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
1. Genetics-related course offerings for spring 2003:
2. Ch 10: problems 1,4,13, 15 - not to turn in
Restriction Digest Lab: Use This Gel!
1 2 3 4 5
1 - Markers
2 - Uncut plasmid
3 - EcoRI cut
4 - DraI cut
5 - EcoRI + DraI
markers in bp
3 real bands
2 real bands
Supercoiled form runs
faster, nicked form runs
slower than linearized
Bright band is cut;
faint band is uncut
Review of Last Lecture
Outline of Lecture 18
Variation in structure/arrangement of chromosomes
III. DNA structure and analysis
Hybridization of closely related species; often sterile.
Additional sets identical to parents.
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?
Somatic Cell Hybridizationin Plants createsAllopolyploidHybridsAmerican Cotton is natural 13 + 13 hybrid
II. Types of Chromosomal Rearrangements, Caused by Breakage and Rejoining
Part is lost - a deletion
Synapsis with a chromosome
with a large intercalary deletion - loop formation.
Cytology showed that bar is not due to a gene mutation.
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 don’t add or delete genetic info, but can have effects on gamete formation.
Robertsonian translocation: most common type in humans
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
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
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?
III. DNA Structure and analysis
What is the genetic material?
Chromosomes contain protein and DNA - which is it?
What must genetic material do?
2. Storage of information
3. Expression of information
4. Variation by mutation - evolution
The Flow of Genetic Information (The Central Dogma)
Is the Genetic Material Protein or DNA?
Evidence for DNA as Hereditary Molecule
Griffith’s Transformation Expt.
Living rough +
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”
Phage Made Radioactive
Phage Infect Cells
RNA is the Hereditary Material in RNA Viruses, e.g. TMV
Tobacco Mosaic Virus
Reconstitution of Hybrid TMV (Fraenkel-Conrat & Singer)
Hybrid most like TMV, not HR,
therefore RNA is genetic mat’l
Bases and Sugars
Bases and Sugars in DNA and RNA
Nucleoside = Base + SugarNucleotide = Nucleoside + Phosphate
dNDP’s and dNTP’s:Note Errors in the Text
3’ to 5’ Phosphodiester Bonds Make the Sugar-Phosphate Backbone
Strand has 5’-PO4
end and 3’-OH end