UNIT 1: Chemistry of Life
What type of bond is responsible for base pairing in DNA?
Hydrogen bonds.
Which organelle is responsible for ATP production through anaerobic respiration?
None - anaerobic respiration does not take place in an organelle
What do enzymes do to the activation energy of a reaction?
They lower it
How does a phosphorylation cascade amplify a signal?
It activates different molecules which in turn activate other molecules
What type of graph is appropriate for showing reaction rate vs. temperature?
Line graph
During hydrolysis of a carbohydrate, what happens?
Water is added to break a covalent bond between monomers.
Which molecules can cross the cell membrane easily?
Small and non-polar
Why does cellular respiration require oxygen?
Oxygen serves as the final electron acceptor in the electron transport chain.
What must a ligand bind to in order to begin a signaling pathway?
A receptor protein.
What does non-overlapping 2SEM error bars suggest when comparing two means?
A statistically significant difference.
Why do unsaturated fatty acids tend to be liquid at room temperature?
Double bonds introduce kinks, preventing tight packing of molecules.
Why does a plant cell become turgid in a hypotonic environment?
Water enters the cell, but the rigid cell wall prevents bursting.
Why does fermentation allow glycolysis to continue without oxygen?
It regenerates NAD⁺ by reducing pyruvate or pyruvate derivatives.
What are the three basic stages of cell signaling?
Reception → Transduction → Response.
A solution has Ψs = –4.0 bars and Ψp = +1.5 bars. What is the water potential?
–2.5 bars.
Which functional group/s is/are found in all amino acids and help form peptide bonds?
The amino group (—NH₂) and carboxyl group (—COOH).
Explain how adding more folds to a membrane increases its efficiency.
Increased surface area enhances diffusion and space for reactions.
What effect does inhibiting the electron transport chain have on NADH levels?
NADH accumulates because it cannot be oxidized back to NAD⁺.
What is the role of cyclin-dependent kinases (CDKs)?
They phosphorylate proteins that regulate cell cycle transitions.
A student measures mass change in potato cores placed in sucrose solutions. Mass change is zero at 0.35 M sucrose. What is the approximate solute concentration of the potato cells?
0.35M
If a quaternary protein is exposed to very high temperatures, how will the different levels of protein structure be affected?
Tertiary and secondary will be disrupted, primary will be intact.
How does compartmentalization improve metabolic efficiency in eukaryotic cells?
It isolates incompatible reactions and creates optimal microenvironments (e.g. pH in lysosomes)
Explain how chemiosmosis powers ATP synthesis.
A proton gradient drives protons through ATP synthase, phosphorylating ADP.
How can failure of the G₂ checkpoint lead to cancer?
Damaged or unreplicated DNA is allowed into mitosis, increasing mutation accumulation.
If chromosomes fail to separate during anaphase I or anaphase II, what will be the consequences for the gametes?
Some will have excess chromosomes and some will lack chromosomes