Chapter 6

The Chemistry of Life

Atoms & Their InteractionsOrganic compounds are molecules in which

Carbon(C) combines with other elementsAll living systems contain Carbon (C),

Oxygen (O), Hydrogen (H), and Nitrogen (N)Element - A substance that cannot be broken down

into a simpler substance - Periodic TableElements are made up of hundreds of atomsAtomssmallest particle of an element (building

blocks)

Periodic Table•The number of particles in an atom determine the element •The number of electrons in the outer ring determines how reactive it is•If all electrons are paired then they are stable and will not react Noble Gases

Atoms contain the following:1. Nucleus - center of an atom it

contains A. Proton - positively charged + B. Neutrons - no charge2. Electrons - located in a cloud around

the nucleus with a negative charge -

Bohr Model of an atomIsotopes- atoms of the same element

with different numbers of neutrons

Chemical Bonding•Free electrons, that are unpaired, are also unstable and looking to form a chemical bond•Electrons are very important to the chemical bonding process

•Chemical bonding occurs when an electron moves from one atom to another•When this happens the atom giving up the electron becomes positive and the atom gaining the electron becomes negative

Covalent bondoccurs when two atomsshare electrons to become more stable Molecule group of atoms held together by

covalent bonds and having no overall charge

The physical and chemical properties of a compound differ from the physical and chemical properties of the individual elements that compose it

CompoundSubstance that is composed of atoms of two or more different elements that are chemically combined example H2O

Ion A charged particle it has gained or loss

electronsIonic BondChemical bond formed by the attractive

forces between two ions of opposite charge NaCl

Chemical reactions - bonds formed or broken

Metabolism – all of the chemical reactions that occur within an organism

Elements combine to form compounds the elements do not have their original properties

Mixture – a combination of substances in which the individual components retain their own properties

Solutions – mixture in which one is dissolved into the other (Kool-aid)

Acids and BasespH – measure of how acidic or basic a

solution is pH scale is from 0-14Must remain very stable for biological

reactions to occurOrganisms have a tendency to remain

stable under a wide range of conditions

Acid – substances with a pH < 7 forms H+ ions Bases – substances with a pH > 7 forms OH-

ions

Water and DiffusionWater makes up 70-95% of most

organismsPolar molecule – molecule with an

unequal distribution of charge one end is positive, one is negative (attraction causes it to dissolve many ionic compounds like salt, sugar)

Hydrogen BondH+ attract the O- holds many large

molecules together, proteins, also water tension allows water to creep, plants use this to water from ground called capillary action

Characteristics of Water1. Polar Molecule – has a slight

charge2. Water resists temperature

changes – requires more heat to increase , insulator, cells exist in an aqueous environment helps maintain an optimum environment

3. Water expands when it freezes therefore ice is less dense than water and it floats

DiffusionDiffusion – net movement of particles

from an area of higher concentration to an area of lower concentration

Kinetic energy – the energy of motionBrownian motion – 1827 observed the

evidence of random motion of molecules

3 factors affect diffusion: 1. Concentration – internal factor

2 external factors which speed molecular motion are: 2. Temperature 3. Pressure

Dynamic equilibrium – concentration distributed evenly through molecules still in motion

Concentration gradient – area between the two levels of concentration

November 19, 2010

Differentiate between a mixture and a solution.

Stamp on Vocab 6.3Collect McMush Lab GradeNotes on 6.3Protein Building..

6.3 Life SubstancesCarbon © is the central element for all

living things and combines with H, O, N, S and Ph to form organic compounds

Organic compounds are essential building blocks for living things and are also a major source of energy

Carbon is able to form single, double and triple covalent bonds this gives it greater strength, diversity and energy potential

Isomers – compounds with the same chemical formula but different structures

Isomers

Polymer – large molecule formed when many smaller molecules bond together

Condensations – chemical reaction by which polymers are formed covalent bond formed when water removed

Hydrolysis – method that polymers are broken apart OH and H ions come from water to break it apart

4 Basic Carbon Containing Molecules:

1. Carbohydrates – sugars starch

2. Lipids – oils, fats3. Proteins – cell structure,

muscles, enzyme4. Nucleic Acids – hereditary or

genetic material coordinates cell activity

CarbohydratesContain only C,H,O in same proportions as

water H2OBuilding blocks are simple sugars or

monosaccharides ex: glucose, fructose C6H12O6

Glucose can change its molecules (hydrolysis) within the cell and is a major source of energy

Disaccharide – double sugar sucrose formed by the synthesis of glucose and fructose

Synthesis reactions of glucose build complex carbohydrates like starch and cellulose

Polysaccharides – largest carbohydrate molecules composed of many monosaccharide subunits

Starch is a storage compound in plants used by humans

Cellulose is part of wood and cotton and gives plant cell walls rigidity

Carbohydrates are stored as glycogen in human liver and muscle (animal starch)

Starch, cellulose and glycogen consist of thousands of glucose molecules

LipidsContain only C,H,O abut fewer O ex

C57H110O6

Building blocks fatty acids and glycerolNon polar molecule – doesn’t dissolve in

waterEssential structural part of all cellsInclude simple fats, oils, plant waxes and

cholesterolContain 2x the energy per gram of

carbohydrates

LIPIDSUnsaturated – double bondSaturated – Single bond

ProteinsContain C,H,O,N and some SBuilding blocks – amino acids there

are 20 different types =1 proteinGreen plants can synthesize amino

acids, animals cannot produce all of them

Polypeptide- Long chain of amino acids

Peptide

AminoAcids

Enzymes

Enzymes are made up of proteins and used as catalysts in specific biochemical reactions

Enzymes: Promote reactions Not used up Need only small amounts

Enzymes in Action