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BIOL 1500

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Biology Chapter 2 Notes : Chemistry • All matter is made up of atoms; an element cannot be broken down any simpler (chemically) • Each atom has a Nucleus (Protons + Neutrons) and Electrons (Negatively charged particles) • Body Composed of primarily: Oxygen (65%), Carbon (18.5%), Hydrogen (9.5%), Nitrogen (3%) • An atom's electrons determine how and whether it will bond with other atoms: 2, 8, 8... • An atom with a charge is called an ion Bonds: • A group of atoms held together by bonds are called molecules (requires energy); releases energy when bonds are broken • Polar: magnet-like molecules with distinctive positive and negative regions Covalent Bonds: Strong bonds formed when two atoms share electrons (H and O )2 achiev2s stability by from sharing; sharing of two atoms are called double bonds Ionic Bonds: one atom transfers one or more of its electrons completely to another; creates an unequal amount of protons/electrons; ionic bonds form compounds as the two oppositely charged ions attract each other; ions of equal charges attract together and form a neutral charge Hydrogen Bonds: important in bonding multi-atom molecules together; hydrogen bonds are already covalently bonded with another molecule but the electrons in the covalent bonds are not equally shared; weaker than covalent & ionic Water Molecules: • V-shaped through the bond structure makes bonds just strong enough to give water a surface tension with net-like properties • Cohesion: hydrogen bonds allow water molecules to pull up adjacent water molecules ; chain of linked molecules extends • Large heat capacity: as more heat is set towards the water molecules, hydrogen bonds get disrupted but are formed else-where again very quickly; water molecules itself don't increase their movie • Low density as a solid: V-shaped molecules spreads as a net due to low movement and the substance decreases the density • Good Solvent: water molecules are able to pry other molecules apart because they are polar; other polar substances thus, dissolves in water; non-polar molecules like oil has a hard time Acids & Bases: • In water, there are H and OH ions; however, other fluids can have either more of H or + - OH • the amount of H in a solution measures the acidity; the measure of this is the pH scale • pH below 7.0 are acidic while pH above 7.0 are basic; each number on the pH scale is a 10-fold • Acids can donate protons to other chemicals; bases bind with free protons • In blood, there are things chemicals called buffers: they absorb excess H ions if it is too + acidic and release H ions if it because basic; buffers act to resist changes in pH Molecules • a molecule's shape gives it unique characteristics (taste, smell); the shape of the molecules matches the shapes of its taste receptors • Macromolecules: large molecules made from smaller building blocks/subunits Carbohydrates • contains mostly carbon, hydrogen and oxygen in the format of (CH O) 2 n • primary fuel for cellular respiration; the carbon-hydrogen bonds store a great deal of energy; the C-H bonds are also easily broken • classified into several categories based on size and composition; simple carbs are monosaccharides/simple sugars • most important carb: glucose (found naturally in most fruits, table sugar, potatoes, are also converted) • Glucose: fuel for cellular activity (once it arrives, it is ready to use through a series of reactions); stored temporarily as glycogen (released during times of exertion); converted to fat for long-term storage if the "blood sugars" are in excess • Carbo-loading: depletion phase& loading phase • a large amount of water bound to glycogen: 4 ounces of water for every 1 ounce of glycogen • Complex carbohydrates: polysaccharides (can be in the form of starch) • Digestion breaks bonds between
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