Chemistry of Living
Things
Unit 2 Objectives
Relate importance of chemistry &
biochemistry in health care
 Define matter & energy
 Explain structure of atom, element,
compound
 Describe main groups of organic
compounds
 Explain difference between DNA & RNA
 Explain difference between acid, bases,
salts
 Describe why homeostasis is necessary
 Define key words related to the chapter

Chemistry
 Chemistry:
– The study of the structure of matter &
composition of substances, their
properties and their chemical reactions
– The chemical reactions necessary to
sustain life occur in the cells
 Biochemistry:
– Study of the chemical reactions of living
things
Matter & Energy
 Matter:
– Anything that has weight (mass) and
occupies space.
– Exists as solids, liquids, and gases
– Neither created nor destroyed, but
changes form through physical or
chemical means
Matter & Energy
 Energy:
– Ability to do work or to put matter into
motion
– Potential energy: stored in cells waiting
to be released
– Kinetic energy: work resulting in
motion
Atoms




Smallest piece of an
element
Made up of subatomic
particles:
– Protons: (+) electric
charge
– Neutrons: no electric
charge
– Electrons: (-) electric
charge
Protons & neutrons make
up nucleus
Electrons arranged around
nucleus in orbital zones or
electron shells
Atoms
 Protons
equal to electrons and are
electrically neutral
 Can share or combine electron(s)
with another atom to form a
chemical bond
Atoms

Isotopes:
– Atoms of a specific element that have same
number of protons, but different number of
neutrons
– All isotopes of a specific element have same
number of electrons

Radioactive isotopes:
– Unstable & decay; emit energy as radiation
– Radiation can be detected & computerized to
form image of its distribution within body
Elements
 Atoms
that are alike combine to form
elements
 Can exist in more than one phase in
our bodies
– Bones contain Ca
– Air in lungs contain oxygen
Compounds
Various elements combine in proportion by
weight to form compounds
– Water is 2 parts hydrogen and 1 part
oxygen
 Represented by formulas which shows
types of elements & their proportions
 Molecule: The smallest unit of a compound
that still has the properties of the
compound & the capability to lead its own
stable existence

Types of Compounds

Inorganic compounds:
– Made of molecules that do not contain carbon
– Exceptions: CO2, & CaCO3
– Water is the most important inorganic
compound as it comprises 55-65% of body
weight

Organic compounds:
– Always contain carbon combined with
hydrogen & other elements
– Main groups: carbohydrates, lipids, proteins,
nucleic acids
Create Power Point
Sonography
 Positron emission tomography (PET)
 Computerized axial tomography (CAT)
 Magnetic resonance imaging (MRI)
 Will need:

–
–
–
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Only 6 per group
Description
Explanation
Special instructions for the patient
Types of Organic
Compounds
Carbohydrates
 All
carbs are compounds of the
elements carbon, hydrogen & oxygen
 Have 2x hydrogen as oxygen &
carbon atoms
 Subdivided into three groups:
– Monosaccharides
– Disaccharides
– Polysaccharides
Carbohydrates

Monosaccharides
– Simple sugars that cannot be broken down any
further
 Ex:
glucose, fructose, galactose, ribose, deoxyribose
– Glucose main source of energy
 Carried
by bloodstream to cells & stored as glycogen
in liver & muscles cells
 Combines w/ O2 (oxidation) to produce energy
– Fructose found in fruit & honey
– Deoxyribose found DNA
– Ribose found in RNA
Carbohydrates

Disaccharides
– Double sugar formed from two
monosaccharide molecules
 Dehydration
synthesis: forming large molecule from
small ones by loss of a molecule of water
– Ex: sucrose, maltose, lactose
– Must be broken down by digestion process to
monosaccharides to be absorbed & used by
body
 Hydrolysis:
large molecule broken down into smaller
molecules by addition of water
Carbohydrates
 Polysaccharides
– Large, complex molecules of glucose
molecules bonded together in one long
chainlike molecule
– Ex: starch, cellulose, glycogen
– Can be broken down into
monosaccharides under proper
conditions
Lipids
 Molecules
containing the elements
carbon, hydrogen, oxygen
 Have much less oxygen in relation to
hydrogen
 Characteristics:
– Important source of stored energy
– Make up essential steroid hormones
– Help insulate body
 Ex:
fats, phospholipids, steroids
Lipids

Fats:
– Consist of glycerol & fatty acids
– Triglyceride most abundant fat in body

