Announcements 1. Genetics-related course offerings for spring 2003: - BIO 324 Cell biology, 3 credits; 3 hours in lecture - BIO 325 Biotechnology, 3 credits; 5 hours in lab -BIO 397 Seminar in Human gene therapy, 1 credit -BIO 403 Undergraduate Research, 3-4 credits; needs to be arranged one semester in advance with faculty -BIO 597Q Confocal microscopy, 4 credits -BIO 597Y Techniques in molecular biology, 3 credits; 3 hours in lecture - no lab. -BIO 620G Conservation Genetics, 3 credits; lecture and lab -BIO 629B Eukaryotic Molecular Genetics seminar, 1 credit 2. Ch 10: problems 1,4,13, 15 - not to turn in

Restriction Digest Lab: Use This Gel! 1 2 3 4 5 Start measuring from here. Lanes 1 - Markers 2 - Uncut plasmid 3 - EcoRI cut 4 - DraI cut 5 - EcoRI + DraI Molecular weight markers in bp 3 real bands 2 real bands Supercoiled form runs faster, nicked form runs slower than linearized plasmid. Bright band is cut; faint band is uncut

Review of Last Lecture I. Sry and sex determination II. Dosage compensation - different in humans and flies III. Nondisjunction Monosomy Trisomy

Outline of Lecture 18 Polyploidy Variation in structure/arrangement of chromosomes - deletion - duplication - inversion - translocation III. DNA structure and analysis

I. Polyploidy Hybridization of closely related species; often sterile. Additional sets identical to parents.

How does polyploidy arise naturally How does polyploidy arise naturally? - DNA is duplicated in S phase but cell doesn’t go into M phase - Generation of Tetraploids Using Colchicine, a Microtubule Inhibitor Triploids can be created by inhibition of polar body formation during oogenesis, followed by fertilization.

How is polyploidy relevant to our daily lives? Polyploids are generally bigger than diploids; therefore, in horticulture and agriculture they are useful. Examples: -Bananas and tiger lilly - 3n -coffee, peanuts, McIntosh apples - 4n -strawberry - 8n

Somatic Cell Hybridization in Plants creates Allopolyploid Hybrids American Cotton is natural 13 + 13 hybrid

II. Types of Chromosomal Rearrangements, Caused by Breakage and Rejoining

Deletions Chromsome breaks Part is lost - a deletion Synapsis with a chromosome with a large intercalary deletion - loop formation.

Duplications Cytology showed that bar is not due to a gene mutation. Gene redundancy Phenotypic variation Source of genetic variation during evolution Unequal crossing over

Ohno’s hypothesis on the role of gene duplication in evolution Question: How do “new” genes arise? Duplications might allow for major mutation in the extra copy of the gene. Over time, mutations could result in a new function for the duplicated gene - essentially a new gene. Example: myoglobin and hemoglobin

Inversions Inversions don’t add or delete genetic info, but can have effects on gamete formation.

Translocations Robertsonian translocation: most common type in humans One example: SRY in an XX “male”

Inheritance of 14/21 Translocation In Families with Down Syndrome

Familial Down Syndrome Patient with 14/21 Translocation 21 21 14/21 14

Learning check What types of chromosome mutations are required to change this chromosome into each of the following? A B  C D E F G A B A B  C D E F G a. inversion of A B b. deletion of A B c. duplication of A B A B  E D C F G a. translocation of C D E b. inversion of C D E c. deletion of C D E O O

Learning check #2 A species has 2n = 16 chromosomes. How many chromosomes will be found per cell in each of the following mutants in this species? Monosomic Autotriploid Trisomic Autotetraploid 15 24 17 32

III. DNA Structure and analysis What is the genetic material? Chromosomes contain protein and DNA - which is it? What must genetic material do? 1. Replication 2. Storage of information 3. Expression of information 4. Variation by mutation - evolution

The Flow of Genetic Information (The Central Dogma) Trait

Is the Genetic Material Protein or DNA? Many favored proteins until the mid-1940’s. DNA is simple chemically; how could it then hold complex genetic information? Proteins are much more complicated chemically; perhaps they might hold genetic information.

Evidence for DNA as Hereditary Molecule Transformation studies Griffith (1927) Avery, MacLeod and McCarty (1944) Hershey-Chase experiment (1952) Chargaff’s Rules Molecular Studies

Griffith’s Transformation Expt. Bacteria Used Living smooth (virulent) Living rough (avirulent) Killed smooth Living rough + killed smooth Conclusion: Killed smooth converted living rough to virulent cells - a Transforming Principle (some smooth component) is responsible.

Avery, MacLeod, and McCarty Expt: DNA is the “Transforming Principle”

Hershey-Chase Experiment Radioactively labeled DNA and protein: 32P atom is in phosphate molecules in DNA and RNA, only low levels in protein (phosphorylated proteins). 35S atom is in sulfur containing-amino acids (cysteine and methionine), not in DNA, RNA.

Phage Made Radioactive Non-radioactive medium + bacteria

Phage Infect Cells 32P Phage 35S Phage

RNA is the Hereditary Material in RNA Viruses, e.g. TMV Tobacco Mosaic Virus

Reconstitution of Hybrid TMV (Fraenkel-Conrat & Singer) Strain 1 Strain 2 Hybrid most like TMV, not HR, therefore RNA is genetic mat’l

Bases and Sugars pyrimidines purines Ribose sugars

Bases and Sugars in DNA and RNA In DNA: deoxyribose + A, T, G or C dA deoxyadenosine dT deoxythymidine dG deoxyguanosine dC deoxycytidine In RNA: ribose + A, U, G, or C A adenosine U uridine G guanosine C cytidine

Nucleoside = Base + Sugar Nucleotide = Nucleoside + Phosphate dAMP

dNDP’s and dNTP’s: Note Errors in the Text deoxy deoxy deoxy deoxy dNDP (dTDP) dNTP (dATP)

3’ to 5’ Phosphodiester Bonds Make the Sugar-Phosphate Backbone New Monomers Add Here Strand has 5’-PO4 end and 3’-OH end

Chargaff’s Rules 1949-1953, quantified amounts of each base in DNA from different species. In every species, amount of A = Amount of T, and Amount of G = Amount of C If that’s true, then A + G = C + T The % GC and % AT varied from species to species, but always adds up to 100%.