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Doncouse_Jeremy_Week3

Doncouse_Jeremy_Week3 - Running head Chapter 3 1 Week 3...

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Running head: Chapter 3 1 Week 3 Written Assignment: Chapter 3 Jeremy Doncouse Mountain State University
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Running head: Chapter 3 2 Chapter 3: Cells: The Living Units Overview of the cellular basis of life 1. List the three major regions of a generalized cell and indicate the general function of each region. The three main regions of a generalized cell are the plasma membrane, the cytoplasm, and the nucleus. The plasma membrane is the outer boundary of the cell. The cytoplasm is inside the plasma membrane and is made of intracellular fluid that is full of organelles, small structures which perform specific functions. The nucleus is located near the cell’s center and controls cellular activity. The plasma membrane: Structure 1. Describe the chemical composition of the plasma membrane and relate it to membrane functions. The plasma membrane is composed of a lipid bi-layer with protein molecules dispersed in it. The membrane lipids are mostly made of phospholipids, but also contain cholesterol and glycolipids. The phospholipids have a polar head and a nonpolar tail—the heads being hydrophilic and the tails being hydrophobic. The plasma membrane is in constant flux. Glycolipids, which contain sugar, account for 5% of the structure. Another 20% of the structure is made of cholesterol, which stabilize the membrane. Another 20%
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Running head: Chapter 3 3 contains lipid rafts made of saturated phospholipids and include or exclude specific proteins. There are also membrane proteins which account for specialized membrane functions. Integral proteins are those that mostly protrude from both sides of the plasma membrane and are involved in transport, are channels/pores, carriers, or receptors. Peripheral proteins are only attached to the integral proteins. These proteins are enzymes, motor proteins, and can link cells together. The plasma membrane: membrane transport 1. Relate the plasma membrane structure to active and passive transport mechanisms. The two main types of passive transport are diffusion and filtration. Diffusion is the tendency of molecules or ions to move from an area of higher concentration to an area of lower concentration and is influenced by molecular size and temperature. A molecule will diffuse through the membrane if it is lipid soluble, small enough, or assisted by a carrier molecule. In Simple diffusion nonpolar and lipid-soluble substances diffuse directly through the lipid bilayer. In facilitated diffusion glucose, other sugars, amino acids, and ions are transported either by binding to protein carriers in the membrane or by moving through water-filled protein channels. Carriers are proteins in the membrane that have a tendency
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Running head: Chapter 3 4 to bind to certain molecules and allow them to pass through the membrane. Channels are selective proteins which allow certain molecules to pass through the membrane.
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