Proteins

Organic compounds made of C, O, H, N and S

Building blocks – 20 different amino acids
Peptide and Polypeptides:
Dehydration (Condensation)/ Hydrolysis Reactions

Functions of proteins (directly related
to the shape of the protein)
 Contraction
of muscles
 Hormones (signals our cells)
 Receptors (found on surface of cells)
 Carriers (oxygen to cells)
 Antibodies (fight off invaders)
 Enzymes
20 Amino Acids
Amino Acids *color sheet
Which part of this
structure gives an amino
acid its uniqueness?
a. amino group
b. side chain
c. carboxyl group
d. central carbon
Review
https://www.wisc-online.com/learn/naturalscience/chemistry/bic007/peptide-bond-formation
Protein
Structure
www.rand.org/.../Rosetta/images/Proteins.gif
4 Classes of Protein
Structure
1.Primary Structure-chain sequence of amino acids
Phenylalanine
The Secondary Structure is
a. hydrogen bonds making alpha helix and pleated sheets
b. chain of amino acids
c. chain of monosaccharides
d. folded chains of many amino acids
b. Pleated Sheet
a. alpha
3. Tertiary Structure-Attractions between alpha helix and
beta sheets folding onto each other
• Hydrophobic interactions
• Disulfide bridges (bonding of 2 cysteine
molecules)
4. Quarternary Structure- more than one amino
acid chain
Ex: Hemoglobin (transport protein)
FUNCTIONS
LET’S REVIEW ON THE BOARD
The following is what gives a protein its particular function.
a. polarity
b. shape
c. activation energy
d. number of substrates
Enzymes
Enzymes - catalytic organic molecules
 Lock & Key model
 Induced fit model
 Enzyme Reactions – temperature & pH
dependant
Enzyme Specificity
Enzymes are nature’s catalysts
 Proteins or RNA
 Are reuseable
 Generally catalyze only one reaction


Enzyme-substrate complex


Substrate – reactant(s) an enzyme acts on
Active site – where substrate binds to the enzyme; has
a specific shape created by folds
This enzyme model is an example
of lock and key or induced fit.
a. lock and key
b. induced fit
Induced Fit Model
What happens to the enzyme after the product leaves?
a. retains the shape of the substrate
b. does not change at all
c. goes back to its original shape
d. keeps the shape of the product
Factors that affect enzyme activity
1.
Temperature – optimal temperature at which
rate of reaction in fastest
2.
pH – optimal pH at which rate of reaction is
fastest
Denaturation
 Protein
loses structure due to some other
outside compound or stress
- adding acid or base
- change in temperature
- large amounts of certain chemicals
 Enzymes will not function
 May or may not be reversable
Ex: eggs and meat
Denaturation
Closing
 1.
What is the building blocks of proteins?
 2. What are 2 functions of proteins?
 3. What controls the function of a protein?
 4. Explain what an enzyme is?
 5. Why is it important for your body to
maintain its internal temperature?
 6. What does it mean for an enzyme to be
denatured?
Animated Denaturation
 http://highered.mcgraw-
hill.com/sites/0072943696/student_view0/
chapter2/animation__protein_denaturation
.html
Nucleic Acids
 Very
large & complex molecules
 Store hereditary information for cells
 DNA & RNA
 Building block: Nucleotide
 A nucleotide contains a
Phosphate Group
5 – C sugar
Nitrogen Base
Differences between DNA and
RNA
DNA

RNA
Double stranded
 Deoxyribose sugar
(5C)
Nitrogen bases






Thymine
Adenine
Guanine
Cytosine
Single strand
 Ribose sugar (5C)
Nitrogen bases



Uracil
Adenine
Guanine
Cytosine
Nucleic
Acid
www.steve.gb.com/.../nucleotides/ssRNA.png