Biology Cellular and Molecular Flashcards

Which organelle is the site of fatty acid oxidation (beta-oxidation) in eukaryotic cells?

Answer: Mitochondria

Beta-oxidation of fatty acids occurs in the mitochondrial matrix, where the acetyl-CoA produced enters the Krebs cycle.

What is the significance of the reading frame in mRNA translation?

Answer: It specifies the correct sequence of codons from which amino acids are assembled

The reading frame defines the grouping of nucleotides into codons; a frameshift mutation shifts the reading frame and alters every downstream amino acid.

Which type of cell junction allows direct communication of small molecules between adjacent animal cells?

Answer: Gap junction

Gap junctions form channels (connexons) that allow ions and small signaling molecules to pass directly between neighboring cells.

What does the fluid mosaic model describe?

Answer: The structure of the plasma membrane with embedded proteins in a phospholipid bilayer

The fluid mosaic model depicts the plasma membrane as a flexible phospholipid bilayer with proteins that can move laterally within it.

During meiosis, homologous chromosomes exchange genetic material through which process?

Answer: Crossing over (recombination)

Crossing over occurs during prophase I when non-sister chromatids of homologous chromosomes exchange segments at points called chiasmata.

Which molecule serves as the 'universal energy currency' of cells?

Answer: ATP

ATP (adenosine triphosphate) is the primary energy carrier in cells, releasing energy when its terminal phosphate bond is hydrolyzed.

What is the function of signal peptides on newly synthesized proteins?

Answer: They direct proteins to the endoplasmic reticulum for secretory pathway entry

Signal peptides are short amino acid sequences that direct ribosomes to the ER membrane, allowing the protein to enter the secretory pathway.