1. Macromolecules Part 3
Proteins

2. Proteins!

3. Functions of Proteins Structural support Storage Transport
Cellular communications
Movement
Defense against foreign substances

4. Proteins Monomer: amino acids Polymer: polypeptide chains (proteins)
Amine (NH2) and carboxyl (COOH) groups attached to carbon
Only thing different is side chain…R-group
Polymer: polypeptide chains (proteins)
Link between monomers is called: polypeptide bond
Made by a dehydration reaction
(between amine group of one aa and carboxyl group of another aa)
STRUCTURE of A.A.
Amino group on one end (-NH2)
Carboxyl group on one end (COOH)
Hydrogen
R-group/side chain (changes)  ALANINE
Proteins account for more than 50% of the dry mass of most cells

6. Polypeptide bonds
DEHYDRATION!!!

9. Some famous proteins… Essential components of cell membranes
Oxygen-carrying pigment hemoglobin (hemoglobin)
Antibodies which attack and destroy invading microorganisms

10. Protein Structure the association of the polypeptide chains
Primary structure 1’
Order of amino acids in a polypeptide chain
Secondary structure 2’
Polypeptide chain folds because of interactions between amino acids
HYDROGEN BONDING
Tertiary Structure 3’
Gives proteins 3-D shape
VERY IMPORTANT to function of protein
Beta pleated sheets and alpha helices fold based on interactions between R-groups of a.a.
Hydrogen bonds, polar/non-polar interactions, acid/base interactions, disulfide bonds, van der Waals forces
Quaternary Structure 4’
the association of the polypeptide chains
some proteins contain more than one polypeptide chain
Each polypeptide chain in the protein is called a subunit
Two or more subunits come together for a specific function
HEMOGLOBIN
On Red blood cells
Its shape allows RBCs to carry oxygen all around your body!

11. Primary Structure Sequence of AA in a long polypeptide chain
AA= letters of alphabet
Sequence of AA= arrangement of letters to make words
HUGE amount of different primary structures
Changing ONE AA is polypeptide chain GREATLY changes the properties of the polypeptide chain and PROTEIN

12. Three possible 2o structures
Determined by order R-groups
No particular arrangement
Alpha helix
Polypeptide chains that coil tightly
Beta pleated sheet
Looser, straighter shape created by hydrogen bonds
Secondary Structure
The order of AA in polypeptide chain determine interactions between functional groups of AA
Functional groups interact via HYDROGEN BONDS
Attraction between oxygen in the –CO end of one AA and the hydrogen in the –NH end of another AA
H-bond easily broken
Change pH and change Temperature

14. Tertiary Structure Secondary structure gets coiled and folded
Precise 3D shape
Folding is determined by interactions between R-groups
Hydrogen bonds
Tryptophan
Arginine
Asparigine
Disulphide bonds
Between 2 cystine molecules
Ionic bonds
b/t R groups containing amine and carboxyl groups
Hydrophobic interactions
b/t R groups that are non-polar (hydrophobic)

16. Quaternary Structure
Proteins are made up of multiple polypeptide chains, sometimes with an inorganic component (for example, a haem group in haemoglogin)
Prosthetic Group (inorganic component of protein)
These proteins will only be able to function if all subunits are present
Made by same bonds found in tertiary structure
Interactions between R-groups
Hydrogen bonds
Tryptophan
Arginine
Asparigine
Disulphide bonds
Between 2 cystine molecules
Ionic bonds
b/t R groups containing amine and carboxyl groups
Hydrophobic interactions
b/t R groups that are non-polar (hydrophobic)

19. Denaturation Unraveling/unfolding of protein
Why would this be a problem?
When protein loses its 3-D shape and thus its specific function
Caused by:
Unfavorable changes in pH, temperature or other environmental condition
Disrupts the interactions between side chains and causes loss of shape
Examples:
Frying an egg
Straightening your hair

21. Why do you think we can compare it to this?
Enzymes!
Why do you
think we can
compare it to this?

22. ENZYMES!!! A special type of protein…???
In order for a protein to work at its SPECIFIC JOB, it must have….???
Because an enzyme is a protein, it MUST have….???
Can any key unlock the door to your house???
Can any substrate/reactant fit into a specific enzyme?
How many different enzymes do we have???

23. Proteins
Biological catalysts that speed up the rate of chemical reactions
They help make products faster!
Never used up!
“Matchmaker”
ENZYMES!!!

24. Enzymes in Action
Enzymes speed up chemical reactions that take place in cells
They DECREASE ACTIVATION ENRGY
The energy needed to get the reaction started (or energy needed to start making product)

25. break up hydrogen peroxide
Catal-ASE is an enzyme
that helps
break up hydrogen peroxide

26. Proteins: Enzymes What is a chemical reaction?
Do they happen on their own?
If we stare at the piece of paper, are we going to be able to make the oxygen molecules in the air collide with the cellulose in the paper?
What do we need to do?
What are reactants?
What are products?

27. Factors that Effect the Rate of Reactions
Temperature
Hot
Breaks bonds that give proteins its tertiary structure DENATURES
Cold
Slow down chemical reaction (formation of enzyme substrate complex) pH
Acids and bases produce OH- and H+ ions
too many ions are present, the enzyme may be denatured (twisted and pulled so out of shape that it can no longer function)
Inhibitors
Non-competitive
react with portions of the active site, changing of its shape
Allosteric Inhibitors
Change shape of the enzyme
Attach to regulatory site (not active site) and change the shape of the entire enzyme (specifically the active site)
Competitive
look like substrate, bind to active site, but do not make the intended product

30. Examples of endothermic reactions:
Melting of ice absorbs energy
Dissolving ammonium nitrate in water( the essence of commercial cold packs)
PHOTOSYNTHESIS
Examples of exothermic reactions:
Digestion of food releases energy (CELL RESPIRATION)
All combustion reactions (fires)
C + O2 CO2 + E
Adding an alkali metal to water
2 Na + 2 H2O 2 NaOH + H2 + E
Condensation of water
Explosion of bombs

31. Endothermic Reactions
the reactants have less potential energy than do the products. Energy must be input in order to raise the particles up to the higher energy level.
Energy + A + B --> AB

32. Exothermic Reactions
the reactants have more potential energy than the products have. The extra energy is released to the surroundings.
A + B --> AB + Energy

33. Enzymes Substrate Molecule/compound that attaches to enzyme
Catalyst
Anything that speeds up the rate of a reaction by lowering the ACTIVATION ENERGY
Activ. E: energy required for a chem. Rxn to start making products
used to regulate the rate (speed) of chemical reactions
Protein that helps speed up a reaction that occurs in a biological system
Name of enzymes end in –ASE
all enzymes are proteins, but not all proteins are enzymes
each chemical reaction in an organism requires its own specific enzyme
enzymes are never changed by their reactions!
Substrate
Molecule/compound that attaches to enzyme
Active Site
Specific location on enzyme for substrate to attach
Where the enzymatic reaction occurs
Enzyme-substrate complex
When substrate binds to active site of enzyme
Products
molecules produced at the end of an enzymatic reaction

34. Acetylcholinesterase
catalyzes the breakdown of the neurotransmitter acetylcholine at several types of synapses as well as at the neuromuscular junction — the specialized synapse that triggers the contraction of skeletal muscle.
One molecule of acetylcholinesterase breaks down 25,000 molecules of acetylcholine each second
makes possible the rapid "resetting" of the synapse for transmission of another nerve impulse.

36. Lock and Key Model

39. Class work! Label Each box!2. 3. 4. 1. 5.

40. 6.
Class Work! Label Boxes! 7. 8. 9.
10.