Amino Acid Chemistry Slides Lesson 1
Amino Acid
Chemistry
Classifying the building blocks of life to predict the future of a protein.
The Universal Template
01 // STRUCTURE
\[ H_2N - CH(R) - COOH \]
Amino Group
\( -NH_2 \)
Carboxyl Group
\( -COOH \)
The Variable "R" Group
The side chain that determines identity and chemical behavior.
1
Every amino acid shares the same backbone. This allows them to link into long chains.
2
The R-group is what makes each of the 20 amino acids unique.
3
Side chains interact with water, lipids, and each other to fold the protein.
The Three Major Classifications
Non-Polar
"Hydrophobic"
Water-fearing
Tuck into the center
Mostly C-H bonds
Oil-Liking
Polar
"Hydrophilic"
Water-loving
Stay on the surface
Uneven charges (O, N, S)
Water-Liking
Charged
"Ionic Interaction"
Basic (+ charge)
Acidic (- charge)
Form salt bridges
Highly Reactive
The Mystery Powder Challenge
In today's lab, you will be given three unknown substances. Based only on their interaction with water and lipid (oil), you must determine which one mimics a Hydrophobic R-Group.
Substance A
Clumps at the surface of water, dissolves instantly in mineral oil.
Substance B
Dissolves in water, sinks to the bottom of the oil beaker.
Amino Acid Classification Worksheet Chemical Persona Worksheet
BIO // UNIT 4 // L1
Student Name:
Date:
Part 1: The "R" Groups
Below are four specific amino acids. Your task is to analyze their side-chain (R-group) and classify them based on their chemical properties.
1. Valine (Val)
\[ -CH(CH_3)_2 \]
Classification (Circle One):
Non-Polar Polar Charged (+/-)
Prediction:
Where would this amino acid be found in a folded protein in water?
2. Glutamic Acid (Glu)
\[ -CH_2CH_2COO^- \]
Classification (Circle One):
Non-Polar Polar Charged (+/-)
Prediction:
What kind of intermolecular force could this side chain form?
3. Serine (Ser)
\[ -CH_2OH \]
Classification (Circle One):
Non-Polar Polar Charged (+/-)
Prediction:
Will this side chain interact with water or avoid it? Why?
4. Phenylalanine (Phe)
\[ -CH_2C_6H_5 \]
Classification (Circle One):
Non-Polar Polar Charged (+/-)
Prediction:
How would this side chain behave in a lipid (oil) environment?
Part 2: Synthesis & Mystery Powder Prep
Predictive Logic
Proteins fold in aqueous (water-based) environments. Based on what you observed in Part 1, explain the Hydrophobic Effect : why do non-polar side chains end up in the interior of a protein?
Mystery Powder Hypothesis
"I have Substance X. When I place it in water, it forms a tight bead and does not dissolve. When I place it in oil, it dissolves completely."
Identify the Property:
Choose a Proxy:
Which amino acid from Part 1 (1, 2, 3, or 4) would act MOST like Substance X?
Mystery Powder Lab Guide Mystery Powder Guide
TEACHER RESOURCE // LESSON 1 // INQUIRY LAB
Pacing
20 - 30 Minutes
Group Size
2 - 3 Students
Objective
Connect solubility behavior to amino acid side-chain classification.
Materials & Preparation
Per Group:
3 small clear beakers or test tubes
Distilled Water
Mineral Oil or Vegetable Oil
Substance A (Cornstarch - Non-polar proxy)
Substance B (Salt - Charged proxy)
Substance C (Sugar - Polar proxy)
Small spatulas or toothpicks for stirring
Teacher Tip: "The Proxy"
While cornstarch isn't technically a single amino acid, its inability to dissolve in water and its tendency to clump or float mimics the hydrophobic effect observed in non-polar side chains. Salt (ionic) is the perfect proxy for charged residues.
