Class Notes (923,021)
US (356,261)
Berkeley (8,464)
L&S (78)
L & S C30Y (22)
Lecture 11

L & S C30Y Lecture 11: Lecture 11
Premium

8 Pages
29 Views

Department
Letters And Science
Course Code
L & S C30Y
Professor
Urnov Fyodor

This preview shows pages 1-3. Sign up to view the full 8 pages of the document.
Lecture 11 2/24/2017 1:42:00 PM
The awesome power of genetics
“One gene = one enzyme”
probably the second most important genetic experiment after
Mendel
The Beadle-Tatum Experiment
o Can one isolate mutants in biochemical processes?
o Specifically, a mutant that will not grow without a specific
amino acid?
o Step 1: Mutagenesis
Wild type(x-rays) mutagenized conidiacrossed with
wild type of opposite mating typefruiting
bodiesmicroscopic ascospores are dissected and
transferred one by one to culture tubes.
o Step 2: Screening for mutants
o Beadle and Tatum deduced that each mutation that generated
a nutrient requirement was inherited as a single-gene
mutation because each gave a 1:1 ratio when crossed with a
wild type.
o Conclusion: there is a gene in the Neurospora genome that is
responsible for the biosynthesis of the amino acid arginine.
Yeast can live as haploid or diploid cells
Haploid yeast grow, mitotically, just fine.
They exist in two sexes, which yeast biologists do not call sexes,
and instead call “mating types”
Two haploid yeast cells of different mating type can fuse, and form
a diploid.
That diploid can do one of two things
o Grow mitotically, as a diploid
o Go through meiosis, and form 4 haploid cells, each of which
can go back to living as haploid cells
A useful termprototrophic
Capable of synthesizing everything necessary from simple salts
Antonym: auxotrophicneeding a specific nutrient for growth.
find more resources at oneclass.com
find more resources at oneclass.com
E.g. Humans are auxotrophic for lysine, we cannot live without it in
the diet
E. Coli is prototrophic for lysine, it can make it just fine.
Neurospora is really prototrophic. It will grow in inorganic salts and
one vitamin.
How the “genes for long life” were found
Caenorhabditis elegans and Sydney Brenner
“Model organism” (sort of like model citizen):
Wormsmall
o Cheap to grow
o Eats bacteria
o Hermaphroditeeasy genetics
o Transparentcan see cells
o Adult animal composed of a defined number of cells, and can
identify which cell came from which cell during development.
o Has interesting behaviors that can be studied.
o Dies after 2 weeks
A correction
The radiolab folks say that Cynthia Kenyon found the “grim reaper”
gene by “stumbling upon it by pure luck.”
Nothing could be further from the truth.
She did this in highly targeted fashion.
Worm: 19,735 protein-coding genes
And all this BIOLOGYit does all these things!!!! It develops into a
worm from a single egg, it eats, it mates, it moves around, etc.
Which genes are behind which feature of its biology?
Insulinthe hormone of the well-fed state
Let’s be very clear
In worms, there’s one insulin IGF-1 Pathway
During evolution, things diverged, so in us (and in mice) there are
TWO pathways
find more resources at oneclass.com
find more resources at oneclass.com
Insulin itselfmetabolismmutations in animals strongly adversely
affect lifespan, but there’s an interesting exception in humans.
IGFgrowth and developmentmutations increase lifespan.
Cell signaling as a social network
NOT LIKE THIS:
o Person A Person B Person C
LIKE THIS:
o Person A All person A’s friends all their friends
snowballs
The goal is a > millionfold amplification of signal
~1 gram of sugar per liter of blood.
Five liters total of blood
During rapid sudden exercise, need to pour more glucose into
bloodstream like a fire hose, but it’s not stored as powdered
glucose
The hormone is a million times less abundant than the sugar.
Four outstanding questions regarding insulin / IGF-1 and longevity
What biological mechanism explains the fact that mutants in this
pathway affect lifespan?
o A shift of physiology toward cell protection / maintenance /
stress resistance.
Is there a connection between this pathway and the fact that caloric
restriction affects lifespan? (Insulinfood, duh!)
o Yes. This has been shown in worms, flies, and in mice.
Do mutations in the pathway affect lifespan in other animals?
o Yes,
Is there naturally occurring genetic variation in humans in genes for
