Chapter 3: Biochemistry Honors Biology 2011

What are we made of? Why do we have to eat?

96% of living organisms is made of: carbon (C) oxygen (O) hydrogen (H) nitrogen (N) Elements of Life % Composition by Volume

The Chemistry of Carbon Living organisms are made of carbon based molecules known as organic molecules. Carbon’s versatility is the key to the structure of organic molecules:  Carbon can bond with up to 4 other atoms at once.  Carbon can form single, double or triple bonds.  Carbon bonds easily with other carbon atoms to form the backbone of large organic molecules.  Carbon can bond with many different elements such as H, O, P, S, N.

Macromolecules Most molecules in cells are so large they are macromolecules or “giant molecules” made from thousands of smaller molecules Polymerization: large molecules are made from joining smaller ones together  Monomers: small building blocks  Polymers: long chains of monomers

Building large molecules of life Chain together smaller molecules  building block molecules = monomers Big molecules built from little molecules  polymers

Small molecules = building blocks = monomers Bond them together = polymers Building large organic molecules

How to build large molecules Dehydration Synthesis Condensation Reaction  building bigger molecules from smaller molecules  building cells & bodies repair growth reproduction + Energy

Making Polymers Monomers link to form polymers in a reaction called a condensation reaction One small molecule comes out each time two monomers form a bond.  When that molecule is water, it’s called dehydration synthesis. Monomer + Monomer  Polymer + Water

Example of synthesis amino acidsprotein amino acids = building block protein = polymer Proteins are synthesized by bonding amino acids

How to take large molecules apart Digestion Hydrolysis  taking big molecules apart  getting raw materials for synthesis & growth  making energy (ATP) for synthesis, growth & everyday functions + Energy

Breaking Down Polymers Polymers can be broken down back into monomers by a reaction called hydrolysis. Water is added to break a bond between monomers. Exergonic reaction (energy comes out) Polymer + Water  Monomer + Monomer

Example of digestion starchglucose Energy Starch is digested to glucose

Energy Currency Life processes require energy Adenosine Triphosphate (ATP) is a molecule that contains LOTS of energy When P is removed, energy is released and can be used by the cell.

Section 3-3: Molecules of Life

Put C, H, O, N together in different ways to build living organisms What are bodies made of?  carbohydrates sugars & starches  proteins  fats (lipids)  nucleic acids DNA, RNA

Why do we eat? We eat to take in more of these chemicals  Food for building materials to make more of us (cells) for growth for repair  Food to extract energy Unit = calorie to make ATP ATP

What do we need to eat? Foods to give you more building blocks & more energy for building & running bodies  carbohydrates  proteins  fats  nucleic acids  vitamins  minerals, salts  water

Water  65% of your body is H 2 O  water is inorganic doesn’t contain carbon Rest of you is made of carbon molecules  organic molecules carbohydrates proteins fats nucleic acids Don’t forget water

Carbohydrates Elements: C, H, O in a 1:2:1 ratio Monomer = Building block molecules = monosaccharide or simple sugar (glucose, fructose, galactose) sugar sugar - sugar - sugar - sugar - sugar

sucrose Carbohydrates Function:  quick energy  energy storage  structure cell wall in plants Examples  sugars  starches  cellulose (cell wall) glucose C 6 H 12 O 6 starch

Monosaccharides = Sugars = building blocks Names for sugars usually end in  glucose  fructose  sucrose  maltose OH H H HO CH 2 OH H H H OH O glucose C 6 H 12 O 6 sucrose fructose maltose -ose

Building carbohydrates Disaccharides = 2 monosaccharides put together by dehydration synthesis. Example: Maltose = glucose + glucose | glucose | glucose monosaccharides 2 sugars = disaccharide | maltose

Building carbohydrates Dehydration Synthesis | fructose | glucose monosaccharides | sucrose (table sugar) 2 sugars = disaccharide

BIG carbohydrates Polysaccharides  starch energy storage in plants  potatoes  glycogen energy storage in animals  in liver & muscles  cellulose structure in plants  cell walls  chitin structure in arthropods & fungi  exoskeleton

Cellulose Cell walls in plants  herbivores can digest cellulose well  Cross-linking between polysaccharide chains hard to digest, most carnivores cannot digest cellulose that’s why they eat meat to get their energy & nutrients cellulose = roughage  stays undigested  keeps material moving in your intestines

Lipids Concentrated energy molecules Elements: C, H, O Lipids are not polymers- only made of 4 parts, not a long repeating chain  Made of Glycerol & Fatty Acids (long, unbranched carbon chains) Lipids are large, nonpolar organic molecules that do not dissolve in water.

Lipids Function:  energy storage very concentrated twice the energy as carbohydrates!  cell membrane  cushions organs  waterproofing  insulates body think whale blubber!  some hormones

Lipids Examples  fats  oils  waxes  hormones sex hormones  testosterone (male)  estrogen (female)

Molecular Structure of Fat not a chain (polymer) = just a “big fat molecule” Many C-H bonds that store more energy than the C-O bonds common in other organic compounds.

Saturated fats Each carbon atom is covalently bonded to four atoms. They are full or saturated. Contain LOTS of energy Most animal fats  solid at room temperature Limit the amount in your diet  contributes to heart disease  deposits in arteries

Unsaturated fats Carbon atoms that are not bonded to the maximum number of atoms that they can bond to, form double bonds and are said to be unsaturated, not full. Contain less energy than saturated fats. Plant, vegetable & fish fats  liquid at room temperature the fat molecules don’t stack tightly together Better choice in your diet

Other lipids in biology Cell membranes are made out of lipids  phospholipids  forms a barrier between the cell & the outside

Other Types of Lipids Wax - long fatty acid joined to long alcohol chain.  Waterproof, form a protective coating on outer surfaces. Steroids - four fused carbon rings with various functional groups attached.  Many animal hormones are steroids  Cholesterol is needed by the body for nerve cells and other cells to function normally.

Other lipids in biology Cholesterol  good molecule in cell membranes  make hormones from it including sex hormones  but too much cholesterol in blood may lead to heart disease