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Chemical Basis of
Life – Biochemistry
What is Biochemistry
Biochemistry is the study of the chemical
interactions of living things.
 Living things require millions of chemical
reactions within the body, just to survive.
 Biochemists study the structures and
physical properties of biological molecules.

 Often
are involved in the manufacture of new
drugs and medical treatments
Chemical Organization
Matter – anything that has mass
and takes up space

Atoms – the smallest,
stable unit of matter



Made of protons (+ charge),
neutrons (neutral charge),
and electrons (- charge)
Protons and neutrons are
located in the nucleus of the
atom
Electrons are in an electron
cloud outside of the nucleus
Atomic Structure

Elements – all matter composed of them;
found on periodic table




Atomic
number
Oxygen, carbon, hydrogen, and nitrogen make up
more than 95% of the human body
Atomic number – unique to each element;
equals number of protons and electrons in a
neutral atom
Isotopes – atoms of same atomic number, but
different atomic mass due to differing amounts
of neutrons; normal in nature; average of
isotopes = atomic mass on periodic table
Electron Shell/ Electron Cloud – electrons
are found moving around the nucleus in the
“cloud”
Atomic
mass
Chemical Bonding
Molecule – particle formed when two or more
atoms chemically combine (H2)
Compound – particle formed when two or more
atoms of different elements chemically
combine (H2O)
Molecular formulas – depict the elements
present and the number of each atom
present in the molecule or compound
H2
C6H12O6
H2O
Ionic Bonds

Ionic Bond – attraction between a cation and an
anion; formed when electrons are transferred
from one atom to another atom

Cation – atoms that have lost electrons and have a net positive charge
Anion – atoms that have gained electrons and have a net negative charge

Covalent Bonds - Formed when atoms
share electrons
Hydrogen atoms form single bonds
Oxygen atoms form two bonds
Nitrogen atoms form three bonds
Carbon atoms form four bonds
H―H
O=O
N≡N
O=C=O
Nonpolar covalent – atoms remain electrically neutral and share electons
equally
Polar covalent – an unequal sharing of electrons between atoms causes a
slightly positive end and a slightly negative end
Chemical Reactions

Metabolism = all the chemical reactions
occurring in the body.
2H2 + O2  2H2O
reactants
products
 Chemical reactions occur when chemical
bonds form or break among atoms, ions,
or molecules
Hydrogen Bonds
a
weak attraction between the positive end
of one polar molecule and the negative
end of another polar molecule
 formed between water molecules
 important for protein and nucleic acid
structure
Types of Reactions




Synthesis Reaction – more complex chemical structure is
formed; Anabolism – the synthesis of new compounds in the
body
A + B  AB
Decomposition Reaction – chemical bonds are broken to form a
simpler chemical structure; Catabolism – decomposition of
complex molecules within cells
AB  A + B
Double Replacement/Exchange/Metathesis Reaction – chemical
bonds are broken and new bonds are formed
AB + CD  AD + CB
Reversible Reaction – the products can change back to the
reactants; at equilibrium the rates of the two reactions are in
balance
A+B
AB
Enzymes or catalysts





Most chemical reactions do not
occur spontaneously; they need
something to speed it up or make it
happen
The amount of energy required to
start reactions is the activation
energy.
Enzymes belong to a class of
substances called catalysts –
compounds that accelerate
chemical reactions without
themselves being permanently
changed.
If it releases energy it is
exergonic.
If more energy is required to begin
the reaction than is released, it will
absorb energy as a whole and is
endergonic.
Organic vs. Inorganic

Organic molecules





contain C and H
usually larger than inorganic molecules
dissolve in water and organic liquids
carbohydrates, proteins, lipids, and nucleic acids
Inorganic molecules




generally do not contain C
usually smaller than organic molecules
usually dissociate in water, forming ions
water, oxygen, carbon dioxide, and inorganic salts
Inorganic Substances

