What are Lysosomes?
A lysosome is a membrane-bound organelle that can be found in many animal cells. These are spherical vesicles containing hydrolytic enzymes that can break down many biomolecule kinds. A lysosome contains a specific composition, of both its lumenal proteins and its membrane proteins. The lumen's pH (~4.5 to 5.0) is optimal for the enzymes that are involved in hydrolysis and analogous to the activity of the stomach. Besides, the degradation of polymers, the lysosome is involved in different cellular processes, including plasma membrane repair, secretion, apoptosis, energy metabolism, and cell signaling.
Lysosomes act as the cell's waste disposal system by digesting the obsolete or un-used cytoplasm materials, both from outside and inside the cell. Material from outside of the cell is taken-up via endocytosis, while material from the inside of the cell is digested through autophagy. The organelles sizes vary greatly; the larger ones can be more than ten times the size of the smaller ones. They were discovered and named by a Belgian biologist, Christian de Duve, who eventually received the Nobel Prize in 1974, in Physiology or Medicine.
Lysosomes are membrane-bound vesicles that arise from the Golgi apparatus.
1. Which of the Following are Not the Hydrolytic Enzymes of the Lysosome?
Lipases
Sulfatases
Phosphatases
Aldolase
Answer: (d)
Explanation
Lysosomes have 40 types of hydrolytic enzymes, which include sulphatases, phosphatases, lipases, glycosidases, and more. These enzymes optimally work in the acidic environment, and also the lysosome provides an acidic environment for these enzymes.
2. Which of the Following Organelle Controls the Intracellular Digestion of Macromolecules Taking the Help of Hydrolytic Enzymes?
Plastid
Peroxisome
Lysosome
Actin
Answer: (c)
Explanation
Lysosomes are the membrane-bound compartments filled with hydrolytic enzymes that control intracellular digestion in the macromolecules. It contains about 40 types of various hydrolytic enzymes.
3. Digestion of Cell’s Own Component is Referred to as __________?
Autophagy
Heterophagy
Phagocytosis
Pinocytosis
Answer: (a)
Explanation
Autophagy is the self-digestion process; autophagic vacuoles contain the own components of cells, called the autophagosome, further which fuse to the lysosome where the digestion of components takes place.
4. The Melanosomes Release from Melanocytes is Mediated by the Process. Identify Such a Process from the Options Given Below?
Autophagy
Endocytosis
Exocytosis
Pinocytosis
Answer: (c)
Explanation
In the stress conditions, the cell releases undigested content by exocytosis of lysosomes. But it is a very small pathway. Melanocyte in skin stores its pigment in the lysosomes, which release it into the extracellular epidermis space.
5. What is an Amphisome?
Early endosome
The fusion of autophagosome and endosome
Vacuole
The bigger size of lysosome
Answer: (b)
Explanation
Amphisome is produced when the autophagosome is fused with the endosomes. This amphisome is further fused with lysosome for digestion purposes. It will result in the release of macromolecules into the cytosol.
6. Identify the Following True Statement Considering the Acidic pH of Lysosomes?
Presence of hydrolytic enzymes
Presence of anabolic enzymes
Deposition of waste materials
All of the above
Answer: (b)
7. Why are Lysosomes Considered as the “Garbage Trucks” of Cells?
Due to the transport materials between two cell organelles
Due to the pump materials from outside to the inside of a cell
Due to they remove all unwanted cellular materials
Due to the transport materials from one cell to another
Answer: (c)
8. How Do the Lysosomes Originate?
By budding off from the trans-Golgi network membrane
From the cytoplasm
Phospholipid bilayer
None of the above
Answer: (a)
9. Which of the Following Biomolecules are the Lysosome Components?
Ribosomes and Matrix
Amino acid chain and tRNA
Phosphate esters and nucleases
Glyco protein and Carbohydrates
Answer: (c)
10. Identify the Techniques Used in the Isolation of Liposomal Fractions from the Following?
Electrophoresis
Sucrose density gradient centrifugation
Ultracentrifugation
All of the above
Answer: (b)
11. Which of the Below Given Organelle is Known as the Dense Perinuclear Bodies?
Lysosomes
Nucleolus
Peroxisome
All of the above
Answer: (a)
