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The Chemical Basis of Life
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Organic Compounds Compounds containing carbon
(Actually contain carbon, hydrogen, and oxygen) Compounds that come from living things
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Q1)Give two examples of organic compounds?
Sugar, Starch
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Inorganic compounds Don’t contain carbon Don’t come from living things
Exceptions: Carbon dioxide, Carbon monoxide
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Q2) Give 2 examples of inorganic molecules
Water, Salt
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Unique bonding properties of carbon
Carbon has four electrons in its outer shell Carbon can form 4 covalent bonds Carbon can form complex molecules because of its ability to form 4 bonds at the same time
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Chemistry of carbon Carbon can form Single covalent bonds
Shares 1 electron with one other atom. Double covalent bonds Shares 2 electrons with one other atom Triple covalent bonds (rare) Shares 3 electrons with one other atom (See examples of these bonds on the bottom of page 49)
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Functional groups Common parts used molecule building Hydroxyl
-OH Carboxyl -COOH Amino -NH2
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Monomers Simple building block molecules
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Polymers Two or more monomers covalently bonded together.
Can be two or two thousand… Allow very large molecules to built with only a few basic parts.
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Two chemical reactions used
Dehydration Synthesis Covalent bond is formed by the removal of water. Two monomers become joined together.
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Dehydration Synthesis Reaction
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Two Chemical Reactions Used
Hydrolysis Separation of two monomers by adding water and breaking the covalent bond
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Hydrolysis Reaction
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Carbohydrates Made from glucose molecules (sugars)
Carbohydrates are used by living things as a source of energy.
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Monosaccharides Simple sugars Have the formula C6H12O6
Mono = one Saccharide = sugar Have the formula C6H12O6 Form rings when in water
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Some Sample Monosaccharides
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Q2) Where do people get glucose molecules?
Plants produce glucose during photosynthesis and animals get glucose by eating plants.
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Disaccharides Di = Two Saccharide = sugar
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Polysaccharides Two or more monosaccharides joined together by a covalent bond. The bond forms by a Dehydration Synthesis Reaction.
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Four types of polysaccharides Made of Glucose
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Starch Energy storage in plants
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Glycogen Energy storage in plant seeds and short term energy storage in animals (1 day)
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Cellulose Structural support in plants
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Starch Vs. Cellulose STARCH CELLULOSE
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Chitin Used in insect exoskeletons for structural support
Harvested and used as surgical stitches
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Lipids Fats Oils Waxes Do not dissolve in water!!!
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Molecules made from lipids
Fats Energy storage in animals and plant seeds A gram of fat stores more than twice as much energy as a gram of a polysaccharide.
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Phospholipids Used in cell membranes
Separations between inside and outside of cell
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Waxes Water proof molecules, many uses
Example: Waxy coating on leaves prevents water loss
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Chemistry of Fats Glycerol 3 fatty acids
Chains of carbons with a carboxyl (acid) group at one end of each fatty acid
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Two major types of fats Saturated fats – single bonds between carbon atoms Unsaturated fats – double bonds between carbon atoms
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Q3) Which type of fat is unhealthy?
Saturated fats
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What is the difference between fats and oils?
Fats are solid at room temperature and oils are liquids at room temperature.
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Proteins The molecules that do the work inside of the cell.
Proteins are responsible for most of what happens inside of the cell.
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Functions of a protein Movement Structural support Storage Defense
Regulation of chemical processes
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What are two examples of things made of protein?
Enzymes (thousands of different types) Speed up chemical reactions Hemoglobin Used in red blood cells to transport oxygen
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Structure of protein Amino acid The monomer of proteins
There are 20 different amino acids They can make billions of different proteins
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Peptide Bond Holds these monomers together.
Formed by a dehydration synthesis reaction
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Polypeptides Many amino acids bonded together making a long chain
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How proteins are formed
Proteins are complexly folded polypeptide chains There are four levels of protein structure Each level of folding makes the protein more complex.
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One change can be devastating
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Stop for today.
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The function of enzymes
Enzymes are Protein Catalysts Increase the speed of chemical reactions without being used up themselves. NOT CHANGED BY REACTION
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Substrates The molecule that binds to the enzyme
These are the ones changed in the reaction
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Enzyme-substrate complex
Active site The space where the substrate fits Lock and key Each enzyme is specific for one substrate!!
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Activation Energy Energy needed to get a reaction started.
Bonds are weakened by activation energy New bonds form to make products
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Activation Energy Enzymes lower a reaction’s activation energy
A lower activation energy makes a reaction happen faster
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Enzymes Catalysts in the body are enzymes
Enzymes work best at a certain temperature and pH
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If the temperature or pH changes, the enzyme may not function.
If the bonds that hold the enzyme’s shape are changed, the enzyme will come apart. If this happens, the enzyme will denature.
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Nucleic Acids Polymers which are used to store genetic information
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Nucleotide Monomer of nucleic acids Made from 1 sugar 1 base
1 phosphate
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Two types of nucleic acids and their uses:
Deoxyribonucleic Acid DNA Stores genetic information and passes it on to the next generation Ribonucleic Acid RNA Takes information and uses it to make proteins
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The information is stored in bases
The differences in the nucleotides is in the bases. The order of these bases makes up the genetic CODE.
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DNA Bases There are four bases used in DNA Cytosine (C), Thymine (T) Adenine (A), Guanine (G)
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RNA Bases There are four bases used in RNA Cytosine (C), Uracil (U)
Adenine (A), Guanine (G) Thymine is replaced by Uracil in RNA
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