|cell division|| cellular reproduction.|
-unicellular organisms: one cell divides, reproduce entire organism.
multicellular organisms: development from a fertilized cell, growth, repair.
|cell cycle||the life of a cell from formation to its own division.|
|most cell division results in...||daughter cells with identical genetic information, DNA.|
|meiosis||produces nonidentical daughter cells.|
|genome||all the DNA in a cell: can consist of single or many DNA molecules.|
|chromosomes|| Packaged DNA molecules in a cell.|
-each species has a set number of chromosomes (humans 46, hedgehogs 90).
|somatic cells||(nonreproductive cells) have two sets of chromosomes.|
|gametes||have half of chromosomes (humans 23)|
|before cell division:||DNA replicated, chromosomes condense.|
|sister chromatids||duplicated chromosomes|
|centromere||site where chromatids most closely attached.|
|what is chromatin made up of?||DNA and proteins|
|mitosis||division of genetic material in nucleus.|
|cytokinesis||division of cytoplasm.|
|mitotic (M) phase||mitosis and cytokinesis.|
|interphase||90% of the cycle; cell growth and copying of chromosomes in preparation for cell division.|
|eukaryotic cell division|| -mitosis|
|overall cell cycle|| -mitotic phase|
|interphase|| -g1 phase (first gap; cell growth)|
-s phase (synthesis; cell growth and chromosome duplication)
-g2 phase (second gap; cell growth)
|what is being synthesized in the S phase of interphase?||DNA|
|at what stage is the cell just prior to mitosis?||G2|
|G2 of interphase|| -nuclear envelope surrounds nucleus.|
-centrosome has duplicated.
-chromatin has duplicated (but not yet condensed).
|centrosome||microtubule organizing center. has two centrioles. part of the mitotic spindle.|
|mitotic spindle|| apparatus of microtubules that controls chromosome movement during mitosis.|
-includes centrosomes, spindle microtubules, and asters.
|aster||radial array of short microtubules extending from each centrosome.|
|prophase||chromatin condenses into sister chromatids; assembly of spindle microtubules begins, centrosomes migrate to opposite poles as spindle microtubules grow out from them.|
|kinetochores|| a structure of proteins associated with specific sections of DNA at each centrosome.|
-a chromosome has 2 kinetochores facing in opposite directions.
|prometaphase||nuclear envelope fragments; chromatids get kinetochores; some spindle microtubules attach to kinetochores and jerk back and forth; nonkinetochore microtubule attachments also form.|
|metaphase|| -centrosomes at opposite poles.|
-chromosomes line up at the metaphase plate, the midway point between the spindle's two poles.
-kinetochores arranged so for each chromosome, one kinetochore attached towards each pole.
|anaphase|| sister chromatids separate (cohesion proteins cleaved); each chromosome moves along kinetochore microtubules toward opposite poles.|
-microtubules shorten by depolymerizing at kinetochore ends.
-nonkinetochore microtubules from opposite poles overlap and push against each other, elongating cell.
|telophase||genetically identical daughter nuclei form at opposite ends of the cell; nuclear envelopes form; chromosomes become less dense; spindle dissolves.|
|what material is the metaphase plate made of?||nothing it is imaginary.|
|cytokinesis|| separation of cytoplasm occurs differently in animal and plant cells.|
-each new cell gets its share of cytosol, organelles, etc.
|cytokinesis (animal cell)||cytokinesis occurs by cleavage; a process of forming a cleavage furrow, or contractile ring of actin microfilaments associated with myosin, that pinches the parent cell in two.|
|cytokinesis (plant cell)||cytokinesis occurs by forming a cell plate; coalesced vesicles containing cell wall materials, that eventually grows to fuse with membrane around cell, dividing cell into two.|
|centrosome, centriole, centromere|| centrosome: microtubule organizing center that is part of the mitotic spindle.|
-centriole: this is one of the two bodies marking the location of the centrosome.
-centromere: this is the tight point of connection between two sister chromatids (region of specific DNA sequences where chromatids attach most closely).