Transcript Chapter 2: Chemistry of Life

Name & describe the subatomic particles of an atom,
& indicate which one accounts for the
occurrence of isotopes. LT#1
 Protons (+), neutrons (0), electrons (-)
 p & n have mass weight of 1 amu; e- have ~ no mass
 Isotopes = same atomic # but different #s of neutrons
so different mass weights
14 C*
C
*radioactive = break apart to form
6
6
smaller atoms and release radioactivity in the process –
useful in medical diagnostics (radioactive Iodine is
used to assess thyroid activity)

12 C
6
13
Distinguish between ionic & covalent reactions, &
between ionic & covalent bonds.
 Ionic reactions/bonds – atoms give up or take on
electrons to achieve stability
 E.g. salts NaCl
 Covalent reactions/bonds – atoms share electrons to
achieve stability
 E.g. molecules like proteins, lipids/fats, carbohydrates
 E.g. water – bipolar – electrons are shared unevenly
List & discuss the functions of ions in the
body.
 Salt = ionic bond & too much or too little is a problem
 Too much = retain water & increase BP
 Too little = muscle cramps, dizziness
 Too much water & too little salt = water intoxication
(flu-like symptoms)
 Ca2+ is needed for bone strength
 K+ is needed for muscle contraction
 Fe2+ is needed to transport oxygen
Describe the structure of water, & give examples
of how it functions in the body.
 Water molecules are bipolar
 Relatively weak H bonds allow water to be
cohesive=cling so boiling & freezing points are
extreme allowing it to be liquid at body T°
 Absorbs heat before evaporating & releases heat as it
cools down (sweat cools)
 Tubular vessels –
water’s shape/cohesiveness allows for
ease of transport & distribution
of substances & heat
Relate the term electrolyte to the presence
of ions in body fluids & tissues.
 Electrolyte = a substance containing free ions that
make a substance electrically conductive
 Electrolytes = substances that break apart and release
ions when put into water & can conduct an electric
current
 Electrolyte balance is important in body fluids to
maintain health/functioning of vital organs –heart,
brain, nerve impulses, muscle contraction
Define the terms acid and base. Describe the pH
scale, & explain the significance of buffers.
 Acids dissociate in water releasing hydrogen ions (H+)
in excess
 Bases dissociate in water releasing hydroxide ions
(OH-) in excess (= low H+)
 Water has an equal number of H+ and OH- releasing
only one of each ion (H+ = OH-)
 Blood pH ~ 7.4 [<7.35 = acidosis >7.45 = alkalosis]
 pH 6.9 or 7.8 is fatal!
Significance of buffers
 Buffers help keep pH constant by taking up excess H+
or OH- {resist changes in pH}
 Maintaining the proper pH is critical for the chemical
reactions that occur in the body. In order to maintain
the proper chemical composition inside the cells, the
chemical composition of the fluids outside the cells
must be kept relatively constant = homeostasis.
 Carbonic acid – bicarbonate buffer in blood is
maintained by respiration, elimination, sweat
Compare & contrast the structures & functions of
carbohydrates, lipid, proteins, & nucleic
acids.
 Carbohydrates = saccharides
 Lipids = insoluble in water [NONPOLAR]
 made up of fatty acids & glycerol
 Proteins = amino acids
 Nucleic acids = nucleotides
Carbohydrates:
structure & function
 Monomer = monosaccharide (i.e. glucose)
 Ring structure C6H12O6
 Disaccharide = 2 monosaccharides condensed
together (maltose=glucose + glucose; sucrose = glucose
+ fructose)
 Carbs are for quick energy
 Polysaccharide = many monos. condensed together so
lots of E stored (glycogen in liver, starch in plants)
Lipids:
Structure & function
 Carbon chains with hydrogen attached
 Saturated = no double bonds – all hydrogens possible
are held
 Unsaturated
= has double bonds
between Carbons
 Glycerol has H-C-OH
attached to 3 Cs
Glycerol structure
Glycerol is a unit molecule of fats (along with fatty acids)
Lipid function
 Long term energy storage
 Membrane structure – phospoholipid bilayer
 Steroids – 4 fused carbon rings – to form cholesterol
which is the building block for many other steroids
 Adosterone – regulation of sodium level in blood
 Sex hormones – estrogen, testosterone
Proteins
Structure & function
 Kerotin – hair & nails
 Collagen – connective tissue: cartilage, bone,
ligaments & tendons
 Muscles – contractile proteins actin & myosin
 Enzymes – organic catalysts
 Amino acids are monomers and are joined together by
peptide bonds
 Polymers are polypeptides with 3 levels of structures
(fig 2.13 page 28) – heat, low pH can cause unraveling
Nucleic Acids
Structure & function
 Monomers are nucleotides
 Nitrogen base, 5 carbon
sugar, & a phosphate
Explain what enzymes are, & describe their
role in the body.
 Enzymes are protein catalysts =
speed reactions – both synthetic
and metabolic rxns
 A rxn that normally would take
several hours/days without an
enzyme can take a split second.
 Examples: formation of glycogen,
breakdown of foods
The seven categories of food (digestive)
enzymes and their activities are:
 Amylase: breaks down
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starches. (pictured)
Cellulase: breaks down fibers.
Lactase: breaks down dairy
products.
Lipase: breaks down fats.
Maltase: breaks down grains.
Protease: breaks down
proteins.
Sucrase: breaks down sugars.
Describe how the structure & function of
DNA & RNA differ.
 DNA & RNA are polymers of
nucleotides
 DNA – genetic code,
double strand
 RNA – protein synthesis
role in conjunction with
DNA, single strand
 The genes we inherit
determine the types of
proteins we can make
Describe the structure of ATP, & explain how
ATP functions in the body
 Adenosine triphosphate is a nucleotide
 Adenine & 3 phosphate groups = high E phosphate
bonds
 Breaking phosphate bonds releases E
 When cells need E they spend ATP
 If ATP is $1 then cells get 36 pennies per ATP
 Synthetic rxns
 Active transport
 Nerve impulses
 Muscle contraction
ATP  ADP releases E
 ADP  ATP requires glucose
metabolism