Chapter 19The Chemistry of

Life

The Molecules of Life

• 4 molecules necessary for life functions formed from smaller subunits–proteins–carbohydrates–nucleic acids – lipids

• Many of the most important molecules in your body are polymers.

biochemistry - study of the chemistry of living things

elements needed to make these molecules

• hydrogen

• oxygen

• carbon

• nitrogen

• phosphorous

• sulfur

The Role of Proteins

• Proteins are the worker bees and have many functions–Structural – keratin – hair, nails

- collagen – ligaments, tendons

- Transport – hemoglobin- Metabolism – insulin

- lactase

- Catalyst - enzyme

The Structure of Proteins

A protein is polymer composed of amino acids bonded together in chains

Structure of Proteins

• amino acids bond to each other by forming a peptide bond – aka protein synthesis

• water is released in this reaction

Three-Dimensional Protein Structure

• Proteins can fold into either globular structures or long, fibrous structures.

• The shape determines how chemical reactionstake place

Three-Dimensional Protein Structure

• denaturation – breaking the forces that hold a protein in it’s shape

– high temps– extreme pH–mechanical agitation– chemical treatments

antibodies

• antibodies bind to surface of invader–once bound invader is destroyed

binding is very specific…….your body must make different antibodies for different invaders

The Role of Proteins as Enzymes

• enzymes - proteins that catalyze chemical reactions—(speeds up reactions)

• Substrates are brought close together in the active sites of an enzyme

Carbohydrates

• carbohydrate – molecule that contains carbon, hydrogen, oxygen– in ratio of• 2 hydrogen – • 1 oxygen – • 1 carbon

The Role of Carbohydrates

• when carbohydrates break down glucose is formed

• glucose provides most of the energy needed for life

• glucose is also called blood sugar.

• animals store excess glucose in liver and muscles as glycogen

Structures of Carbohydrates

• simple sugars are 5 -7 carbon ring structure

• 3 common simple sugars = glucose, fructose, and ribose

Polysaccharides• sucrose is table sugar =–1 glucose and 1 fructose

• A polymer of many monosaccharides bonded into a chain is called a polysaccharide

–examples: starch and cellulose

Lipids

• lipids are fatty acids, which are long chain carboxylic acids

• fat =from animals• oil = from plants

The Structure of Lipids

• triglycerides, molecules in which three fatty acids are bonded to a glycerol

• saturated fatty acids - have single bonds between carbon atoms.– single bond = tightly packed–= solid at room temp

• unsaturated - one or more double bonds between carbon atoms (healthier)– double bond prevents tight packing –= liquid at room temp

Fats in your diet• diet high in saturated fats linked to

heart disease• high saturated fat = high

cholesterol• cholesterol lines artery walls

• steroid – lipid with 4 ring structure–includes hormones, vitamin D, and cholesterol

Steroids

The Functions of Lipids

• 2 major functions of lipids• store energy

• Form cell membranes

Nucleic Acids• genetic information is coded into long-

chain polymers called nucleic acids. –monomers that make up nucleic acids are called nucleotides

–2 types = DNA & RNA•

The Structure of Nucleic Acids

• nucleotides are made up of three parts: a phosphate group, a five-carbon sugar, and a nitrogen base

Function of DNA & RNA

• DNA – holds genetic information

• RNA - transfers genetic info from DNA (nucleus) to place in cell where proteins are formed

Vitamins• Vitamin – molecule necessary for life

but needed only in small amounts

• 2 classes of vitamins– fat-soluble – vitamins A, D, E, and K–water soluble – vitamins B and C

How can I get too much vitamins?

• excess water - soluble vitamins are dissolved in urine and excreted out – you can’t get too much

• excess fat- soluble vitamins are stored in body fat – be careful you don’t take too much