The Investigation Script
1. The Hook (5 mins)
Show the class a bottle of oil and water dressing. Ask: "If you were a protein molecule and 80% of your body was water, where would you hide your 'oil-loving' parts?"
2. Guided Inquiry (15 mins)
Students add a small amount of each substance to water and observe. They then repeat the process with oil.
Key Question: "Which powder is actively 'pushed away' by water molecules?" (The cornstarch). Explain that this 'push' is what drives protein folding.
Expected Alignment
SUBSTANCE A
Non-Polar
Valine / Phenylalanine
SUBSTANCE B
Charged
Glutamic Acid / Lysine
SUBSTANCE C
Polar
Serine / Threonine
Protein Folding Levels Slides Lesson 2
Protein Folding
Levels
From a linear sequence of letters to a three-dimensional machine.
The Hierarchy of Structure
Blueprint
1°
Primary
The amino acid sequence. (Beads on a string)
2°
Secondary
Alpha helices & Beta sheets. (Local folding)
3°
Tertiary
Global 3D shape. (Determined by R-groups)
4°
Quaternary
Multiple chains working together.
Level 2: Hydrogen Bonding
α-Helix
A delicate coil stabilized by hydrogen bonds between the backbone atoms.
β-Pleated Sheet
Segments of the chain lying side-by-side, held together by transverse H-bonds.
Crucial Fact:
Secondary structure does NOT involve R-groups yet. It is a property of the backbone itself.
The Final Fold
What Holds Tertiary
Structure Together?
Ionic Bonds
Salt bridges between Acidic (-) and Basic (+) R-groups.
Disulfide Bridges
Strong covalent bonds between Cysteine sulfur atoms.
Hydrophobic Effect
Non-polar groups clustering away from water.
H-Bonds
Interactions between Polar R-groups.
Protein Folding Activity Guide Pipe Cleaner Proteomics
LAB // L2
Modeling the four levels of protein structure using simple materials.
Student Name:
Date:
Structural Key
Pipe Cleaner = Backbone
Red Bead = Acidic (-)
Blue Bead = Basic (+)
Yellow Bead = Non-Polar
Green Bead = Polar
Tape = H-Bond / Bridge
1° & 2° Construction
Slide 10 beads onto your pipe cleaner in any order. This is your Primary Sequence .
Twist one section of the pipe cleaner into a tight spiral (coil). This is an Alpha Helix .
Zig-zag another section back and forth. This is a Beta Sheet .
Observation:
What is holding your helix and sheet in place physically? In a real protein, what holds these together?
3° The Final Fold
Now, fold the entire structure into a globule based on these R-group rules :
Yellow beads must be inside the fold.
Red and Blue beads must be touching each other.
Green beads must be on the outside.
Challenge:
Why must the yellow beads stay on the inside? (Hint: The room is filled with water molecules!)
Quaternary Structure (4°)
Find another group in the classroom. Join your two folded proteins together using one piece of tape.
Definition Check
A quaternary structure is not just a larger fold. It is the interaction between two or more polypeptide subunits . Hemoglobin, for example, has four!
Identify one physiological function that requires multiple proteins to work together:
Structural Bonds Reference Sheet REF // PROTEIN_STABILITY_FORCES
Molecular Glue
Intermolecular forces that dictate protein architecture.
Secondary Structure (2°)
Hydrogen Bonds
Occur between the backbone amino group (N-H) and the backbone carboxyl group (C=O). These are weak individually but strong in numbers, creating stable geometries.
α-Helix
β-Pleated Sheet
Note: R-groups are NOT involved in Level 2 stabilization.
Tertiary Structure (3°)
1
Hydrophobic Interactions
Drive: Water exclusion.
Non-polar R-groups cluster in the protein core to avoid water molecules.
2
Ionic Bonds (Salt Bridges)
Drive: Electrostatic attraction.
Full positive (Basic) and negative (Acidic) charges attract across the fold.
3
Polar Hydrogen Bonds
Drive: Partial charge attraction.
