Biology- Animal cell The NUCLEUS is the largest organelle in the majority of cells. It contains genetic information in DNA‚ which is responsible for the cells unique characteristics. The nucleus is separated from the rest of the cell by.... ...The NUCLEAR ENVELOPE is used as a barrier which separates the contents of the nucleus from the cytoplasm‚ all in all keeping the DNA safe and intact. The nuclear envelope regulates the flow of substances into and out of the nucleus. The NUCLEOLUS is an important
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4Action of hormones in the Menstrual Cycle The Ovarian Cycle The cycle begins with the release from the hypothalamus of gonadotrophin – releasing hormone (GnRH)‚ which stimulates the pituitary to secrete small amounts of Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH). The FSH stimulates follicle growth‚ aided by LH and the cells of the growing follicles start to make estrogen. Notice in figure(d) that there is a slow rise in the amount of estrogen
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Cell: The cell is the basic structural‚ functional and biological unit of all known living organisms. Cells are the smallest unit of life that is classified as a living thing‚ and are often called the "building blocks of life". Discoverer: The cell was discovered by Robert Hooke in 1665. The cell theory‚ first developed in 1839 by Matthias Jakob Schleiden andTheodor Schwann‚ states that all organisms are composed of one or more cells‚ that all cells come from preexisting cells‚ that vital functions
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produce two new daughter cells containing chromosomes identical to the parent cell. Significance of mitosis Growth- allows a zygote to produce more cell in order to grow Repair and replacement- allow the multicellular organism maintain its tissues‚ example skin cells and blood Asexual reproduction- clone The cell cycle divided into two major phases a. Interphase b. Mitosis Interphase is the period between division‚ divided into 3 sub phases (G1‚ S and G2) a. G1- cells grow rapidly and new organelle
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Describe the cell cycle. Include in your discussion the role cyclins and CDKs play in controlling this cycle. The cell cycle is a process that cells undergo to grow‚ reproduce‚ and divide to make 2 daughter cells. The cell cycle has different stages including G1‚ S‚ G2‚ and the M phase. Also we have the G0 phase. There are checkpoints that control the transitions between the phases of the cell cycle in which the process is regulated by cyclins and cyclin-dependent kinases (CDKs). G1 is known as
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Chapter 3 Cell Structure and Function Section 3.1: Cell Theory: Cells are the smallest building unit of living organisms that can carry out all processes required for life. Almost all cells are too small to see without the aid of a Microscope. Although glass lenses used to magnify images for hundreds of years‚ they were not enough to reveal individual cells. The invention of Compound microscope was in the late 1500s by the Dutch eyeglass maker Zacharias Janssen. In 1665‚ the English scientist
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production of the male gametes (reproductive or sex cell) otherwise known as sperm. The production of sperm takes place in the seminiferous tubules within the testes and are formed from cells by a type of cell division called mitosis and then meiosis. This process begins at puberty. Spermatogonia cells are made by mitotic division of the primordial germ cell. Mitotic cell division produces diploid cells that are identical to the Parent cell with 46 chromosomes. The Spermatogonia increases in
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Cell cycle checkpoints are control mechanisms in eukaryotic cells which ensure proper division of the cell. The Cell Cycle consists of three checkpoints. These checkpoints are the G1 checkpoint‚ the G2 checkpoint‚ and the M checkpoint. These checkpoints all have different functions. Cells have many different mechanisms to restrict cell division‚ repair DNA damage‚ and prevent the development of cancer. Cancers are formed as cells acquire a series of mutations‚ or changes in DNA‚ that make them divide
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It is important that cells go through mitosis because it makes each new cell contain the same gentic information. If meiosis did not occur the reproduction would cease to exist. Mitosis is the process of chromosomes dividing. There are four steps that it goes through. Between cell division the cells are in interphase. During this there is cell growth and the genetic material such as DNA is contained in the chromosomes‚ duplicated so that when the cell divides each new cell has a full version of
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CELL ANATOMY Microbodies Brief History Microbodies were first discovered and named in 1954 by Rhodin. De Duve chose the name of Peroxisome because of its relationship with hydrogen peroxide. In 1967‚ Breidenbach and Beevers were the first to isolate microbodies from plants‚ which they named Glyoxysomes because they were found to contain enzymes of the Glyoxylate cycle. Definition Any of the membrane-bound‚ ovoid or spherical‚ granular cytoplasmic particles containing enzymes and other substances
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