Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
90 Cards in this Set
- Front
- Back
Order Liver, Hair cells, and Intestinal cells by frequency of cell division |
Most Frequent: Intestinal Infrequent: Liver Cells Never divide: Hair cells |
|
What is the product of a stem cell division? |
When a stem cell divides it makes 1 differentiable cell + a new stem cell |
|
What are the 3 checkpoints in internphase? |
G1, S, and G2 |
|
Most of a cells life is spent in what phase of the cell cycle? |
Interphase |
|
During what stage of interphase does most growth occur? |
G1 |
|
What is the purpose of G2 checkpoint? |
To check if S phase went properly and to check if we're ready for M phase |
|
The cell cycle starts after ____ phase |
After M phase |
|
What are the 3 pathways possible after the restriction point? |
1) Halt cell cycle and go to G0 2) Try to fix the damage 3) If we can't fix the damage --> Apoptosis |
|
What is the point of no return where a cell is committed to the cycle? |
G1 checkpoint |
|
What if the the cell fails to pass the G1 checkpoint? |
It goes back to G0 |
|
When is the start of organelle replication? |
Start after restriction point |
|
during what stage of the cell cycle is the most cell growth observed |
G1 |
|
What is the Rb protein? |
Retinoblastoma protein is a tumor suppressor protein |
|
The Rb protein is the major protein in the __ checkpoint |
G1 |
|
Rb is tightly bound to the ___ transcription factor |
E2F |
|
What happens to the Rb protein after the G1 restriction point? |
The Rb protein gets hyperphosphorylated and dissociates from the E2F transcription factor |
|
How does Rb act as a tumor suppresor? |
Hyperphosphorylation only occurs after the restriction point which frees up the E2F TF for transcription of products needed for S phase. Thus it prevents premature transcription of E2F products |
|
Growth factors induce a transition from __ to __ phase |
G0 --> G1 |
|
What cyclin is responsible for the hyperphosphorylation of Rb? |
Cyclin D binds to CDK4, then CDK6, then CDK2 which each phosphorylate Rb |
|
When is the ONLY stage in the cell cycle where a cell is sensitive to growth factors? |
G1 |
|
What is the longest phase of the cell cycle? |
G1 Phase |
|
What is the second longest phase in the cell cycle and how long does it last? |
S phase lasts 9 hours |
|
What is the second shortest phase of the cell cycle and how long does it last? |
G2 lasts 4 hours |
|
What is the shortest phase in the cell cycle and how long does it last? |
M phase lasts 1 hour |
|
What is the difference between a chromosome and chromatid? |
2 chromatids = 1 chromosome |
|
When are chromatids produced? |
S phase |
|
What cyclin and CDK partners are involved in the mid-G1 phase-CDK complex? |
Cyclin D with CDK4 and CDK6 |
|
What cyclin and CDK partners are involved in the late-G1/S phase-CDK complex? |
Cyclin E with CDK 2 |
|
What cyclin and CDK partners are involved in the S phase-CDK complex? |
Cyclin A with CDK 2 and CDK 1 |
|
What cyclin and CDK partners are involved in the M phase-CDK complex? |
Cyclin B with CDK 1 |
|
Concentration of cyclins ____ while concentration of CDK _____ |
Cyclin cycle but CDK's are constant |
|
What proteins are capable of pausing the cell cycle and in what stage would this be most effective? |
Cyclin-CDK inhibitors and most inhibition occurs at G1/S |
|
What is the role of ATP in an inactive Cyclin-CDK Complex? |
The ATP provides an inorganic phosphate to the partly active cyclin-cdk complex to further expose the T-loop and to fully activate the complex |
|
What's so important about the T loop? |
T-loop exposure is necessary for catalytic activity and further exposure of the T-loop is essential in complete activation |
|
Inhibition of the Cdk-activating Kinase (CAK) results in? |
This slows the cell cycle but doesn't halt it since the Cyclin-CDK complex is partially functional Inhibition would prevent further exposure of the T-loop and phosphorylation of the T-loop |
|
What's the purpose of ubiquitin-protein ligases |
Tag for degradation to the proteosome in an effort to prevent retrograde movement through the cell cycle |
|
SCF and APC have the same purpose. How do they achieve this in terms of their relation to E1 and E2 and what is this purpose? |
SCF/APC bind to a protein and ligates the E1-activated Ub that was transported by E2 to tag it for destruction
|
|
SCF doesn't degrade which cyclin |
Cyclin B is not degraded by SCF |
|
What is the function of each of the 3 components of the ubiquitin degradation system |
E1 = Ubiquitin activating enzyme = Activates ubiquitin E2 = Ubiquitin-conjugating enzyme = Transfer Ub from E1 -- > E3 E3 = Ubiquitin Protein Ligase = Ligases the poly ub chain |
|
What are the 3 components of the SCF trimer complex? |
Skp - Cullin - F-box |
|
____ protein is critical is stabilizing components of the internal transport system and it's strands form tangles inside neurons of Alzheimer sufferers |
Tau! |
|
What signals E1 to activate Ub? |
Phosphorylation of Serine, Threonine, and Tyrosine |
|
SCF acts mostly in ____ phase by ____ inhibitors involved in cell cycle arrest at the ___ phase? |
G1/S, degrading, G1 |
|
What are the 2 ubiquitin-protein ligases (E3) critical to the cell cycle? |
SCF and Anaphase-promoting complex |
|
What is unique about how SCF recognizes a substrate compared to APC/C? |
SCF recognizes a phosphorylated protein rather that a specific AA sequence |
|