12. Lysosomes are Involved in ______?
Digestion
Intracellular digestion
Extracellular digestion
Both intracellular and extracellular digestion
Answer: (d)
13. Identify the Following Ones that Pump Excess Water Out of the Cell?
Contractile vacuole
Lysosome
Peroxisome
Vacuoles
Answer: (a)
14. Identify the Single Membrane from the Given List Which Surrounded the Vacuoles?
Contractile vacuole
Meninges
Tonoplast
Sarcolemma
Answer: (c)
15. Identify the Enzymes that are Used as a Marker for the Lysosomes from the List Given Below?
Phospholipase
Acid phosphatase
Pyruvate dehydrogenase
Succinate dehydrogenase
Answer: (b)
16. From the Given List, Which of the Following Organelle is Referred to as “Suicidal Bags” of the Cell?
Cytoplasm
Lysosomes
Mitochondria
Endoplasmic reticulum
Answer: (b)
17. Lysosomes are Absent in Which of the Following Cells?
Animal cells
Erythrocytes
Hepatocytes
Muscles cells
Answer: (b)
18. Identify the Below Biomolecules as the Components of Lysosomes?
Glyco protein and Carbohydrates
Phosphate esters and nucleases
Amino acid chain and tRNA
Ribosomes and Matrix
Answer: (b)
FAQs on MCQs on Lysosomes
1. What are lysosomes and what is their primary role in a cell?
Lysosomes are small, membrane-bound organelles found in eukaryotic cells that contain powerful digestive enzymes. Their primary role is to act as the cell's waste disposal and recycling system. They break down excess or worn-out cell parts, as well as foreign substances like bacteria and viruses that have been engulfed by the cell.
2. Where are lysosomes formed inside a cell?
Lysosomes are formed through a collaborative process involving the endoplasmic reticulum and the Golgi apparatus. The digestive enzymes are first synthesized in the rough endoplasmic reticulum (RER) and then transported to the Golgi apparatus for further processing and packaging. Finally, they bud off from the Golgi complex as vesicles, forming mature lysosomes.
3. Why do phagocytic cells like macrophages have a high concentration of lysosomes?
The number of lysosomes in a cell is directly related to its function. Phagocytic cells, such as macrophages (a type of white blood cell), are responsible for engulfing and destroying pathogens like bacteria and other debris. They require a large number of lysosomes to efficiently digest these engulfed materials through a process called phagocytosis.
4. How do lysosomes maintain their acidic internal environment, and why is this important?
Lysosomes maintain a highly acidic internal pH of about 4.5-5.0. This is achieved by proton pumps (H+ pumps) in the lysosomal membrane that actively transport hydrogen ions from the cytoplasm into the lysosome. This acidic environment is crucial because the hydrolytic enzymes within the lysosome are only active at this low pH. This acts as a safety feature; if a lysosome were to leak, its enzymes would be largely inactive in the neutral pH of the cytoplasm, preventing widespread cellular damage.
5. What are lysosomal storage diseases and can you give an example?
Lysosomal storage diseases are a group of rare genetic disorders caused by a deficiency in one or more of the digestive enzymes found in lysosomes. When an enzyme is defective or missing, the substance it is supposed to break down accumulates within the lysosomes, leading to cell damage and dysfunction. An example is Tay-Sachs disease, where a deficiency in an enzyme that breaks down lipids leads to their harmful accumulation in nerve cells.
6. Why are lysosomes often called 'suicidal bags,' and is this term accurate?
The term 'suicidal bags' comes from the lysosome's ability to rupture and release its digestive enzymes, leading to the self-digestion of the entire cell (autolysis). However, this term can be misleading. This process is not random but a highly controlled mechanism called apoptosis, or programmed cell death. It is a vital process for removing old, damaged, or infected cells and for normal embryonic development.
7. What is the difference between autophagy and heterophagy as carried out by lysosomes?
Both are digestive processes involving lysosomes, but they differ in the origin of the material being digested:
- Autophagy ('self-eating'): This is the process where lysosomes digest the cell's own internal components, such as old or damaged organelles. It is a crucial cellular housekeeping process for recycling materials and maintaining cell health.
- Heterophagy ('other-eating'): This involves the digestion of materials that have been brought into the cell from the outside environment through endocytosis. This includes breaking down nutrients or destroying invading pathogens like bacteria.
