CHAPTER 5

Biological compounds play an important role

in life processes

•Most molecules of a cell are carbon based

•These “biomolecules”- backbones of carbon atoms bonded to one another – called “organic molecules”, can be gigantic in size

•Carbon+hydrogen – “hydrocarbons”-methane (CH³)-in natural gas

•Functional group – group of atoms within a molecule that interacts in a predictable way

•Carbon skeleton + attached functional group determines the properties of an organic molecule

•Hydroxyl group – hydrophilic: attracts water molecules

•Hydrophobic water avoiding molecules

•Monomer - Small building block of a larger molecule

•Polymer – straight chain of monomers, about a total of 50 in number

Carbohydrates

Lipids

Proteins

Nucleic AcidsProtein that makes up a spider’s web

•Dehydration Reaction or Dehydration Synthesis – two monomers bond to each other, making a polymer chain longer, The Hydroxyl group(OH) of one monomer reacts with the Hydrogen(H) atom from another monomer.The reaction releases a water molecule.

•Hydrolysis - Cells break bonds between monomers by adding water to them•Water (hydro) is used to break down( lysis ) a molecule

Inorganic compounds

no carbonexception - carbon dioxide, calcium carbonate, examples - water, salts

•CARBOHYDRATES – “energy source”Organic compound made up of 1 carbon :2 hydrogen:1 Oxygen

Molecular formula CH2O

Ring shaped carbon skeleton•Monosaccharide – simple sugars with 1 sugar unit : glucose(main fuel supply for cells), fructose•Disaccharide – “double sugar”: sucrose

Glucose

•Polysaccharide – long polymer chains,complex carbohydrates : starch

•Glycogen – animal cells, stored in liver

•Cellulose – plant cell walls

•LIPIDS (FATS) – Three carbon backbone called “glycerol” attached to 3 “fatty acids”which contain long hydrocarbon chainsSome solid at room temperature Oils – liquid at room temperature•Function – stores energy, cushions organs, insulation

•“Saturated fat” – all three fatty acid chains contain the maximum possible number of hydrogen atoms : animal fats,butter,lard

•“Unsaturated fat” – less than the maximum number of hydrogen atoms in one or more of it’s fatty acid chains : corn oil, olive oil

Cholesterol

animal products like butter and meatbuildup of deposits that narrow arteries ;leads to heart attacks and strokes

•Steroids – lipid molecule in which the carbon skeleton forms four fused rings. While all steroids have the core of 4 rings, they differ in the kinds and locations of functional groups•Circulate in the body as chemical signals

Nucleic Acids

carbon, hydrogen, oxygen, phosphorous, nitrogenDNA(Deoxyribonucleic Acid)- transmits genetic information that is passed from one generation to the next-double helixRNA (Ribonucleic Acid)

structure

long chains of repeating units called NUCLEOTIDE(a) 5 carbon sugar - deoxyribose(b) phosphate group© nitrogenous base - adenine=thymine;cytosine=guanine

Structure of RNA

single strandeach nucleotide(a) 5 carbon sugar - ribose(b) phosphate group© nitrogenous bases - adenine=uracil ; cytosine=guanine

•PROTEIN from the Greek word meaning “first place”-suggests the importance of this class of polymers.•Each one has a unique 3-dimensional structure that corresponds to a specific function

Texture of animals coat

Powerful muscles

Food value in nuts

•Responsible for the day to day function of organisms

•Example – hair,fur,muscles control chemical reactions in the cell

•Protein is a polymer constructed from a set of 20 kinds of monomers called “amino acids”

•Each amino acid consists of a central carbon atom bonded to 4 partners : amino group, carboxyl group,hydrogen atom

•4th group is a “side group” or “R-group” is responsible for the particular chemical properties of each amino acid.

hydrocarbon

•Cells create proteins by linking amino acids together in a chain called a “polypeptide”

•Each link is created by the dehydration reaction between the amino group of one amino acid and the carboxyl group of the next amino acid in the chain.

•Proteins are composed of one or more polypeptide chains ,usually at least 100 amino acids in length

•Protein Shape – a functional protein consists of one or more polypeptides precisely twisted, folded,and coiled into a unique shape•Influenced by the surrounding environment•Unfavorable change in the environment (pH,temperature) can cause the protein to unravel.This is called “denaturation”

•The chemical reactions within a cell requires “activation energy”(start-up energy)•Provided indirectly by “catalysts”(compounds that speed up a chemical reaction without themselves changing)•“Enzymes” or “organic catalysts” are specialized proteins example - maltase acts on maltose

Enzymes lowers the energy requirement barrier so that the reaction can proceed at normal cell temperatures

Enzyme action - Lock and key

on surface of the protein is the active sitesubstrate molecule fits the active site forms a temporary enzyme-substrate complex - Lock and Key mechanism

Induced Fit Mold

enzyme, not with rigid shape, changes slightly so that the it can fit snugly around the substrate

Factors affecting the Rate of Enzyme reactionsmall amount of enzyme for large amounts of substraterate of reaction dependent on enzyme:substrate concentrationcoenzymes may be required sometimes

allow optimal reactions at normal temperature-36*works best at certain pH -7ex. Pepsin in stomach acts only when HCL is present