BIOLOGICALLY IMPORTANT MOLECULES

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BIOLOGICALLY IMPORTANT MOLECULES

• CARBOHYDRATES
• FATS
• PROTEINS
• NUCLEIC ACIDS

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BIOLOGICALLY IMPORTANT MOLECULES

• The following four types of molecules are
  biologically important enough for us to consider
  in this class
• CARBOHYDRATES
• FATS
• PROTEINS
• NUCLEIC ACIDS

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Organic Molecules

• Carbon SKELETON
• H and O bonded to Cs
• Specific FUNCTIONAL groups

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Functional GroupsHydroxyl group

• Alcohols
• Chemical formula -OH

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Functional GroupsCarboxyl group

• Organic acids
• Chemical Formula -COOH

CARBON
OXYGEN
HYDROGEN
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Functional GroupsAmino group

• Ammonia, amino acids
• Chemical Formula -NH2

CARBON
OXYGEN
HYDROGEN
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Functional GroupsSulfhydryl group

• Rubber, proteins
• Chemical Formula -SH

CARBON
OXYGEN
HYDROGEN
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Functional GroupsPhosphate group

• ATP, Nucleic acids
• Chemical Formula -PO4

CARBON
OXYGEN
HYDROGEN
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Building Macromolecules

• Anabolic reactions
• Require cellular energy
• Dehydration Synthesis
• Most built using same kind of reaction

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Dehydration Synthesis
H2O
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Digestion of macromolecules

• Catabolic reactions
• Breaks down into building block units
• Releases energy in the bonds that holds units
  together
• Hydrolysis reaction
• Most macromolecules digested by this reaction type

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Hydrolysis Reaction
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CARBOHYDRATES

• Sugars and starches
• They usually have a 121 ratio of CHO in their
  empirical formulas
• Glucose C6H12O6

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Carbohydrates Use

• Main energy source molecules
• Short term storage and transport of energy
• Structural Molecules in many forms of life

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3 TYPES OF CARBOHYDRATES

• MONOSACCHARIDES - SIMPLE SUGARS
• DISACCHARIDES - DOUBLE SUGARS
• POLYSACCHARIDES - STARCHES -MANY SUGAR

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Carbohydrates

• Monosaccharides are energy sources
• Disaccharides are often transport forms
• Polysaccharides are often structural, also used
  for storage

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A MONOSACCHARIDE GLUCOSE

• The empirical formula for glucose is
• C6H12O6
• The structural formula may vary somewhat
  depending on several factors

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DRY GLUCOSE
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GALACTOSE (stereoisomer of glucose)
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DISSOLVED GLUCOSE
ALPHA GLUCOSE
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MOLECULAR TRIVIA

• Notice that molecules can be expressed in a
  variety of ways

C6H12O6
STRUCTURAL FORMULA
EMPIRICAL FORMULA

• ISOMERS are molecules which have the same
• empirical formulas but different structural ones

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MAKE A DISACCHARIDE
GLYCOSIDIC BOND - AN OXYGEN BRIDGE BETWEEN
MONOSACCHARIDES
WATER MOLECULE
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DEHYDRATION SYNTHESIS

• Dehydration synthesis or Condensation reactions
  remove water from between molecules to form bonds
• This is the principal way in which ANABOLISM
  occurs
• How would you digest a glycosidic bond to break
  it down or do CATABOLISM ?

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DIGEST DISACCHARIDES
Water may be inserted to digest this bond and
break it down !
WATER MOLECULE
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DIGEST DISACCHARIDES
HYDROLYSIS - water splitting is how
digestion occurs
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LIPIDS

• Lipids include the fats, oils , waxes and
  steroids
• Basically insoluble in water

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Lipid Functions

• LONG TERM ENERGY STORAGE
• INSULATION
• PADDING
• CELL MEMBRANES
• HORMONES

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TYPES OF LIPIDS

• Lipids occur in three basic types
• TRIGLYCERIDES - used for storage, insulation and
  padding
• PHOSPHOLIPIDS - cell membranes
• STEROIDS - hormones (chemical messengers)

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TRIGLYCERIDES
Triglycerides consist of GLYCEROL with
three attached FATTY ACIDS
H
FATTY ACIDS
GLYCEROL
Dehydration Synthesis Reactions attach fatty
acids to glycerol
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FATTY ACIDS
Fatty acids have an even number of carbons
between 12 20
Hydrocarbon chain with many carbon and hydrogen
atoms
Carboxyl group makes this an ACID molecule
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SATURATED OR UNSATURATED
SATURATED
Animal fat, solid at room temp, bad fat
UNSATURATED
Plant fat, liquid at room temp, good fat
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TRIGLYCERIDES
Three dehydration reactions to form three ester
bonds makes a triglyceride
3 water molecules
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PHOSPHOLIPIDS

