Biology Cell Structure & Function Flashcards
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Read the first 7 Biology Cell Structure & Function flashcards as text
Which of the following organelles contains its own DNA and ribosomes, supporting the endosymbiotic theory?
Answer: Mitochondria and chloroplasts
Mitochondria and chloroplasts possess circular DNA and 70S ribosomes similar to prokaryotes, supporting the idea they evolved from ancient endosymbiotic bacteria.
What is the function of the nucleolus within the nucleus?
Answer: Synthesizing ribosomal RNA and assembling ribosome subunits
The nucleolus is a dense region within the nucleus where rRNA genes are transcribed and ribosomal subunits are assembled before export to the cytoplasm.
How do nuclear pores regulate traffic between the nucleus and cytoplasm?
Answer: They use FG-nucleoporins to selectively allow proteins and RNA to pass
Nuclear pore complexes contain FG-repeat nucleoporins that create a selective barrier, allowing small molecules to diffuse freely while large proteins and RNA require importin/exportin receptors.
In a secretory cell like a pancreatic acinar cell, what is the correct order of organelles a newly synthesized digestive enzyme passes through before secretion?
Answer: Rough ER → Golgi → Secretory vesicle → Plasma membrane
Secretory proteins are synthesized on rough ER ribosomes, processed in the ER lumen, transported to the Golgi for modification, packaged into secretory vesicles, and released by exocytosis.
Peroxisomes differ from lysosomes in that peroxisomes:
Answer: Use hydrogen peroxide as an oxidative tool to detoxify substances
Peroxisomes use oxidative reactions (often generating and then neutralizing H₂O₂) to break down fatty acids and detoxify alcohol, while lysosomes use acid hydrolases.
Which cytoskeletal element forms the core of cilia and flagella in a '9+2' arrangement?
Answer: Microtubules
Cilia and flagella contain an axoneme with 9 outer doublet microtubules and 2 central singlet microtubules, all cross-linked by dynein motor proteins that produce movement.
A mutation that disrupts dynein function in respiratory epithelial cilia would most likely result in:
Answer: Impaired mucus clearance leading to chronic respiratory infections
Dynein powers ciliary beating that sweeps mucus and trapped pathogens up the airway; its dysfunction causes primary ciliary dyskinesia, characterized by recurrent lung infections.