Chapter 3

Molecules of Life

Main Elements

Over 98% of an organism’s mass is made up of 6 elements.

• Oxygen

  • Aids in cellular respiration, part of water and most organic compounds

• Carbon

  • Backbone of all organic compounds

• Hydrogen

  • Component of water and most organic compounds

• Nitrogen

  • Part of proteins and nucleic acids (DNA/RNA)

• Calcium

  • Bones, teeth, clotting, muscle and nerve function

• Phosphorous

  • Bones, nucleic acids, energy transfer (ATP)

Biomolecules

• Macromolecules

  • complex structure: carbohydrates, proteins, lipids, nucleic acids

• Micromolecules

  • Simple structure: simple sugars, fatty acid, amino acid, and nucleotides

Monomer: Monomers are small molecules which may be joined together in a repeating fashion to form more complex molecules

Polymer: A polymer may be a natural or synthetic macromolecule comprised of repeating units of a smaller molecule (monomers). A chemical compound where molecules are bound together in long repeating chains.

Structure Dictates Function

The building blocks of lipids, proteins, carbohydrates, and nucleic acids bond in different arrangements that make different complex molecules.

All of the previously mentioned compounds have functional groups attached to a backbone of carbon atoms

Carbohydrates

• Molecular compounds made of 3 elements: Carbon, Hydrogen, Oxygen

• Most abundant biological molecule

• Found in plant products: cell walls of plants; fruits, vegetables, peas, beans

• Sugar, flour

• Found in animal products: milk

Simple Carbs

• Monosaccharides

  • Simple Sugars

    • The simplest carb

    • Used as an energy source or structural material

  • Glucose

    • Blood sugar

    • Basic subunit of other larger carb molecules

  • Fructose

    • Sweetest of the sugars

    • Occurs naturally in fruit and honey

    • Frequently derived from sugar cane, sugar beets, and corn

• Disaccharides

  • Pairs of monosaccharides bonded together; one of which is always glucose

  • Sucrose, lactose, maltose

Complex Carbs

All complex carbs are made of polymers. Most common monomer in complex carbs is glucose.

• Oligosaccharides

  • Short chains of 3-10 simple sugars

  • Provides health benefits as probiotics

  • Found in legumes, human milk

• Polysaccharides

  • Straight or branched chains of many sugar monomers

  • Most common polysaccharides are cellulose (fiber), starch, and glycogen

    • All consist of glucose monomers

    • Each has a different pattern of covalent bonding, and different chemical properties

Polysaccharide Examples

Glycogen

Highly branched chains of glucose units. Animal storage form of carbohydrates (found in liver and muscle)

Starch

Plant storage form of carbohydrate. Long branched or unbranched chains of glucose. The branching gives different properties.

Fiber

Dietary fiber found in all types of plant foods. Refinement removes fiber from whole grains and other foods.

Function of Carbohydrates

Digestion of carbohydrates yields ATP. ATP produces energy. All living things must have an energy source for metabolism. Living things use carbon as the energy source.

Lipids

Aka Fatty Acids. Insoluble in water. Fatty, oily, or waxy organic compounds. Lipids function as the body’s major energy reservoir, and as the structural foundation of cell membranes.

Fatty Acid

Unsaturated Fat: primarily plant sources (veggies, nuts, seeds). Nonlinear chains so molecules aren’t closely packed. Low melting points, liquid at room temp. Essential Fatty Acids

Saturated Fat: primarily animal sources (meat, milk, cheese, eggs). Closely packed molecules. High melting point, solid at room temp. “Unhealthy”

Phospholipids

Make up the inner bilayer of membranes. Heads are hydrophilic, tails are hydrophobic; this allows them to form membranes. Organelles - brought to you by phospholipids.

Protein synthesis is the main feature of growth, development, and reproduction; genes code for amino acids which make up protein.

Nucleic Acids

Nucleic acids code for amino acid synthesis in regions of DNA known as genes. DNA is made of nucleic acids. Nucleotides function as energy carriers, enzyme helpers, chemical messengers, adn subunits of RNA and DNA.

RNA

Has 4 types of nucleotide monomers including ATP. important in protein synthesis

DNA

2 chains of nucleotides in a double helix, held by hydrogen bonds. The information necessary to build an organism is coded in the order of nucleotide bases. Cells use the order of the nucleotide bases to to guide the production of RNA and proteins.

Proteins

A three dimensional polymer made of a set of 20 different monomers called amino acids. The most diverse biological molecules. Composed of 20 types of amino acids. All amino acids have the same base molecule and an R group that varies, this gives the amino group different functions. There are two types of amino acids, both are needed for body functions. Essential amino acids can’t be made by the body and must be found in diet. Nonessential amino acids can be made by the body.

Peptide Bonds

Formed through a process called condensation. Groups of amino acids joined together.

Polypeptide

Protein synthesis involves the formation of amino acid chains called polypeptides.

Levels of Protein Structure

1. Primary

   1. Linear sequence of amino acids in the polypeptide chain

   2. Each protein has a different primary structure

2. Secondary

   1. Amino acids bonded as sheet or coiled polypeptide chain.

   2. Nonlinear, three dimensional

   3. Formed and stabilized by hydrogen bonding

3. Tertiary

   1. coiled/sheet polypeptide chain, 3D, globular

   2. Hydrophobic amino acids tend to arrange themselves on the inside of the molecule and hydrophilic on the outside.

4. Quaternary

   1. Folded polypeptide chains join together to form big molecule

   2. Nonlinear, 3D, globular

   3. Formed by hydrogen bonding, covalent bonding, hydrophobic packing and hydrophilic exposure

The SHAPE of a protein in CRITICAL. Any errors in the folding process can cause non functioning, malfunctioning, or inactive proteins.

Denaturation

When a complete, functioning protein unravels. Due to weak hydrogen bonding. Extreme conditions can disrupt the hydrogen bonds shaping the protein.

Functions of Proteins

Most enzymes are proteins. They are important structural components of cells. Many hormones are proteins. Antibodies and hemoglobin are proteins.