• Are similar to the triglycerides in structure...
• Glycerol and fatty acids are present
• But so is a PHOSPHATE GROUP

FATTY ACID
FATTY ACID
PHOSPHATE GROUP
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PHOSPHOLIPIDS
Let this represent a phospholipid
HYDROPHOBIC
FATTY ACIDS
PHOSPHATE GROUP
HYDROPHILIC - WATER-LOVING
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PHOSPHOLIPIDS

• Because of their hydrophobic and hydrophilic
  ends, they make great cell membrane molecules if
  arranged like this

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STEROIDS

• Steroids are not true lipid molecules
• The only lipid-like feature of steroids is their
  insolubility in water

Steroids look something like this
Four or Five carbon rings bonded together
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STEROIDS
TESTOSTERONE AND ESTROGEN ARE ALSO STEROIDS
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PROTEINS

• Proteins are very large, nitrogen-containing
  compounds that are very important to living
  things
• They are the largest and most complex molecules
  found in cells

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Protein Functions

• Major structural molecules
• Enzyme functions - help along our chemical
  reactions as catalysts

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PROTEINS

• Some examples of structural proteins would be
• keratin - as in our hair, skin and fingernails
• actin and myosin in our muscles
• An example of an enzyme would be
• Amylase which breaks starch down into simple
  sugar units in digestive tract

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AMINO ACIDS
This is
GLYCINE
One of twenty common amino acids
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PEPTIDE BONDS
Amino acids bond together to form large protein
molecules. The covalent bonds in a protein are
called peptide bonds
DEHYDRATION SYNTHESIS
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PROTEIN STRUCTURE

• There are four levels of protein structure that
  we will consider
• PRIMARY
• SECONDARY
• TERTIARY
• QUATERNARY

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PRIMARY STRUCTURE
The primary structure of a protein is simply
the sequence of the amino acids. IT IS THE MOST
IMPORTANT!!!
any of the 20 common amino acids
a peptide bond
1 7 3 5 19
TWO PROTEINS
1 3 5 7 19
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SECONDARY STRUCTURE

• The most common secondary structure is the helix
  or spiral
• Notice that some amino acids can form hydrogen
  bonds and others cannot
• The result is that the primary sequence chain is
  coiled or twisted to produce a helix like a
  telephone cord.

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Secondary Structure

• Protein secondary structures include
• Helix
• Pleated sheet

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TERTIARY STRUCTURE

• A folded structure is a common tertiary
  structure
• Hydrogen bonds , proline and disulfide bonds
  help form tertiary structure

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QUATERNARY STRUCTURE
Quaternary proteins consist of two or more
tertiary proteins bonded together by some
cofactor like the iron in hemoglobin.
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NUCLEIC ACIDS

• The nucleic acids include the following types of
  molecules
• DNA
• RNA
• ATP
• Each of these molecules has different functions
  within living organisms.

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Nucleic Acid Functions

• DNA is the molecule of heredity which stores
  the necessary information to build and operate a
  cell
• RNA is sometimes called the translator of
  heredity because it translates the DNA
  information into protein structure

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Nucleic Acid Molecule Functions

• ATP is called the fuel of life because it
  provides the energy required by living cells in
  their chemical reactions

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NUCLEOTIDE (building block of Nucleic Acids)
FIVE-CARBON SUGAR deoxyribose in DNA ribose
in RNA
Phosphate group
A Adenine (one of the bases) T
Thymine C Cytosine G Guanine
U Uracil (in RNA only)
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NUCLEOTIDES
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DNA molecule
Double Helix A pairs with T C pairs with G
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PROCESSES INVOLVING DNA

• DNA can automatically self-copy its molecules in
  a process called REPLICATION
• REMEMBER C to G and A to T

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PROCESSES INVOLVING DNA

• DNA can be copied into RNA molecules easily by a
  process called TRANSCRIPTION
• The RNA molecules can then be used to produce
  protein molecules in a process called TRANSLATION

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RNA

• RNA differs from DNA in several ways
• single strand of nucleotides
• ribose
• URACIL replaces thymine
• RNA is involved in transcription and translation
  but NOT replication

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ATP

• ADENOSINE TRIPHOSPHATE
• One adenine RNA nucleotide with THREE phosphate
  groups
• Third phosphate is attached by a high-energy bond
  which can be easily broken by hydrolysis to
  release tremendous amounts of energy
• Provides energy for cellular reactions

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ATP
A
ADP
H2O
ENERGY
P