The Chemical Basis of Life

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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

• Dont contain carbon
• Dont 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
• 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 reactions 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 enzymes 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 DNACytosine (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