The cell cycle Flashcards
(28 cards)
Name the 2 phases of the cell cycle
Interphase and the mitotic phase
What makes up interphase
G1, G0, S phase and G2
What makes up mitotic phase
Prophase, metaphase, anaphase, telophase, cytokinesis
What is the longest part of the cell cycle
G1
What is the shortest part of the cell cycle
mitotic phase
Describe G1
- Genes involved in cell cycle progression are switched off so the cell cannot initiate a new round of initiation and cell proliferation.
- If there is a poor nutrient suplly/ if there are antiproliferative stimuli’s present, the cell cycle Is delayed and the cell will exit the cycle to the G0 phase
- If there is a good nutrient supply and positive proliferative stimuli, the cell will pass through the regulator off the cycle, resulting in DNA replication and cell division to occur
Describe G0
- This is a highly regulated stage of the cell cycle
- In this stage, cells normally become differentiated to form specialised functions, and therefore no longer undergo cell division.
Describe S phase
The pre-replication complex that forms during the G1 phase that ensures that DNA replication only occur once is dismantled, resulting in the formation of 2 sister chromatids. Thee 2 sister chromatids are linked by cohesion
Describe G2
• Enzyme activity triggers the entry of the cell into the mitotic stage. A checkpoint is present here, and if un-replicated/damaged dna is detected, then the entry of the cell into the mitotic phase is delayed.
Describe prophase
• This is where the chromosome condenses. The centromeres separate, forming the 2 poles of the spindle fibres.
Describe metaphase
• Here the chromosome attaches to the spindle fibre at the pole of the cell.
Describe anaphase
• 2 sister chromatids are separated by the spindle fibres separating and being pulled apart to different ends of the cells
`Describe telophase
• The nuclear envelope reforms on the surface of the chromatin
Describe cytokinesis
• The 2 newly formed daughter cells separate from one another
Describe the g1 checkpoint
Check for DNA damage and favourable environmental conditons. Involves retinoblastmo
Describe G2 checkpoint
Check for damaged and unreplicated DNA
Describe mitotic checkpoint
Checks correct chromosomal attachment to spindle
Describe cyclin dependent kinase role in cell cycle regulation
During g1, cyclin proteins accumulate. These combine with kinase to form CDKs.
CDKs cause phosphorylation of proteins that stimulate the cell cycle.
• Retinoblastoma (Rb) restricts progression from the g1 phase to s phase. Rb binds to a transcription factors
• When cell are about to enter the s phase, CDKs phosphorylate the Rb protein, inhibiting its activity so it can no longer bind to the transcription factor.
• Transcription factor released and transcripts genes that are require for dna replication, allowing cell to enter s phase.
At what stage of the cell cycle does nuclear division occur
mitotic
Name a characteristic that highlights malignant tumours metastatic ability
They can give rise to distant secondaries
What does VEGF stimulate in tumours
stimulates the formation of a blood supply for tumour
Define neoplasm
a new growth
Define anaplastic
describes the undifferentiated appearance of malignant cells
Define dyssplastic
containing abnormal cells or showing abnormal development.
