10-8-09 Biology Essay: Parts of a Cell Describe the fluid-mosaic model of a plasma membrane. Discuss the role of the membrane in the movement of materials through each of the following processes: a.) Active Transport b.) Passive Transport All living cells contain a plasma membrane‚ which acts a boundary for the cell. The plasma membrane regulates the cell’s chemical composition because it uses selective permeability to allow certain substances to enter or exit the cell more easily than others. The
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Cell Division Why must cells divide? To start it off‚ cells can’t keep growing forever‚ so when they reach a certain size they will have to divide. Cells divide for four important reasons; reproduction‚ growth‚ repair‚ and replacement of damaged or worn out cells. Most cells divide at least once during their life cycle and some divide divide dozens of time times before they die. There are three types of cell division. They are binary fission‚ mitosis‚ and meiosis. When cell division is
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The cell membrane is made up of fats‚ proteins‚ lipids‚ and carbohydrates‚ and is a permeable structure. However‚ this permeation is very discerning because it only lets certain things pass through it. The cell membrane has a layer of phospholipids with hydrophobic ends and hydrophilic tops. The “tails” are made out of phosphate‚ while the “heads” are made up of two strings of fatty acids. There are two layers of these phospholipids‚ called the “bilayer”‚ and the tips of each phospholipid are facing
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Stem Cell Controversy Stem cells were first isolated and cultured in November of 1998 and have been surrounded with much debate and controversy since day one. “Although the ethical debates have been mostly static and have closely mimicked the ethical debates over abortion‚ the political determinations concerning federal funding of stem cell research have gone through numerous evolutions in the years since the first hESCs were isolated and cultured” (Saltzberg 505). Research is currently being
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Synchronizing Cells at Specific Stages of the Cell Cycle The protocols presented here describe procedures used to synchronize cells in various stages of the cell cycle (Fig. 8.3.1). Synchronization is particularly useful for investigating a particular cell cycle–regulated event or preparing cells for extraction of transient factors whose expression is dependent on cell cycle stage. Exponentially growing cultures are generally asynchronous; i.e.‚ each cell progresses through the cell cycle independently
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Aim: The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato tubes as they provide a ready supply of homogeneous material. I did the investigation in two parts‚ the first part of my investigation was my preliminary investigation and then I did my official investigation. In both of my investigations there are several similarities‚ such as fair testing‚ variables‚ key variables‚ reliability
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After reading the “‘Bubble baby’ stem cell” paper I have come to the conclusion that stem cell research is an excellent thing. The reason why I think that is if we never do research and create a cure for “Bubble baby disease” then we will continue to lose babies. But‚ if we risk a few lives of babies for research in the long run it will save millions if not billions of lives. In this essay I will give three reasons on why I think stem cell research is a great thing. “Bubble baby disease.” In my
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the solution and a potato tuber of a given size. The purpose of this experiment is to demonstrate how living cells rely on osmosis‚ the diffusion of water. Osmosis is the movement of water molecules (H20) from a region in which they are highly concentrated to a region in which they are less concentrated. This movement must take place across a partially permeable membrane such as a cell wall‚ which lets smaller molecules‚ such as water‚ through but does not allow bigger molecules‚ such as glucose
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CELL TRANSPORT MECHANISMS AND PERMEABILITY Zack Johnson Human Anatomy & Physiology Lab 2101 Instructor: Alan Byboth‚ M.S. 10/4/12 Abstract- The cell is invaluable building block of all biological life on this planet‚ and one of its most important and unique characteristics is its ability to be selectively permeable with its plasma membrane. This outer membrane’s sophisticated mechanisms of transport through its bilayer are vital in maintaining homeostasis in the cell and the entire
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century‚ little was known about cell membranes. Until the early 1950s‚ the biological cell membrane was rarely mentioned in scientific literature. It was recognised that something was probably there‚ but hardly anything about it was known. Considering the lack of technical equipment available a century ago‚ scientists such as Charles Overton and Edwin Gorter were not only exploring new territory in looking at the properties of cell membranes‚ but laying the way for future cell biologists. Scientists had
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