Water







most abundant compound in living material
two-thirds of the weight of an adult human
major component of all body fluids
medium for most metabolic reactions
important role in transporting chemicals in the body
absorbs and transports heat
Oxygen (O2)



used by organelles to release energy from nutrients
in order to drive cell’s metabolic activities
necessary for survival
Inorganic Substances

Carbon dioxide (CO2)

waste product released during metabolic
reactions
 must be removed from the body

Inorganic salts

abundant in body fluids
 sources of necessary ions (Na+, Cl-, K+, Ca2+, Mg2+
etc.)
 play important roles in metabolism
Acids, Bases, & Salts




Acids – any substance that dissociates in solution to release
hydrogen ions (H+); the pH is the H+ concentration
 HCl  H+ + ClBases – A substance that removes the hydrogen ions from a
solution; most dissociate to liberate a hydroxide ion (OH-)
 NaOH  Na+ + OHBuffers – compounds that stabalize pH by either removing or
replacing hydrogen ions
 Antacids like Tums, Rolaids; baking soda (sodium
bicarbonate)
Salts – electrolytes formed between the reaction of an acid and
a base; composed of oppositely charged ions
 Electrolytes can conduct an electrical current in solution
 Important electrolytes for body functions: Na+, K+, Ca2+, Cl-,
Mg2+
Macromolecules of Cells

Macro = large

4 types of macromolecules in cellular biology
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
Macromolecule #1: Carbohydrates

Sugars and groups of sugars

Purposes: energy and structure

Includes three types:
 Monosaccharide (1 sugar – quick energy)
 Disaccharide (2 sugars – short storage)
 Polysaccharide (many sugars – energy
long storage & form structures)
Macromolecule #1: Carbohydrates

Polysaccharide Examples:

Glycogen—glucose polymer stored for future energy
needs. Found in liver, muscle and sperm, etc.

Cellulose—glucose polymer used to form fibers for plant
structures. Humans can’t digest (fiber). Most abundant
organic molecule.

Chitin—glucose polymer for exoskeletons of some
crustaceans & insects.
Polysaccharides
Polysaccharides
Macromolecule #2: Lipids
Insoluble in water (think oil & water)
Types:

 1-Fats: triglycerides (fats & oils)
 (long-term energy storage, insulation)
 Building blocks are fatty acids and glycerol
 2-phospholipids
(primary component of cell
membrane)

A glycerol and two fatty acids linked to a nonlipid group by a
phosphate group
 3-steroids (cell signaling)
 cholesterol molecules modified to form sex hormones. (e.g.
testosterone, estrogen, etc.)
Triglycerides
Phospholipids
Steroids
Macromolecule #3: Proteins


Probably the most complicated of all biological
molecules.
Serve the most varied purposes, including:
Support
structural proteins (e.g., keratin, collagen)
Enzymes
speed up chemical reactions
Transport
cell membranes channels, transporters in blood
(e.g., Hemoglobin)
Defense
antibodies of the immune system
Hormones
cell signaling (e.g., insulin)
Motion
contractile proteins (e.g., actin, myosin)
Collagen
Antibodies
Cellular Transport
*Note*
Red blood cells are RED…not
blue!
Motion
Actin & myosin
fibers in muscles
Macromolecule #3: Proteins
The building blocks of proteins are AMINO
ACIDS. There are only 20 types of Amino
Acids.
 There are millions of different proteins,
and they are all built from different
combinations of the 20 amino acids.
 Amino acids join together to form peptides,
polypeptides, and polypeptide chains.

Macromolecule #4: Nucleic Acids

Nucleotides: building blocks of nucleic acids.
 Each nucleotide contains
 (a) phosphate molecule,
 (b) nitrogenous base, and
 (c) 5-carbon sugar

Several types of nucleic acids, including:
 DNA: deoxyribonucleic acid
 Genetic material, double stranded helix
 RNA: ribonucleic acid
 Genetic material, single stranded
 ATP: adenosine triphosphate
 High energy compound
DNA
Nucleotide structure
THE BIG
PICTURE
Chemistry is
essential for
life…