MEMBRANE STRUCTURE AND FUNCTION Fluid-mosaic model for biological membrane In human beings, all cells are surrounded by a cell membrane, are called the plasma membrane. Our current understanding of the structure of biological membranes is summarized in the fluid-mosaic model. It describes both the "mosaic" arrangement of proteins embedded throughout the lipid bilayer and also the "fluid" movement of lipids and proteins alike. Structure of membranes Biological membranes are sheet-like structures
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THE MICROSCOPE Much of the laboratory work in General Botany I involves the study of minute structures which are invisible of poorly seen with the naked eye. This requires the use of the microscope, the primary purpose of which is to magnify or greatly enlarge the image of the objects or organisms so their detailed structures may be studied. For our purposes, the monocular compound microscope will be used. It is an optical instrument with two lens systems: the objectives and the eyepiece or ocular
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www.asbiology101.wordpress.com An introduction to the microscope and magnification MAGNIFICATION AND RESOLUTION Because cells are too small to be seen with the naked eye, the light microscope was developed to produce enlarged and more detailed images of cells. The magnification of an image is how much bigger it appears under the microscope than it is in real life, and is worked out using the following formula: magnification = image size ÷ actual size unit metre decimetre centimetre
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and molecules via facilitated diffusion (A). Others couple molecule movement against a concentration gradient (uphill) with another molecule movement down its concentration gradient (B and C). 8 9 11.2 Uniport Transport of Glucose into Cells via
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functions of the cell membrane The cell membrane is the outer cover for a cell, and something that lets things out and into the cell. The function is to protect the interior of the cell by allowing some substances into the cell, and also blocking some substances from coming in. Main functions of the nucleus The nucleus is the centre of the cell which controls things. Nuclei contains genetic material e.g. DNA and also controls the cells growth and reproduction. In red blood cells, the nucleus is
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Cell membrane: The cell membrane surrounds the cytoplasm of a cell and its job is to protect the inside of a cell by only allowing certain substances into the cell and keeping other substances out. It also helps to support the cell and maintains its shape. Nucleus: This is the biggest part of the cell and is the part of the cell which acts like the brain. It is not always in the middle of the cell but will be placed within the cytoplasm. In some cases a cell may have many nuclei and these are
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Biology AP October 2, 2014 In the early twentieth century, little was known about cell membranes. For years scientists looked through the microscope in search of answers. Since the discovery of many new information conducted through observations and research, they were able to understand that plasma membrane is an essential biological structure to all cells. It functions as an envelope by keeping all a cells organelles contained. It also serves as a gateway and barrier to certain foreign substance
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nanoT - VaryCell TM Micro stage for time lapse imaging and temperature mediated cellular studies. Cells derived from mammals have an optimum in vitro growth rate between 36°C to 37°C as their in vivo physiological temperature ranges between 36.5–37.5 °C (97.7–99.5 °F) in a normal individual. Homeostasis process maintains the constancy of the organism’s internal environment in response to changes in external conditions. Thermoregulation is part of the aforementioned process as controlled by the
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scientists have now discovered one vital clue to unravel the riddle. Human genome is a collection of 4 million gene switches. Some reside in bits of DNA that once were discarded as ‘junk’ but that turns out to play critical role in controlling how cells, tissues and organs behave -- the junk DNA is often referred to as the ‘dark matter’ instead. As a result of a huge project involving 440 scientists from 32 laboratories around the world, the discovery is considered as a major medical
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Animal Cell | Cell functions | Smooth endoplasmic reticulum | associated with the production and metabolism of fats and steroid hormones | Rough endoplasmic reticulum | involved in some protein production, protein folding, quality control and despatch. | Nuclear envelope | surrounds the nucleus with a double membrane with multiple pores. | Chromatin | Mass of genetic material composed of DNA and proteins that condense to form chromosomes during eukaryotic cell division. | Nucleolus
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