genetic material of an organism (in prokaryotes is 1 long DNA molecule; in eukaryotes is several)
DNA and proteins; long linear mc in Eukaryotes; each species has a specific number of chromosomes
all body cells except reproductive cells
sex cells (egg, sperm), have half the number of chromosomes than a somatic cell (in humans has 23)
the DNA and associated proteins in a chromosome
the 2 identical parts of a duplicated chromosome
where the chromatids are held together
a protein structure in the centromere, where the mitotic spindle attaches
aka microtubule organizing center; area in animal cell from which the spindle fibers originate; in animal cells there are 2 centrioles in the centrosome; the centrosome duplicates in interphase
produces 2 identical cells called daughter cells; used to repair cells, renew old / dead cells
division of the nucleus of a eukaryotic cell
division of the cytoplasm of a eukaryotic cell; creates 2 daughter cells, typically follows mitosis
only in sex cells; produces non-identical daughter cells
drawing in of the cell membrane in an animal cell to create 2 cells; done by an actin belt (microfilament)
in plants, forms new cell wall to form 2 daughter cells; vesicles from Goldi go to middle of cell and join together; have cell wall material in them
What is the first phase of the cell cycle? (what are the phases in it)
interphase; is about 90% of a cell's life; contains the G1 phase in which the cell grows, makes organelles; may be sent to the G0 phase where it does not duplicate (rests); S phase where DNA replicates, more growth; G2 phase where continues growth and prepares for cell division; some will go on to divide, others will go into G0 phase
What is the M phase?
about 10% of cell's life; mitosis
G2 of interphase...
nuclear envelope bounds the nucleus, two centrosomes have formed by replication of a single centrosome; each centrosome features 2 centrioles; chromosomes cannot be seen separately
chromatin fibers become more tightly coiled (form chromosomes); nucleoli dissapear; appears as sister chromatids and are joined at their centromeres; mitotic spindle begins to form (composed of centrosomes and microtubules that extend from them); centrosomes move away from each other
nuclear envelope framents; microtubules invade the nuclear area; each of the two chromatids of each chromosome now has a kinetochore (the thing connected to the kinetochore miscotubule); nonkinetochore microtubules interact with those from the opposite pole of the spindle
longest stage of mitosis; centrosomes are not at opposite poles of the cell; chromosomes convene on the metaphase plate (in the middle of the centrocomes); the kinetochores of the sister chromatids are attached to kinetochore microtubules coming from opposite poles
shortest stage; begins when the cohesion proteins are cleaved( chromatids are parted from one another); move towards opposite sides of cell; cell elongates as the nonkinetochore microtubules lengthen
two daughter nuclei form in cell; nuclear envelopes form from fragments of the parent cell's; chromosomes become more condensed; mitosis complete / actin pinches in the cell; forms cleavage furrow
what are the three types of spindle fibers?
aster, kinetochore and nonkinetochore
cell division in prokaryotes; prokaryotes have 2 circular chromosome; it attaches to the wall of the cell and replicates from the origin of replication (attached to plasma membrane)
frequency of division
varies by cell type; skin frequently; liver normally don't but can be called back into cell cycle; nerve and muscle do not
restriction point; most important checkpoint in animal cells; if it is stopped at this point, cell will go into G0 or into apoptosis
checks to see if DNA was correctly copied
What are the stages of mitosis in order?
interphase, early prophase, late prophase, metaphase, anaphase, telophase/cytokinesis
M phase checkpoint
when all kinetochores are attached to the spindle in metaphase, a regulatory protein is activated to cause the cohesins holding sister chromatids to be cleaved (so anaphase can begin)
what gives the go ahead signal at G1 and G2 checkpoints?
WHat must protein kinases attach to to be activated?
needed for mammalian cells to divide (chemical signals from outside of cell)
a phenomenon where crowded cells stop dividing (will tell cell whether it needs to divide or not)
to divide, most animal cells must be attached to something
lack density dependent inhibition, lack anchorage dependence; do not need growth factors to divide; have abnormal cell cycle controls; cancer cells are immortal; ignore normal signals that would cause apoptosis; normally out immune system would destroy cancer cells
invasive and impairs organs; may have: excess proliferation, abnormal number of chromosomes, abnormal metabolism, can lose attachment to nearby cells and tissues (mestasis- will move around body); may secrete signal molecules that can cause blood vessels to grow into a tumor
localized (high NRG radiation, damages cancer cells' DNA); mestatic tumors- chemotherapy- toxic to rapidly dividing cells