BIOLOGY 1 H FINAL EXAM Essay

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BIOLOGY 1 H FINAL EXAM

Chemical Bonding
Elements combine to form compounds
Compound – a substance containing 2 or more elements in a fixed ratio
-Most common elements: C, H, O, N
Bonding
Ionic bonding – attractions between ions of opposite charge; includes the transfer of electrons
Ion – an atom or molecule with an electrical charge resulting from a gain or loss of 1 or more electrons
-cation – (+) charged ion
-anion – (-) charged ion
Covalent bond – bond in which 2 atoms share 1 or more pairs of outershell electrons
Forms a molecule – 2 or more atoms held together
Single bond – 1 pair of electrons being shared
Double bond – 2 pairs of electrons being shared
Triple bond – 3 pairs of electrons being shared
Nonpolar covalent bonds – equal sharing of electrons
Polar covalent bonds – unequal sharing of electrons
Caused by levels of electronegativity – the tendency for an atom to pull shared electrons towards itself more than its own electrons
Results in 1 side of the molecule being (-), and one (+)
Hydrogen bond – a weak bond between the negative side of one atom contained in a polar covalent bond and the positive side of another atom contained in a polar covalent bond
Weak because the (+) and (-) charges of each atom within the bond are not strong
Readily broken and formed
Weak individually but strong in a group
Properties of Water
Cohesion – tendency of hydrogen bonds to hold water molecules together
Hydrogen bonds give water high cohesion
Adhesion – attraction between two different substances
Hydrogen bonds give water high adhesion
Surface tension – a measure of how difficult it is to stretch or break the surface of a liquid
Hydrogen bonds give water high surface tension
Thermal buffer – water reduces the heating and cooling load on another space
Hydrogen bonds give water the ability to resist temperature change
Important to e life (i.e. our body temp. regulations)
Water can absorb heat energy without a change in temperature
Universal solvent – water can dissolve all or most substances
Solution – a liquid consisting of a uniform mixture of 2 or more substances
Solvent – dissolving agent
Solute- substance being dissolved
Aqueous solution – solution in which water is the solvent
Water’s polar molecules surround other polar molecules in a solution
Water does not mix with nonpolar substances
Capillary action – water’s tendency to use cohesive and adhesive forces to rise or fall in tubes
Molecules of Life
All living things are made up of 4 classes of large biological molecules:
Carbohydrates
Lipids
Proteins
Nucleic acids
Polymer – long molecule consisting of many similar building blocks (monomers)
3 classes of life’s organic molecules are polymers (carbohydrates, proteins, & nucleic acids)
Biological reactions within polymers
Dehydration (condensation) reaction
2 monomers bond together through the loss of a water molecule
Forms a longer polymer chain
Enzymes aid this reaction
Requires enzymes and E
Hydrolysis reaction
Breaking a polymer chain by adding a water molecule
Enzymes aid this reaction
Requires enzymes and E
Reactant – the starting material in a chemical reaction
Product – the ending material in a chemical reaction
ATP Energy – the energy currency of life
E required for a reaction to take place
Carbohydrates
Contain C, H, & O
Main functions: E source & structural purposes
Glucose
Major E source for most cells
Exist in different structural isomers
Difference in the position of the –OH group
Broken into three groups: monosaccharides, disaccharides, & polysaccharides
Mono-
Simplest carbohydrate
Contain one monomer
Primary E source utilized by the cell to carry out cellular functions
Di-
Constructed from two monosaccharides through a dehydration reaction
Primary E source utilized by the cell to carry out cellular functions
Poly-
Long chains of monosaccharides linked together by dehydration reactions
Ex. cellulose, chitin, starches
Difficult to break down; extremely fibrous
Main function is for structural purposes…