1. Cell division functions-___________,_____________ and ___________________ Cell division requires the distribution of _________ genetic material (DNA) to two __________ cells. Fig. 12.1c CHAPTER 8 Cell Division and Mitosis

2. Cell division distributes identical sets of chromosomes to daughter cells A cell’s genetic information, packaged as DNA, is called its _____________ In prokaryotes, _______ DNA molecule. In eukaryotes,- _____ DNA molecules. DNA molecules are packaged into _____________ Every eukaryotic species has a characteristic number of chromosomes in the nucleus. Human __________ (body cells) have 46 chromosomes. Human _______sperm or eggs) have 23 chromosomes, half the number in a somatic cell.

______ - The process of the formation of the ____ daughter nuclei from a single parental cell is usually followed by division of the cytoplasm, _________________. Result- two cells that are the genetic __________ of the parent. _______ – one parental cell produces __ daughter cells Occurs only in the ______(ovaries and testes), Result- Each cell has half the chromosomes. In humans, meiosis reduces the number of chromosomes from __to ___ Fertilization fuses two ______ together and doubles the number of chromosomes to ___ again.

The ___________ of the cell cycle alternates with the much longer ________. The M phase includes ____ and __________. Interphase accounts for ____ of the cell cycle. 3. The mitotic phase alternates with interphase in the cell cycle: an overview Interphase has three subphases: the _______ (“first gap”) centered on growth the _____ (“synthesis”) when the chromosomes are copied the ______ (“second gap”) where the cell completes preparations for cell division G1 G2 S M

Chromosome _________Chromosomes coiled Sister ________joined Mitotic _______ forms _________ disappear Nuclear envelope _________ Microtubles attach to _________ on centromere Fig left 1. __________ 2. _________ 3. _____________ Mitosis- 6 phases

Sister chromatids arranged in “_____” by spindles 4. __________ 5. ________6. ________and ____________ Centromeres divide Chromosomes pulled to poles Nuclei begin forming Chromatin relaxes ____________ begins Mitosis

The ________________ fibers composed of _________and associated proteins is a major driving force in __________. Assembled during _______from cytoskeleton components. The spindle fibers elongate by incorporating more subunits of the protein tubulin. 4. The ____________ distributes chromosomes to daughter cells

Cytokinesis divides the cytoplasm ____________ follows ______ In animals- A contractile ring of ____ microfilaments and the motor protein ______ form to pinch the cell in two. In plants- vesicles from the Golgi coalesce at the metaphase plate, forming a _________. The plate enlarges until its membranes ______ vesicles convergin g

5. Prokaryotes reproduce by __________, not mitosis. Bacterial genes located on a single chromosome In binary fission, chromosome replication begins at one point in the circular chromosome, the __________________ site. These copied regions begin to move to opposite ends of the cell. Mechanism is unknown ______________ are unknown in bacteria.

The cell cycle is driven by specific _________signals. Evidence-Fusion of an M phase and a G 1 phase cell, induces the __ nucleus to start ___ phase. 6. A molecular control system drives the cell cycle Fig The _______ and _____ of cell division varies with cell type. Skin cells divide often, mature nerve and muscle cells not at all

The distinct events of the cell cycle are directed by a distinct cell cycle ___________________. Fig Three major checkpoints are found in the __-___, and __ phases. A ___________ - control point where stop and go signals regulate the cycle. If no go-ahead signal, the cell exits the cycle and switches to a nondividing state, the ___ phase. Most human cells are in the G0 phase

7. Internal and external cues help ________ the cell cycle Growth factors stimulate cells to ________ Example: Platelet-derived growth factors (PDGF), produced by platelet blood cells, bind to tyrosine-kinase receptors of fibroblasts, and triggers a signal-transduction pathway that leads to cell division.

The role of _____ is easily seen in cell culture. Fibroblasts in culture will only divide in the presence of medium that also contains PDGF. Fig

Growth factors appear to be a key in_______- _______________________ of cell division. Cultured cells normally divide until they form a ___________ on the inner surface of the culture container. If a gap is created, the cells will grow to fill the gap. Most animal cells also exhibit _______ __________for cell division. Must be anchored to a __________, typically the ____________________ of a tissue

Cancer cells divide excessively and invade other tissues because they are free of the body’s control mechanisms. If and when cancer cells stop dividing, they do so at random points, not at the ______________ in the cell cycle. 8. Cancer cells have escaped from cell cycle controls Cancer cells are free of both 1-____________________ and 2-_________________________. Cancer cell may divide indefinitely if they have a continual supply of ________________. In contrast, nearly all mammalian cells divide _______ times under culture conditions before they stop, age, and die.

________________- a single cell in a tissue converts to a cancer cell. Normally, the immune system recognizes and destroys transformed cells. However, cells that evade destruction proliferate to form a tumor, a mass of abnormal cells. ________ tumor- The abnormal cells remain at the originating site. __________ tumor- the abnormal cells leave the original site to impair the functions of one or more organs (Known as __________). _________- Cancer cells are carried by the blood and lymph system to new sites and start more tumors.

Fig A typical cancer senario- breast cancer Treatments for metastasizing cancers include high-energy ______________ and _____________with toxic drugs. These treatments target actively __________cells.