Molecules of Life

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Molecules of Life
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Molecules of Life

• Carbohydrates
• monosaccharides
• energy supply
• Proteins
• amino acids
• structural components
• Lipids
• fatty acids
• structural components, energy, hormones
• Nucleic acids
• nucleotides
• DNA-genetic material

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Composition of Molecules of Life

• most are carbon based
• organic compounds
• unique to living systems
• with exception of CO2 carbides
• carbon is necessary for life
• electroneutral
• never loses or gains electrons
• always shares or forms covalent bonds

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Covalent Bonding
H H--C--H H

• carbon can form 4 covalent bonds with other
  elements or with itself
• has 4 electrons in outermost shell
• makes each carbon atom a connecting point from
  which another molecule can branch in four
  directions

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Covalent Bonding

• since carbon can bind to itself
• has capacity to construct endless numbers of
  carbon skeletons varying in size branching
  patterns

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Organic Compounds

• chain of carbons in organic molecule is-carbon
  skeleton
• branched or unbranched
• double or single bonds
• straight or arranged in ring form
• each has unique 3-D shape
• properties depend on carbon skeleton on atoms
  attached to skeleton
• groups of atoms participating in chemical
  reactions are functional groups

H C C H
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Functional Groups

• OH- (hydroxyl)
• CO (carbonyl)
• COOH (carboxyl)
• NH2 (amino)
• SH-sulfhydryl group
• PO3 (phosphate)

Phosphate group
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Classes of Molecules Functional Groups

• COOH NH2- amino acids
• hydroxyl groups-alcohols
• carboxyl groups-carboxylic acids-acetic acid
• sugars contain both-carbonyl group several
  hydroxyl groups
• phosphate groups-found on nucleic acids

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Macromolecules

• 4 main classes
• macromolecules or polymers
• consist of many identical or similar molecular
  units strung together
• monomers
• cells link monomers in anabolic reactions by
  dehydration synthesis
• chemical reaction which removes water
• broken down into constituent monomers by adding
  water
• catabolic reactions-hydrolysis

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Carbohydrates

• composed of C, H O
• 121 ratio
• Formula (CH2O)n should give formula for any
  carbohydrate
• may contain nitrogen, phosphate and/or sulfur
• Monomers-monosaccharides
• simple sugars
• building blocks for all other carbohydrates
• 2-10 monosaccharides form oligosaccharide
• hundreds- polysaccharide.
• hydrophilic
• water loving
• larger molecules are less soluble in water

Glucose
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Monosaccharides

• simple sugars
• single chain or ring of 3-7 carbons
• named for number of carbons they contain
• 5 carbons-pentoses
• 6 carbons-hexoses
• glucose contains 6 carbons-hexose
• formula-C6H1206
• most important metabolic fuel in body
• broken down?ATP CO2
• fructose-6 carbon monosaccharide
• same formula as glucose
• fructose glucose are isomers
• chemical compounds with same molecular formula
  but with elements arranged in different
  configurations
• Galactose-isomer of glucose fructose

Glucose
Galactose
Fructose
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Disaccharides

• double sugars
• covalent bond- between hydroxyl groups of two
  simple sugars
• physiologically important disaccharides Sucrose
• sugar cane sugar beets
• Glucose fructose?sucrose H2O
• Lactose-found in milk of mammals
• disaccharide of galactose glucose
• Maltose
• major degradation product of starch
• composed of 2 glucose monomers
• Disaccharides-too large to pass through cell
  membranes
• must be broken down into constituent parts by
  hydrolysis
• Sucrose H20? glucose fructose.

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Polysaccharides

• complex carbohydrates
• dehydration synthesis reactions add more
  monosaccharides? polysaccharides
• most carbohydrates in nature are in this form
• fairly insoluble
• make perfect storage molecules
• Glycogen
• major stored carbohydrate in animal liver
  muscle cells
• highly branched at about every 8-10 residues
• Starch
• major form of stored carbohydrate in plants
• Structure-identical to glycogen-less branching at
  every 20-30 residues
• Cellulose
• found in plants
• most abundant compound on earth
• cannot be digested by humans

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Lipids

• contain mostly C H
• 12 ratio
• also contain oxygen but less than carbohydrates
• often have N, S phosphorous
• hydrophobic
• do not dissolve in water
• include neutral fats, phospholipids steroids

