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Biomolecules & Enzymes

9th Grade Biology Β· Self-Paced Learning Module

4 Macromolecules Enzyme Mechanics 6 Modules 10-Question Quiz Assignment
Module Progress0 of 6 complete

Video Lessons

3 Videos
Learning Objectives β€” Biomolecules & Enzymes Students will identify the four classes of macromolecules (carbohydrates, lipids, proteins, nucleic acids), describe their monomers, structure, functions, and food sources, and explain how enzymes catalyze biological reactions through induced fit, lowering activation energy, and the role of active sites.
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Video

Key Concepts

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CrashCourse Β· ~10 min

Biological Macromolecules β€” CrashCourse

Carbohydrates, lipids, proteins & nucleic acids β€” structure, monomers, and functions

CrashCourse ~10 min
β–Ά Open on YouTube β†—
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Amoeba Sisters Β· ~9 min

Enzymes β€” Amoeba Sisters

Active site, induced fit, activation energy, enzyme-substrate specificity & inhibition

Amoeba Sisters ~9 min
β–Ά Open on YouTube β†—
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CrashCourse Β· ~11 min

Activation Energy & Enzymes β€” CrashCourse

How enzymes lower activation energy, energy diagrams, and enzyme regulation explained

CrashCourse ~11 min
β–Ά Open on YouTube β†—

Lesson Slides

8 Slides

Macromolecule Explorer

Interactive Reference
How to Use This Section Click each macromolecule tab to explore its structure, function, examples, and food sources in detail. Use this as a study reference alongside the slides and vocabulary.

Carbohydrates

The body's primary energy source β€” made of carbon, hydrogen, and oxygen in a 1:2:1 ratio. Monomer: monosaccharide (simple sugar)

Structure

Monomer β†’ Polymer

Monosaccharides link by glycosidic bonds to form disaccharides and polysaccharides. Ring structures made of C, H, O. General formula: (CHβ‚‚O)β‚™

Functions

What They Do

β€’ Quick energy source (glucose β†’ ATP)
β€’ Energy storage (glycogen in animals; starch in plants)
β€’ Structural support (cellulose in plant cell walls)
β€’ Cell recognition (glycoproteins on cell surface)

Examples

Types of Carbohydrates

Monosaccharides: Glucose, Fructose, Galactose
Disaccharides: Sucrose (table sugar), Lactose (milk sugar), Maltose
Polysaccharides: Starch, Glycogen, Cellulose, Chitin

Food Sources

Where to Find Them

🍞 Bread🍚 Rice🍝 Pasta🍌 BananasπŸ₯” Potatoes🍎 Fruit🧁 Sugar🌽 Corn
πŸ”‘ Key Distinction: Starch (plant energy storage) and glycogen (animal energy storage) are both polysaccharides made of glucose β€” but cellulose, also made of glucose, cannot be digested by humans because of its different glycosidic bond orientation (Ξ²-1,4 bonds). This is why fiber passes through the digestive system.

Lipids

Hydrophobic molecules made of carbon, hydrogen, and oxygen. Not true polymers β€” built from glycerol + fatty acids (fats/oils) or other arrangements.

Structure

Building Blocks

Fats/Oils: 1 glycerol + 3 fatty acid chains (triglyceride) linked by ester bonds
Phospholipids: Glycerol + 2 fatty acids + phosphate head (hydrophilic head, hydrophobic tails)
Steroids: 4 fused carbon rings (e.g., cholesterol)

Functions

What They Do

β€’ Long-term energy storage (fats store 2Γ— more energy per gram than carbs)
β€’ Cell membrane structure (phospholipid bilayer)
β€’ Hormone production (steroid hormones)
β€’ Insulation and protection of organs
β€’ Fat-soluble vitamin absorption (A, D, E, K)

Examples

Types of Lipids

Saturated fats: Butter, lard (solid at room temp β€” single bonds)
Unsaturated fats: Olive oil, fish oil (liquid at room temp β€” double bonds)
Phospholipids: Cell membranes
Steroids: Cholesterol, estrogen, testosterone, cortisol
Waxes: Cuticle on plant leaves