What is the structure of APC/C? |
It is a apoenzyme until bound by Cdc20 |
|
What is the function of Wee1 Kinase? Where is Wee1 kinase mostly active? |
To add an inhibitory phosphate in order to pause the cell cycle until repairs can be completed It is mostly active in G2 and closer to mitosis |
|
How is Wee1 kinase's action reversed? |
Cdc25 phosphatase |
|
Binding of a growth factor stimulates production of which cyclin? |
Cyclin D |
|
What is the order in which cyclins are produced and degraded? |
Cyclin D --> Cyclin E --> Cyclin A --> Cyclin B |
|
What is the maturation-promoting factors aka what is M cyclin? |
Cyclin B + Cdk1 and Cdk2 |
|
What lamins are found in the nuclear pore and which are not? |
A and C are intermediate structures found in the nuclear pore and B is in the nucleoplasmin |
|
What would lead to less lamin B? |
DNA replication + ageing |
|
What cyclin-cdk complex is responsible for degradation and reformation of the nuclear envelope? |
M cyclin-Cdk1 complex |
|
How does the APC aid in promoting anaphase? |
APC tags and destroys cyclin B between metaphase and anaphase which allows reformation of nuclear envelope |
|
How does the APC aid in separation of sister chromatids? |
APC tags securin which consequently releases separin |
|
What is the function of separin? |
It cleaves condensin and cohesin |
|
APC won't degrade cyclin ___ until the spindle fiber checkpoint has ensured that all fibers are attached and tensed |
Cyclin B! |
|
how does helicase separate DNA? |
Heicase breaks AT bonds which are weaker and the consequential destabalization leads to breaking of the GC bonds |
|
What is responsible for relieving stress and then ligating during DNA replication? |
Topoisomerase/Gyrase |
|
Why do we need a primase? |
Polymerase cannot make DNA denovo so we need a primer which is supplied by primase |
|
How is rapid weight loss a symptom of cancer? |
Cancer is #1 usage of ATP due to the constant energy needed for divisions |
|
How accurate is DNA preservation after proofreading? |
1 mutation/ 1 billion bases |
|
What is SSBP? |
Single Strand Binding Protein |
|
Why do we write 5' --> 3'? |
We use the 5' triphosphates to couple the formation of a phosphodiester with the 3' hydroxyl |
|
What is unique about the replication bubbles of eukaryotes? |
Eukaryotes use ultipe origins to replicate the chromosome. These bubbles then merge |
|
What molecule is responsible for fusing 2 adjacent bases in DNA? |
DNA Ligase |
|
Why does more sunlight lead to elevated mood? |
In the absense of light, seratonin is degraded to melatonin, thus depleting this hormone |
|
What direction does exonuclease (proof-reading) activity write? |
3' --> 5'
|
|
If DNA Pol I can remove primer and replace it with DNA, why do we need DNA Pol III? |
DNA Pol I can only produce short strands due to a missing "clamp" that DNA Pol III has |
|
What activates the 3' --> 5' exonuclease activity? |
An unpaired base due to the kink that it will introduce to the DNA which has a constant width which destabilizes Pol exposing the exonuclease core |
|
What is the function of DNA Pol II |
Fix mutations |
|
What's different between the proof reading ability of DNA Pol I and DNA Pol II |
DNA Pol I ONLY takes care of replication mistakes, not mutations |
|
What does the RNA Primase provide that is necessary for extension? |
It provides an -OH at the 3' |
|
Who has a longer primer, E. Coli or eukaryotes? |
Eukaryotes are ~35 nucleotides total while E. Coli is 2-5 nucleotides |
|
What enables the SSBP to do their job? |
SSBP's have a higher affinity for ssDNA than dsDNA |
|
What is the role of Mg2+ in the Pol complex? |
Mg2+ increases the nucleophilicity of 3' Oxygen |
|
The __' end is always shortened after replication |
5 and this is the telomere region that we lose due to a inability to write over where the primer was |
|
HIgher methylation levels are observed in telomerase gene promoter regions of _____ cell types |
Differentiated |
|
Accumulation of ____ leads to shortnened telomeres due the compounds _____ and an insufficient amount of ____ to metabolize the compound |
Acetyl Aldehyde, cytotoxicity, ADH2 enzyme |
|
Fructose gets uptaken faster than glucose due to passive channels in the gut. How does this lead to oxidative stress? |
Fructose gets degraded to glucose when its needed or to triglycerides when we dont It's the accumulation of triglycerides that is bad because they're easily oxidizable. |
|
Why did Carol Geider get a Nobel prize in 2009? |
She figured out that telomeres shorten progressively in telomerase-null mice which led to shorter lifespans |
|
How can we prevent amyloid fibril aggregation in terms of tubulin? |
Irreversibly bind GTP to beta tubulin to prevent catastrophe |
|
What element of the SCF allows for specificity of binding? |
F-box |
|
What ultimately dictates the exit of mitosis? |
Proteolysis |
|
What would be the effect of improper spindle fiber attachment on APC? |
It would inhibit CDC20-APC complex |
|
How is lamin effected in progeria? |
A mutated lamin will retain it's fernesyl anchor and form a deformed nuclear membrane --> Apoptosis |
|
Define Semi-conservative replication |
Each daughter DNA contains 1 parental strand |
|
Polymerase can only replicate while reading __ --> __ and can only synthesize __ --> __ |
Reading 3' --> 5' Synthesize 5' --> 3' |
|
How does Zovirax prevent Herpes Simplex replication? |
Inhibits Helicase-Primase complex |