Phospholipids:
– Contain carbon, hydrogen, oxygen, & phosphorus
– Found in cell membranes, brain & nerve tissue

Steroids
– Lipids that contain cholesterol
– Cholesterol essential in structure of semipermeable
membrane of cell, manufacture of vitamin D, production
of sex hormones, production of cortisol
Proteins
Organic compounds containing carbon,
hydrogen, oxygen, nitrogen, phosphorus &
sulfur
 Found in every part of cell serving as
binding & structural components
 Amino acids:

– small molecular units making up proteins
– 22 essential amino acids can combine in any
number or sequence to make up proteins

Must be ingested-cannot be made by body
Enzymes
 Organic
catalyst: affects rate or
speed of chemical reaction without
being changed
 Help provide energy for cell
 Made of all protein or part protein
(apoenzyme) attached to a
nonprotein part (coenzyme)
 Can be used over and over
Nucleic Acids
 Contain
elements carbon, oxygen,
hydrogen, nitrogen, phosphorus
 Two major types:
– Deoxyribonucleic acid (DNA)
– Ribonucleic acid (RNA)
Nucleic Acids

Structure:
– Made of smaller repeating nucleotide subunits
– Nucleotide subunits composed of three
molecular groups
 Group 1 a phosphate or phosphoric acid
 Group 2 a five-carbon sugar
 Group 3 a nitrogenous base of either
purines or pyrimidines
 Purines: adenine (A); guanine (G)
 Pyrimidines: cytosine (C); thymine (T)
DNA Structure & Function
A
double stranded molecule or
double helix resembling twisted
ladder
 Sides formed by alternating bands of
sugar units and phosphate units
 Rungs formed by nitrogenous bases
which always pair thymine w/
adenine; cytosine w/ guanine
DNA Structure & Function
 DNA
molecule passes on genetic
information
 Nucleus of every human cell contains
46 chromosomes (23 pairs), creating
a long coiled molecule of DNA
 Chromosomes contain about 100,000
genes which tells a cell what
structure & function it will possess
RNA Structure & Function
 Consists
of a phosphate group, the
ribose sugar, & one of the
nitrogenous bases: adenine,
cytosine, guanine, & uracil
 Single stranded
 Three types:
– Messenger RNA (m-RNA): carries
instructions for protein synthesis from
nuclear DNA to ribosomes in cytoplasm
RNA Structure & Function
 Three
types (cont):
– Transfer RNA (t-RNA): picks up amino
acid molecules in cytoplasm & transfers
them to ribosomes where they combine
to form proteins
– Ribosomal RNA (r-RNA): helps in
attachment of m-RNA to ribosomes
Acids, Bases, and
Salts
Acids
A
substance that, when dissolved in
water, will ionize into positively
charged hydrogen ions and
negatively charged ions of some
other element
 A substance that yields hydrogen
ions in solution
 May have a sour taste
Acids
 Common
Acids
– Acetic: found in vinegar
– Boric: weak eyewash
– Carbonic: carbonated beverages
– Hydrochloric: in stomach
– Nitric: industrial oxidizing acid
– Sulfuric: batteries
Bases
 Also
known as an alkali
 When dissolved in water, ionizes into
negatively charged hydroxide ions &
positively charge ions of a metal
 May have bitter taste & feel slippery
Bases
 Common
bases:
– Ammonium hydroxide: household liquid
cleaners
– Magnesium hydroxide: MOM
– Sodium hydroxide: Lye
Salts
 Neutralization:
when an acid & base
combine to form a salt & water
 Hydrogen ions from the acid &
hydroxide ions from the base join to
form water
 Negative ions of the acid combine
with positive ions of base to form salt
 HCL + NaOH= NaCl + H2O
pH Scale
pH: measure of acidity or alkalinity of a
solution i.e. number of hydrogen ions in
solution
 pH scale:

– ranges from 0 to 14
– 7 is neutral (equal hydrogen & hydroxide ions)
– 0 to 6.9 indicates an acidic solution & higher
hydrogen ion concentration
– 7.1 to 14.0 indicates an alkaline (basic)
solution & lower hydrogen ion concentration
Buffers
 Buffers
help maintain a constant pH
value, which contributes to
homeostasis or balanced state within
all living things
 When there is either excess acid or
base, buffers help neutralize the
excess acid or base until eliminated
by respiratory or urinary systems
Buffers
 Four
sets of buffers:
– Alkaline & acid phosphate
– Proteins
– Bicarbonate-carbonic acid
– Hemoglobin