Macromolecules and Human Body Composition

Macromolecules and Organic Molecules

• Macromolecules are organic molecules.

Chemical Constituents of the Human Body

• Body weight consists of H2O, proteins, lipids, minerals, and nucleic acids.
• Water makes up 62% of body weight
• Proteins make up 17% of body weight
• Lipids make up 16% of body weight
• Minerals make up 5% of body weight
• Nucleic Acids make up 2% of body weight
• Carbs make up 1% of body weight
• The elemental composition of the human body includes:
• 65% Oxygen
• 18% Carbon
• 9.5% Hydrogen
• 3.2% Nitrogen
• 1.5% Calcium
• 1.2% Phosphorus
• 0.4% Potassium
• 0.2% Sulfur
• 0.2% Sodium
• 0.2% Chlorine
• 0.1% Magnesium

• 1% Other

Organic Compounds

• Organic compounds contain chains of carbon and hydrogen (hydrocarbon chains).
• Carbon and hydrogen atoms are held by covalent bonds, storing energy.
• The chain of carbon atoms forms the carbon skeleton of an organic molecule.
• Carbon skeletons can vary in length, branching, and arrangement in rings.

Carbon Skeleton Variation: Length

• Carbon skeletons vary in length.
• Ethane has a shorter carbon Skelton
• Propane has a longer carbon skeleton

Carbon Skeleton Variation: Branching

• Carbon skeletons can be un-branched or branched.
• Butane has an un-branched carbon skeleton
• Isobutane has a branched carbon skeleton

Carbon Skeleton Variation: Rings

• Carbon skeletons may be arranged in rings.
• Cyclohexane are example of ringed carbon skeleton
• Benzene is an example of a ringed carbon skeleton

Functional Groups in Organic Molecules

• Organic molecules often contain attached molecules called functional groups.
• Functional groups can make a molecule polar, nonpolar, acidic, or basic.
• Functional groups affect how molecules bond.
• Ketone, Carboxylic acid, aldehyde, ester and amide are examples of organic molecules than contain functional groups

Macromolecule Structure and Function

• Organic chemicals in living organisms fall into four categories:
  • Carbohydrates (sugars)
  • Lipids (fats, phospholipids, steroids)
  • Proteins
  • Nucleic acids (RNA and DNA)
• Macromolecules are composed of subunits:
  • Monomers (building blocks)
  • Polymers (building blocks strung together)
• Molecules consist of hydrocarbon chains.

Making and Breaking Down Organic Molecules

• Dehydration reaction:
  • Removal of water allows subunits to link into larger molecules.
• Hydrolysis reaction:
  • Addition of water breaks larger molecules into their subunits.

Carbohydrates

• Chemical formula: (CH2O)n
  • If n=6, then glucose has the formula C6H12O6.
• Carbohydrates are a major source of energy for cells.
• Carbohydrates are found in simple and complex forms.
• Types of Carbohydrates
  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• Most carbohydrates have the suffix "ose".

Monosaccharides (Simple Sugars)

• Five-carbon sugars are found in nucleic acids.
• Six-carbon sugars are used for energy.
  • 5-carbon sugar → (CH2O)5 → C5H10O5
    • Examples: Deoxyribose-DNA and Ribose-RNA.
  • 6-carbon sugar → (CH2O)6 → C6H12O6.
    • Examples: Glucose, Fructose, Galactose
  • These molecules are chemical isomers.

Disaccharides

• Disaccharides consist of two carbon rings joined by covalent bonds.
  • Sucrose (table sugar) = glucose + fructose
  • Lactose (milk sugar) = glucose + galactose
  • Maltose (grain sugar/barley malt) = glucose + glucose

Polysaccharides (Complex Carbohydrates)

• Polysaccharides are polymers of sugar with many carbon rings.
  • Starch (amylose) is a storage form in plants.
  • Cellulose is found in plants (fiber).
  • Glycogen is a storage form in animals.
• Complex Carbohydrates vs Simple Carbohydrates
  • Simple carbohydrates are digested quickly
  • Complex carbohydrates are digested slow.
  • Simple carbohydrates are mono- or disaccharides
  • Complex carbohydrates are polysaccharides
  • Simple carbohydrates do not contain additional nutrients
  • Complex carbohydrates often contain additional nutrients - Vitamins and minerals
  • Examples: simple carbohydrates - Table sugar, fruit, fruit juice and milk
  • Examples: complex carbohydrates - Vegetables, bread, pasta

Lipids

• Lipids are characterized by their inability to dissolve in water.
• They are a rich energy source.
• Divided into two simple classes:
  • Saturated fatty acids
  • Unsaturated fatty acids

Fatty Acid Composition

• Carboxylic acid, hydrocarbon chains.

Saturated vs. Unsaturated Fatty Acids

Examples of Lipids

• Essential fatty acids
• Trans-fats
• Prostaglandins
• Triglycerides
• Phospholipids
• Steroids

Essential Fatty Acids

• The body can make most required fatty acids.
• Omega-3 and omega-6 are essential fatty acids and must be obtained from the diet.

Trans-Fats

• Cis configuration:
  • Hydrogen atoms are on the same side of the carbon-carbon double bond and occur in nature.
• Trans configuration:
  • Hydrogen atoms are on opposite sides of the double bond and are not found in nature. They source of potential health risks.

Prostaglandins

• Prostaglandins are released when tissue is injured, leading to inflammation. Plasma membrane →injured, activating phospholipase (enzyme) → converted into prostaglandins
• People take non-steroid anti-inflammatory drugs (NSAIDs) for chronic inflammation. Ex: ibuprofen
• Symptoms of inflammation:
  • Redness
  • Warmth
  • Swelling
  • Pain

Formation of Triglycerides

• Triglycerides are formed from glycerol + 3 fatty acids = Triglyceride + water
• R = any fatty acid chain of hydrocarbons
• Fatty acid: hydrocarbon bonded to a carboxyl group.
• Lipid types: Monoglyceride (1 fatty acid tail), Diglycerides (2 fatty acid tails), triglycerides (3 fatty acid tails).

Phospholipids

• Importance in cells
• Similar to triglycerides
• Phosphate group gives electrical polarity (hydrophilic), tails are hydrophobic => amphipathic.

Steroids

• Most steroid hormones are made from cholesterol.
  • Present in the diet and can be synthesized (liver) from saturated fatty acids.
  • Used by cells to manufacture steroid hormones

Cholesterol and its derivatives

• Cholesterol is needed to make LDL
• Androgens: Testosterone & Adrenal androgen (DHEA)
• Female hormones: Estrogen & Progesterone
• Mineral corticosteroids: From the adrenal gland (cortex), control mineral balance (Na+ or K+)
• Glucocorticosteroid: Cortisone and vit D (calciferol)