Macromolecules


I. Macromolecule Basics.
macromolecules: are giant molecules of life.
they consist of carbon atoms and other elements.
carbon has 4 electrons in its outer shell
since atoms can hold 8 electrons in their outer shells and carbon is driven to fill its outer shell
it can share 4 electrons with 4 other atoms
this allows it to make possible covalent bonds
carbon is therefore well-suited to make stable large molecules called macromolecules
a hydrocarbon - exists when a carbon atom only covalently bonds with hydrogen atoms
e.g., methane, methyl and ethyl groups
organic macromolecules are said to have a carbon backbone
this means that although macromolecules can get complex their basic structure is carbon
 
functional groups are built onto the carbon backbones to increase the diversity of macromolecules.
e.g., hydroxyl, amino, carboxyl, aldehyde and ketone groups
 
monomers: are small molecules that form the building blocks of polymers.
 
polymers: are macromolecules that consist of many small molecules linked together
a protein is a polymer of amino acids linked together
a carbohydrate is a polymer of glucose molecules linked together
polymers are formed by dehydration synthesis
polymers are broken down by hydrolysis
 
dehydration synthesis (also called condensation):
    monomers are linked together through the removal of a water molecule so that
    the two monomers covalently bond to one another.
hydrolysis:
    the addition of water to break covalent bonds between two monomers.
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II. Carbohydrates.
    are the most abundant macromolecules of life
    are made up entirely of C, H, O
     
    The Functions of Carbohydrates are to:
     
     
      1. give structure to plants
        cellulose is an example of a carbohydrate that gives structure to many plant walls
       
      2. allow for the body's immediate energy needs
        carbohydrates are broken down to glucose which is used to make ATP (adenosine triphosphate)
        ATP is the body's energy currency
         
      3. allow for the body's long term energy storage
        the body stores excess glucose as glycogen in the liver and muscles
         
     
    Carbohydrate Classification (by size):
1. Monosaccharides
are simple sugars
they readily dissolve in water and form a ring-like structure
the rings are classified by the number of carbons they contain
pentoses contain 5 carbons – 5C
hexoses contain 6 carbons – 6C
Examples are:
    Glucose
glucose formed by plants following photosynthesis
is the main source of our fuel
it is found in fruit, honey and in our blood
C6H12O6
    Galactose
        used to produce lactose which is present in milk
    Fructose
        found in fruit and honey
    Ribose
        is the simple sugar found in RNA (ribonucleic acid)
    Deoxyribose
        is the simple sugar found in DNA (deoxyribonucleic acid)
 
2. Disaccharides
    are composed of two or more simple sugars (monosaccharides) covalently bound together
    Examples are:
        Sucrose
            a product of glucose and fructose
            found in table sugar, sugar cane, and maple syrup
            C12H22O11
        Maltose
            found in the starch found in many foods
 
        Lactose
            is a product of glucose and galactose
            found in milk
 
3. Polysaccharides
     are complex carbohydrates that store energy and are structural elements
        starch
            used for energy storage in plants
                the bulk of potatoes, rice, corn, and wheat
        glycogen
            used for energy storage in animals
        cellulose
            used for structure in plant walls
            important form of dietary fiber
            we lack the necessary enzyme to break it down
        chitin
            used for the structure of exoskeletons of insects and crustaceans
 
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III. Lipids.
are non-polar molecules and are therefore not soluble in water
 
The Functions of Lipids are to:
 
1. give structure to the body's cells
phospholipids and cholesterol make-up each cell's plasma membrane
 
2. allow for long term energy storage
triglycerides are stored in adipose or "fat" tissue
 
3. regulate bodily functions
steroid hormones like testosterone and estrogen are derived from cholesterol
 
4. protect the body's organs
          fat tissue surrounds many of our internal organs and offer protection from wear and tear
 
5. insulate the body
          fats fill the outer layers of the body to insulate us from cold temperatures
 
 
Classification of Lipids:
 
    1. Triglycerides (also referred to as "fats")
consists of 1 glycerol molecule and 3 fatty acid molecules
these molecules bind together via dehydration synthesis
they are used for long-term energy storage
they also supply energy, protection, and insulation
There are three main types:
 
    A. saturated fats
generally come from animal products
they are easily identified by their solid form
    examples are butter and lard
they contain no double covalent bonds in their fatty acid chains
    this means that they are saturated with H molecules
        this saturation allows the molecules to pack tightly together
this results in saturated fats being solid at room temperature
 
