Unit 3: Macromolecules

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Unit 3Macromolecules
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What are Macromolecules?

Macromolecules are the very large molecules of
living organisms. Most macromolecules are built
from combining subunits with the removal of water.
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Types of Macromolecules

• There are 4 classes of macromolecules
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
• Lets look at each of these individually.

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The Carbohydrates
Carbohydrates or polysaccharides are made from
simple sugars or monosaccharides that are joined
in long chains. Carbohydrates may be used for
energy storage or for structure.
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Carbohydrates

• Made mostly of carbon, hydrogen and oxygen
• Subunits are called monosaccharides or simple
  sugars.
• Most common monosaccharide is glucose C6H12O6
• In cells, glucose looks like C6
• 
  C5
  
• 
  C4 C1
• 
  C3 C2
• 
  

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The Condensation or Dehydration Reaction

• The individual monosaccharides are assembled into
  polysaccharides by removing water from 2 sugars,
  forming a bond between them.
• 
  H2O
• This is a common link between C1 and C4.

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Storage Carbohydrates I

• Many glucose molecules connected C1 to C4 with
  the C6 always sticking up (a orientation) will
  make the plant starch, amylose.
• Sometimes there will be a branch point made by
  attaching glucoses C1 to C6. Amylopectin (plant
  starch)
• Plants use the carbohydrate starch for long-term
  energy storage, often in seeds such as wheat,
  corn or rice, or in tubers such as potatoes.

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Storage Polysaccharides II

• Animals will put together glucose as C1 to C4 in
  the a configuration with C1 to C6 branches like
  the plants, except with many more branching.
• The resulting polysaccharide of glycogen
  contains thousands of glucoses.
• Animals use the carbohydrate glycogen for
  short-term energy storage stockpiled in the liver
  and muscle fibers.

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Structural Carbohydrates I

• Plants will put together up to 1,000,000 glucose
  molecules as C1 to C4, but in the ß
  configuration
• so the
  glucoses alternate up
• down.
• This is cellulose.
• Plants use cellulose to make cell walls.
• Animals cannot break down cellulose (we call it
  fiber) depend on microbes to do this vital job.

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Structural Carbohydrates II

• Glucose may be modified by adding a
  Nitrogen-containing group to C2.
• Chitin is the polysaccharide made from these
  modified glucose molecules.
• Chitin is the exoskeleton of insects, spiders,
  crabs and other animals.
• Chitin is also found in fungi such as mushrooms.
• Surgical thread made of chitin dissolve over
  time, making them useful in surgery.

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Summary of Carbohydrates

• Made of monosaccharides, often glucose
• Polysaccharides are made by combining 2
  monosaccharides and removing water.
• Storage Polysaccharides
• starch in plants
• glycogen in animals.
• Structural Polysaccharides
• cellulose in plants
• chitin in animals fungi

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Lipids
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What are Lipids?
Lipids or fats are a diverse group of
macromolecules that are all hydrophobic or water
hating.
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Types of Lipids

• Many types of lipids.
• We will focus on 3 important lipids
• Fats or triglycerols
• Phospholipids
• Steroids

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Fats or Triglycerols

• Subunits are
• Glycerol, a 3-carbon molecule
• H
• H-C-OH
• C-OH
• H-C-OH
• H
• 3 Fatty acids, each 8 22 carbons long
• CH3CH2CH2CH2CH2CH2COO- A SATURATED FATTY
  ACID
• CH3CH2CHCHCH2CH2COO- AN UNSATURATED FATTY
  ACID

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Saturated Fatty Acids

• Saturated fatty acids
• Contain all single bonds between the carbons
• Often shown as
• Triglycerols made with saturated fats are solid
  at room temperature.
• Examples are butter, lard, margarine, animal fat.
• Saturated fats can collect in the blood vessels
  and cause heart disease.

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Unsaturated Fatty Acids

• Have at least 1 double bond
• Cis unsaturated fatty acids
• Double bond makes kink in fatty acid
• Liquid at room temperature as oils
• Cause much less heart problems.
• Trans unsaturated fatty acids
• Double bond not kinked
• Looks and behaves like saturated fat
• Causes heart problems like saturated fats

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A Triglycerol

• The 3 fatty acids are combined with the glycerol
  in a condensation reaction, removing water.
• An example
• -C-O-C-
• -C-O-C-
• -C-O-C-
• Used for long-term energy storage in plants
  animals.

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The Phospholipids

• Made of
• Glycerol
• A phosphate group
  water-loving head group
• A nitrogen-containing group
• 2 fatty acids water-hating tails

Hydrophobic or water-hating
Tails
Hydrophilic or water-loving Head
group
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Phospholipids Make Membranes

• Membranes of all cells are made of a double layer
  of phospholipids.
• Head groups face outward and inward towards
  water.
• Tails form hydrophobic core.
• Phospholipids make strong, flexible membranes
  like that around the yolk of an egg.

