MICR 302 Lecture Notes - Lecture 15: G1 Phase, Mutagen, S Phase
1 May 2018
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Lecture 15
Classic Yeast Genetic Screens
-pathways failure is the source of most disease, our goal is to understand pathways and their
regulations to understand why they cause mutated phenotypes.
THE CELL CYCLE:
-defined via yeast
-100’s of proteins involved, co-ordination, check points.
-can mutate things and put them into the pathways even without knowing total number of
genes
THE OG’S
-Hartwell (budding yeast)
-Hunt (purified key kinase that was master regulator, identified in both budding and fission
yeast)
-Nurse (fission yeast)
S. cerevisiae lifecycle
G1 phase
-cells in G1 decide to divide and form bud = SINGLE MOTHER CELL
S phase:
-initial bud (mother cell much larger than duaghter
G2:
-slightly larger bud
M phase:
-daughter and bud equal size
-daughter buds off.
Lee took advantage of these phenotypes to understand the cell cycle.
Lee Hartnell’s Genetic Approach:
1. Simple Mutagenesis (via chemicals or radiation)
- using proper dose of mutagen (goly-locks zone) enough mutations that most cells survive.
2. incubate (23C for 5 hrs)
3. plate out individual aliquots
4. incubate
5. replica play and incubate
TEMP SENSITIVE: from at 23 and 36
GOAL: find factors involved in driving cell forward
-need a CONDITIONAL mutant
-making mutations at certain frequency replaces hydrophobic amino acid with hydrophilic —>
unstable at high temp
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Pathways failure is the source of most disease, our goal is to understand pathways and their regulations to understand why they cause mutated phenotypes. 100"s of proteins involved, co-ordination, check points. Can mutate things and put them into the pathways even without knowing total number of genes. Hunt (puri ed key kinase that was master regulator, identi ed in both budding and ssion yeast) Cells in g1 decide to divide and form bud = single mother cell. Initial bud (mother cell much larger than duaghter. Lee took advantage of these phenotypes to understand the cell cycle. Lee hartnell"s genetic approach: incubate (23c for 5 hrs: simple mutagenesis (via chemicals or radiation) Using proper dose of mutagen (goly-locks zone) enough mutations that most cells survive. Goal: nd factors involved in driving cell forward. Making mutations at certain frequency replaces hydrophobic amino acid with hydrophilic > incubate replica play and incubate unstable at high temp. 1000s of shits to plate and catalogue.