    B. unsaturated (monounsaturated) fats
generally come from plant products
    examples are corn oil and olive oil
they contain only one double covalent bond in their fatty acid chains
    this double bond puts a kink in the fatty acid tails
       this prevents the smooth molecular bonding needed for solids
therefore unsaturated fats are in liquid form
 
    C. polyunsaturated fats
they contain more than one double covalent bond in their fatty acid chains
and so for the same reason as above are in liquid form
 
2. Phospholipids
consist of 1 glycerol molecule, 2 fatty acid molecules, and 1 phosphate group
the fatty acid end is non-polar (hydrophobic- water dreading)
phosphate head is polar (hydrophilic - water loving)
this allow the formation of the bipolar molecule found in cell membranes
 
3. Sterols
consist of a firm carbon ringed backbone with no fatty acids
cholesterol is a sterol lipid
    cholesterol is essential to cellular structure
    too much cholesterol in circulation can cause:
atherosclerosis
    clogging of the arteries
heart disease
steroid hormones are derived from cholesterol
    hormones are chemical messengers in the body
    examples of steroid hormones are- testosterone, estrogen, and cortisol
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IV. Proteins.
    are composed of one or more chains of amino acids held together by peptide bonds
    all proteins are polymers made from a set of 20 monomers or amino acids
     
    The Function of Proteins are to:
     
     
      1. give support to body and cellular systems
        collagen in your skin, hair, bones, and arteries give them their strength
                CAM (cell adhesion molecule) proteins anchor cells together
       
      2. allow for organ and body movement
        actin and myosin filaments in muscle regulate muscle contraction of
            skeletal muscles involved in locomotion
            visceral muscles involved in peristalsis of food through the GI tract
            cardiac muscles involved in the heart beat
         
      3. allow for cellular communication
                glycoprotein receptors on the cell surface are used for communication
                protein hormones are used for communication
                MHC (major histocombatability proteins) allow the immune system to communicate
                      with individual cells
       
      4. allow for transportation of nutrients
        the protein hemoglobin carries oxygen via red blood cells throughout the body
         
      5. regulate physiological functions
        enzymes regulate chemical reactions
                hormones and neurotransmitters regulate many activities
Protein Structure:
 
    1. Amino Acids
        the building blocks of proteins are Amino Acids
        amino acids bind together forming peptides and polypeptides
        an amino acid consists of:
a single C atom
a single H atom
an amino group (NH2)
a carboxyl group (COOH),
and a side group (R)
    the 20 amino acids that we use are only different in the R groups
    2. Peptides, Polypeptides, and Proteins
an amino group of one amino acid is linked with carboxy group of another amino acid
    via dehydration synthesis
a peptide is chain of a few amino acids
a polypeptide is a chain of 10 or more amino acids
proteins consist of a chain of 50 or more amino acids (up to 27,000 to date)
    3. Enzymes
speed up chemical reactions without being consumed (10,000 to 1 million times faster)
a substrate binds to an enzyme at its active site and becomes an enzyme-substrate complex
the substrate is then converted to products that leave the active site
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V. Nucleic Acids and Nucleotides.
 
The Function of Nucleic Acids and Nucleotides are to:
 
    1. carry the genetic material
        DNA carries our genetic material
 
    2. make proteins
        RNA is used to synthesize proteins
 
    3. convert our nutrients into energy
        ADP converts glucose into energy
 
    4. regulate physiological activity
        coenzymes regulate many different types of physiological activity
 
Nucleic Acid Structure:
 
    Nucleotides
are the building blocks of nucleic acids
they consist of:
    a pentose (5C) sugar
    one phosphate group
    1 of 5 nitrogenous bases which can be either
pyrimidines
C - cytosine
T - thymine (only in DNA)
U - uracil (only in RNA)
or purines
A - adenine
G - guanine
 
    Other Nucleotides:
 
Adenosine Triphosphate (ATP)
contains energy for human use
is a nucleotide containing
1 adenine base
1 ribose sugar
3 phosphate groups
energy is release as ATP loses a phosphate group to become ADP
1 molecule of glucose is converted into 36 molecules of ATP
 
Coenzymes
assists enzymes in cellular regulation
 
cAMP
is involved in cellular regulation
Nucleic Acid Classification:
 
    are made up of nucleotides
 
DNA (deoxyribonucleic acid)
is a double stranded, double helix held together by H bonds at nitrogenous bases
forms genes and directs protein synthesis
is a nucleotide polymer
uses the nitrogen base pairs C-G and A-T
 
RNA (ribonucleic acid)
is single stranded
directs protein synthesis
is a nucleotide polymer
uses the nitrogen base pairs C-G and A-U

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