Weismann‚ who noted that two cell divisions were necessary to transform one diploid cell into four haploid cells if the number of chromosomes had to be maintained. In 1911 the American geneticist Thomas Hunt Morgan observed crossover in Drosophila melanogaster meiosis and provided the first genetic evidence that genes are transmitted on chromosomes. The term meiosis was introduced to biology by J.B. Farmer and J.E.S. Moore in 1905 Meiosis i/maɪˈoʊsɨs/ is a special type of cell division necessary for
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students from using cell phones at school and at all school functions? By Olivia Acuña ENG 111G27 9/11/2011 Cell phones have created a new era of communication between students around the world. Some students believe cell phones are helpful to communicate with their friends and family. Others disagree and believe that cell phones are being used in an inappropriate manner‚ during and after school activities. I strongly believe that cell phones should be banned during school hours because
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Name: ______________________________________ Date: ________________________ Student Exploration: Osmosis Vocabulary: cell membrane‚ concentration‚ diffusion‚ dynamic equilibrium‚ osmosis‚ semipermeable membrane‚ solute‚ solvent Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. Suppose you were trapped on a desert island with no sources of fresh water. Should you drink water from the ocean? Explain why or why not. _________________________________________________________________________
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Bacterial cells are Prokaryotic cells. These cells have several internal structures and surface structures. The cell walls are of two types‚ gram positive and gram negative. Out of all the structures‚ the two selected structures are the cell- wall and endospores. The cell- wall of bacterial cells is found in three distinct shapes such as spherical‚ spiral and rod shaped. The cell wall of the bacterial cells is composed of the proteins and polysaccharides. This is collectively called peptidoglycan
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Cell Fractionation * Cell Fractionation: takes cells apart and separates the major organelles and other subcellular structures from one another. * Tissue cells are the first one to be homogenate or broken apart. * Plasma membranes are broken up so that there internal contents spill out and mix together and this is called homogenate. * Homogenate is in spun in a higher rate of speed in a process called centrifugation. And that speed can vary that why it’s called differential
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Cells are some of the smallest organisms around. All living things consist of cells‚ and yet they are invisible to the naked eye. Cells are the basic structural and functional units of life. Cells are made up of many different parts which allow them to function properly. All cells are separated from their surrounding by a cell membrane. The cell membrane regulates what enters and leaves the cell and also aids in the protection and support of the cell. A cell membrane
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Reference Data Sheet: BATTPRIM.PDF (1) PRIMARY CELLS & BATTERIES Many portable electrical and electronic devices are designed to be powered from batteries and in a lot of cases‚ from primary or non-rechargeable batteries. This is the familiar kind of battery which has a fixed amount of energy stored in it during manufacture‚ and once that energy has been used up the battery is simply thrown away and replaced. There are many different types of primary battery now available‚ each with its own
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Stem Cells and Tissue Renewal 1 The Multicellular “Habitat” • Cells of multicellular organisms – highly specialized – over 200 types in human body • Arranged into tissues‚ organs‚ organ systems • Unable to survive outside body “habitat” skin wont survive in heart tissues. They all start up identicals 2 Specialized Cell Types • Cells of early embryo identical • Differentiation results in specialized cell types – some differentiated cells continue to divide – many others are
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characteristics of a healthy cell and a cancer cell is very different. Healthy cells stop reproducing when there are enough cells‚ however‚ cancer cells continue to reproduce. Due to this continued growth a tumor‚ which is a cluster of cancer cells‚ is formed. Cancer cells do not interact with other cells like the healthy cells. Healthy cells stop growing when they hear signals from the nearby cells‚ in contrast‚ cancer cells do not respond to these signals. When healthy cells get old or damaged they
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The Cell Cycle Mitosis: the process by which cells reproduce themselves‚ resulting in daughter cells that contain the same amount of genetic material as the parent cell. Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Cell Division Occurs in a series of stages of phases Interphase occurs before mitosis begins Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start‚ but each chromosome and its copy(sister chromosome) change to sister
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