During mitosis, what structure forms around sister chromatids to hold them together until anaphase?

• A. Ribosomal subunits
• B. Cohesin protein complex
• C. Nuclear lamina
• D. Spliceosome

Answer: (B)

Verified step by step guidance

1. Understand the context: During mitosis, sister chromatids are duplicated chromosomes that need to be held together until they are separated during anaphase.
2. Recall the key structures involved in chromosome cohesion: The protein complex responsible for holding sister chromatids together is called cohesin.
3. Recognize the role of cohesin: Cohesin forms a ring-like structure around sister chromatids, physically linking them to ensure proper alignment and segregation.
4. Differentiate cohesin from other options: Ribosomal subunits are involved in protein synthesis, nuclear lamina supports the nuclear envelope, and spliceosomes are involved in RNA processing, so they do not hold chromatids together.
5. Conclude that the cohesin protein complex is the structure that forms around sister chromatids to hold them together until anaphase.