Food Sources

Where to Find Them

πŸ₯‘ Avocado🧈 ButterπŸ«’ Olive oil🐟 FishπŸ₯œ NutsπŸ§€ CheeseπŸ₯š Egg yolkπŸ₯© Meat
πŸ”‘ Key Distinction: Saturated fatty acids have no double bonds between carbons β€” they pack tightly and are solid at room temperature. Unsaturated fats have one or more double bonds, creating kinks that prevent tight packing, making them liquid oils at room temperature. Trans fats are artificially hydrogenated unsaturated fats and are linked to cardiovascular disease.

Proteins

The most diverse and versatile macromolecules. Monomer: amino acid. 20 different amino acids linked by peptide bonds form all proteins.

Structure

Four Levels of Structure

Primary: Sequence of amino acids (peptide bonds)
Secondary: Ξ±-helices and Ξ²-pleated sheets (H-bonds)
Tertiary: 3D folded shape β€” determines function
Quaternary: Multiple polypeptide chains (e.g., hemoglobin)

Functions

What They Do

β€’ Enzymes β€” catalyze reactions
β€’ Structural β€” collagen, keratin, actin
β€’ Transport β€” hemoglobin carries Oβ‚‚
β€’ Hormones β€” insulin regulates blood sugar
β€’ Antibodies β€” immune defense
β€’ Movement β€” myosin in muscle cells
β€’ Cell signaling β€” receptor proteins

Examples

Proteins in the Body

Enzymes: Amylase, lipase, DNA polymerase
Structural: Collagen (connective tissue), Keratin (hair/nails)
Transport: Hemoglobin, albumin
Hormones: Insulin, glucagon
Antibodies: Immunoglobulins
Motor: Myosin, kinesin

Food Sources

Where to Find Them

πŸ₯© Meat🐟 FishπŸ₯š Eggs🫘 BeansπŸ₯› DairyπŸ₯œ Nuts🌾 QuinoaπŸ§† Tofu
πŸ”‘ Key Concept β€” Denaturation: When proteins are exposed to extreme heat, pH changes, or chemicals, they lose their 3D shape (tertiary structure) β€” this is called denaturation. A denatured protein can no longer perform its function. This is why cooking changes the texture of egg whites (albumin denatures) and why high fever is dangerous (enzymes denature).

Nucleic Acids

Carry genetic information and direct protein synthesis. Monomer: nucleotide (phosphate group + sugar + nitrogenous base).

Structure

DNA vs RNA

DNA: Double helix, deoxyribose sugar, bases A-T-G-C, stable, found in nucleus
RNA: Single strand, ribose sugar, bases A-U-G-C, short-lived, multiple types (mRNA, tRNA, rRNA)
Nucleotides linked by phosphodiester bonds

Functions

What They Do

β€’ DNA β€” stores and transmits genetic information
β€’ mRNA β€” carries instructions from DNA to ribosomes
β€’ tRNA β€” brings amino acids to ribosomes during translation
β€’ rRNA β€” makes up ribosome structure
β€’ ATP β€” energy currency of the cell (nucleotide derivative)

Examples

Types of Nucleic Acids

DNA: Deoxyribonucleic acid β€” the genome
mRNA: Messenger RNA β€” transcription product
tRNA: Transfer RNA β€” translation adapter
rRNA: Ribosomal RNA β€” ribozyme activity
ATP: Adenosine triphosphate β€” energy carrier

Food Sources

Where to Find Them

Every cell contains nucleic acids β€” eating any whole food provides them.

🐟 Sardines🫘 LentilsπŸ– Organ meatsπŸ„ MushroomsπŸ₯¦ Broccoli🌾 Whole grains
πŸ”‘ Central Dogma: DNA β†’ (transcription) β†’ RNA β†’ (translation) β†’ Protein. Nucleic acids control which proteins are made, and proteins carry out virtually every function in the cell. This is why nucleic acids are considered the "master blueprint" of life.

