Biomedical Sciences Flashcards

Which phase of the cell cycle is characterized by centrosome duplication and the cell committing to division past the restriction point?

Answer: G1 phase

During G1, cells grow, centrosome duplication begins, and passage through the restriction point commits the cell to completing division.

Which epigenetic modification is most directly associated with transcriptional silencing?

Answer: H3K27 trimethylation

H3K27me3, catalyzed by the PRC2 complex, is a hallmark of facultative heterochromatin and transcriptional repression.

A gene knockout mouse lacks functional macrophages. Which process of innate immunity would be most directly impaired?

Answer: Phagocytosis of bacteria

Macrophages are professional phagocytes; their absence severely impairs phagocytic clearance of pathogens and debris.

Which technique uses chain-terminating dideoxynucleotides to determine DNA sequence?

Answer: Sanger sequencing

Sanger sequencing incorporates ddNTPs that lack a 3'-OH group, terminating chain elongation at specific bases to generate length-sorted fragments.

What is the main advantage of using a lentiviral vector over an adenoviral vector for gene therapy?

Answer: Lentiviruses can infect non-dividing cells and integrate stably into the genome

Lentiviral vectors integrate into host chromatin and can transduce non-dividing cells, enabling long-term transgene expression.

Which statistical test is most appropriate for comparing the means of three or more independent groups?

Answer: One-way ANOVA

One-way ANOVA tests whether means differ across three or more independent groups while controlling the family-wise error rate.

Which protein domain is responsible for recognizing phosphotyrosine residues in receptor tyrosine kinase signaling?

Answer: SH2 domain

SH2 (Src Homology 2) domains bind specifically to phosphorylated tyrosine residues, enabling downstream signal transduction.