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42 Cards in this Set
- Front
- Back
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Why do cells divide? (3)
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-organismal reproduction
-growth -repair |
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Mitosis
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an asexual form of reproduction where daughter cells are identical copies of mother cells that occurs everywhere
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Meiosis
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sexual form of reproduction where daughter cells are not identical copies but are formed by 2 different sets of DNA
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Diploid
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cell made from egg and sperm DNA
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binary fission
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process by which prokaryotes divide by
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process of binary fission (4)
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-DNA is duplicated
-one chromosome moved to each side of cell -cell is split into 2 -takes 20 min |
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process of meiosis (6)
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-eukaryote division is much more complex
-cell grows and duplicates organelles -DNA is duplicated -DNA is evenly divided and moves to opposite sides of cell -cell is split in 2 -takes 90 min |
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Karyotype
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amount of chromosomes in an person's DNA
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Genome
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all DNA in a cell
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human genome
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46 chromosomes
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Chromosomes
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can be unwound or condensed
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Chromatid
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one of 2 identical copies of a chromosome
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centromer
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connection in the middle of a chromosome between 2 sister chromatids
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Cell Cycle (3)
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-cell growth and DNA duplication
-mitosis (division of nucleus) -cytokinesis (division of cell) |
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Interphase (3)
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-most cells in an organism are in this stage
-DNA is loose -chromatin and nucleus are still present |
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G1
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first growth phase-downtime
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S phase
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replication occurs, DNA is copied
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G2
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Second growth phase (downtime)
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Cell Cycle Clock
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series of checkpoints regulated by internal and external controls
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G1 Checkpoint
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for many cells this is the most important because it means 1 of 2 things
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yes at G1 checkpoint
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complete S, G2 and M phases and divide
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No at G1 checkpoint
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No=exit the cycle because cell division is unnecessary and go into a nondividing stage called G0 phase.
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cancer
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cells dividing uncontrollably
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M-Phase (5)
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-Prophase
-Prometaphase -metaphase -anaphase -telophase |
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Prophase (4)
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-DNA begins to condense
-nuclear membrane begins to break down -spindle begins to form -chromatin fibers become distinct chromosomes |
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Prometaphase (3)
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-chromosomes are connected to spindle microtubules at their centromere
-nuclear membrane ER and golgi finish breaking down -spindle fibers move to opposite poles |
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Metaphase(2)
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-microtubules have "tug-of-war" against chromosomes
-chromosomes line up in center of cell |
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Anaphase(2)
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-centromeres seperate and sister chromatids moved toward opposite poles
-spindles elongate the cell |
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Telophase(2)
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-chromosomes begin to unravel
-nuclear envelope beings to reform |
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Cytokinesis(3)
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-cytoplasm seperates
-creates 2 distinct cells -occurs at the same time as telophase |
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Cleavage Furrow
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ring of microfilaments that contract until the cell is pinched in two (during cytokinesis) in animal cells
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Cell Plate
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is created between the two cells and eventually forms two cell walls in plant cells.
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gametes
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haploid and contain half the chromosomes of an adult body cell
-from meiosis |
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somatic cells
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diploid
-2 sets of chromosomes -from mitosis |
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asexual division
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daughter cells are identical to parent cells-clones
-occurs in all organisms |
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sexual
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-fertilization by meiosis
-only in eukaryotes |
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meiosis
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haploid gametes are formed from diploid parent cells
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sexual reproduction
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completed by the fusion of gametes to produce a diploid zygote
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life cycles of sexual reproducing organisms
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involve the alternation of diploid and haploid cells
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differences between meiosis and mitosis (3)
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-in prophase I, chromosomes line up and genetic info can be exchanged (crossing over)
-after cytokinesis I, the resulting cells are now haploid, but still have doubled chromosomes -no prometaphase |
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Prophase I (3)
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-chromosomes coil and nuclear envelope dissolves
-homologues become closely associated in synapsis -crossing over occurs between non-sister chromatids |
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Metaphase I (3)
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-chiasmata holds homologues together after crossing over
-microtubules from opposite poles attach to each homologue not sister chromatid -homologues are aligned at the metaphase plate |
