The Four Major Groups of Organic Compounds: Carbohydrates, Lipids, Proteins, and Nucleic Acids; and Their Functions in Living Systems

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The Four Major Groups of Organic Compounds
Carbohydrates, Lipids, Proteins, and Nucleic
Acids and Their Functions in Living Systems
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Carbon a Most Versatile Atom

• -The Carbon atom has
• 6 protons
• 6 neutrons
• 6 electrons
• -Carbon has 4 electrons in its outermost energy
  level, therefore it needs four electrons to
  complete its octet.
• -Carbon covalently shares
• electrons with up to four other atoms. This
  characteristic makes Carbon very versatile when
  it comes to chemical structures.

C
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Carbons Chemical Properties and Molecular
Diversity

• Carbon Skeletons Vary
• Carbon chains
• Vary in length
• May be linear or branched
• May contain only c-c single bonds or may contain
  double and/or triple bonds at various locations
• Carbon rings
• May contain only single c-c bonds, or may contain
  double bonds

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Functional Groups Confer Specific Properties to
Carbon Compounds

• Carbon skeletons come in may shapes and forms.
  These are basically Hydrocarbons (molecules
  composed of only Carbon and Hydrogen atoms).
• Functional groups, have specific properties
  characteristic to their chemical structure and
  further add variety to the Hydrocarbon skeleton
  molecular structures.

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Functional Groups and Their Functions
Hydroxyl Group OH Alcohols
Carbonyl Group C O Aldehydes Ketones
Carboxyl Group COOH Organic Acids Carboxylic Acid
Amino Group NH2 Organic Bases Amines
Phosphate Group OPO32- Organic Phosphates
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Monomers ? PolymersDehydration ? Hydrolysis

• Monomers are molecules that are chemically bonded
  through dehydration synthesis to make polymers,
  which are the functional macromolecules.
• Polymers can be broken down into their monomer
  components through hydrolysis.

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Carbohydrates aka Saccharides Are Aldoses and
Ketoses

• Carbohydrates have the atomic ratio CH2O.
• They are composed of many monosaccharide
  (monomers) chemically combined through
  dehydration synthesis into polysaccharides
  (polymers).
• Glucose C6H12O6 is made by plants and is the most
  common monosaccharide.
• Serve as energy sources for plants, animals and
  other organisms. Converted into ATP energy.
• Serve as structural molecules in plants and other
  organisms.
• Dietary source plant products.
• Cellulose is bulk or fiber.

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Polysaccharides
Cellulose Most abundant glucose polymer, component of plant cell walls
Starch Plants store glucose in starch polymers (grains, tubers). Serve as glucose source for animals.
Glycogen Very branched glucose polymer. Animals store glucose as glycogen. AKA animal starch.
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Lipids Are Hydrophobic

• Lipids include
• fatty acids, steroids,
• phospholipids, and waxes.
• Because they are not soluble in water, they are
  good structural, insulation, transport, and
  storage macromolecules,
• such as
• Adipose tissue
• cell membranes components
• hormones
• triglycerides
• oils and waxes

Saturated Fats from animal sources

Unsaturated Fats from plant sources
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Fatty Acids Are Long Hydrocarbons with a
Carboxylic Acid Functional Group

• Saturated fatty acids usually come from animal
  sources and are solid at room temperature, these
  are high in caloric value.
• Unsaturated fatty acids usually come from plant
  sources and are liquid at room temperature, these
  are lower in caloric value.

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Triglycerides Three Fatty Acids Dehydrated to
One Glycerol
-The diagram to the left, depicts a glycerol being dehydrated with a fatty acid. -This reaction occurs a total of three times to form a triglyceride, as seen on the diagram to the right -Triglyceride molecules transport fats in the bloodstream and serve as building blocks for other lipids, such as phospholipids.
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Steroids

• . A steroids structure is composed of carbon
  rings.
• . Steroids serve as the structural components of
  many hormones, such as
• estrogen and testosterone.
• . Steroids are essential for maintaining the
  fluidity of cell membranes.
• . Diets rich in saturated fats promote
  accumulation of LDL bad cholesterol in the wall
  of arteries, reducing blood flow and promoting
  hypertension and the incidence of strokes.

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Proteins

• Proteins are the structural components of living
  tissue. They also serve as enzymes, hormones,
  and immunoglobulins, among many other roles.
• Proteins are composed of amino acids (a.a.). We
  acquire a.a. by consuming meat, fowl, fish,
  dairy, eggs, legumes, and nuts

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Proteins Composed of Amino Acids

• Amino acids are the monomers that are dehydrated
  to form polypeptides or proteins.
• Humans have about 20 different amino acids from
  which proteins are synthesized. The difference
  between one protein and another has to do with
  the number of amino acids that a protein
  contains and the unique sequences in which the
  amino acids are arranged.
• Protein synthesis occurs in the ribosomes of
  cells and is controlled by genetic information.

Amino Acids (a.a.) Have both amino and carboxyl functional groups. The R group varies for each of the 20 a.a.

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Protein Synthesis

• Amino acids are chemically combined through
  dehydration synthesis by peptide bonds to form
  polypeptides (protein)
• The sequence of amino acids in a polypeptide is
  determined by genetic information

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A Protein Structure Determines Its Function
Primary structure determined by a.a. sequence
Secondary structure determined by Hydrogen bonding a helix or ß sheet
Tertiary structure polypeptide folding due to covalent and ionic bonds
Quaternary structure Two or more polypeptides chemically combined
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Nucleic Acids Have Sugars, Nitrogenous Basesand
Organic Phosphate Components

• Nucleic Acids serve as information
  macromolecules, such as DNA and RNA. (We will
  study these further in the future.)
• Another type of Nucleic Acid, ATP, serves as the
  energy currency of cells. (We will study ATP
  further in the future.)
• Nucleotides (picture at left) are the molecular
  components of Nucleic Acids.

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DNA for Hereditary Information
Nucleotides are chemically joined to form DNA, a double stranded helix. The bases, of each strand, hydrogen bond to each other. The phosphates and sugars form the backbone of the double helix. The sequence of bases on the DNA determines the amino acid sequence of proteins. Four types of bases Adenine (A), Guanine (G), Thymine (T), and Cytosine (C). These bases bind to each other. A always binds with T, G always binds with C.

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Structure Is Always Related to Function

• Living organisms require thousands of different
  types of molecules to maintain their structure
  and sustain their bodys functions.
• The ability of Carbon to bond with four other
  atoms is the basis for the vast variety of
  chemical structures found in organisms.