Carbohydrates, proteins, lipids, and nucleic acids

macromolecules

Organic compoundcontain carbon Carbohydrates

Contain elements: hydrogen, oxygen, and carbon

Hydrogen and oxygen are found in the same ratio as water 2:1

Three types of carbohydrates:

1. Monosaccharides (simple sugars)Glucose, fructose, galactoseHave same molecular formula C6H12O6

Differ in their structural formulas

DisaccharidesTwo simple sugars joined together by

dehydration synthesisSucrose, maltoseHave same formula C12H22O11

PolysaccharidesHundreds of simple sugars bonded

togetherCellulose (supporting material found in

cell walls of plant cells)Starch (plant storage of sugar)Glycogen (animal storage of sugar,

found in muscle and liver cells)

Dehydration synthesis (Condensation reaction)

Building up of complex molecules from simpler molecules, with the release of water

Hydrolysis

Reverse process, large molecules are broken down to their building blocks, with the addition of water

Polymer

Collection of many similar, repeating units to form a large molecule

Lipids

Fats, oils, and waxes, contain hydrogen, carbon, and oxygen

Typically consists of a glycerol molecule bonded to 3 fatty acids known as a triglyceride

Formed by dehydration synthesis

Saturated fats

Role in heart disease Have animal origins Butter, lard, whole milk, and milk products Solid at rm temp Saturated with hydrogen atoms which are

attached to each of the carbon atoms

Unsaturated fats

Have at least one carbon to carbon double bond

Missing hydrogen atoms Liquid at rm temp Plant oils such as corn oil, olive oil,

sunflower oil, and fish oils

Proteins

Contain carbon, hydrogen, oxygen, and nitrogen and in many instances, sulfur

Large polymers of many repeating amino acid units

20 different types of amino acids More than 3,000 amino acids in a

protein

Bond between amino acids is called a peptide bond

A chain of amino acids is a polypeptide Shape of protein molecule itself depends

on the nature of the attraction between the different parts of the polypeptide chain

Formed by dehydration synthesis

Polypeptide, not necessarily same as a protein Example Polypeptide would be a strand of

yarn Protein would be a sweater

Shape of protein

Sequence of amino acids determines proteins shape

Shape determines how protein functions

Function of protein depends on its ability to recognize and bind to some other molecules

4 levels of protein structure

1. Primary=sequence of covalently joined amino acids in a polypeptide (linear)

2. Secondary=bending and hydrogen bonding of a polypeptide to form helices and pleated sheets

3. Tertiary=overall shape of polypeptide 4. Quaternary=association between 2 or

more polypeptides

Nucleic acids

Contain carbon, hydrogen, oxygen, nitrogen, and phosphorus

Largest organic molecules known Made up of thousands of repeating

units called nucleotides

Nucleotides consist of three parts: 1. phosphate 2. a five carbon sugar (ribose or deoxyribose) 3. nitrogen base

DNA plays key role in determination of heredity

RNA important in the synthesis of protein

Enzymes

Organic catalysts, they affect the rate of a chemical reaction w/out being changed

Can be used over and over again Protein in nature and specific to their action Often work with coenzymes which are

smaller and not protein, and are active only with enzymes Example of coenzymes (B-complex vitamins)

How enzymes function: Enzymes are huge compared to the molecules on which

they interact Only a small portion of the enzyme functions when it is

active, called the active site The molecule on which the enzyme acts is called the

substrate They work like a “lock and key” The name of the enzyme usually has the ending –ase,

added to the stem of the word which is taken from the substrate Examples:

Enzyme Maltase; substrate Maltose “ Lipase; “ Lipids “ Protease; “ Protein

Factors affecting enzyme action: pH

Depends on enzyme; maltase functions best in a pH of 7; pepsin, found in the stomach at a pH of1.5-2.2; trypsin, in the small intestine, pH 7.9-9.0

Temperature Most function best at body temperature 370 C Lower temp activity of enzyme decreases As temp is raised activity increases until a maximum is reached at

about 400 C; beyond this point enzyme becomes distorted and enzyme deactivation occurs

Relative amounts of enzyme and substrate Amt of enzyme increased, while substrate remains constant; rate of

reaction is increased to a point; after that rate remains constant Amt of substrate is increased, while concentration of enzymes remains

the same; rate of reaction will increase and will continue up to the point where every available enzyme molecule is actively involved in the reaction