11. Ex: Heterozygotes
• May express both alleles which can have
benefits
• Ex: In sickle cell- heterozygotes have
some
12. Example, Antifreeze Gene in
Fish• Arctic cod: enzyme in cells called Sialic Acid
Synthase
• Through duplication and slight alterations
it became a protein in blood that allows
fish to
swim in water below freezing point
13. More Protein Diversity than Gene
Diversity
http://www.piercenet.com/browse.cfm?fldID=7CE3FCF5-0DA0-4378-A513-
15. Essential Knowledge
• Essential knowledge 4.B.1: Interactions
between molecules affect their structure
and function.
• a. Change in the structure of a molecular
system may result in a change of the function
of the system.
• b. The shape of enzymes, active sites, and
interaction with specific molecules are
essential for basic functioning of the enzyme.
16. • Structural support, storage, transport,
cellular
communications, movement, and defense
against foreigners
• Make up more than 50% of dry mass of cells
Protein Functions!
19. Example: Lactase, an Enzyme
• Enzyme that helps break down sugar lactose into
galactose and glucose. Speeds up reactions rates:
• Lactose intolerant: Mutation of Chrom. 2.
• Cramps, bloating, flatulence
20. • Hormonal protein: regulates sugar in
blood (tells cells to take it in), pancreas
Example: Insulin
24. Protein Structure and Function
• Consists of 1/more polypeptides
twisted, folded, and coiled into a
unique shape (determined by amino
acid sequence)
25. Four Levels of
Protein Structure
• Primary,
Secondary,
Tertiary,
Quartenary!
• Watch
Videos!
26. Hollow
cylinder
Cap
Chaperonin
(fully assembled)
Polypeptide
Steps of Chaperonin
Action:
1 An unfolded poly-
peptide enters the
cylinder from one end.
2 The cap attaches, causing the
cylinder to change shape in
such a way that it creates a
hydrophilic environment for
the folding of the polypeptide.
3 The cap comes
off, and the properly
folded protein is
released.
Correctly
folded
protein
•Chaperonins are protein molecules that
assist the proper folding of other proteins
27. Sickle-Cell Disease: A Change in
Primary Structure
• A change in primary structure can affect
a
proteiŶ’s struĐture aŶd aďility to fuŶĐtioŶ
• Ex: Sickle-cell disease: results from a
single
30. Fig. 5-22c
Normal red
blood cells are
full of individual
hemoglobin
molecules, each
carrying oxygen.
Fibers of abnormal
hemoglobin
deform red blood
cell into sickle
shape.
10 µm 10 µm
31. Messing Up Proteins?
• Alterations in pH, salt concentration,
temp.,
or other environmental factors can cause a
protein to unravel denaturation
inactive protein
32. • Acts as a catalyst to speed up
chemical
reactions
• Can perform functions repeatedly
workhorses!
Enzyme Proteins!
33.
34.
35.
36. Cofactor
s
• A non-protein chemical compound
required for enzyme activity Ex: Fe
• “Helper MoleĐules" that assist iŶ
ďioĐheŵiĐal
37. Coenzym
es
• A protein chemical compound required for
enzyme activity
• “Helper MoleĐules" that assist iŶ
ďioĐheŵiĐal
38. Cofactors and
Coenzymes
• Work together to regulate enzyme function.
• Usually the interaction relates to a structural
change that alters the activity rate of the
enzyme
41. Allosteric Competition
• Binding of
inhibitor to
another
(allosteric) site
of enzyme
(rather than
active site)
prevents
binding of
42. Model Interpretations
• The change in function of an enzyme can
be interpreted from data regarding the
concentrations of product or substrate as a
function of time. These representations
demonstrate the relationship between an
eŶzyŵe’s aĐtivity, the disappearaŶĐe of
substrate, and/ or presence of a
competitive inhibitor.
