Energy
Which type of chemical bond stores more potential energy: a nonpolar covalent bond or a polar covalent bond?
a nonpolar covalent bond
What is the role of enzymes in chemical reactions within living cells?
They speed up reactions by lowering activation energy.
Which macromolecule is made of amino acids, and which is made of nucleotides?
Proteins are made of amino acids; nucleic acids are made of nucleotides
Why is DNA’s double-stranded, complementary structure essential for replication?
Each strand serves as a template for creating a new complementary strand.
What is the main purpose of mitosis in multicellular organisms?
Growth, repair, and maintenance of tissues
What does entropy measure in a chemical system?
the amount of disorder or randomness
What part of an enzyme binds to the substrate and helps reduce activation energy?
the active site
What type of reaction links monomers together in proteins, nucleic acids, and carbohydrates?
Condensation (dehydration) reaction
Why is the lagging strand synthesized in fragments during DNA replication?
Because DNA polymerase can only synthesize in the 5’ to 3’ direction, opposite to the fork movement on the lagging strand.
How does the chromosome number of daughter cells compare to the parent cell in meiosis?
Daughter cells have half the chromosome number of the parent cell.
What makes a chemical reaction spontaneous?
A negative change in Gibbs free energy (ΔG).
What are the steps of enzyme catalysis?
Enzyme binds substrate → enzyme-substrate complex forms → products released
Which macromolecule stores genetic information, and which one performs most cellular work?
Nucleic acids store genetic information; proteins perform most cellular work
Which enzyme unzips the DNA double helix at the replication fork?
DNA helicase.
In which phase of mitosis do sister chromatids separate and move to opposite poles?
Anaphase
How does ATP hydrolysis help drive endergonic reactions in cells?
By coupling the exergonic hydrolysis of ATP to the endergonic reaction, making the overall process spontaneous.
How can competitive inhibition affect enzyme activity?
It blocks the active site, preventing substrate binding.
Why is DNA more chemically stable than RNA, and how does this difference relate to their cellular roles?
DNA lacks a hydroxyl group at the 2' carbon of its sugar, making it less reactive and more stable than RNA. This stability allows DNA to serve as long-term genetic storage, while RNA’s reactivity suits its temporary roles in protein synthesis and regulation.
At the replication fork, which enzyme synthesizes RNA primers, and why are these primers necessary?
Primase synthesizes RNA primers, which provide a starting point for DNA polymerase to begin replication.
During which phase of meiosis does crossing over occur, and what is its significance?
Prophase I; it increases genetic variation.
How do changes in enthalpy (ΔH), entropy (ΔS), and temperature (T) affect whether a reaction is spontaneous?
A reaction is spontaneous when ΔG = ΔH – TΔS is negative
How does substrate concentration affect the rate of an enzyme-catalyzed reaction?
The rate increases with substrate concentration until the enzyme becomes saturated.
Which macromolecule has the most structural diversity and why?
Proteins, due to 20 different amino acid R-groups and complex folding into 4 levels of structure.
How does UV light damage DNA, and which repair mechanism fixes this type of damage?
UV light causes thymine dimers; nucleotide excision repair removes and replaces the damaged section
Compare the number of divisions and final cell products (including ploidy) in mitosis vs. meiosis.
Mitosis: 1 division, 2 identical diploid cells.
Meiosis: 2 divisions, 4 unique haploid cells