The Structure and Function of Macromolecules

I. PolymersWhat is a polymer?

Poly = many; mer = part. A polymer is a large molecule consisting of many smaller sub-units bonded together.

What is a monomer?

A monomer is a sub-unit of a polymer.

II. Classes of Organic Molecules:What are the four classes of organic molecules?

Carbohydrates

Lipids

Proteins

Nucleic Acids

CarbohydratesSugars

Carbo = carbon, hydrate = water; carbohydrates have the molecular formula (CH2O)n

Functions:

Store energy in chemical bonds

Glucose is the most common monosaccharide

Glucose is produced by photosynthetic autotrophs

1. Structure of Monosaccharides

An OH group is attached to each carbon except one, which is double bonded to an oxygen (carbonyl).

Classified according to the size of their carbon chains, varies from 3 to 7 carbons.

Triose = 3 carbons Pentose = 5 carbons Hexose = 6 carbons

Many monosaccharides form rings:

2. Structure of DisaccharidesDouble sugar that consists of 2 monosaccharides

Examples of Disaccharides:Lactose = glucose + galactose Sucrose = glucose + fructose

3. Polysaccharides

Structure: Polymers of a few hundred or a few thousand monosaccharides.

Functions: energy storage molecules or for structural support:

Starch is a plant storage from of energy, easily hydrolyzed to glucose units

Cellulose is a fiber-like structureal material -tough and insoluble - used in plant cell walls

Glycogen is a highly branched chain used by animals to store energy in muscles and the liver.

Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls.

LipidsStructure: Greasy or oily nonpolar compounds

Functions:

Energy storage

cell membrane structure

Protecting against drying out.

Insulating against cold.

Absorbing shocks.

Regulating cell activities by hormone actions.

1. Structure of Fatty AcidsLong chains of mostly carbon and hydrogen atoms with a -COOH group at one end.

When they are part of lipids, the fatty acids resemble long flexible tails.

Saturated and Unsaturated Fats

Unsaturated fats :◦ liquid at room temp

◦ one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails

◦ most plant fats

Saturated fats:◦ have only single C-C bonds in fatty acid tails

◦ solid at room temp

◦ most animal fats

Saturated fatty

acid

Unsaturated

fatty acid

2. Structure of TriglyceridesGlycerol + 3 fatty acids

3. PhospholipidsStructure: Glycerol + 2 fatty acids

Function: Main structural component of cell membranes, where they arrange in bilayers.

Phospholipids in Water

4. Waxes

Function:

Lipids that serve as coatings for plant parts and as animal coverings.

5. SteroidsStructure: Four carbon rings with no fatty acid tails

Functions:

Component of animal cell membranes

Modified to form sex hormones

ProteinsStructure:

Polypeptide chains

Consist of peptide bonds between 20 possible amino acid monomers

Have a 3 dimensional globular shape

1. Functions of ProteinsEnzymes which accelerate specific chemical reactions up to 10 billion times faster than they would spontaneously occur.

Structural materials, including keratin (the protein found in hair and nails) and collagen (the protein found in connective tissue).

Specific binding, such as antibodies that bind specifically to foreign substances to identify them to the body's immune system.

Specific carriers, including membrane transport proteins that move substances across cell membranes, and blood proteins, such as hemoglobin, that carry oxygen, iron, and other substances through the body.

2. Structure of Amino Acid MonomersConsist of an asymmetric carbon covalently bonded to:

Hydrogen

Amino group

Carboxyl (acid) group

Variable R group specific to each amino acid

Nucleic AcidsTwo kinds:◦ DNA: Deoxyribose Nucleic Acid

double stranded

can self replicate

makes up genes which code for proteins

is passed from one generation to another

◦ RNA: Ribose Nucleic Acid

single stranded

functions in actual synthesis of proteins coded for by DNA

is made from the DNA template molecule

1. Nucleotide StructureBoth DNA and RNA are composed of nucleotide monomers.

Nucleotide = 5 carbon sugar, phosphate, and nitrogenous base

Deoxyribose in DNARibose in RNA

DNA:

• Double helix

• 2 polynucleotide chains

wound into the double helix

• Base pairing between

chains with H bonds

• A - T

• C - G

Summary of the Organic

Molecules: