Eukaryotic Cell Cycle Flashcards
What do multicellular eukaryotes depend on cell division for?
Development from a fertilised egg, growth and repair
What does mitosis result in?
2 daughter cells with identical genetic information (dna)
Meiosis?
Yields non identical daughter cells that have half as many chromosomes as the parent cell
What are the sub phases of interphase?
90% if cell cycle is interphase
G1- cells grow
S-DNA synthesis (chromosome and centrosome duplicate)
G2- organelles replicate and chromatin begin to condense
What does the mitotic phase include?
Prophase
Metaphase
Anaphase
Telophase
What happens in prophase?
Chromosomes condense (become visible) Centrosome assemble (2centrosomes move away from each other)
Metaphase?
Spindle forms
Nuclear membrane breaks down
Chromosomes align on spindle equator
Anaphase ?
Chromatid seperate, each chromatid moves to opposite poles of the cell
Telophase?
Chromosome decondenses (can’t see it anymore)
New nuclear membrane forms
Formation of 2 new cells
What’s the mitotic spindle made of ??
Microtubules that control chromosome movement during mitosis
In animal cells assembly of spindle microtubules begins where?
The centrosome (microtubules organising structure)
What happens to the centrosomes during interphase?
They replicate so there’s 2 centrosomes that migrate to opposite ends of the cell during prophase and prometaphase
What’s cytokinesis ?
Cytoplasm seperation
What is the cell cycle controlled by?
Cell cycle control system (clock) this is regulated by internal and external factors
The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is received
What are checkpoints in the cell cycle?
M checkpoint- anaphase is blocked if chromatids aren’t properly assembled on mitotic spindle
G1- checkpoint- entrance into S is blocked if genome is damaged
S checkpoint- Dna replication is halted if genome is damaged
G2 checkpoint- entrance into m is blocked if DNA rep isn’t completed
Controls of the cell cycle?
-cyclins:
Control G1, S and M phase
CDKs:
APC
Disruption of the cell cycle leads to?
Dysregulation of the cell cycle is common (uncontrollable growth): leads to tumours
Increased levels of CDK and cyclins and common in tunours such as breast and brain tumours
Inhibition of certain CDKs has been shown to inhibit tumour cell growth, induce apoptosis and cause tumour regression