Oxygen or Nitrogen atoms in Polar R-groups attract Hydrogen atoms on other Polar groups.
4
Disulfide Bridges
Drive: Covalent bonding.
The only covalent bond in tertiary structure. Occurs between two Cysteine residues.
Key takeaway
Structure is Dynamic. Changing a single amino acid in the 1° sequence can break any of these bonds, causing the entire protein to misfold.
Digital Modeling Slides Lesson 3
Digital Protein
Modeling
Using bioinformatics to zoom into the active sites of life's tiny machines.
Visualizing the Invisible
X-Ray Crystallography
Proteins are frozen in crystal form and hit with X-rays. The diffraction pattern tells us where every atom is located.
The PDB
The Protein Data Bank stores the 3D coordinates of over 200,000 biological molecules for anyone to use.
Bioinformatics Tools
1
PyMOL : Professional structural biology tool.
2
Jmol / Mol* : Web-based interactive viewers.
3
AlphaFold : AI-driven shape prediction.
Rendering Styles
Cartoon
Shows α-helices and β-sheets clearly. Hides individual atoms.
Stick
Shows every bond and atom. Great for looking at Active Sites .
Surface
Shows the overall volume. Best for seeing "pockets" where drugs bind.
Virtual Tour:
Hemoglobin
Hemoglobin (PDB ID: 1A3N) is the protein that carries oxygen in your blood. In our scavenger hunt, you will search for the Heme Group—the non-protein molecule held in the center.
Today's Goal:
Identify how a single mutation in the amino acid sequence changes the shape of the entire pocket.
Coordinates Loaded
Molecular Scavenger Hunt Worksheet Molecular Scavenger Hunt
BIOINFORMATICS WORKSHOP // PDB ID: 1A3N
Investigator:
Station #:
Deployment Orders
Navigate to rcsb.org and search for 1A3N (Human Hemoglobin). Open the 3D Viewer (Mol*). Follow the checkpoints below to explore the structure.
1
Global Hierarchy
How many chains (subunits) make up the total protein complex?
2
The Heme Pocket
Switch to "Surface" view. Locate the non-protein ligand (the Heme group). What color is it by default? Describe the 'pocket' where it sits.
3
The "Stick" Detail
Select His87 (Histidine at position 87). This amino acid coordinates the iron atom. Change its rendering to "Ball & Stick." Does it appear to be Inside the protein fold or Outside near the water?
Structural Mutation Analysis
Case Study: In Sickle Cell Anemia, the Glutamic Acid (Polar/Charged) at position 6 is replaced by Valine (Non-Polar).
A. Locate Residue #6 on one of the Beta chains. Based on your view, is it normally exposed to the aqueous surroundings?
B. If this Residue becomes Valine (Non-Polar), how will its interaction with the water change? (Recall the "Hydrophobic Effect")
C. Final Prediction: What happens when this "sticky" non-polar patch on one hemoglobin molecule touches another hemoglobin molecule in the blood?
Enzyme to Phenotype Slides Lesson 4
Enzymes &
Phenotypes
Connecting molecular architecture to the visible world: How shape creates color and life.
From Gene to Color
PATHWAY ANALYTICS
Substrate
Tyrosine
(Raw Material)
Enzyme
Tyrosinase
The 3D Fold
Product
Melanin
(Visible Pigment)
"If the Tyrosinase enzyme doesn't have the exact right 3D fold, it cannot bind to Tyrosine. No binding means no melanin. No melanin means no pigment."
Case Study: The Heat-Sensitive Switch
Why are their ears dark?
Siamese cats carry a version of Tyrosinase that is thermally unstable . It misfolds and becomes non-functional at core body temperatures.
"Pigment only forms on the coldest parts of the body (ears, paws, tail) where the enzyme can hold its correct 3D shape."
Cold = Pigment Warm = No Pigment
Structural Albinism
In many cases of albinism, the gene for tyrosinase contains a mutation that replaces just one amino acid.
