Cell+Cycle

Daniel Dogar
 * __Cell Cycle__**


 * Chapter 12 Objectives 1-9

Related Activities** Lab 3 Outline: Cell cycle And Communication Ch. 11&12

Genome:** a cell's total hereditary endowment of DNA. Mitosis II.
 * Vocabulary
 * Somatic Cells:** all body cells except for reproductive cells.
 * Gametes:** reproductive cells.
 * Chromatin:** DNA-protien complex.
 * Sister Chromatids:** replicated forms of a Chromosome joined together by the centromere and eventually seperated during
 * Centromere:** the centralized region joining two sister chromatids.
 * Mitosis:** a process of nuclear division in eukaryotic cells conventionally divided into five stages:prophase, prometaphase, metaphase, anaphase and telophase.
 * Cytokinesis:** the division of the cytoplasm to form two separate daughter cells immediately after mitosis.
 * Meiosis:** a two-stage type of cell division in sexually reproducing organisms that results in gametes with half the chromosome number of the original cell
 * Mitotic Phase:** includes both mitosis and cytokinesis.
 * Interphase:** The cell grows and copies its chromosomes in preparation for cell division. accounts for 90% of cell cycle.
 * G1 Phase:** sub-phase of interphase. First Gap. During all three of the subphases the cell grows by prducing proteins and cytoplasmic organelles.
 * S Phase:** sub-phase of interphase. During all three of the subphases the cell grows by prducing proteins and cytoplasmic organelles.
 * G2 Phase:** sub-phase of interphase. second gap. During all three of the subphases the cell grows by prducing proteins and cytoplasmic organelles.
 * Prophase:** The stage in which chromatin fibers become more tightly coiled condensing into discrete chromosomes. Centromeres move away from each other.
 * Prometaphase:** stage of mitotic division in which the nuclear envelope fragments, bundles of microtubules extend from each pole and some of the microtubules attach to the kinetochore.
 * Metaphase:** stage of mitotic cell division in which the chromosomes convene on the metaphase plate, the centromeres of all the chromosomes are aligned and sister chromatids from each chromosome straddle the metaphase plate.
 * Anaphase:** stage of mitotic cell division in which the paired centromeres of each chromosome separate, microtubules shorten, and once joined sisters move towards opposite poles.
 * Telophase:** stage of mitotic cell division in which nuclear envelopes arise from fragments, chromatin fiber becomes less tightly coiled and the equal division of one nuclei to two identical ones is complete.
 * Kinetochore:** region on the centromere that links each sister chromatid to the mitotic spindle.
 * Metaphase Plate:** an imaginary plane that is equidistant between the spindle's two poles.
 * Cleavage Furrow:** a shallow grove in the cell surface near the old meatphase plate.
 * Cell Plate:** a double membrane across the middle line of a dividing plant cell, between which the new cell wall forms during cytokinesis.
 * Binary fission:** the type of cell division by which prokaryotes reproduce.
 * Cell Cycle Control System:** a cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle.
 * Checkpoint:** critical control point where stop and go-ahead signals can regulate the cycle.
 * G0 Phase:** when a cell does not recieve a go-ahead signal at the G1 stage it enters a nondividing state.
 * Cyclin:** a protein that gets its name from its cyclically fluctuating concentration in the cell wall.
 * Growth Factor:** is a protein release by certain body cells that stimulates other cells to divide.
 * Transformation:** the process that converts a normal cell into a cancer cell.
 * Malignant:** a tumor that becomes invasive enough to impair the functions of one or more organs.
 * Benign:** a tumor that is not harmful.
 * Metastasis:** the spread of cancer cells throughout the body.


 * Important Content**
 * Cell division functions in reproduction, growth and Repair.**
 * Cell division enables multicellular organisms to develop from a single cell
 * Continues to repair and renew cells even after organism is fully grown
 * i.e. Cells that divide in your bone marrow supply new blood cell
 * Involves the distribution of identical genetic material (DNA) to two daughter cells
 * Cell division distributes identical sets of chromosomes to daughter cells**
 * Cell division distributes identical sets of chromosomes to daughter cells**
 * typical human cell has about 3 meters of DNA
 * every eukaryotic species has a characteristic number of chromosomes in each nucleus
 * somatic cells contain 46 chromosomes while reproductive cells have only 26
 * after a cell duplicates its genome in preparation for division the chromatin condenses
 * each duplicated chromosome consists of two sister chromatids containing identical copies of the chromosomes DNA
 * each chromosome i has a centromere where it will be conected to the microtubules
 * mitosis and cytokinesis only take up 10% of cell cycle. the rest is interphase
 * The Mitotic Cell Cycle**[[image:file:moz-screenshot-2.jpg]]
 * during interphase the cell grows and copies its chromosomes in preparation for cell division
 * during the three stages G1, S and G2 the cell grows by producing proteins and cytopasmic organelles.
 * chromosomes are duplicated only in the S phase
 * mitosis is broken down into five subphases:
 * Prophase:**The stage in which chromatin fibers become more tightly coiled condensing into discrete chromosomes. Centromeres move away from each other.
 * Prometaphase:** stage of mitotic division in which the nuclear envelope fragments, bundles of microtubules extend from each pole and some of the microtubules attach to the kinetochore.
 * Metaphase:** stage of mitotic cell division in which the chromosomes convene on the metaphase plate, the centromeres of all the chromosomes are aligned and sister chromatids from each chromosome straddle the metaphase plate.
 * Anaphase:** stage of mitotic cell division in which the paired centromeres of each chromosome separate, microtubules shorten, and once joined sisters move towards opposite poles.
 * Telophase:** stage of mitotic cell division in which nuclear envelopes arise from fragments, chromatin fiber becomes less tightly coiled and the equal division of one nuclei to two identical ones is complete
 * The mitotic spindle distributes chromosomes to daughter cells**
 * many events of mitosis depend on the mitotic spindle which begins to form in the cytoplasm during prophase.
 * it is made up of microtubules and associated proteins
 * the assembly of the microtubules starts in the centromere
 * during interphase the single centrosome replicates to form two centrosomes located just outside the nucleus
 * the centrosomes move apart during prophase and prometaphase
 * the chromosome's two kinetochores face opposite directions and gets attached to the microtubules this pulls the chromosomes towards the poles of the microtubule.
 * Cytokinesis divides the cytoplasm**
 * in an animal cell cytokinesis occurs by a process known as cleavage.
 * first sign of cleavage is the cleavage furrow.
 * on the cytoplasmic side of the furrow is a contracile ring of actin microfilaments associated with molecules of the protein myosin
 * actin and myosin are the same proteins that are responsible for muscle contraction
 * the contraction is like pulling a drawstring it is pinched until there are two separate cells.
 * Mitosis in eukaryotes may have evolved from binary fission in bacteria**
 * prokaryotes reproduce by a type of cell division called binary fission
 * most bacterial genes are carried on a single chromosome that consists of circular DNA molecule and associated proteins
 * after bacterial cell replicates its chromosome in preparation of fission the two copies remain attaches to the membrane at adjacent sites
 * growth of the membrane between the attachment site separates the two copies of the chromosome.
 * when the bacterium has reached twice its size the plasma membrane starts to grow inward dividing the cell into two daughter cells.
 * A molecular control system drives cell cycle.**
 * the sequential events of the cell cycle are directed by a distinct cell-cycle control system.
 * this cyclically operating set of molecules in the cell both triggers and coordinates key events in the cell cycle.
 * like a washer machine the control system has its own clock and runs on it own.
 * checkpoint in the cell cycle is a critical control point where stop and go-ahead signals can regulate the cycle
 * animal cell generally have built in stop signal that halt the cell cycle at checkpoints until overridden by go-ahead signals
 * Internal and external cues help regulate cell cycle**
 * anaphase does not begin until all the chromosomes are properly attached to the spindle at the metaphase plate
 * the gatekeeper is the m-phase checkpoint and it ensures that daughter cell do not end up with a missing or extra chromosome(s).
 * an example of an external signal is cells fail to divide is an essential nutrient is left out of the culture medium
 * Cancer cells have escaped from cell-cycle controls**
 * cancer cells do not respond normally to the body's control mechanisms
 * they divide excessively and invade other tissues and can kill the organism
 * the problem begins when a cell goes through transformation. the body usually recognizes a cancer cell and destroys it but if the cell avoids destruction it can form a tumor
 * a benign tumor which isnt harmful to the organism or a malignant one which is harmful.
 * if left untreated the tumor spreads its cancer cells this is called metastasis.