Ch22

Molecules of Life

Chapter 22

Great Idea:A cell’s major parts are constructed from a few simple molecular building

blocks

Chapter Outline

• Organic Molecules• Proteins: The Workhorses of Life

• Carbohydrates• Lipids• Minerals and Vitamins

Organic Molecules

Four Basic Characteristics

• Most molecules based on chemistry of carbon– Organic molecules

• Life’s molecules form from few elements– H, O, C, N 97.5% of body weight

Four Basic Characteristics –cont.

• Molecules composed of simple building blocks– Arranged differently

• Shape determines behavior– Determines ability for bonding

Atoms in the Human Body

• No H atoms or bonds to H are shown

• C atoms are not shown explicitly

Chemical Shorthand

Shorthand

Science in the Making

• The synthesis of urea– Friedrich Wohler

Proteins: The Workhorses of Life

Amino Acids: Building Blocks of Proteins

• Amino acid– Carboxyl group– Amino group– Carbon atom– Side group

• Side group– Makes amino acid unique

Amino Acid Structure

Distinctive Side Chain on Amino Acids

Amino Acids - cont.

• Bonding– Two amino acids

•H bonds with OH

•Forms H2O

•Forms peptide bond

– Polypeptide• Chain

Proteins

• Protein– Large molecule– Chain of amino acids

• Only 20 amino acids in living organisms

Structural Proteins

The Structure of Proteins

• Primary structure– Linear sequence of amino acids

• Secondary structure– Bending due to hydrogen bonds

• Tertiary structure– Disulfide bridges and other bonds

• Quaternary structure– More than one polypeptide chain

The Structure of Proteins

Science by the Numbers

• How many proteins can you make?

Proteins as Enzymes

• Enzymes– Specific shape and structure– Facilitates bonding– Recycled

An Enzyme in Action

Computer-Generated Image of an Enzyme in Action

The Science of Life

• Proteins and diet– Essential amino acids– High-quality proteins– Low-quality proteins

Essential Amino Acids in Eggs and Cornmeal

Balanced Protein Meal

How Drugs Work

• Blocking enzymes– Block active site– Molecules cannot bond– Reaction does not take place

• Shape of molecules– Block membrane transport– Block neurotransmitters

Carbohydrates

Carbohydrates

• Structure– C, H, O

• Simplest - sugars – CnH2nOn

• Monosaccharides• Polysaccharides

– Starches– Cellulose

Glucose

Fructose

Polysaccharides

Lipids

Lipids

• Lipids– Insoluble in water

• Role of lipids– Cell membranes– Store energy

• Phospholipids– Make up cell membrane

Lipids and Water Are Immiscible

Structure of a Phospholipid

Saturated and Unsaturated Fats

• Saturated– Carbon is fully bonded– Basis of cholesterol

• Unsaturated– Monounsaturated– Polyunsaturated

•Hydrogenation

Saturated vs. UnsaturatedLipids

Technology

• Nonfattening fats

Cell Membranes

• Cell membrane– Hydrophilic– Hydrophobic

Lipid Bilayer

Minerals and Vitamins

Vitamin and Mineral Supplements

Minerals

• Minerals– All chemical elements except C, H, N, O

• Example– Calcium

•2% of weight

RDAs for Minerals

Vitamins

• Vitamins– Organic molecules– Must be taken in with food

•Except vitamin D

• Function– Assist enzymes

Types of Vitamins

• Water soluble– Vitamins B & C

• Fat soluble– Vitamins A, D, E, & K

Citrus Fruit and Vitamin C

RDAs for Vitamins