this pathway that affects lifespan?
o OOOOH.
An advantage of being a petite woman of Ashkenazi Jewish descent
“Functionally significant insulin-like growth factor receptor
mutations in centenarians”
find more resources at oneclass.com
find more resources at oneclass.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
find more resources at oneclass.com Lecture 11 2/24/2017 1:42:00 PM The awesome power of genetics “One gene = one enzyme”  probably the second most important genetic experiment after Mendel  The Beadle-Tatum Experiment o Can one isolate mutants in biochemical processes? o Specifically, a mutant that will not grow without a specific amino acid? o Step 1: Mutagenesis  Wild type(x-rays) mutagenized conidiacrossed with wild type of opposite mating typefruiting bodiesmicroscopic ascospores are dissected and transferred one by one to culture tubes. o Step 2: Screening for mutants o Beadle and Tatum deduced that each mutation that generated a nutrient requirement was inherited as a single-gene mutation because each gave a 1:1 ratio when crossed with a wild type. o Conclusion: there is a gene in the Neurospora genome that is responsible for the biosynthesis of the amino acid arginine. Yeast can live as haploid or diploid cells  Haploid yeast grow, mitotically, just fine.  They exist in two sexes, which yeast biologists do not call sexes, and instead call “mating types”  Two haploid yeast cells of different mating type can fuse, and form a diploid.  That diploid can do one of two things o Grow mitotically, as a diploid o Go through meiosis, and form 4 haploid cells, each of which can go back to living as haploid cells A useful term—prototrophic  Capable of synthesizing everything necessary from simple salts  Antonym: auxotrophic—needing a specific nutrient for growth. find more resources at oneclass.com find more resources at oneclass.com  E.g. Humans are auxotrophic for lysine, we cannot live without it in the diet  E. Coli is prototrophic for lysine, it can make it just fine.  Neurospora is really prototrophic. It will grow in inorganic salts and one vitamin. How the “genes for long life” were found Caenorhabditis elegans and Sydney Brenner  “Model organism” (sort of like model citizen):  Worm—small o Cheap to grow o Eats bacteria o Hermaphrodite—easy genetics o Transparent—can see cells o Adult animal composed of a defined number of cells, and can identify which cell came from which cell during development. o Has interesting behaviors that can be studied. o Dies after 2 weeks A correction  The radiolab folks say that Cynthia Kenyon found the “grim reaper” gene by “stumbling upon it by pure luck.”  Nothing could be further from the truth.  She did this in highly targeted fashion.  Worm: 19,735 protein-coding genes  And all this BIOLOGY—it does all these things!!!! It develops into a worm from a single egg, it eats, it mates, it moves around, etc.  Which genes are behind which feature of its biology? Insulin—the hormone of the well-fed state Let’s be very clear  In worms, there’s one insulin IGF-1 Pathway  During evolution, things diverged, so in us (and in mice) there are TWO pathways find more resources at oneclass.com find more resources at oneclass.com  Insulin itself—metabolism—mutations in animals strongly adversely affect lifespan, but there’s an interesting exception in humans.  IGF—growth and development—mutations increase lifespan. Cell signaling as a social network  NOT LIKE THIS: o Person A  Person B  Person C  LIKE THIS: o Person A  All person A’s friends  all their friends  snowballs The goal is a > millionfold amplification of signal  ~1 gram of sugar per liter of blood.  Five liters total of blood  During rapid sudden exercise, need to pour more glucose into bloodstream like a fire hose, but it’s not stored as powdered glucose  The hormone is a million times less abundant than the sugar. Four outstanding questions regarding insulin / IGF-1 and longevity  What biological mechanism explains the fact that mutants in this pathway affect lifespan? o A shift of physiology toward cell protection / maintenance / stress resistance.  Is there a connection between this pathway and the fact that caloric restriction affects lifespan? (Insulin—food, duh!
More Less
Unlock Document


Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit