Mitosis Mitosis with cancer and cloning
Chromosome- a portion of the DNA in a cell, a chromosome is created when the DNA segment coils around histones then twists further to create a long twisted mass. Histones- protein molecules that are used to fold and package DNA into chromosomes. Nonhistone proteins do not help turn strands of DNA into chromosomes but instead help control the activity of specific regions of the DNA.
Chromosomes are seen as an x shaped structure, each side of the x holds the same information and is known as a chromatid. Two sister chromatids make up one chromosome and during Mitosis, one chromatid from each chromosome will end up in each new cell. Centromere- place in the middle of the chromosomes where two chromatids are attached to one another. Sex Chromosomes- chromosomes that are responsible for determining the sex of an individual and may carry other traits as well. These are only alike if an organism is homolous (xx in humans) otherwise this is the only set of chromosomes that have no homologue
Autosomes- chromosomes that are found in pairs, All of the chromosomes except the sex chromosomes can easily be separate into pairs, each containing information for the same characteristics at corresponding loci, these are known as homologous chromosomes. A chart that can be produced using the similarities between homologous chromosomes is known as a karyotype which can be used to determine chromosomal abnormalities before birth. Diploid cells- have both chromosomes of each homologous pair. For humans, 22 pairs of autosomes and one pair of sex chromosomes. All cells that are not sex cells are diploid
PPMAT Mitosis- The actual act of cell division, this takes place in five distinct phases. Prophase- The first phase of mitosis, Chromatin condenses into chromosomes, mitotic spindle begins forming, centrosomes move away from one another Prometaphase- The second phase of mitosis, this is when the nucleus breaks down, Spindle fibers interact with chromosomes by binding to the kinetochore, Chromosomes become more condensed, centrosomes move to the poles of the cell.
Metaphase- The third phase, all of the chromosomes are lined up equidistant from the centrosomes (in a line along the cell s equator), Chromosomes are held in this arrangement by spindle fibers. Chromosimes line up along this metaphase plate with one of their chromatids facing each pole. One chromatids kinetochore from each chromosome is bound by spindles from one pole and the other chromatid is bound to spindle fibers from the other. Each cetrosome pulls and the result is the chromosomes remain stationed at the equator. Anaphase- Paired centromeres of the chromosomes separate allowing the chromatids to be pulled toward opposite ends of the cell. The result is a full collection of the DNA diversity that was present in the parent cell. Spindle fibers from the two centrosomes push on each other to lengthen the cell as well.
Telophase- Nonkinetochore microtubules elongate further stretching the cell along the poles. Nuclei form around each new collection of chromatids, and the chromatids start to relax into chromatin again. A cleavage furrow begins to form where there was once the metaphase plate or the cell equator. Cytokinesis- The cleavage furrow deepens until the cell is pinched in two.
Chromatin refers to the unwound DNA that is inside of a nucleus when a cell is not actively dividing. Centromere- central portion of a chromosome where both chromotids are still attached to one another. Centrosomes- structures that develop in the cell during mitosis. These produce microtubles known as spindle fibers. Non-kinetochore fibers or polar fibers are spindle fibers which project out from a centrosome and interact with spindle fibers from another centrosome. These fibers push on each other shoving the centrosomes to opposite poles, helping elongate the cell, and providing an anchor from which the chromosomes may be attached.
Kinetochore fibers-spindle fibers that attach to the chromosomes on the kinetochore proteins found at the centromeres. These fibers are responsible for pulling the sister chromatids to opposite ends of the poles. Kinetochore- protein that is attached to the chromosome at the centromere Mitotic spindle- all spindle fibers found in a cell. Metaphase plate- the center-plane of the cell during metaphase when all of the chromosomes are pulled to the center of the cell directly in between the centrosomes
Cleavage furrow- this is where the cell actually pinches in two where the metaphase plate once was. The cleavage furrow represents the end of mitosis and the beginning of cytokinesis In plant cells, a cell plate forms instead of having a cleavage furrow. For this to occur, the golgi of the cell produces little droplets of sugars and fats which travel along the polar fibers until they reach the middle of the cell where they join to form a new cell wall
Cell Cycle is the life cycle of a cell and mitosis is really cell pregnancy Mitosis makes up only a small portion of the cell cycle known as the M phase. The G 1 Phase is the portion of a cells life after Mitosis when it grows and matures into a mature, functional cell. The cell then has two choices, leave the cell cycle and go into G 0 Phase which is essentially what cells are in when they perform their intended function, or begin preparation for a new division by entering the S Phase.
S Phase is the Synthesis Phase and refers to the duplication of all of the DNA in the cell. This is when DNA that makes the sister chromatid is built. G 2 Phase is the point of the cell cycle that is like pregnancy where the cell has to grow and duplicate organelles and cytoplasm enough that the two daughter cells are well equipped to survive. Interphase is a large blanket term describing all of the phases that are not the M Phase or mitosis
Apoptosis-programmed cell death or cellular suicide. This is a process that triggers a protein cascade (chain reaction) that kills the cell. It occurs when the cell does not meet the criteria to carry on at one of the mitotic check points or when the cell line has outlived its intended role. This is what is supposed to prevent cancer.
Vegetative Propagation Layering-bending branches to the ground and burying them so they sprout roots Cuttings- cutting off a piece of a plant and planting it to take root Grafting- binding two different plant parts together to make one plant Tissue culture- taking one piece of tissue and growing it into a new plant on agar
Stolons- Above ground stems that grow a new plant at their tips (Strawberries and Spiderplants) Rhizomes-Underground stems that can branch out separate and each become new plants (Iris) Tubers- Underground stems that grow (potato) that can grow into multiple plants the following year. Root Sprouting- when the root of a plant is exposed to the surface of the soil, it grow a new shoot that turns into a new plant (cherry trees, Elm trees)
Tumor- a mass of cells that are produced during abnormal cell division Benign tumor- do not grow beyond the original mass of cells Malignant tumors- spread to healthy tissue from the original mass Metastasis- when cells break away from the original mass and travel to other parts of the body where they may grow into new tumors. Carcinogens- A substance that is known to increase the chance of developing cancer (smoke, chemicals, radiation, viruses, etc.)
Cancer cell- any cell that has had the growth regulating mechanisms of its DNA damaged enough that it undergoes mitosis uncontrollably. Chemotherapy- Chemicals that are meant to kill cancer cells when injected into the body Radiation- Kills cancer cells by destroying their DNA and other vital molecules within them Drawbacks to treatment- Anything that kills cancer cells also kills healthy cells, but remaining healthy cells should be able to reproduce the other lost cells. Radioisotopes- certain chemicals tend to be preferred by certain tissues allowing us to use radioactive versions of those chemicals to take pictures of tumors in particular tissues.