This tiny change prevents a crucial Disulfide Bridge from forming. The enzyme collapses, and the entire metabolic pathway stops.
GENOTYPE → PROTEIN SHAPE → PHENOTYPE
Pigment Pathway Case Study The Color of Shape
Case Study: Tyrosinase & Pigment Pathways
Lesson 4 PHENOTYPES
Student Name:
Class Period:
Analysis 1: The Siamese Switch
"In Siamese cats, the enzyme Tyrosinase is functional at 33°C (extremities) but denatures (unfolds) at 37°C (core body temperature)."
1. Structural Impact:
Based on Lesson 2, which types of intermolecular forces are likely being broken by the increase in thermal energy (heat)?
2. Predictive Modeling:
If a Siamese cat lived its entire life in a room kept at a constant 38°C, what would you expect its fur color to look like?
Analysis 2: The Single Amino Acid Shift
Wild-Type Enzyme
The amino acid at position 402 is Cysteine . It forms a disulfide bridge with another Cysteine at position 408, locking the active site into a "pocket" shape.
[ Cys402 --- S-S --- Cys408 ]
Mutant Enzyme (Albinism)
The amino acid at position 402 is mutated to Glycine . Glycine cannot form disulfide bridges.
[ Gly402 X Cys408 ]
Question 3: Bonding Loss
How does the loss of the covalent disulfide bridge at position 402 specifically affect the stability of the enzyme's Tertiary Structure?
Question 4: Macro-Effect
Connect the micro to the macro: Explain exactly how a change in ONE atom in the DNA sequence leads to an organism having white fur or skin.
Denaturation and Function Slides Lesson 5
Functional
Denaturation
When the environment attacks: Predicting what happens when proteins lose their shape.
The Point of No Return
Denaturation Definition
The process where a protein loses its native 3D shape due to external stress. The primary sequence remains, but the function is gone.
Is it reversible?
Usually not. Think of an egg white: Once it's cooked (denatured), it cannot be "un-cooked" back into a liquid.
Temperature
Heat vibrates the molecules until weak H-bonds and hydrophobic interactions snap.
pH Level
Excess H+ or OH- ions disrupt the charges in ionic bonds (salt bridges).
Salinity
High salt concentrations interfere with the electrical charges holding the fold.
Inquiry Lab: Catalase
L5 // EXPERIMENT
O&sub2;
\( 2H_2O_2 \xrightarrow{Catalase} 2H_2O + O_2 \)
The Problem
Catalase is an enzyme found in potatoes and liver that breaks down toxic hydrogen peroxide. If we boil the potato, will it still produce oxygen bubbles?
Independent Variable
Temperature / pH
Dependent Variable
Rate of bubbling (O&sub2;)
The Blueprint
is Complete
DNA Code
Amino Acid Chain
3D Protein Fold
Trait / Phenotype
Any break in this chain—whether from a mutation in the code or heat in the environment—changes the phenotype of the organism.
Catalase Lab Report Catalase Inquiry Lab
BIO // L5 // LAB
Investigating the structural limits of biological catalysts.
Investigator:
Date:
Hypothesis
"If I expose the catalase enzyme to (independent variable), then the rate of the reaction will because..."
Observations & Data
Condition Bubble Height (mm) Qualitative Observations (Color, speed, smell) Control (RT Potato) Boiled Potato Acid-Soaked (Vinegar) Freezer-Chilled
Structural Analysis
1. Why did boiling the potato stop the reaction? Be specific about what happened to the Tertiary Structure of the catalase protein.
2. Looking at your Acid-Soaked data: How did the low pH environment disrupt the Ionic Bonds (salt bridges) in the enzyme?
3. Conclusion: The "Active Site" Argument
Imagine a student says: "The boiled potato didn't work because the heat destroyed the atoms in the enzyme."
Correct their reasoning. Did the atoms disappear? What actually changed to prevent the reaction?
