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48 Cards in this Set
- Front
- Back
meiosis |
cell division occurring in sexually reproductive organisms (2n --> n) |
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mitosis |
cell division where offspring has identical genetic material (2n --> 2n) |
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type of cell that meiosis occurs in |
gametes |
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type of cells that mitosis occurs in |
somatic cells |
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chromasome |
long single double helix of DNA organized around proteins called histones |
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chromatin |
a complex of DNA and proteins (histones) |
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interphase |
G1, S, G2 |
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synthesis |
chromosomes double |
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gap phases |
prep and functional phases |
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Prophase |
chromosomes condense, first becoming visible. Spindle apparatus forms, moving replicated chromosomes |
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spindle apparatus |
an array of microtubles that move chromosomes around the cell |
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Prometaphase |
the nuclear envelope dissolves, microtubles attach at the kinetochores. Chromosomes are moved until they reach the spindle |
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Metaphase |
mitotic spindle complete, chromosomes line up on the metaphase place (b/w spindle poles). Each chromosome is help w/kinetochore tubles from opposite poles |
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Anaphase |
cohesions between sister chromatids split, pulled in opposite directions, creating 2 sets of daughter chromosomes |
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Telophase |
new nuclear envelopes form, chromosomes condense. Mitosis is complete when 2 nuclei form. Cytokinesis occurs immediately after cleavage furrow shrinks and tightens until division is complete. |
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G1 |
checkpoint before DNA synthesis. (most important) filters cells to S phase or resting phase |
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quiescence |
resting phase |
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4 factors that determine if cell is to pass to S phase |
size, nutrient availability, "social" signals from surrounding cells (growth factors) & physical DNA damage |
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what is activated by damaged cells |
p53 (protein) "guardian of genome" "tumor suppressor" |
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apoptosis |
cell suicide |
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G2 check point |
after S phase, catches cell in synthesis when replication gets messed up (repairs or kills) |
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M1 phase check point |
b/w metaphase and anaphase, ensures sister chromatids do not split until all kinetochores are attached to spindle apparatus |
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M2 check point |
b/w anaphase and telophase, ensures that chromosomes have fully separated |
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cancer |
40% of Americans will develop it. A complex family of diseases where cells grow uncontrollably |
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malignant |
cancer spreads to nearby cells |
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metastasis |
cancer spreads to other sites in the body |
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homologous chromosomes |
chromosomes with similar size, shape, and genetic info. these are present in mitosis, but do not cross or pair, while the opposite is true for meiosis. |
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ploidy |
karyotype identifies # and types of chromosomes in species |
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diploid |
contains two sets of chromosomes, one from each parent (2n), 2 alleles of each gene |
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haploid |
has a single set of unpaired chromosomes (n), 1 allele of each gene |
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meiosis begins with |
46 chromosomes |
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prophase |
chromosomes condense, spindle forms, nuclear envelope dissolves, homologous chromosomes paid up at synapse, crossover points (2n) |
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Metaphase 1 |
pairs of homo chromosomes line up at metaphase plate (2n) |
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Anaphase 1 |
homologous chromosomes separate, going towards opposite ends of spindle (2n) |
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Telophase 1 |
complete migration to poles, spindle apparatus disassembles (n) |
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Prophase 2 |
spindle forms (n) |
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Metaphase 2 |
chromosomes line up at the metaphase plate |
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Anaphase 2 |
sister chromatids separate, moving to opposite poles |
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Telophase 2 |
daughter chromosomes finish migration to poles, spindle breaks down, nuclear envelope reforms |
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products of mitosis |
2 diploid daughter cells that are genetically identical |
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products of meiosis |
4 haploid daughter cells, genetically distinct from each other and parents |
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crossing over: condensation |
sister chromatids joined by cohesins |
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crossing over: synapsis |
homologous chromosomes join, held together at synaptonemal complex |
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crossing over can only occur b/w |
non sister chromatids |
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partial separation |
homologous chromosomes help together only at chiasmata |
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how does meiosis promote genetic variation |
1. independent association |
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aneuploidy |
wrong # of chromosomes, usually resulting from nondisjunction (bad separation) |
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crossing over definition |
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring |