| A | B |
|---|
| interphase | Most of the cell cycle is spent here, cell performs usual functions, copies its DNA and prepares for division |
| G1 stage | Gap 1-growth, increases number of organelles, normal cell functions |
| S stage | Synthesis-DNA replication occurs, each chromosome is duplicated and is now composed of sister chromatids |
| G2 stage | Gap 2-growth, synthesis of cell division proteins, microtubules |
| G1 checkpoint | main checkpoint, checks if cell is large enough and DNA is not damaged before replication, damaged cells will undergo apoptosis |
| G0 stage | cells have exited the cell cycle and are permanently arrrested (neurons) |
| G2 checkpoint | mitosis will occur if DNA is replicated properly, apoptosis will occur if DNA is damaged and cannot be repaired |
| M checkpoint | spindle assembly checkpoint, will check to make sure the chromosomes are properly aligned on the spindle |
| growth factors | signaling proteins that bind to receptors on the plasma membrane and stimulate cell cycle progression |
| cyclins and CDKs | internal signaling proteins that regulate the cell cycle |
| apoptosis | programmed cell death, triggered when a cell is damaged and cannot be repaired |
| p53 | tumor suppressor protein, initiates DNA repair if damage is detected, mutated in 50 % of cancers |
| RB (retinoblastoma protein) | tumor suppressor protein, binds to E2F growth factor and prevents it from binding to DNA. Responds to growth factors and nutrient availability. Mutated in many cancers. |
| somatic cells | body cells (diploid), mitosis will divide these |
| histones | positively charged proteins that DNA will wrap around to compact it |
| heterochromatin | more highly compacted chromosomal regions that are inactive because genes within them are not frequently transcribed |
| euchromatin | actively transcribed chromatin |
| chromatin | DNA bound loosely with proteins |
| diploid (2n) | an organism or cell that has two sets of chromosomes (somatic cells) |
| haploid (n) | an organism or cell that has 1 set of chromosomes, gametes (egg and sperm) |
| M (mitotic) stage | the cell division stage that includes mitosis (nuclear division) and cytokinesis (cytoplasmic) division |
| centromere | a constriction point on a chromosome, where sister chromatids attach to each other |
| kinetochores | protein complexes that develop on either side of the centromere where the spindle fibers will attach |
| centrosomes (and centrioles in animals) | organize the mitotic spindle |
| Prophase | chromatin condenses and chromosomes are visible, nucleolus disappears, nuclear envelope fragments and the spindle begins to assemble as the centrosomes move away from each other |
| Prometaphase (Late prophase) | spindle fibers attach to the sister chromatids at the kinetochores (kinetochore microtubules) |
| Metaphase | centromeres of chromosomes are lined up in the center of the cell. attached to spindle fibers |
| Anaphase | two sister chromatids separate at the centromere and go to opposite poles of the cell (now called daughter chromosomes) |
| Telophase | spindle disappears as new nuclear envelopes form around the daughter chromosomes |
| Cytokinesis in animal cells | division of cytoplasm happens beginning with the development of a cleavage furrow |
| Cytokinesis in plant cells | division of cytoplasm happens beginning when the Golgi apparatus produces vesicles for the new cell plate between the two cells |
| reproductive cloning | manipulation of cells to encourage development of an adult organism clone |
| therapeutic cloning | manipulation of stem cells (either embryonic or adult) to regenerate or replace damaged tissues |
| cancer cells | cells that lack differentiation, have abnormal nuclei, do not undergo apoptosis, form tumors, undergo metastasis and angiogenesis |
| proto-oncogenes | code for proteins that promote the cell cycle and prevent apoptosis |
| tumor suppressor genes | code for proteins that inhibit the cell cycle and promote apoptosis |
| oncogenes | proto-oncogenes that have been mutated and are now cancer causing genes |
| telomeres | ends of chromosomes that protect the genes, get shorter each cell division |
| telomerase | regulates the length of the telomeres, keeping them at a constant length--allowing the cells to keep dividing, expressed in cancer cells |
| asexual reproduction | single-celled organisms produce two new individuals. Offspring are genetically identical to parent |
| binary fission | asexual reproduction in prokaryotes occurs using this process, cell enlarges and DNA replication occurs starting at the origin of replication. Chromosomes attach to a special membrane site and separate by the elongation of the cell that pulls them apart. |
