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The Chemical Building Blocks of Life
Biological Chemistry
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Questions to ponder…..
1) What elements do all organisms include?
2) What are organic compounds?
3) Next to water, what is the most common substance in living things?
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CARBON
• Carbon is unique because:
1. It has the ability to form stable & strong covalent bonds because of its structure
2. It can form chains of almost unlimited length bonding to other C atoms
3. It can form single, double & triple bonds….no other atom can do all this
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Outline
• Biological or Organic Compounds • The Macromolecules (in a
nutshell) Proteins
Hormones, transport, structure & enzymes Nucleic Acids
Pass genetic info Lipids
E storage & barriers Carbohydrates
E source & structural support
Carbon atom
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Biological Molecules
• The framework of biological molecules consists of carbon bonded to other carbon molecules, or other types of atoms.
– Hydrocarbons consist of carbon and hydrogen.
Covalent bonds store considerable energy.
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Building Biological Molecules
• Functional groups– specific groups of atoms attached to
carbon backbones retain definite chemical properties Ex:??
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The Macromolecules
• Include:– proteins– nucleic acids– lipids– carbohydrates
PLUS:Macromolecules are often polymers.
long molecule built by linking together small, similar subunits
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Macromolecules
Dehydration synthesis removes OH and H during synthesis of a new molecule.
Hydrolysis breaks a covalent bond by adding OH and H.
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Chemical reactions review…..
• Chemical reactions involve the making and breaking of chemical bonds.
• Chemical bonds “store” energy.
• When a bond is broken, energy is released (heat, light, sound)
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Exergonic Reaction
• Exergonic Reaction is one in which more energy is released than used.
• Ex. Fireworks, cellular respiration, digestion
• These reactions involve the breaking of polymers into monomers
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• Endergonic Reaction is one in which more energy
is absorbed (stored in bonds) than is released. • These reactions involve joining monomers into
polymers.• Ex. Photosynthesis, making proteins, etc.
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Proteins
• Protein functions:– structure– movement– storage– defense– transport– regulation– enzymes
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Structure is related to function!
• Structurally sophisticated.
• Shape determines function and is crucial to the job of a protein.
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Monomer: Amino Acids (AA)
• twenty common AA (grouped into • 5 groups) compose all the proteins
AA are made in the ribosomes of
the cell & joined by peptide bonds
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Amino Acids• Peptide bond links two amino acids.
– A protein is composed of one or more long chains of amino acids linked by peptide bonds (These are called polypeptides).
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Protein Structure• Protein function is
determined by its shape.– Protein structure
primary - specific amino acid sequence
secondary - folding of amino acid chains
motifs - folds or creases
supersecondary structure
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Protein Structure
tertiary - final folded shape of globular protein
domains - functional units
quaternary - forms when two or more polypeptide chains associate to form a functional protein
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Enzymes
• Enzymes are proteins that function as a catalyst - they control the rate of a reaction without being consumed by the reaction.
• They usually speed up the rate of a reaction by lowering the amount of activation energy needed to start the reaction.
• End with -ase.• Ex. lactase•
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Reaction with enzyme
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How enzymes work…Induced Fit Model• The substrate (what the enzyme is going to work
upon) comes into contact with the active site of the enzyme.
• The enzyme “wraps” around the substrate breaking or forming bonds.
• The product is released.
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Enzyme at work
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Unfolding Proteins
• Denaturation refers to the process of changing a protein’s shape.
– usually rendered
biologically inactive salt-curing and pickling used to preserve
food temperature - high temperatures break
bonds pH- designed to work at a specific pH
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Nucleic Acids: Main Functions
• Deoxyribonucleic Acid (DNA)– Encodes information used to assemble
proteins.• Ribonucleic Acid (RNA)
– Reads DNA-encoded information to direct protein synthesis.
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Nucleic Acid Structure• Nucleic acids are composed of long
polymers of repeating subunits nucleotides - the monomer.
– five-carbon sugar– phosphate– nitrogenous base
adenine, cytosine,
guanine & either
thymine or uracil
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Nucleic Acid Structure
• DNA :1. Sugar=deoxyribose2. Bases=ATCG3. Phosphate
RNA :• Sugar=ribose• Bases=AUCG• Phosphate
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Structure of DNA
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Lipids• Lipids made up of C & H with nonpolar bonds.
Lipids are not attracted to water-hydrophobic.
Ex: Fats, oils, waxes, and
steroids.• Phospholipids form the core of
all cell membranes.
Ex of a monomer of lipid like in
fats & phospholipids:
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Lipids
• Steroids – include cholesterol (common in animal cell membranes) & hormones
• Anabolic steroids - synthetic variants of testosterone
• Testosterone causes buildup of bone and muscle mass in puberty.
• Too much testosterone can cause serious physical and mental problems: mood swings, depression, liver damage, increased blood cholesterol, infertility, testicular atrophy, breasts development
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Fats:
• SATURATED FATS:
1. animal fats
2. commonly found in meats & dairy products
3. tend to be solid at room temperature
• POLYUNSATURATED FATS:
1. plant fats
2. cooking oils like sesame, peanut & corn oil
3. tend to be liquid at room temperature
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Saturated vs. unsaturated fatty acids
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Fats as Energy Storage Molecules• Fats, on average, yield about 9 kcal per
gram versus 4 kcal per gram for carbohydrates
• Animal fats are saturated while most plant fats are unsaturated
• Consumption of excess carbohydrates leads to conversion into starch, glycogen, or fats for future use.
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Isomers isomers - alternative forms of the same
substance ex. 8 isomers of “glucose”
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Carbohydrates• Carbohydrates :molecules that contain
carbon, hydrogen, and oxygen in a 1:2:1 ratio or sugars
– monosaccharides - simple sugars (the mononomers)
– disaccharides - two monosaccharides joined by a covalent
– bond– polysaccharides -
made of many monosaccharide subunits
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Carbohydrate Transport
a) Humans transport glucose as a simple monosaccharide
b) plants transform glucose into a dissaccharide transport form
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Storage polysaccharides….• Starch - plant storage
from glucose• Glycogen - animal
storage-stored in liver & muscle
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Structural Carbohydrates• Cellulose - plants
– Building material of cell walls-
provides protection/support – animals can not digest cellulose - “fiber”– chitin - exoskeleton of
arthropods and in fungi cell walls
– modified form of cellulose
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Summary
• The Biological Molecules.
Why are each important? Proteins
Nucleic Acid
Lipids
Carbohydrates
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Summary
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