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Chapter 2: Chemistry of Life
Building Blocks of MatterThe basic unit of matter is the atom
◦Atoms are made of subatomic particles: protons (+), electrons (-), and neutrons
◦Protons and neutrons reside in the nucleus
◦Electrons move around in orbitals outside of the nucleus
Atoms of the same element but with different neutrons are isotopes◦Carbon-12, Carbon-13, Radioactive
Carbon-14
Building Blocks of MatterTwo or more elements can combine to
form compounds (H2O)
◦Ionic bonds hold a compound together by a transfer of an electron leading to charged elements (NaCl)
◦Covalent bonds involve sharing of electrons between elements (H2O)
Building Blocks of LifeElement – Substance that can’t be
broken down into simpler chemical substances.
Carbon - the element of life as it can combine with other elements and with itself to form long complex structures. It must have 4 bonds.
MacromoleculesMacromolecules – big molecules
Monomers – small subunits (building blocks) of large molecules, ex. Glucose is the monomer of starch, a polymer
Polymer- made of many molecules, ex. proteins, nucleic acids
CarbohydratesMain source of energy for living
organisms (glucose)Organisms store energy as complex
carbohydrates called starches
CarbohydratesMonosaccharide – single sugar.
Polysaccharide – large molecules formed from monosaccharides.
LipidsComposed predominately of
carbon and hydrogen atoms (limited oxygen)
Includes fats, oils, waxes, steroids
Composed of glycerol and fatty acids
Lipids
Nucleic AcidsComposed of monomers called
nucleotides◦Composed of 5-C sugar, phosphate
group, and a nitrogenous base◦Joined together to form nucleic acids:
ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
Store and transmit hereditary (genetic) information
Nucleic Acids
ProteinsContain nitrogen, carbon, oxygen, and
hydrogenMonomer: amino acids20 different amino acids are found in
nature, leads to significant diversity in proteins
ProteinsProteins are the doers of life
◦Controls rates of reactions◦Regulate cells processes◦Form bones and cells◦Transport substances into and out of
cells
Proteins
Organic MacromoleculesCompound Subunit(s) Elements Function ExamplesCarbohydrates
Glucose or sugar
C, H, O Main energy source
Structure
glucose, starch, cellulose, glycogen
Lipids(fats & oils)
Glycerol and 3 fatty acids
C, H, O Energy storage Protective
coverings
Phospholipids, steroids
Proteins
Amino acids
C,H,O,N, & usu. S
Muscles/bones/ structure
Control reaction rates
Regulation Transport
substances Fight disease
Insulin, enzymes, hemoglobin, muscle fibers
Nucleic acids
Nucleotides C, H, O, N, P
Store and transmit genetic information
DNA, RNA
Chemical ReactionsChemical reactions involve the
breaking of bonds in reactants and the formation of new bonds in products◦Those entering the reaction are
reactants◦Products are produced by the
reaction
Chemical ReactionsEquations must balance. Atoms are not
created or destroyed, just rearranged.
Example: 2H2 + O2 2H2O
Reactants are on the left and enter into the reaction.
Products are on the right and result from the reaction.
Metabolism – All of the chemical reactions that occur within an organism.
Energy in Reactions2H2 + O2 2H2O
◦Occurs naturally, releasing energy◦The reverse reaction: 2H2O 2H2 +
O2 requires so much energy it rarely occurs
Chemical ReactionsActivation energy – energy needed to get a
reaction started.Catalyst – substance that speeds up the rate
of a chemical reaction.
Enzymes – proteins that speed up chemical reactions because they lower the activation energy. Enzymes provide a site where reactants can be brought together. (This reduces the energy needed for the reaction, called activation energy).
Substrate – the reactant(s) the enzymes fit.
Enzymes
Enzymes
EnzymesEnzymes can be affected by any
variable that affects chemical reactions including temperature and pH
Enzyme activity are regulated by cells often by turning them on or off
Characteristics of EnzymesSpecific (a special shape; use induced
fit)ReusableNot consumed (used) in the reactionAffected by factors such as pH and
temperature.
Enzymes are specific because they are proteins made by folding into a 3-D shape (linked to their function).
Properties of WaterAlthough water is neutral, it does have
polarity◦Water molecule is polar because of
uneven distribution of electrons◦The oxygen end has a slight negative
charge◦The hydrogen end has slight positive
charge
Properties of WaterDue to its polarity, water can
hydrogen bond with itself (attract itself)◦Weaker than ionic bonding (NaCl)◦Cohesion is attraction of molecules
of same substance (beads of water)◦Adhesion is attraction of molecules
of different substances (water and graduated cylinder)
Properties of WaterWater is not always pure, it is often
found as a mixture (material composed of two or more elements or compounds that are not chemically combined)◦If the materials are evenly
distributed it is called a solution◦The substance that is dissolved is
the solute◦The substance that dissolves is the
solvent
Properties of WaterWhen material does not dissolve a
suspension is formed◦Example: blood cells and water◦The movement of the water keeps
the small particles suspended
Acids and BasespH – A measure of how acidic or basic a
solution is. Scale is 0 to 14. Below 7 is acidic. Above 7 is basic. 7 is neutral
Acidic solutions have higher concentration of H+ ions than pure water (pH 7)
Basic solutions have a lower concentration of H+ ions than pure water
Buffers – prevent sharp, sudden changes in pH
Acids and Bases
Acids and Bases