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The Steroids

• Steroids are part of the class of lipids that
  include
• Cholesterol
• Sex hormones, such as testosterone and estrogen
• They have a general shape of 4 interconnected
  rings.
• 
  
• 
  cholesterol

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Functions of Steroids

• Cholesterol gives strength to animal membranes
• We make cholesterol in our livers and eat it in
  our food.
• Steroid hormones direct our cells to do
  specialized tasks.
• Sex hormones affect the growth and function of
  reproductive organs
• Cortisone is active in carbohydrate metabolism
  and is used to treat allergic reactions.

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Summary of Lipids

• Triglycerides, made of 3 fatty acids, are used
  for long-term energy storage. Saturated and
  trans fats are unhealthy.
• Phospholipids, with its hydrophilic head group
  and 2 hydrophobic tails form a bilayer to make
  membranes.
• Steroids are made of 4 rings. Cholesterol and
  the sex hormones are examples of steroids.

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Proteins
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What are Proteins?
Proteins are macromolecules made from amino acid
subunits. They do a number of jobs in organisms,
including act as enzymes, hormones, contractile
proteins and receptors.
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Amino Acids

• 20 amino acids are the subunits of proteins
• Have amino (-NH2) and Carboxylic acid (-COOH)
  ends, connected by the a carbon.
• Different amino acids have different R groups
  attached to a carbon.
• R groups may be nonpolar, polar, acidic or basic.
• Amino
  Carboxyl
• Group
  Group
• 
  R group

H H O N C
C H OH R
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Making Polypeptides

• Amino acids undergo a condensation reaction
• between the amino group of 1 amino acid and
  carboxyl group of another
• Peptide bond is formed
• Water is removed
• 
  peptide
• 
  
  bond
• 
  

H H O N C
C H R
H H O N C C
OH R
H H O N C
C H OH R
H H O N C
C H OH R
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Levels of Protein Structure I

• Primary (1o) structure
• Sequence of amino acids
• Determined by gene DNA
• Held together with covalent peptide bonds
• Secondary (2o) structure
• Folding of regions of polypeptide
• May be a helix or ß pleated
  sheet
• Held together by weak hydrogen bonds.

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Levels of Protein Structure II

• Tertiary (3o) structure
• Folding of the entire protein into a
  characteristic shape
• May be globular (enzymes) or fibrous (hair)
• Locked into shape by covalent SS- sulfide
  bridges
• Quartenary (4o) structure
• Interaction of 2 or more polypeptides
• Hemoglobin, oxygen-carrying protein in blood, is
  made of 4 polypeptides together.

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Summary of Proteins

• Subunits are amino acids
• Amino acids undergo condensation reaction forming
  peptide bond and releasing water.
• Sequence of amino acids is the primary structure.
• Local folding of the polypeptides is the
  secondary structure.
• The tertiary structure is the folding of the
  entire polypeptide into its characteristic shape.
• The quartenary structure is the association of
  two or more polypeptides.

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Nucleic Acids
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Nucleic Acids

• Nucleic Acids are the macromolecules DNA and RNA
  that store and transmit inherited information.
  Nucleic Acids are the only macromolecules NOT
  made of subunits.

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DNA Structure I Backbone

• The backbone of DNA is made of alternating
  molecules of phosphate and deoxyribose
• 5 end
  3 end
• 3 end
  
  5 end

Note that the 2 halves of the double helix
backbone are in opposite directions or
anti-parallel.
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DNA Structure II Nucleotides

• Attached to the deoxyribose are the 4 nucleotides
• The pyrimidines are have only 1 ring
• Cytosine and Thymidine are pyrimidines
• The purines have 2 rings
• Adenine and Guanine are purines.
• A forms 2 hydrogen bonds with T A T
• G forms 3 hydrogen bonds with G G C

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The DNA Double Helix

• T
  A
• G
  C
• C
  G
  

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DNA Locations and Functions

• DNA is located
• In the cytosol of bacteria
• In the nucleus of the cells of eukaryotes, such
  as humans
• DNA functions
• Stores information to make proteins as genes
• Is passed from one generation to the next

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RNA Structure

• RNA has
• ribose instead of deoxyribose.
• Uracil instead of Thymidine
• Single stranded instead of double stranded
• Much smaller than DNA

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The Single Stranded RNA

• 5 end
• C or U
• A or G
• C or U
• 3 end

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Summary of Nucleic Acids

• Nucleic Acids are the macromolecules of
  information storage and transfer.
• DNA is a double stranded molecule used for
  information storage by all living organisms.
• RNA is a single stranded molecule used as a
  template to make proteins in all living organisms.

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End of Unit 3 Macromolecules