one
Chromosomes, Genes and Alleles Sickle Cell Normal Normal Hemoglobin Chemistry Normal Attached Attached Ear Lobe Free Free Blue Brown Eye Color: Brown Blue Blue A O Blood Group B O Individual One (Thee) Individual Two (Me)
Genetics of Humans: Sex Determination • Humans = 46 chromosomes or 23 pairs • Sex determination on one pair of chromosomes (Pair No. 21) • X and Y chromosome • Female: two “X” chromosomes • Male: one “X” and one “Y” chromosome • Female produces only X chromosome eggs • Male produces both X and Y chromosome sperm • Who determines the sex of offspring? • Sex-linked traits … examples?
46 chromosomes in each human (23 pairs) ~20,000 different genes in each human Only ~1.5% of genome active … we think (stay tuned!) Millions of nucleotide differences between any two people Complexity of the Human Genome Affymetrix
Genetics: The Old and the New • Introduction • Analogy to an “information broker” • Radical transformation of the science (i.e., revolution) • Genetics of inheritance - Mendelian genetics (> 1860) • Genetics of cell’s operation - molecular genetics (> 1950) • The “Genetic Code” • Genetics “on the cutting edge” (> 2005)
Molecular Genetics • Structure of DNA and RNA - information storage, transmission and expression • Replication of the information - copying/duplication • Transcription of the information - transcribing • Translation of the information - expressing as proteins (requires new language with new alphabet!)
Watson and Crick: a Revolution in the Sciences 1953 Double helix Contribution of Watson and Crick: Monomer = Nucleotides (A, T, C and G) Polymer = polynucleotide (nucleic acid) 3 D Structure of Nucleic Acid = DNA Double Helix Watson Crick
Nucleotides: The Building Blocks of Nucleic Acids • Nucleotide: three components • Sugar • DNA: deoxyribose • RNA: ribose • Phosphate group • Base (N=4) • Adenine (A) • Guanine (G) • Cytosine (C) • Thymine (T)
DNA Structure • Join nucleotides • Alternating phosphate and sugar • DNA • 2 strands of nucleotides • Joined by nitrogen base pairs (A, T, C and G) • Bonding pattern (fidelity!) • Adenine : Thymine • Cytosine : Guanine • Information broker - “biological alphabet” (A,T,C and G)
Question Nucleic acids such as DNA and RNA are polymers (macromolecules) of the monomers called ____. A amino acids B monosaccharides C nucleotides D lipids
Question While the English alphabet contains 26 letters, the biological alphabet of the DNA is based on whopping number of ___ nucleotides/”letters”. A 2 B 4 C 6 D 8
Question The term “fidelity” in base pairing of nucleotides in DNA means that the nucleotide thymine always pairs with nucleotide ___. A europocil B cytosine C another thymine D guanine E adenine
Genetics: The Old and the New (and there is a “Lot” of Newness) • Introduction • Analogy to an “information broker” • Radical transformation of the science (i.e., what is a revolution in the sciences) • Genetics of inheritance - Mendelian genetics (> 1860) • Genetics of cell’s operation - molecular genetics (> 1950) • The “Genetic Code” • Genetics “on the cutting edge”: last five years
Molecular Genetics: Structure of DNA and RNA • DNA - Deoxyribonucleic acid (nucleus; double strand) • RNA - Ribonucleic acid (protoplasm; single strand) • Monomer - nucleotides (N = 4 in DNA) • Guanine (always binds to Cytosine - G:C) • Adenine (always binds to Thymine - A:T) • Cytosine (always binds to Guanine - C:G) • Thymine (always binds to Adenine - A:T) • Polymer - polynucleotide (DNA & RNA)
Sequence of Nucleotides and Genes • Linear sequences of nucleotides • Gene: sequence of nucleotides responsible for a specific trait (e.g., eye color; hemoglobin; attached ear lobes, carbon metabolism, sickle cell anemia, enzyme) • Remember the iphone image Number of nucleotides 431 1150 1225 653 1580 102 954
Molecular Genetics: A Single Gene • Exact sequence of nucleotides is important • Any change in sequence changes the information (“RAT to CAT”) and constitutes a mutation • Daily: you experience 10,000’s of mutations but all are corrected (for the most part) A T T A G C G G T A T G C C G G T T A A G A T C C G A T T A G C G G T A CG C C G G T T A A G A T C C G