Key Vocabulary

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Knowledge Check

10 Questions
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Assignment

5 Parts Β· 45 Points Total

Biomolecules & Enzymes β€” Unit Assignment

Complete all five parts using what you learned from the videos, slides, macromolecule explorer, and vocabulary. Type your answers directly in the boxes below. When finished, use the Print button to submit a paper copy.

πŸ“… Due: See teacher 🎯 45 Points Total ⏱ ~50 minutes

Key Concepts Reference

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Carbohydrates

Monomer: monosaccharide Β· Energy source Β· Starch, glycogen, cellulose

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Lipids

Glycerol + fatty acids Β· Long-term energy Β· Cell membranes Β· Hormones

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Proteins

Monomer: amino acid Β· Enzymes, structure, transport, immunity

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Nucleic Acids

Monomer: nucleotide Β· DNA stores genome Β· RNA directs protein synthesis

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Enzymes

Biological catalysts Β· Lower activation energy Β· Active site + induced fit

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Enzyme Factors

Temperature, pH, substrate concentration Β· Denaturation above optimal

1

Multiple Choice β€” Core Concepts

10 pts β–Ό

Select the best answer for each question.

1. What is the monomer (building block) of proteins?

2. Which macromolecule makes up the cell membrane's bilayer?

3. An enzyme lowers the activation energy of a reaction. What does this mean?

4. Which of the following is a polysaccharide used for energy storage in animals?

5. The monomer of nucleic acids is a:
2

Fill in the Blank β€” Macromolecules Table

8 pts β–Ό

Complete the table by filling in each blank about the four macromolecules.

MacromoleculeMonomerKey FunctionExample
Carbohydrates
Lipids
Proteins
Nucleic Acids
3

Matching β€” Enzyme Concepts

8 pts β–Ό

Match each term on the left to its correct description on the right.

Term

1. Active Site β†’
2. Induced Fit β†’
3. Substrate β†’
4. Denaturation β†’
5. Activation Energy β†’
6. Catalyst β†’
7. Inhibitor β†’
8. Enzyme β†’

Description

A. Region on an enzyme where the substrate binds
B. The enzyme slightly changes shape to fit the substrate
C. The molecule that an enzyme acts upon
D. Loss of protein shape due to heat or pH change
E. Energy needed to start a chemical reaction
F. Substance that speeds up a reaction without being consumed
G. Molecule that blocks enzyme activity
H. Biological catalyst made of protein

4

Short Answer β€” Analysis & Explanation

14 pts β–Ό
1. Explain the induced fit model of enzyme-substrate interaction. How does it differ from the older "lock and key" model? (4 pts)
Hint: Think about what happens to the enzyme's active site when a substrate approaches. What does the enzyme do that a rigid lock cannot?
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2. How do enzymes lower activation energy? Draw or describe what an energy diagram looks like with and without an enzyme, and explain why this matters for cells. (5 pts)
Hint: Think about the energy "hill" a reaction must climb. What does the enzyme do to the height of that hill? Why would cells need reactions to happen quickly at body temperature?
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3. A student boils an enzyme and then tests its activity. She finds it no longer works. Explain why, using the terms denaturation, active site, and tertiary structure. (5 pts)
Hint: What does heat do to the protein's three-dimensional shape? Why does shape matter for an enzyme's function?
0 words
5

Extended Response β€” Real World Application

5 pts β–Ό
Choose ONE scenario and write a well-developed paragraph (minimum 5 sentences) applying your knowledge of biomolecules and/or enzymes:
0 words
β–Ά View Scoring Rubric
CriteriaFull CreditPartial CreditNo Credit
Accuracy (2 pts)All scientific facts are correct and precisely statedMinor factual errors that don't undermine main ideaMajor errors or missing key concepts
Depth (2 pts)Thorough explanation with specific details (macromolecule names, enzyme terms, mechanisms)Some detail but surface-level explanationVery vague or no detail
Connections (1 pt)Clearly links to real-world context of chosen scenarioWeak or unclear connection to scenarioNo connection to scenario
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