Lecture 6 (covers videos A, B, & C) Abbreviations:
Tuesday, February 9, 2021 8:09 PM Ex. = for example,
b/w = between
b/c = because
w/ = with
w/o = without
• Evolution: heritable change in a pop over time, driven by selective pressure. Steps to
v. = versus
INC = increase
evolution:
Imagine mutations only arose in the presence of stress. Which of the following would be true?
• Mutation: change in DNA that leads to expression of different RNA/protein and thus The freq of AR bacteria would INC. Stress from antibiotics would cause selection for bacteria
that are resistant over time.
different phenotype.
To measure factor: use immunostain-- will stain factor and show where localization is.
• Selection: pressure from the environment that makes that phenotype advantageous. Non-repairing antibiotic and antibiotic group. -> Comparing antibiotics means is one antibiotic
better than the other…
No-antibiotic control group measures effectiveness of antibiotic. Clonogenic assay used to
• Mutations occur all the time, but w/o selection we rarely see them appear in populations measure repair.
BLES assay: identify DSB-damage repair.
(selection poses trends).
Soil bacteria that come into contact with antibiotic-treated manure give way to higher frequencies of
antibiotic-resistance in said bacteria than soil bacteria exposed to antibiotic-free manure. (Antibiotics
• Luria and Delbruck, 1943: tested different mutation models to determine which is will be more metabolically active when tested against non-antibiotic manure; other sources of
selective pressure in manure, like nitrogen???)
correct.
○ Induced mutation model: determined that a beneficial *random* mutation only
arises in the presence of stress.
○ Spontaneous mutation model: beneficial mutations occur randomly at any time. ->
mutations can happen early-- can be passed down to progeny. CORRECT
MODEL!
• Presence of jackpot phenotype (half of colony possess mutation) indicates
spontaneous mutation.
• Why are bacteria good models for examining evolution? Small, fast replication time,
cheap to grow, and genomes are easier to manipulate.
• CFU/ml: Colony-Forming Units per milliliter; measures how many cells actually grow
into a colony, viewed on a plate. CFU > OD for cell growth.
Tuesday, February 9, 2021 8:09 PM Ex. = for example,
b/w = between
b/c = because
w/ = with
w/o = without
• Evolution: heritable change in a pop over time, driven by selective pressure. Steps to
v. = versus
INC = increase
evolution:
Imagine mutations only arose in the presence of stress. Which of the following would be true?
• Mutation: change in DNA that leads to expression of different RNA/protein and thus The freq of AR bacteria would INC. Stress from antibiotics would cause selection for bacteria
that are resistant over time.
different phenotype.
To measure factor: use immunostain-- will stain factor and show where localization is.
• Selection: pressure from the environment that makes that phenotype advantageous. Non-repairing antibiotic and antibiotic group. -> Comparing antibiotics means is one antibiotic
better than the other…
No-antibiotic control group measures effectiveness of antibiotic. Clonogenic assay used to
• Mutations occur all the time, but w/o selection we rarely see them appear in populations measure repair.
BLES assay: identify DSB-damage repair.
(selection poses trends).
Soil bacteria that come into contact with antibiotic-treated manure give way to higher frequencies of
antibiotic-resistance in said bacteria than soil bacteria exposed to antibiotic-free manure. (Antibiotics
• Luria and Delbruck, 1943: tested different mutation models to determine which is will be more metabolically active when tested against non-antibiotic manure; other sources of
selective pressure in manure, like nitrogen???)
correct.
○ Induced mutation model: determined that a beneficial *random* mutation only
arises in the presence of stress.
○ Spontaneous mutation model: beneficial mutations occur randomly at any time. ->
mutations can happen early-- can be passed down to progeny. CORRECT
MODEL!
• Presence of jackpot phenotype (half of colony possess mutation) indicates
spontaneous mutation.
• Why are bacteria good models for examining evolution? Small, fast replication time,
cheap to grow, and genomes are easier to manipulate.
• CFU/ml: Colony-Forming Units per milliliter; measures how many cells actually grow
into a colony, viewed on a plate. CFU > OD for cell growth.