Molecular Genetics: General Theme Replication
Molecular Genetics: Replication • Replication: process of duplicating DNA to produce a new and exact copy with fidelity • includes “spell checking”
Molecular Genetics Replication
Molecular Genetics: Transcription • Information in DNA “transcribed” into another type of message - mRNA (messenger RNA) • Analogue to transcribing spoken into written language • mRNA made in nucleus and subsequently shuttled to protoplasm • In protoplasm, mRNA to the ribosome (protein synthesis)
Compartmentation: Ribosome Figure 23.22 23-494
Molecular Genetics: Translation in the Ribosome Replication
Molecular Genetics: Translation • Information in mRNA “translated” into polypeptide and then functional protein (new language and “new letters of the alphabet”!) • Monomer: amino acids • Location: ribosome for protein synthesis • Genetic code: specificity and fidelity • All organisms and all species use the exact same process • Example: genetically modified organisms (GMO’s)
Protein Synthesis and Genetic Code • One gene codes for one protein • Protein drives chemical process in cell (e.g., enzymes) • Original source of information = DNA • Intermediate source of information = RNA • All living things on Earth use the absolute same genetic code
Transcription, Translation and Protein Assembly http://www.youtube.com/watch?v=983lhh20rGY
Question In the following figure, the process linking the DNA to RNA (see white arrow) is called _______. A replication B transcription C translation D gene splicing
Question Making a copy of DNA is called ___. A replication B transcription C translation D. photocopying
Question The sum of all information contained in your DNA and copied in each cell in your body is called your ___. A gene base B gene traits C genome D. genetic material
Mutations and DNA Repair • Mutations • Change in sequence of nucleotides in DNA • Causes of mutations • Oxygen (e.g., aging) • Nuclear radiation • X-rays • UV light (e.g., beach time!) • Higher elevations (e.g., mountain tops, airplanes) • DNA Repair • 10,000 ‘hits’ per day (you and me!!) • Cells repair damage - excision and repair process • BUT …. repair not equal in all individuals
Molecular Genetics: A Single Gene (Single Strand) • Exact sequence of nucleotides is important • Any change in sequence changes the information (“RAT to CAT”) and constitutes a mutation • Excision and repair A T T A G C G G T A T G C C G G T T A A G A T C C G A T T A G C G G T A CG C C G G T T A A G A T C C G
Genetics: The Old and the New • Introduction • Information broker • Radical transformation of the science (i.e., revolution) • Genetics of inheritance - Mendelian genetics (> 1860) • Genetics of cell’s operation - molecular genetics (> 1950) • The “Genetic Code” • Genetics “on the cutting edge” (last five years)
Genetics “on the Cutting Edge” • Genetic counseling (probability of offspring with particular traits) • Forensic sciences (e.g., CSI TV series) • Genetic engineering : GMO’s (Genetically Modified Organisms) • Genetic “Sleuthing” • Human applications (e.g., ice man in the Alps + 5,000 years) • Genetic basis of autism • Genetics, mutations and cancer (next week’s lecture) • Editing of genes
Genetics “on the Cutting Edge” • Genetic counseling (probability of offspring with particular traits) • Forensic sciences (e.g., CSI TV series) • Genetic engineering (e.g., “starlight” strain of corn) • GMO’s (Genetically Modified Organisms) • Genetic “Sleuthing” • Human applications (e.g., ice man in the Alps + 5,000 years) • Genetic basis of autism • Genetics, mutations and cancer (next week’s lecture) • Editing of genes
Genetics: The Old and the New (and there is a “Lot” of Newness) • Introduction • Analogy to an “information broker” • Radical transformation of the science (i.e., what is a revolution in the sciences) • Genetics of inheritance - Mendelian genetics (> 1860) • Genetics of cell’s operation - molecular genetics (> 1950) • The “Genetic Code” • Genetics “on the cutting edge”: last five years