Class Notes (922,930)
CA (543,002)
UTSG (45,883)
BIO (2,273)
BIO120H1 (1,177)
Lecture

Notes taken during lecture

5 Pages
68 Views

Department
Biology
Course Code
BIO120H1
Professor
Jean Jiang Nash

This preview shows pages 1-2. Sign up to view the full 5 pages of the document.
LECTURE March 22, 2011
Cell cycle and programmed cell death
Cell divides into two identical daughter cells
Need to segregate components equally between the daughter cells
oPrecisely
oMany control mechanisms are to ensure precisely equal distribution of
chromosomes
oMany cancers have wrong number or pieces of chromosome
oESSENTIAL STEP
G1 = gap phase number 1
oLiving and growing and duplicating its mitochdonria
oGrowing in size
S phase
oSynthesizes DNA chromosomes replicate
G2 phase
oContinues growing until double in size
oDoubled everything
Mitosis
oNuclear division followed by cytosolic division
oEnd with two equivalent daughter cells
Steps must be in order and controlled
oQuestions and answers come in molecular switches molecules
phosphorylated, ubinquinated, etc.
oDecisions made at special times in cycle called cell cycle checkpoints
S-phase once enter S-phase, its committed can pause but must
divide, otherwise undergo programmed cell death
At any point, cell can wait or go
Cyclin-dependent kinase phosphorylates
Only active when in complex with cyclin
Portrayed on slide is the active form of complex
Regulated by which cyclin it interacts with
Are protein kinases
Different cyclin-Cdk checkpoints at at different stages of
the cell cycle
oDifferent cyclin at M step and S step
S-cyclin transcribed and translated cell indicating its
ready to enter S phase
M-cyclin phosphorylates things for mitosis
Then degraded
Table describing different cdk complexes
Cylin d with cdk4 will drive past g1-cdk point
Cdk2 involved in two different checkpoints a combinatorial effect
www.notesolution.com
oCdk2 a protein that phosphorylates what it phosphorylates
depends on the partner at the time
oDifferent target depending on partner
oIn YEAST, only CDK1 cyclins swapped combinatorial effect
oLike in integrin adhesion sticking to lamina alpha 6 and beta 5
versus alpha 4 and beta 6
oIgnore asterisks
CDK has T-loop in red
Part of its polypeptide chain
In inactive state Tloop in active site of enzyme cannot phosphorylate
targets
Cyclin binds, pulling T-look out but not completely partial activation
Enzyme CDK activating kinase adds activating phosphate to fully activate
Once activated, certain targets
oS-cdk complex activity promotes DNA replication
oInhibits inhibitor positive so DNA replicates
oRequired to start mitosis
Phosphorylates multiple targets
Lamin part of nuclear membrane so it falls apart
Interphase to mitosis kind of cytoskeleton
Actual machinery that causes cell to change shape or
function or divide
Transcription and translation of cyclin makes it available
Protein degradation makes it unavailable
Targeted degradation of cyclins turns Cdks off
To destroy protein, polyubinquainate it so it can be recognized for
degradation
Active APC/C recruits set of ubiqinating enzymes
M-cyclin can be recognized by protesome so can be garbaged
M-cyclin is gone
Necessary to destroy m-cyclin to lallow mitosis to finish
oSo the destruction must occur during mitosis
More control needed
Cdk Inhibitor proteins
oP27 binds to cyclin cdk complex
oP27 blocks active site of cdk
oSo cdk inactivated
oTwo separate steps to activate this cell cycle checkpoint
Activate cdk cyclin complex
Activate p17-cyclin-cdk complex
Two independent controls coming to a decision both must
fail to fail
Phosphorylation
www.notesolution.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
LECTURE March 22, 2011 Cell cycle and programmed cell death Cell divides into two identical daughter cells Need to segregate components equally between the daughter cells o Precisely o Many control mechanisms are to ensure precisely equal distribution of chromosomes o Many cancers have wrong number or pieces of chromosome o ESSENTIAL STEP G1 = gap phase number 1 o Living and growing and duplicating its mitochdonria o Growing in size S phase o Synthesizes DNA chromosomes replicate G2 phase o Continues growing until double in size o Doubled everything Mitosis o Nuclear division followed by cytosolic division o End with two equivalent daughter cells Steps must be in order and controlled o Questions and answers come in molecular switches molecules phosphorylated, ubinquinated, etc. o Decisions made at special times in cycle called cell cycle checkpoints S-phase once enter S-phase, its committed can pause but must divide, otherwise undergo programmed cell death At any point, cell can wait or go Cyclin-dependent kinase phosphorylates Only active when in complex with cyclin Portrayed on slide is the active form of complex Regulated by which cyclin it interacts with Are protein kinases Different cyclin-Cdk checkpoints at at different stages of the cell cycle o Different cyclin at M step and S step S-cyclin transcribed and translated cell indicating its ready to enter S phase M-cyclin phosphorylates things for mitosis Then degraded Table describing different cdk complexes Cylin d with cdk4 will drive past g1-cdk point Cdk2 involved in two different checkpoints a combinatorial effect www.notesolution.com
More Less
Unlock Document


Only pages 1-2 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