1. Describe the structure of lysosomes.
Lysosomes are membrane-bound spherical vesicles containing hydrolytic enzymes. Their membranes protect the cell from the enzymes within, which are active in an acidic environment (pH ~5).
2. Explain the role of lysosomes in autophagy.
Autophagy is the process by which lysosomes degrade and recycle cellular components, such as damaged organelles, to maintain cellular homeostasis.
3. What is the importance of peroxisomes in cellular metabolism?
Peroxisomes play a key role in lipid metabolism, including beta-oxidation of fatty acids, and detoxify harmful substances like hydrogen peroxide using catalase.
4. How are lysosomes formed?
Lysosomes are formed from the trans-Golgi network, where hydrolase enzymes are packaged into vesicles destined to become lysosomes.
5. Compare the pH environments of lysosomes and cytosol.
Lysosomes maintain an acidic environment (pH ~5) for enzyme activity, while the cytosol has a neutral pH (~7.2).
6. What is the function of catalase in peroxisomes?
Catalase decomposes hydrogen peroxide (H2O2), a toxic byproduct of metabolic reactions, into water and oxygen, preventing oxidative damage.
7. Discuss the diseases caused by lysosomal dysfunction.
Lysosomal storage disorders, such as Tay-Sachs disease and Gaucher’s disease, occur due to deficiencies in specific lysosomal enzymes, leading to accumulation of undigested substances.
8. What are the main enzymes found in lysosomes?
Lysosomes contain hydrolases, including proteases, lipases, nucleases, and glycosidases, which degrade proteins, lipids, nucleic acids, and carbohydrates.
9. Describe the role of peroxisomes in detoxification.
Peroxisomes detoxify substances like ethanol and reactive oxygen species. They break down hydrogen peroxide and aid in converting harmful compounds into safer molecules.
10. How do lysosomes contribute to apoptosis?
Lysosomes release enzymes like cathepsins during apoptosis, contributing to the controlled breakdown of cellular components and programmed cell death.
11. What is the difference between lysosomes and peroxisomes?
Lysosomes digest cellular waste and macromolecules using hydrolytic enzymes, while peroxisomes detoxify harmful substances and metabolize fatty acids using oxidative enzymes.
12. Explain the origin of peroxisomes.
Peroxisomes are formed by budding off from the endoplasmic reticulum or by growth and division of pre-existing peroxisomes.
13. What happens if lysosomes rupture in a cell?
If lysosomes rupture, their hydrolytic enzymes can digest cellular components, potentially leading to cell death (autolysis).
14. Why are lysosomes called the “suicide bags” of the cell?
Lysosomes are called “suicide bags” because their enzymes can digest the cell’s own components if the lysosomal membrane is compromised.
15. Discuss the role of lysosomes in immune response.
Lysosomes degrade engulfed pathogens in phagocytic immune cells, such as macrophages, by fusing with phagosomes to form phagolysosomes.
16. What are the oxidative functions of peroxisomes?
Peroxisomes use oxidative enzymes to break down fatty acids and detoxify reactive oxygen species, which helps in maintaining cellular redox balance.
17. How does lysosomal pH affect enzyme activity?
Lysosomal enzymes are active only in acidic pH, ensuring they function within lysosomes and not in the neutral cytosol, preventing unintended damage.
18. What role do peroxisomes play in lipid metabolism?
Peroxisomes are involved in the beta-oxidation of long-chain fatty acids, synthesis of plasmalogens, and degradation of cholesterol intermediates.
19. Explain the significance of lysosomal recycling in cellular health.
Lysosomal recycling prevents accumulation of damaged cellular components, thereby maintaining cellular health and preventing diseases like neurodegeneration.
20. What are the symptoms of peroxisomal disorders?
Symptoms include developmental delays, neurological dysfunctions, and liver abnormalities, as seen in conditions like Zellweger syndrome.
21. Describe the process of phagocytosis and the role of lysosomes.
Phagocytosis involves engulfing extracellular particles into vesicles (phagosomes), which fuse with lysosomes to degrade the contents.
22. How do peroxisomes protect plant cells during stress?
In plants, peroxisomes participate in photorespiration and detoxify reactive oxygen species, protecting cells during oxidative stress.
23. Why are peroxisomes abundant in liver cells?
Liver cells detoxify many harmful substances, and peroxisomes play a critical role in breaking down alcohol, fatty acids, and toxins.
24. Explain the term “lysosomal storage disease.”
Lysosomal storage diseases are genetic disorders caused by enzyme deficiencies, leading to accumulation of undigested substrates in lysosomes.
25. What is the role of lysosomes in nutrient recycling?
Lysosomes degrade macromolecules into smaller units, such as amino acids and sugars, which are recycled for new cellular functions.
26. How does oxidative stress affect peroxisomal function?
Oxidative stress can overload peroxisomes, reducing their ability to detoxify reactive oxygen species, leading to cellular damage.
27. Discuss the importance of lysosomes in aging.
Lysosomal activity declines with age, leading to reduced autophagy and accumulation of damaged organelles, contributing to cellular aging.
28. How do lysosomes contribute to embryonic development?
Lysosomes aid in the removal of obsolete structures and remodeling tissues during embryogenesis through controlled degradation.
29. What is the role of glyoxysomes in plants?
Glyoxysomes, a type of peroxisome in plants, convert stored lipids into carbohydrates during seed germination.
30. How can lysosomal enzymes be targeted for therapeutic use?
Lysosomal enzymes are used in enzyme replacement therapies for treating lysosomal storage disorders, improving patient outcomes.
This detailed set of descriptive questions and answers covers various aspects of lysosomes and peroxisomes, helping learners grasp their structure, function, and significance in cellular waste management.
