Transcript SBI 4U biochem 1

Biochemistry
The Molecules of Life
Chemistry in Living Systems
• Elements: simplest form of a
substance - cannot be broken down
any further without changing what it is
• Atom: the actual basic unit composed of protons, neutrons, and
electrons
The Atom
• Just like cells are the
basic unit of life, the
ATOM is the basic unit
of matter.
• They are very small. If
placed side by side one
million would stretch a
distance of 1cm.
• The atom is made up of
3 particles.
Particle
Charge
PROTON
+
NEUTRON
NEUTRAL
ELECTRON
-
• Electrons are not present within the atom,
instead THEY REVOLVE AROUND THE
NUCELUS OF THE ATOM & FORM THE
ELECTRON CLOUD
• Draw a helium atom. Indicate where the
protons, neutrons and electrons are.
ATOMIC # = 2 (PROTONS)
ATOMIC MASS = 4
(PROTONS &
NEUTRONS)
PROTONS
NEUTRONS
-
ELECTRONS
+
+
-
ISOTOPES
•
•
•
atoms of the same element that HAVE A
DIFFERENT NUMBER OF NEUTRONS
Some isotopes are radioactive. This means
that their nuclei is unstable and will break
down at a CONSTANT RATE over time.
There are several practical uses for
radioactive isotopes:
1. CARBON DATING
2. TRACERS
3. KILL BACTERIA / CANCER CELLS
Common Elements
• The cell is a COMPLEX CHEMICAL FACTORY
containing some of the same elements found in
the nonliving environment.
• carbon (C), hydrogen (H), oxygen (O), and
nitrogen (N) are present in the greatest
percentages in living systems
• Most atoms are found in living systems as
molecules (2 or more non-metal atoms bonded
together).
TWO TYPES OF COMPOUNDS
• Organic - Contain C, H, and O in some
ratio (usually referred to as chemicals
of life)
– Carbohydrates, Proteins, Lipids, Nucleic Acids
• Inorganic - usually "support" life - no
specific ratio of C, H, and O
– Water (H2O), Carbon Dioxide (CO2)
Interactions Within Molecules
• Intramolecular forces: chemical bonds
within a molecule
– Covalent bonds: 2 non-metal atoms share
electrons equally
– Polar Covalent bonds: when one atom
attracts electrons more than the other, it
creates a partial negative charge
Interactions Between Molecules
• Intermolecular forces: forces of attraction
between molecules
– Hydrogen Bonding: a weak bond between an
atom with a partial negative and a hydrogen
atom with a partial positive charge.
– Hydrophobic Interactions: when non-polar
molecules group together to stay away from
the polar molecules.
Functional Groups
• An atom or group of atoms attached to a
molecules that gives the molecules
particular chemical and physical
properties.
Macromolecules
• Molecules that are large and complex
• Often made up of repeating subunits called
monomers.
• Carbohydrates: contain carbon, hydrogen, oxygen in a
1:2:1 ratio
– Monosaccharides: one sugar (glucose, fructose,
galactose.
Fun Bio
Challenge:
You must be
able to draw
these!
– Disaccharides: two monosaccharides join
together forming a glycosidic linkage.
– Polysaccharides: many monosaccharides join
together.
• Starch: alpha glycosidic linkage between monomers.
Stored energy found in plants
• Glycogen: alpha glycosidic linkage between
monomers. Stored energy found in animals
• Cellulose: beta glycosidic linkage between monomers.
Provides structural support in plant cell walls.
• Lipids: made of C, H and O atoms, but have fewer
oxygen atoms and are mainly hydrophobic
– Provides longer-term energy for animals
– Triglycerides: made of one glycerol and 3 fatty acids joined
by an ester linkage
• Saturated fatty acids: no double or triple bonds
• Unsaturated fatty acids: one double or triple bond
• Polyunsaturated fatty acids: more than one double or triple bond.
– Phospholipids: a lipid made of a glycerol bonded to two fatty
acids and an “R” group
• “Head” is hydrophilic, “tail” is hydrophobic
– Steroids: lipids that have four carbon based rings attached to
each other
• Cholesterol
• Estrogen
• Testosterone
– Waxes: long carbon-based chains that are solid at room
temperature.
Macromolecules Continued…
Proteins
• contain the elements carbon, hydrogen,
oxygen, and nitrogen
• composed of MANY amino acid subunits
• It is the sequence of the amino acid that
forms the primary structure of proteins.
• The basic amino acid form has a carboxyl
group on one end, a methyl group that
only has one hydrogen in the middle, and a
amino group on the other end.
• Attached to the methyl group is a R group.
• Uses for Proteins:
– As enzymes that catalyze chemical reactions
in the body
– Structural support in bones, tendons, skin,
hair, nails
– Transporting chemicals in the body
– Locomotion for animals: muscle contraction
– Hormones
– antibodies
• There are 20
common amino
acids with 8 of
them being
essential
amino acids
that cannot be
made in the
body and must
be consumed.
Protein Structure
• Primary Structure: the sequence of
amino acids connected together
through peptide bonds
• Secondary Structure: coil-like alpha
helix shapes and folded beta sheets
due to hydrogen bonds
• Tertiary Structure: 3D shapes of
proteins
• Quaternary Structure: multiple
polypeptide chains arranged together
Macromolecules continued…
Nucleic Acids
• Two types: DNA (deoxyribonucleic
acid) and RNA (ribonucleic acid)
• Contain genetic information
• Made up repeating nucleotide
monomers.
• Each monomer contains:
– A phosphate group
– A sugar with five carbons (deoxyribose or
ribose)
– A nitrogenous base (Adenine, thymine,
guanine, cytosine in DNA and in RNA the
same but thymine is replaced by uracil)
• A polymer of nucleotides is a strand that joins
adjacent nucleotides with a phosphodiester bond
(between the phosphate and the hydroxyl groups)
• DNA is two strands twisted in a double helix
• The two strands are held together by hydrogen bonds
• Thymine always bonds with adenine (with 2 H-bonds)
and cytosine always bonds with guanine (with 3 Hbonds). These are called complementary base pairs.