module 2 - 6.1 the cell cycle Flashcards
what is the cell cycle?
series of events that take place in a cell, causes it to divide into 2 DAUGHTER CELLS that are GENETICALLY DENTICAL
what events occur in the cell cycle?
- replication of DNA
- duplication of some organelles
- partitioning of the cytoplasm and other components
what is mitosis?
nuclear division (nuclei dividing)
what are the 2 phases that eukaryotic cells have in the cell cycle?
- interphase
- mitotic phase (mitosis AND cytokinesis)
why cant prokaryotic cells do mitosis?
they do not have a nucleus
what do prokaryotic cells go through instead of mitosis?
binary fission (2 cells splitting)
what does the cell cycle allow the cell to do?
- zygote becomes an adult organism
- allows growth and repair of tissues
- allows asexual reproduction in animals and fungi
what is a zygote?
when we were 1 cell (when egg becomes fertilised)
where does a cell spend most of its time?
interphase
what is interphase?
- when a cell grows
- when it carries outs its metabolic functions
- end of interphase prepares for cell division (mitotic phase)
what is the mitotic phase?
the cell division phase to produce 2 genetically identical daughter cells
- divided first by mitosis, then cytokinesis
when is the G0 phase?
when the cell stops its own cell cycle
- can be temporary or permanent
what happens during the G1 phase?
cellular contents, apart from chromosomes, are synthesised/ duplicated
what happens during the S phase?
each of the chromosomes (DNA) is duplicated in nucleus
what happens during the G2 phase?
- cell checks the duplicated chromosomes for error, making any repairs that are needed
- energy stores are increased
what is the order of phases in the cell cycle?
. G2
/ \
S MITOSIS & CYTOKINESIS
\ /
. G1
(G0)
when do cells only enter the mitotic phase?
if:
- it has grown to correct size
- DNA replication is error free
- the chromosomes are in the right place in the cell
what ensures the fidelity of cell division?
checkpoints are employed to check eat stage of the cell cycle has happened correctly
what are the 3 checkpoints?
- G1 checkpoint
- G2 checkpoint
- spindle assembly checkpoint
what does fidelity mean?
the accuracy of copying something
what are 5 events that can happen during interphase?
- DNA is replicated and checked for errors in the nucleus
- protein synthesis occurs in cytoplasm
- chloroplasts grow and divide in plant and algal cell cytoplasm
- mitochondria grow and divide
- normal metabolic processes of cells occur
what are the 3 reasons why the cell might enter G0?
- differentiation
- DNA may be damaged
- age
why can differentiation make a cell enter G0?
cells that become specialised may no longer be able to carry out its function
- can re enter cell cycle
why can the DNA maybe being damaged make a cell enter G0?
cell may not be able to divide and so it enters a period of permanent cell arrest (G0)
why can age make a cell enter G0?
as you age the number of senescent cells in your body increases which can lead to many age related diseases
what does it mean if a cell is senescent?
slowly sit until they die
what is apoptosis?
cell death
where does G1 checkpoint occur?
end of G1 phase
what are the requirements that need to be met by G1 checkpoint?
cell size, nutrients, growth factors, DNA damage
what happens if the requirements by G1 have been met?
begins DNA replication
what happens if the requirements by G1 have not been met?
enters G0
where does G2 checkpoint occur?
end of G2 phase
what are the requirements that need to be met by G2 checkpoint?
cell size, DNA replication, DNA damage
what happens if the requirements for G2 have been met?
cell initiates molecular processes that signal beginning of mitosis
what happens if the requirements for G2 have not been met?
enters G0 if attempt to repair at checkpoint fails
where does spindle assembly checkpoint occur?
metaphase
what are the requirements needed to be met by spindle assembly checkpoint?
point in mitosis where all spindle fibres should be attached to chromosomes and have been aligned
what happens if the requirements for spindle assembly checkpoint have been met?
mitosis occurs
what happens if the requirements for spindle assembly checkpoint have not been met?
- enters G0
- mitosis cannot proceed unless passed
