Genome location in eukaryotes — Identify all organelles that contain DNA in a typical eukaryotic cell
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ANucleus
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BMitochondrion
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CVacuole
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DBoth (a) and (b)
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EGolgi apparatus
Answer
Correct Answer: Both (a) and (b)
Explanation
Introduction:Eukaryotic cells compartmentalize functions within organelles, and DNA is housed in specific locations. This question evaluates recognition of all eukaryotic sites that contain their own genetic material.
Given Data / Assumptions:
- Typical animal cell context (though plant chloroplasts also contain DNA).
- Organelles listed: nucleus, mitochondrion, vacuole, Golgi apparatus.
Concept / Approach:Eukaryotes possess nuclear DNA enclosed by the nuclear envelope. Mitochondria also maintain circular DNA and a prokaryote-like translation system, consistent with the endosymbiotic origin. Vacuoles and the Golgi apparatus do not contain their own DNA.
Step-by-Step Solution:
1) Nucleus: primary repository of chromosomal DNA in linear chromosomes.2) Mitochondrion: contains mitochondrial DNA (mtDNA), encoding rRNAs, tRNAs, and key respiratory chain subunits.3) Vacuole: a membrane-bound storage and degradative compartment; no genome.4) Golgi: processing and sorting station for proteins/lipids; no genome.5) Therefore, the correct combined choice is nucleus and mitochondrion.Verification / Alternative check:In plants and algae, chloroplasts also contain DNA (cpDNA). If chloroplast were among options, it would be included; here it is not, so the best answer remains nucleus and mitochondrion.
Why Other Options Are Wrong:
- Nucleus only: ignores mitochondrial DNA.
- Mitochondrion only: ignores the main nuclear genome.
- Vacuole: lacks DNA.
- Golgi apparatus: lacks DNA, functions in post-translational processing and trafficking.
Common Pitfalls:Assuming every membrane-bound compartment contains DNA; most organelles rely on nuclear-encoded proteins and do not carry genomes.
Final Answer:Both (a) and (b).