19.01.06 Cell Cycle, Mitosis, Meiosis, Recombination Flashcards
Cell Cycle, Mitosis, Meiosis, Recombination
quiescent/ senescent cells are in which cell cycle phase
G0. Resting phase after cell cycle where cell has stopped dividing
Interphase is composed of which steps
G1, S and G2
What happens in G1
Growth phase. Proteins and RNA synthesised. At G1 checkpoint cell is commited to division and moves into S phase. 9-12 hours.
S phase
DNA synthesis replicates genetic material. Each chromosome consists of two sister chromatids. 6-8 hours
G2
Cell continues to grow. G 2 check point ensures there is enough cytoplasmic material necessary for mitosis and cytokinesis. 2-5 hours
Cell division
M phase. Cell stops growing. First mitosis (nuclear division) then cytokinesis (cell division). Metaphase check point ensures the cell is ready to complete cell division. 1 hour
What is mitosis
Part of the cell cycle where chromosomes in the nucleus are separated into two identical sets of chromosomes contained within their own nucleus.
Steps of mitosis
Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis.
prophase
Chromosomes condense. Breakdown of nuclear membrane. Spindle fibres appear.
Metaphase
Chromosomes align along metaphase plate
Anaphase
Centromeres divide. Sister chromatids move to opposite poles
Telophase
Nuclear membrane reforms. Chromsomes decondense, spindle fibres disappear.
Cytokinesis
Cytoplasm divides. Parent cell becomes two daughter cells with identical genetic information.
Cell cycle is regulated by
Heterodimeric protein kinases composed of Cyclins and cyclin-dependent kinases (CDKs)
Cyclins
Regulatory subunit
Cyclin- dependent kinases (CDKs)
catalytic subunit of the activated heterodimer which phosphorylates target proteins to orchestrate coordinated entry into the next phase of cell cycle.
Which are constitutively active, cyclins or CDKs?
CDKs are constitutively active