Grade 10 Science Ultimate Study Guide

Mitosis is a cellular process that replicates chromosomes and produces two identical nuclei in preparation for cell division, from the original cell two cells are derived, each of which possesses the same genetic material. Mitosis has five phases: interphase, prophase, metaphase, anaphase and telophase. Interphase The DNA duplicates during interphase to prepare for mitosis. Chromosomes are not clearly discerned in the nucleus. Prophase Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes. The nuclear membrane dissolves. Microtubules attach at the kinetochores and the chromosomes begin moving. Metaphase Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is

Pluripotent stem cells are just like Totipotent cells, but they can only become cell derived from the three germ layers, which contain over 200 specialized cells. Multipotent stem cells can only become blood cells, such as red blood cells, white blood cells, or platelets. Unipotent stem cells can only transform into one type of tissue or specialized cell, but it can divide over and over again (Wikipedia). These embryonic stem cells can divide again and again through mitosis (a type of cell division in all body parts except reproductive parts). Medical specialists and leading scientists conclude, that these cells could help cure as many as seventy-three diseases, which up to now were thought incurable (NIH).

unfortunately the embryonic stem cell is a topic of serious heated debate. It has the most

“How can the use of stem cells be so controversial?”, one may ask. If the stem cells are donated out of free will or were going to be destroyed anyway, how can putting them to better use be controversial? Sure, a potential life must be destroyed to save a life, but only before one can tell that it is a human. Should the use of stem cells for medical research and use be regulated? These questions and more will be discussed and pondered throughout this paper.

Firstly, what even are stem cells? Stem cells are cells that can turn into many different types of cells throughout your bedy. Think of it like a mother cell creating endless amounts of children. There are two kinds; pluripotent, ones that can turn into basically every cell in the body, and multipotent, ones that can only for a small number of cells.

New cells are required for an organism to grow, reproduce or repair damaged tissue. All cells arise from pre-existing cells. Cell replication is the process which facilitates the production of new cells from existing cells. For example, cell replication is required to create new cells to heal a cut to the skin. Another example of cell replication is when gametes are produced in the reproductive organ of a human. Cell replication is a different process for eukaryotic and prokaryotic cells. For eukaryotic cells, the cell life cycle consists of three main stages; Interphase, Mitosis and Cytokinesis. In interphase, the cell expands and organelles replicate to prepare for the cell division. The replication of DNA occurs in the synthesis phase of interphase. During mitosis, the now replicated DNA within the parent cell splits into two equal parts for the daughter cells. finally, in the cytokinesis stage of the cell cycle, the cytoplasm (all the contents of the cell within the cell membrane excluding what is in the nuclear

What is a cell cycle? The activities that occur within a cell cycle from the end of one cell division to the end of another.

This division of the nucleus is called mitosis. Another part of cell division is cytokinesis, where the cytoplasm divides and the cell becomes two cells. The first steps in cell division begin with mitosis, and mitosis is divided into five different stages which include: prophase, prometaphase, metaphase, anaphase, and telophase. (pg. 571) Prophase is the first step in mitosis. During prophase the chromosomes become compact together. The centrisomes begin to form the mitotic spindle. Prometaphase is the next step in cell division, which the nuclear envelope breaks apart and the paired chromatids connect. (pg. 572) Then the chromatids connect with spindle microtubules to form kinetochores and migrate to the poles of the cell. In metaphase the chromosomes line up in the middle of the cell. (pg. 573) The next step in mitosis is anaphase, which is where the chromatids of each chromosome separate at the centromere and are pulled to opposite ends. The last step in mitosis is telophase. During telophase the spindle fibers disassembled and the chromosomes uncoil into chromatin. At this point the cell enters into cytokinesis. (pg. 574) During cytokinesis the cytoplasm splits along the cleavage furrow. (pg 578) In plant cells, during cytokinesis a cell wall must be formed. Vesicles migrate toward the center and form a cell plate, which becomes the cell wall. (pg.580) In either a plant cell or animal cell, at this

There are two main types of human stem cells—embryonic stem cells and adult stem cells (“Stem Cell Basics,”

In very simple terms, stem cells are cells that have the strong ability to become any number of other cells. “Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division . . . Second, they can be induced to become tissue-or organ-specific cells with special functions” (NIH 2002, 1). There are two extensive groupings of stem cells in which scientists primarily work with. These include embryonic stem cells and adult stem cells. Embryonic stem cells are “derived from the developing

Stem cells are found in early embryo (blastocyst), the foetus, umbilical fluid, the placenta and umbilical cord blood.(9) During the stages of life after birth and the rest of life stem cells continue to reside in many parts of the body including skin, hair follicles, bone marrow and blood, brain and spinal cord, gut, lung, joint fluid, muscle and fat just to name a few.(9) Researchers are trying to harness the regenerative potential of stem cells to be able to grow new cells for medical treatments that require the replacement of damaged cells in the body.

In prophase, chromosomes begin to condense while the nucleoli and nuclear membranes fragmented. Metaphase begins with complete nuclear membrane fragmentation. Chromosomes will attach to the kinetochore microtubules, which extend from the centrioles and align the chromosomes at the center of the cell. Anaphase will begin to shorten microtubules drawing one chromatid to each pole of the cell. Telophase will decondense the nuclear membrane fragments in order to go through cytokinesis and form two new daughter cells. Throughout the entire mitosis cell cycle the number of different sets of chromosomes remained the same, 2n. The number of different set of genes began with 2N, increased to 4N and then ended with 2N at the end of the

The changes in the cell become more noticeable. The chromosomes become coiled and can be viewed under a microscope. Each chromosome that was duplicated is a pair of sister chromatids joined by the duplicated but unseparated centromere. The nucleolus in the cell disappears in this stage of mitosis. The cytoplasm is also involved in prophase. The mitotic spindle of the cytoplasm consists of microtubules. The microtubules form between two pairs of centrioles as they move to opposite poles of the cell. At the end of this phase, the nuclear envelope disappears.

Stem cells, as stated previously, are cells that have the potential to develop into any kind of tissue. In the body they serve as a repair system, continually dividing without limit to repair damaged tissues. As they divide the cells can either continue to be stem cells or convert into a specialized type of cell, such as, a red blood cell, a muscle

Stem cells are vital in the process of developing organisms. They are duplicating cells which have the potential to create other types of specific cells such as blood cells, brain cells, tissues cells or muscle cells. In addition, in many tissues they function as an internal repair system. The stem cell divides without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential to either continue as a stem cell or become another type of cell with a more specialized function. Scientists mainly work with two kinds of stem cells from animals and humans: embryonic stem cells and non-embryonic which are commonly referred to as somatic or adult stem cells.