DNA & RNA
The nitrogenous bases of DNA pair by hydrogen bonding: A with T, and G with this base.
What is cytosine?
These three domains make up the Tree of Life.
What are Bacteria, Archaea, and Eukaryotes?
Hydrolysis of ATP releases energy by converting it into this molecule.
What is ADP?
The Central Dogma describes the flow of genetic information from DNA to RNA to this.
What is protein?
The first theme of molecular biology states: Sequence informs Structure, which informs this.
What is function?
RNA differs from DNA in three ways. Name one.
What is single-stranded, contains ribose instead of deoxyribose, or uses uracil instead of thymine?
Prokaryotes lack this structure found in eukaryotic cells.
What is a nucleus?
Which principle states that when a system at equilibrium is disturbed, it will shift to counteract the change?
What is Le Chatelier’s Principle?
Transcription is like “copying the same alphabet,” while translation is like what?
What is copying the message into a new alphabet (nucleotides to amino acids)?
The second theme of molecular biology is based on this thermodynamic principle.
What is Gibbs Free Energy?
Deamination of cytosine creates this base, which is normally only found in RNA.
What is uracil?
The Serial Endosymbiotic Theory proposes that mitochondria and chloroplasts originated from these.
What are symbiotic bacteria?
Gibbs Free Energy (ΔG) tells us whether a reaction is this.
What is favorable or unfavorable?
The first theme of molecular biology can be summarized as: Sequence → Structure → _______.
What is function?
A positive ΔG value means a reaction is:
What is unfavorable (requires energy input)?
Why does DNA, and not RNA, serve as the stable long-term storage molecule?
What is because DNA lacks the reactive OH group on ribose and uses thymine instead of uracil, making it more stable?
Why is rRNA highly conserved across life?
What is because its sequence is essential for maintaining the structure and function of ribosomes in protein synthesis?
Why do cells couple unfavorable reactions to ATP hydrolysis?
What is to make unfavorable reactions proceed by using the released energy?
How many different amino acids are used to build proteins in cells?
What is 20?
The third theme of molecular biology is based on this principle of equilibrium.
What is Le Chatelier’s Principle?
Why does the cell immediately remove uracil if it appears in DNA, and how does this relate to cytosine deamination?
What is because uracil in DNA likely results from deamination of cytosine; keeping it would cause mutations (U pairs with A instead of G), so the cell must remove uracil to preserve fidelity?
The slides describe that some parts of rRNA are highly conserved while others evolve rapidly (stems vs loops). Explain why this pattern exists.
What is because stem regions are structurally critical and must remain conserved to maintain rRNA function in ribosomes, while loop regions are less constrained and can mutate, providing sites for evolutionary variation?
Why is Gibbs Free Energy (ΔG) the unifying principle of biology, and how do cells exploit ATP hydrolysis in terms of coupling reactions?
What is because ΔG predicts whether reactions are favorable; cells link ATP hydrolysis (a highly negative ΔG) to unfavorable processes, effectively “spending” stored energy to drive necessary biochemical reactions forward?
Why are translation errors less dangerous than replication errors for the cell?
What is because mistranslated proteins are temporary and disposable, while replication errors alter DNA permanently and are inherited?
The slides state “equilibrium = death.” Explain why life depends on maintaining reactions away from equilibrium.
What is because biological systems must maintain fluxes of matter and energy; at equilibrium no net reactions occur, halting metabolism and causing cell death?