Reading...
Play button
Play button
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;
27 Cards in this Set
- Front
- Back
|
What is the 'G1' phase?
|
Standard diploid genetic makeup - ready to divide when conditions are correct
|
|
|
What is the 'S' phase?
|
Replication of DNA - once a cell begins DNA replication, it is committed to divide
|
|
|
What is the 'G2' phase?
|
Cell looks normal, but has double the normal amount of DNA
|
|
|
What is the 'M' phase?
|
Mitosis - physical division of nucleus and cytoplasm to form two daughter cells.
|
|
|
What is the 'G0' phase?
|
Cells have either temporarily or permanently ceased to participate in the cell division process. Most cells in a multicellular organism are in this sate.
|
|
|
What are the events in prophase?
|
Chromosomes compact and become visible as paired chromatids. Centrosomes separate to opposite sides of nucleus. NE intact
|
|
|
What are the events in prometaphase?
|
NE breaks down
Microtubules extend and attach to kinetochore (on centromere) Individual centrosomes, which remain as microtubule organising centres are called spindle poles |
|
|
What is the 'spindle'?
|
The structure of microtubules spanning the space where the nucleus used to be
|
|
|
What are the events in metaphase?
|
Chromosomes lined up at spindle equator (metaphase plate) - may wait many minutes - complex mechanisms check that two chromatids within a pair are connected to different spindle poles
Chromosomes are most condensed here - useful for determining genetic conditions |
|
|
What is the event in anaphase?
|
Chromatids separate and move towards opposite spindle poles
|
|
|
Are telophase and cytokinesis necessarily separate events?
|
No - they can occur in parallel
|
|
|
What are the events in telophase?
|
Nucleus returns to interphase state - chromosomes decondense, spindle disassembles, microtubule cytoskeleton reforms, NE reassembles
|
|
|
What is the event in cytokinesis?
|
Cell divides in an ACTOMYOSIN based process
|
|
|
What is a 'kinase'?
|
A type of enzyme that transfers phosphate groups from high-energy donor molecules, such as ATP, to specific substrates
|
|
|
What is a 'check point'?
|
A point where the cell checks that everything is ready to proceed to the next stage of cell division.
|
|
|
What triggers the next stage of the cell cycle in karyokinesis?
|
Kinases (such as Cdk) Cdks require to be bound to a particular cyclin in order to be catalytically active.
|
|
|
What is a 'cyclin'?
|
A family of proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinase (Cdk) enzymes
|
|
|
What does Cdk stand for?
|
Hope and dignity!
Or, cyclin-dependent kinase |
|
|
What stages make up interphase?
|
G1, S, G2
|
|
|
Entry into mitosis requires active Cdk1. Cdk1 is only catalytically active when...
|
...bound to cyclin B. Cyclin B is synthesised throughout interphase - when its concentration is high enough the cell can enter mitosis :)
|
|
|
Entry into S phase requires active...
|
Cdk4
|
|
|
What compound makes Cdk4 catalytically active?
|
Cyclin D
|
|
|
Cyclin D is synthesised when...
|
...specific transcription factors are phosphorylated by mitogen associated protein kinase (MAPK)
|
|
|
What is a mitogen?
|
A chemical substance that encourages a cell to commence cell division, triggering mitosis. A mitogen is usually some form of a protein.
|
|
|
What is the main target of Cdk4?
|
Retinoblastoma protein RB
|
|
|
What does unphosphorylated RB bind to?
|
A critical transcription factor called E2F-1 (phosphorylated RB cannot bind to E2F-1). E2F-1 is a tumour suppressor gene.
Unphosphorylated RB cannot bind to E2F-1, which is then free to activate transcription of proteins for DNA synthesis |
|
|
How do external signals control initiation of cell division?
|
Most growth factor receptors are 'receptor tyrosine kinases'. Series of steps leads to cyclin D
|