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Lipid Functions

• physiologically important lipids have 4 major
  functions
• structural components of biological membranes
• cholesterol, phospholipids and glycolipids help
  form and maintain intracellular structures
• energy reserves
• provide 2X as much energy as carbohydrates
• hormones vitamins are a type of lipid-steroids
• lipophilic bile acids
• important for lipid solubilization

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Lipids

• composed of fatty acids glycerol (an alcohol)
• fatty acids-long-chain hydrocarbon molecules
• hydrocarbon chains make lipids nonpolar and
  therefore insoluble in water
• fat synthesis involves attaching 3 fatty acid
  chains to one glycerol by dehydration
  synthesis-producing triglycerides
• glycerol is always the same fatty acid
  composition varies
• length of neutral fats fatty acid chains
  degree of saturation determine how solid a fat is
  at room temperature
• saturated
• fatty acids with no carbon to carbon double bonds
• unsaturated
• have double bonds
• monounsaturated fats have one unsaturated bond
• polyunsaturated fats have multiple unsaturated
  bonds
• double bonds make for lower melting points
• presence of unsaturated fatty acids makes fat
  liquid at room temperature

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Hydrolysis of Triglycerides

• Hydrolysis breaks triglycerides?
• fatty acid glycerol

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Steroids

• large lipid molecules with carbon skeleton bent
  into 4 rings
• most important one-cholesterol
• obtained by absorption from animal products in
  diet
• meat, cream egg yolks
• can also be made by the body
• absolutely essential for life
• component of cell membranes
• raw material for Vitamin D, steroid hormones and
  bile salt synthesis
• without cholesterol there would be no steroid
  hormones such as estrogen and testosterone and
  therefore no reproduction
• without corticosteroids we would die

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Proteins

• C, H, O, N small amounts of S sometimes
  phosphorous
• monomer-amino acids
• 1-7 amino acids form peptide
• up to 100 form polypeptide
• more than 100 comprise a protein

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Proteins

• most abundant organic compounds in human body
• provide support for cells, tissues organs and
  create a 3-D framework for body
• contractile proteins allow for movement via
  muscle contractions
• transport proteins carry insoluble lipids,
  respiratory gases minerals in blood
• serve as buffers help to prevent dangerous pH
  changes
• enzymes are proteins important in metabolic
  regulation
• needed to speed rate of chemical reactions
• protein hormones coordinate, control influence
  metabolic activities of nearly every cell
• important for defense
• skin, hair, nails protect underlying tissues
  from environment
• antibodies protect us from disease
• clotting proteins protect from us from bleeding
  out

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Amino Acids

• 20 amino acids
• (excluding proline) contain carboxylic acid-COOH
  amino-NH2 or amine group
• functional groups are attached to same carbon
  atom
• R group attaches to same carbon
• amino acid is distinguished by its particular
  R-group
• 2 broad classes based upon whether R-group is
  hydrophobic or hydrophilic
• hydrophobic repel aqueous environments
• reside predominantly in interior of proteins
• hydrophilic amino acids interact with aqueous
  environments often form H-bonds
• found predominantly on exterior of proteins

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Protein Structure

• each protein contains unique sequence of amino
  acids
• four levels of protein structure
• Primary
• Secondary
• Tertiary
• Quaternary

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Structure Function

• structure determines function
• shape of protein allows it to carry out specific
  duties
• proteins whose job is to fill in a space (active
  site) on another molecule are globular in shape
• those that make up something like muscles or
  tendons are fibrous
• shapes depend on environmental characteristics
• ionic composition, pH temperature
• non homeostatic change in any of these will
  denature protein
• denaturation causes protein to lose shape
• loss of shape?cannot function properly

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Nucleic Acids

• largest, organic molecules in body
• C, H, O, N, phosphorous
• consists of long stretches of nucleotides
• monomer for nucleic acids
• provide directions for building proteins
• 2 main types
• RNA
• translates DNA code
• DNA
• contains genetic information that is inherited
  from our parents

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Nucleic Acids

• RNA
• single polynucleotide chain
• DNA
• double helix form
• two polynucleotide chains wrapped around one
  another

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Nucleic Acids

• exist in mono-, di-, tri-phosphorylated forms
• often abbreviated to AMP
• Mono, Di- tri-phosphorylated forms of adenosine
  are abbreviated AMP, ADP ATP
• phosphate bonds are high energy bonds
• meaning they contain energy
• When broken they yield 7kcals
• ATP ?ADP Pi energy
• ATP is energy currency of all cells