Announcements. 1. Mean on multiple choice section of exam 3 = 71% Range from 22% - 100%; 5 people didn’t take exam 3. 2. Reminder - no labs week of Thanksgiving!
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1. Mean on multiple choice section of exam 3 = 71%
Range from 22% - 100%; 5 people didn’t take exam 3.
2. Reminder - no labs week of Thanksgiving!
3. Be sure to get lab report guidelines for last lab report - due in class Dec. 6th. We’ll be much more stringent in grading second lab report; ask questions if unsure.
1. First approach to determine whether a behavior has genetic components - examine differences in behavior between closely related organisms
2. Second approach -selection of a preferred behavior from a genetically heterogeneous population; can trait be transferred by genetic crosses?
3. Third approach -A single gene can control a single behavior (but most behaviors are more complex)
4. Genetics of behavior in Drosophila - courtship behavior and the yellow mutation
I. Genetics of behavior in Drosophila
II. Genetics of human behavior
III. Genetics of behavior in C. elegans
Nov 15 2002 10:27AM
BERLIN (Reuters) - A leading German magazine reported on Friday that researchers have found a certain type of fly can show homosexual tendencies when temperatures are increased above 86 degrees Fahrenheit. The monthly natural science magazine "Geo" said researchers at the Beckman Research Institute in Los Angeles had found the fruit fly "drosophila melanogaster" had developed
a "homosexual preference" when the laboratory temperature was increased from about 19 degrees to above 30 degrees.
"The male flies displayed clear heterosexual activities when temperatures were at 19 degrees, but above 30 degrees their behavior changed within minutes," the report in the December issue of "Geo" released on Friday said.
"The male flies ignored the female partners at that point and chased after their male counterparts. As soon as the temperature was reduced again, they returned to their
The fruit fly, which is about 3 mm long, typically accumulates around spoiled fruit. It is one of the most valuable organisms in biological research, particularly in
genetics and developmental biology.
The scientists that made the discovery were led by Toshihiro
More difficult to characterize genetic control of behavior in humans - why?
monoamine oxidase syndrome
Using RFLP analysis, locus mapped to X chromosome, near MAOA gene.
In which gene was genetic variation observed that allowed mapping to X chr.?
How would you confirm MAOA gene is involved in this syndrome in this family?
Of 300 induced mutations, 77 affected movement of animal
What are two movement mutants you’ve seen in lab?
Rollers (rol): go in circles on agar plates
- defects in nerve cord or body musculature
Uncoordinated (unc): from twitching to nearly complete paralysis
- defects in nerve cord or body musculature
- many unc mutants on each of 6 chromosomes
How do worms eat? What do worms eat?
Three phenotypic mutant classes:
eat (41 mutations) - affect nervous system function and muscle functions
pha (2 mutations) - defects in morphogenesis
phm (9 mutations) - affect muscle contraction
Cloned genes = ion channels and signaling cascades
Paper by Bargmann et al., 1993. Cell 74: 515-527.
Known at start of study:
in vertebrates, olfaction is used to detect presence of any volatile organic molecule and discriminate among different molecules
Odorants bind to receptors in cilia of olfactory neurons and induce a signaling cascade in the cell
Questions: 1. How specific is interaction of odorants and receptors?
2. How many receptors are expressed on a single olfactory neuron?
3. How is information about odorants trnsmitted to brain to generate appropriate behavior?
Approach: determine whether C. elegans is attracted to volatile organic molecules; then screen for mutants that fail to chemotax to particular odorant; characterization of mutants will help address questions and allow for genes involved in process to be identified
- tested 121 volatile organic chemicals: 50 strong attractants, 11 variable, weak attractants; 60 not attractive