Molecular Cell Biology | Knowt

What is the central dogma of molecular biology?

The flow of genetic information within a biological system from DNA to RNA via transcription, and from RNA to protein via translation.

What is the primary function of the plasma membrane in eukaryotic cells?

To enclose cellular contents and selectively regulate the passage of molecules into and out of the cell.

What is the primary role of the nucleolus within the cell nucleus?

The synthesis of ribosomal RNA (rRNA) and the assembly of ribosome subunits.

Which enzyme is responsible for synthesizing mRNA during transcription in eukaryotic cells?

RNA polymerase II.

What is the main function of mitochondria in eukaryotic cells?

To generate ATP through cellular respiration and oxidative phosphorylation.

Which organelle is primarily responsible for lipid synthesis and metabolic detoxification?

Smooth endoplasmic reticulum (SER).

What is the primary role of the rough endoplasmic reticulum (RER)?

Synthesis, processing, and folding of membrane and secretory proteins via attached ribosomes.

Which cellular organelle modifies, sorts, and packages proteins for secretion or transport?

The Golgi apparatus.

What is the main function of lysosomes?

Degradation and recycling of cellular waste, cellular debris, and foreign macromolecules using hydrolytic enzymes.

Which cytoskeletal structure is composed of actin protein subunits?

Microfilaments (actin filaments).

What are the structural monomer subunits that assemble to form microtubules?

Tubulin heterodimers composed of $\alpha\text{-tubulin}$ and $\beta\text{-tubulin}$.

What type of intercellular junction allows direct cytoplasmic communication between adjacent animal cells?

Gap junctions.

What process refers to regulated, programmed cell death in multicellular organisms?

Apoptosis.

During which phase of the cell cycle does DNA replication occur?

S phase (Synthesis phase).

Which regulatory protein complexes control progression through cell cycle checkpoints?

Cyclins and cyclin-dependent kinases (CDKs).

What is the specific role of tRNA during translation?

To match specific amino acids with corresponding codons on the mRNA sequence.

What chemical interaction stabilizes complementary base pairing in a DNA double helix?

Hydrogen bonding.

Which enzyme unwinds the DNA double helix at the replication fork?

DNA helicase.

What enzyme joins Okazaki fragments on the lagging strand during DNA replication?

DNA ligase.

Which membrane lipid regulates fluid state and stability across temperature variations in animal cells?

Cholesterol.

Which motor protein moves along microtubules toward the plus end (anterograde transport)?

Kinesin.

Which motor protein carries cargo along microtubules toward the minus end (retrograde transport)?

Dynein.

Which cellular organelle neutralizes metabolic toxic products using hydrogen peroxide ($H_2O_2$) reactions?

Peroxisome.

What active transport protein directly consumes ATP to pump ions against their gradient across the plasma membrane?

Primary active transport pump (e.g., $\text{Na}^+/\text{K}^+\text{-ATPase}$).

What pathway mediates the uptake of extracellular molecules via vesicular internalization?

Endocytosis.