Cell Cycle Flashcards
what two states do cells in the body alternate between
division & non-division
what is a cell cycle
sequence of events from one division to another
what are the 3 phases of somatic cells cell cycle
interphase, mitosis, cytokinesis
longest phase; period of non-division
interphase
division of the nucleus
mitosis
division of the cytoplasm
cytokinesis
Describe cell cycle variations
Some cells like bone marrow cells, pass through the cell cycle continually to form red blood cells (RBCs)
Some cells enter a “resting” or G0 phase
This state can be temporary and most cells in Go can reenter the cell cycle if conditions change
Other cells, like cochlear hair cells and neurons, that have reached an end stage of development will stay permanently in Go and will no longer divide
when do cells become cancerous
when they escape from the control of the cell cycle
where most cells spend their time
interphase
period with active cell division
mitosis
phase in interphase that most of the cell’s spend their lives and where extra organelles (ribosomes & proteins) are made
G1
phase during interphase that DNA replicates (23 pairs to 46 pairs of chromosomes)
S phase (synthesis)
what are the 3 phases of interphase
G1, S, G2
preparing for mitosis (make microtubules) during this interphase
G2
What do cells use the continuous supply of new cells for?
growth
development
repair
phase with rapid growth and metabolic activity; centriole replication (8-10) hours
G1
chromosome replication
DNA synthesis
6-8 hrs
S phase
growth and final preparations for cell division
4-6 hrs
G2
cell division
mitosis
first phase of the cell cycle and is the longest part
time interval between cell divisions
interphase
what occurs during the 3 phases of interphase
daughter cells that resulted from mitosis undergo a period of growth and synthesis
immediately follows mitosis
cell doubles in size
G1
what organelles are synthesized in G1
RNA, proteins, cell membranes, ribosomes, and other organelles in the cytoplasm
describe what happens during G1 of interphase
cell doubles in size
directly after mitosis
organelles in cytoplasm synthesize
cell pieces lost in cell division get replaced
chromosomes are unduplicated (1 molecule of DNA)
describe what happens during S phase
duplication of each chromosome occurs (two identical daughter DNA molecules)
DNA is replicated and doubles
chromosomes very long and spread throughout the nucleus
what apoptosis
cell suicide
happens when damage to a cell is too severe to repair itself
causes damage to surrounding cells
necrosis
doesn’t cause damage ot surrounding cells
apoptosis
describe G2 phase
interval following DNA replication and before mitosis
2nd period of cellular growth
mitochondria divide
spindle fiber precursosrs form
when are the cells ready to divide
at the end of G2
what are the checkpoints built into the cell to prevent defective cells from going through mitosis and dividing
G1 - ensure readines for DNA synthesis
G2 - determines if cell is ready to enter mitosis and divide
what is the second phase of the cell cycle
mitosis
This type of cell division is essential to allow multicellular organisms to grow and repair damaged tissue
mitosis
before mitosis do the chromosomes double in number?
yes, they go from 46 to 92
how can we see genetic consequences?
errors in distrution of chromosomes to the two daughter cells
at the end of mitosis, what do each daughter cell receive?
one half (diploid number) of the doubled chromosomes material that occurs prior to mitosis maintaining the same number of chromosomes as the mother cell
how many phases does mitosis have
4
prophase
metaphase
anaphase
telophase
during the DNA replication (S) phase, chromosomes are
extremely long and diffusely spread through the nucleus
when do chromosomes coil thicken and shorten to become the recognizable chromosome
prophase in mitosis
which phase do each replicated chromosome comprise of two sister chromatids, with identical genetic info joined at the centromere
end of prophase in mitosis
when do centrioles duplicate
at the start of mitosis
what is an aster
Arrangement of microtubules, star like pattern, mechanically strengthens the spindle apparatus
