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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chapter 3

Molecules

Of Life

3.1 Building Big Molecules

 Carbon can share electrons with as many as FOUR other atoms

 Organisms consist mainly of oxygen, hydrogen, and carbon

3-2

Macromolecules  Carbohydrates, lipids, proteins, and nucleic acids

are called macromolecules because of their large size

 The largest macromolecules are polymers because they contain many subunits called monomers that are connected to each other.

3-3

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3.2 Proteins  Important for structure and

function

 50% of dry weight of most cells

 Several functions

 Some proteins are enzymes  all enzymes are proteins

 enzymes increase the rate of a reaction

 Support

 Keratin, collagen 3-4

Proteins cont.

 Contractile  muscle cells use protein to

contract

 Transport

 channels, carriers, hemoglobin

 Defense  antibodies and clotting

proteins

 Some hormones are proteins  insulin, growth hormone

3-5

Amino Acids

 Proteins are macromolecules with amino acid subunits

 20 different amino acids

 Identical backbones

 Different side chains (R group)

 Peptide bonds (covalent bonds) hold the amino acids together

3-6

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Amino acid diversity.

 Variety is due to the R group

3-7

Protein Structure & Shape

 Primary structure

 order of amino acids

 Secondary structure

 coiled or folded shape

 hydrogen bonds between negative C=O and positive N-H groups

Protein Shape 2  Tertiary structure  further folding and

bending into globular and fibrous shapes

 Quaternary structure  associations of two

or more separate polypeptide chains

 only some proteins have a quaternary structure such as hemoglobin

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Denaturation  Denaturation - the irreversible change of protein shape

caused by heat or pH

 causes the loss of 2o and 3o

structure

 enzyme can no longer function

3-10

Protein Structure Determines Function

 Proteins must have the correct shape for them to function.

 Enzymes have a shape that is specific for a given molecule.

 They must fit each other like a key in a lock.

 The protein must be made

right for it to take its final shape correctly. 13-11

3.3 Nucleic Acids

 These are long chains of nucleotides

 Nucleotides are made of a sugar, a nitrogen- containing base, and a phosphate

 DNA – deoxyribonucleic acid

 The genetic material

 RNA – ribonucleic acid

 A copy of DNA used to make proteins

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5.6 ATP: The Energy Currency of the Cell, pg 100

 Adenosine Triphosphate (ATP)

 A nucleotide with the base adenine and the

sugar ribose making a compound adenosine

 Is broken down to release energy and form adenosine

diphosphate (ADP) 3-13

3.4 Carbohydrates

3-14

 Used as an immediate energy source

 Hydrophilic molecules

 Simple sugars

 Major monosaccharides

 glucose glc

 galactose gal

 fructose frc

 glucose is blood sugar

Disaccharides

 Sugar molecule composed of 2 monosaccharides

 Major disaccharides  sucrose = table sugar

 glucose + fructose

 Lactose = sugar in milk

 glucose + galactose

 Maltose = grain products

 glucose + glucose

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Complex Carbohydrates

 Polymers of monosaccharides

 Used for short-term or long-term energy storage

 Plants store glucose as starch

 Animals store glucose as glycogen

 1 lbs glycogen has 4 lbs of water associated with it

3-16

Complex carbohydrates provide structural support

 Some are used for structure

 Cellulose is used by plants

 structural – tree trunk is mostly cellulose

 humans can’t digest

 fiber in diet

 protozoans in termites can digest

 Chitin is used in animals and fungi

 found in the shell 3-17

3.5 Lipids

 Hydrophobic organic molecule

 not soluble in water

 composed of carbon, hydrogen and oxygen

 Three primary types in humans

 triglycerides, phospholipids, and steroids

 Functions of fat

 high caloric compound, good at storing calories (no water stored, hydrophobic)

 insulation

 protection (behind eyeball, surrounds spinal cord)

3-18

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Triglyceride

 Triglycerides are the fats and oils.

 Triglycerides are made up of glycerol (orange balls) and 3 fatty acids (long chains).

 Saturated fats have no double bonds  They are saturated with

hydrogens

 Unsaturated fats have double bonds  They are not saturated with

hydrogens 3-19

Saturated Fat

 Fat is solid at room temperature

 saturated fats from animals

 also palm and coconut oil

 causes your body to make more cholesterol

Unsaturated Fat

 Oils are liquid at room temperature

 the double bonds cause kinks in the structure

 pushes the fatty acids from each other

 often polyunsaturated fats from plants

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Other lipids

 Phospholipids are found in plasma membranes

 Cholesterol is a steroid

 Steroid hormones come from cholesterol

 estrogen

 testosterone

3-22

Anabolic Steroids in Sports

 Synthetic forms of testosterone

 Stimulates protein synthesis

 Inhibits protein breakdown

 Side Effects

 Stop growing in height

 Liver cancer

 High blood pressure

 Low sperm count

 Balding

13-23

Type Intramolecular e- polar Example

of bond Intermolecular

Ionic NaCl

shared unequally

no C-

C-

Intermolecular water

Types of Bonds

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Organic Molecules Organic Building Examples Function

Molecule Blocks Carbohydrates Sugars

Lipids Store energy

Hormones

Cell membrane

Amino Structural Acids Enzymes

DNA ATP