Mitosis Interphase; first growth phase: the cell produces new proteins and organelles. Synthesis phase: the dna is replicated in preporation for mitosis. Second growth phase: the cell produces the organelles and structures needed for cell division. Prophase; Chromatic condense into chromosomes, which are sister chromatids at this point. The mitotic spindles form. In animal cells, centrioles will move to opposite ends of the cell. The nuclear structures and membranse break apart. Metaphase; Chromatids line up at the cell’s equator and the mitotic spindle fibres attach to the chromatids.
The fibres link each sister chromatid to opposite poles. Anaphase; The sister chromatids are pulled apart by the spindle fibres. The seperated chromosomes move to opposite ends of the cell. Telophase; cytokineses occurs. In animal cells, a cleavage furrow forms. In plant cells, a new cell wall is formed between the two new cells. Telophase finishes with the formation of two new nuclei, and the disaperance of the mitotic spindle. Cell Death/Cancer Cells usually die because they sustain injury (rap feuds), or are no longer needed. Cell necrosis is when the cell dies because of external forces, ex: infection, toxins, etc.
Apoptosis is cell suicide, which happens when a cell is no longer needed (“nobody loves me”). Example, the body gets an infection, so army cells go off to fight the infection. When the infection is over, these army cells have nothing to do with themselves so they die. Some cells are such badass motherfuckers that they can avoid apoptosis at the right time and start multiplying like rabbits. These cells are called Cancer! Unlike normal cells, which live for about 50-60 divisions, these cancer cells can live forever! (do not stop dividing). Cancer occurs when DNA is mutated (from smoking) in some way so that the cell’s instructions are damaged.
Things that cause cancer are called carcinogens, and fall under 3 catergories: viruses, radiation or harazardous chemicals. Cancer cells divide so fast that they form a tumor. Cancer gets really bad when it metastisizes and goes to other organs and shit like that. Cancer spreads 2 ways: invasion or metastasis. Invasion is the migration into neighboring tissues, metastasis is where the cancer gets into the bloodstream and travels all over the body. Cancer is incureable, but there are 3 treatments. Chemotherapy: destroys cells which are in mitosis. Since cancer cells replicate fast they are targeted. Radiation: directed at tumors.
Radiation mutates the dna of a cell, and since cancer cells have already mutated dna they cannot repair themselves as easily Regeneration Regeneration is the ability to regrow a tissue, organ or part of the body through mitosis. Humans cannot regenerate because our bodies are made up of many complex cells and tissues. Specialized cells are cells that have specific roles within the cell, as a resuilt they lose the ability to regenerate. Some specialized cells may never undergo mitosis again once they have specialized. Unspecialized cells are referred to as stem cells. Stem cells are cells that can become any other type of cell.
Organisms that have many stem cells can regenerate because any cell can replace the ones that were lost, or the unspecialized cells that remain can become any that were lost. Embryonic vs Adult stem cells Embryonic stem cells are found in embryos, and are totipotent. This means they can become any type of cell. After 4 days the totipotent cells differentiate slightly and become pluripotent. At this point they can still become most cell types, but not all. Adult stem cells are only multipotent; they can make certain lines of cells ex: a bone marrow cell can produce different blood cells but not a neuron.
Plants… and other stuff Stem cells in plants are called meristematic cells. They are found in places where the plant grows, aka roots, leaves and stems. Cells specialize by turning off or turning on different genes in the same set of DNA. Specialized cells turn off genes required to initiate mitosis, which is why many of our tissues do not regenerate. Only a few human tissues regenerate, such as skin and bone marrow. There is a big debate between smart people and li’l bitches about how stem cell research is inhumane. Fortunately according to Darwinism li’l bitches will die off soon so there will be no more debate.
There is a bunch of shit in the notes about stem cell history, you can look it up for yourself… Cloning Cloning is the process of forming identical offspring from a single cell or tissue. Clonging is part of asexual reproduction. Some ways to make clones: binary fission, budding, etc. How to split an embryo: enuculate and egg. Isolate some embryo cells. Take one of the embryos nucleus and stick it in the enucleated cell (because enucleated cells need love too). Let that bitch divide. Once you have a nice little cell mass growing, stick it in your surrogate mother.
Let her warm it up for a bit and then have her give birth. <an animal cell. You should know those parts, and be able to label them. Tissues Animal tissues Type | Functions | Examples | Specialized | epithelial | -Lines body cavities -Protects organs and keeps the in place -Forms glands | -skin -lung lining -adrenal glands | In the skin -milanocytes produces pigment -langerhans’ cell fights infection | connective | -supports and protects structures -forms blood -stores fat -fills empty space | -bones -cartilage -blood | In bones -osteoblasts secrete bone material -osteoclasts break down bones if more calcium is needed.
| Muscle tissue | -allows movement | -skeletal (voluntary) -smooth (involuntary) -cardiac(involuntary) | -cardiac myocytes contract to pump blood -pacemaker myocytes initiate the contraction of the heart | Nervous | -respond to stimuli -transmit and store info | -brain/spinal cord -peripheral nerves | -neurons transmit messages.