Download I. elements

Chapter 2 Lecture Outline
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I. elements
 matter is made of chemical elements
 the most common elements in living organisms are
carbon
hydrogen
oxygen
nitrogen
 other important elements are
calcium
iodine
chloride
phosphorus
sodium
potassium
iron
 chemical elements are represented by symbols
II. energy
 energy is needed to change the structure or location of matter
 energy exists in several forms:
 kinetic energy is the energy of movement
 potential energy is stored energy
 when energy is converted between potential and kinetic, some is
always given off as heat
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
page 2
III. basic chemical structures
A. atoms
 the smallest unit of matter is the atom
 the atoms of each element are very similar in size but there are minor
variations called isotopes
examples:
H
C
 some isotopes are unstable: they give off energy waves (radiation) or
subatomic particles or both
 in health sciences, radioactive isotopes (radioisotopes) are used in
both diagnosis and treatment, but they can damage tissue and kill
living organisms so they must be handled carefully
I
B. molecules
 atoms can attach to each other by chemical bonds to make larger
structures called molecules
examples: H2O
O2
H2CO3
 atoms and molecules do not have electrical charges
C. ions
 some molecules called electrolytes are held together by fairly weak
bonds that break when the molecules are placed into water
 when they break apart, their electrical charges are unevenly
distributed
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
page 3
 the “pieces” are called ions
 ions have electrical charges
 a solution that contains electrolytes conducts electricity
examples:
NaCl
NaOH
IV. inorganic substances
A. water
1. good solvent - allows chemical reactions to occur
2. high heat capacity - the body gains and loses heat very slowly
3. used in many chemical reactions
B. salts, acids and bases, pH
salts, acids and bases are all ionic molecules
they split apart (dissolve, dissociate) when placed in water to form
ions
 positively charged ions are called cations
 negatively charged ions are called anions
1. salt molecules consist of a cation (except H+) plus an anion
(except OH-)
NaCl 
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
page 4
2. acid molecules consist of the cation H+ plus an anion (not OH-)
when placed into water, they release H+:
HCl 
H+ can be dangerous because they can damage
other molecules
3. base molecules consist of a cation (not H+) plus an anion
when placed into water, they dissociate :
NaOH 
the anion picks up acid (H+)
4. pH is the name of a scale used to measure how much acid is in a
solution
high levels of H+ (more H+ than OH-)
solution is acidic
pH is below 7
equal numbers of H+ and OHsolution is neutral
pH is exactly 7
low levels of H+ (fewer H+ than OH-)
solution is basic or alkaline
pH is above 7
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
page 5
V. biomolecules
 the most complex molecules in the body are large and are based on
chains or rings of carbon (organic)
 most of these molecules are based on repeating units called
monomers
 a chain of monomers is called a polymer
A. carbohydrates - made of carbon, hydrogen and oxygen - 1C:2H:1O
1. monosaccharides
glucose C6H12O6
main energy source for cells
2. disaccharides
sucrose = glucose + fructose
lactose = glucose + galactose
maltose = 2 glucose
3. polysaccharides
starch
glycogen
B. lipids
1. fatty acids - long chains of C ending in -COOH
secondary energy source for cells
2. triglycerides - glycerol + 3 fatty acids
storage form for fatty acids (adipose tissue)
3. phospholipids - glycerol + 2 fatty acids + 1 phosphate + 1 non-lipid
membranes
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
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4. steroids - 4 connected carbon rings
examples: cholesterol, cortisol, estrogen
membranes, hormones,
C. proteins
1. amino acids
2. peptide - amino acids attached by peptide bonds
3. protein - peptide with 100 or more amino acids
major functions:
a. structure
b. contraction
c. transport
d. buffers
e. enzymes
f. hormones
g. antibodies
function depends on 3-dimensional structure
structure depends on bonds between amino acids
if the bonds are broken, the shape changes and the protein
loses its function
loss of shape is called denaturation
bonds that hold protein shape are broken by abnormal levels of
ions, pH, or heat
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
page 7
D. nucleic acids
1. nucleotides
2. RNA - single chain of nucleotides
located in nucleus, cytosol
used to make proteins
3. DNA - double chain of nucleotides
located in nucleus and mitochondria
stores genetic information
E. ATP (adenosine triphosphate)
 ATP is the direct energy source for cell activities
 ATP consists of a nucleotide (adenosine) that has three phosphates
attached
 when one of the phosphates is removed, energy is released and can
be used to do work in the cell
 builds or breaks down molecules
 moves materials into and out of cells
 ATP is made by the cell using glucose (or fats) as fuel
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
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VI. enzymes
A. why do we need enzymes?
in chemical reactions, reactants are converted to products
this conversion requires making or breaking chemical bonds
in either case, activation energy is required
catalysts are chemicals that reduce the amount of activation energy
needed for a reaction
by doing this, they speed up the reaction
catalysts are not used up in the reactions-they can be used over and
over again
increasing the temperature of the reactants will also reduce the
amount of activation energy needed, but heat damages cells,
so living organisms can’t use heat to speed up reactions
enzymes are proteins that act as catalysts
B. how do enzymes work?
enzymes bind to molecules called substrates
binding occurs at a specific part of the enzyme molecule called the
active site
BIOL 2404
Strong/Fall 2006
Chapter 2 Lecture Outline
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the active site has a shape that matches the shape of the substrate
molecule
once the enzyme binds to the substrate, it facilitates the making or
breaking of chemical bonds
C. what factors affect enzyme activity?
enzymes are sensitive to pH and temperature
optimal pH and optimal temperature are the conditions under which
the enzyme works best
pH and temperatures outside the optimal range denature the enzyme
and decrease its activity
BIOL 2404
Strong/Fall 2006