Study guide: Biomolecules and Enzymes
Connect molecular structure to biological functions and reaction catalysis.
Ideas to explain in your own words
- Biological molecules have varied functions. Proteins are amino-acid polymers; nucleic acids store and express sequence information. Lipids and carbohydrates are chemically diverse, so no single job describes every member.
- Enzymes accelerate reactions by lowering activation-energy barriers. They do not change the reaction’s overall free-energy difference or get used up in the net reaction. Conditions can alter their activity.
- Average product rate equals product molecules in model count divided by seconds. Rate comparisons require matched conditions.
- A useful comparison separates activity changes from changing measurements or conditions. Temperature and pH can affect shape and interactions. A one-factor test supports a narrower claim than a confounded one.
Useful vocabulary
- carbohydrate
- sugars and related structural or energy molecules
- substrate
- molecule acted on by enzyme
- model molecules/s
- Supplied product-formation rate measured as model molecule count per second.
- Average product rate
- Average product rate equals product molecules in model count divided by seconds.
- matched temperature test
- only temperature changes
Watch your reasoning
- Confusing carbohydrate with lipid although their functions or changes differ.
- Confusing substrate with active site although their functions or changes differ.
- Using the distractor operation a*b instead of a/b; Divide product count by duration.
A worked review example
Worked supplied problem: A cell contains DNA, an enzyme and phospholipids. Connect molecular groups to three different functions. Solution: DNA stores sequence information; the protein enzyme can catalyze a reaction; phospholipids contribute to membrane structure. No one group replaces every role of the others. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place. Worked supplied problem: Catalyzed and uncatalyzed models have the same products and overall energy difference but different rates. Explain the mechanism. Solution: The enzyme lowers the activation barrier, enabling faster reaction under the stated conditions. It does not change the products’ overall energy difference or create energy. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place. Worked distinct example: A distinct record produces 45 model molecules in 5 s: 45/5=9 per second. Method: identify the quantities in the stated rule, substitute using compatible units, and perform the operations in the correct order. Divide product count by duration. Model counts are not actual single-molecule measurements. Interpret the final unit and keep the model assumption visible; this calculation is not a measurement of a real learner or site. Worked supplied problem: Trial A changes temperature only; trial B changes temperature and substrate amount. Compare causal scope. Solution: A better isolates temperature under matched stated conditions. B is confounded because substrate amount may also affect the observed rate. Neither establishes universal behavior beyond tested conditions. This conclusion uses the stated observations and the mechanism explained above; it does not establish every unmeasured feature of a real organism, device or place.
Make a practice plan
- Explain the mechanism in Compare major biomolecule groups using a labeled case.
- Complete Explain enzymes and correct the specific misconception in its feedback.
- Resolve a changed case from Calculate a supplied enzyme rate, then combine the four ideas in the transfer task.