Guided notes covering material from Topics 2.4 and 7.3 of the updated IB Biology syllabus for 2016 exams. Notes sequence and prompts are based on the Oxford IB Biology textbook by Allott and Mindorff.

1. IB Biology Chapter 2 Notes: Proteins (2.4 & 7.3) NAME:
Word Definition
Amino acids The monomer of proteins—they are identical except for their side chains
Primary structure The first level of protein structure—consists of a long chain of amino acids held
together by peptide bonds. This determines the remaining levels (what the protein
will be)
Secondary structure The second level of protein structure—consists of hydrogen bonds between the
carboxyl and amine group on the central chain.
Tertiary structure The third level of protein structure—consists of bonds between the side chains—
causes the protein to fold upon itself
Quaternary
structure
When multiple polypeptides join together using a variety of bonds.
Peptide bond The bond that holds amino acids together—formed through condensation
Proteome
Side chains
(R groups)
The variable part of amino acids—determines the properties of the amino acid
-helix One type of secondary structure—forms a coil
-pleatedsheet One type of secondary structure—folds like a fan
Polypeptide A long chain of amino acids
Covalent bond Bonds formed by sharing electrons, usually formed by two non-metals
Van der Waals Attractions between molecules that are non-polar
Hydrophobic Things that don’t mix with water (they are non-polar)
Hydrophilic Things that mix with water (they are polar)
Ionic bonds Bonds formed by an attraction between opposite forces—usually formed between
one metal and one nonmetal
Conjugated protein A protein formed by joining together multiple polypeptide chains
Fibrous protein A protein whose over all structure is long and thin
Globular protein A protein whose overall structure is like a big clump/ball .

2. 2.4.1 Amino acids are linked
togetherby condensation to
form polypeptides.
2.4.11 Draw molecular
diagrams showing the
formation of a peptide bond.
2.4.2 There are twenty
different amino acids in
polypeptides synthesized on
ribosomes.
2.4.3 Amino acids can be
linked togetherin any
sequence giving a huge
range of possible
polypeptides.
2.4.4 The amino acid
sequence of polypeptides is
coded for by genes.
2.4.5 A protein may consist
of a single polypeptide or
more than one polypeptide
linked together.
2.4.6 The amino acid
sequence determines the
three dimensional
conformation of a protein.
2.4.10 Explain the
denaturation of proteins by
heat or deviation of pH from
the optimum.
Draw formation of a peptide bond:
What is different between each of the 20 amino acids?
What are some of structuraland/or chemical differences between the different amino acids?
Number of
Polypeptides
Example Description
Lysozyme
Collagen
Hemoglobin
Globular proteins (describe and give example):
Fibrous proteins (describe and give example):

3. 2.4.7 Living organisms
synthesize many different
proteins with a wide range of
functions.
2.4.9 Identify rubisco,
insulin, immunoglobulins,
rhodopsin,collagen, and
spider silk as examples of
the range of protein
functions.
2.4.8 Every individual has a
unique proteome.
Protein Function Description
Catalysis
Muscle
contraction
Cytoskeleton
Tensile strength
Blood clotting
Transport of
nutrients/ gas
Cell adhesion
Membrane
transport
Hormones
Receptors
Packing DNA
Immunity
Protein Example Function
Rubisco
Insulin
Immunoglobulin
(Antibodies)
Collagen
Rhodopsin
Spider silk
Describe what is meant by a ‘proteome:’

4. 7.3.7 The sequence and
number of amino acids in the
polypeptide is the primary
structure.
7.3.8 The secondary
structure is the formation of
alpha helices and beta
pleated sheets stabilized by
hydrogen bonds.
7.3.9 The tertiary structure is
the further folding of the
polypeptide stabilized by
interactions between R
groups (side-chains).
7.3.10 The quaternary
structure exists in proteins
with more than one
polypeptide chain.
What types of bonds form the secondary structure?
What are the two secondary structures?
What types of bonds/ interactions form the tertiary structure?