22. the transport vesicles formed from the rough er fuse with the golgi apparatus. describe what happens to a transport vesicle and its contents when it arrives at the golgi apparatus.

23. what is a lysosome? what do they contain? what is the ph range inside a lysosome?

24. one function of lysosomes is intracellular digestion of particles engulfed by phagocytosis. describe this process of digestion. what human cells carry out phagocytosis?

25. a second function of lysosomes is to recycle cellular components in a process called autophagy. describe this process.

26. what happens in tay-sachs disease? explain the role of the lysosomes in tay-sachs.

campbell biology in focus (2nd edition)
adapted from campbell biology (9th edition) – © 2011 pearson education, inc.

Question

22. the transport vesicles formed from the rough er fuse with the golgi apparatus. describe what happens to a transport vesicle and its contents when it arrives at the golgi apparatus.

23. what is a lysosome? what do they contain? what is the ph range inside a lysosome?

24. one function of lysosomes is intracellular digestion of particles engulfed by phagocytosis. describe this process of digestion. what human cells carry out phagocytosis?

25. a second function of lysosomes is to recycle cellular components in a process called autophagy. describe this process.

26. what happens in tay-sachs disease? explain the role of the lysosomes in tay-sachs.

campbell biology in focus (2nd edition)
adapted from campbell biology (9th edition) – © 2011 pearson education, inc.

Accepted Answer

### Question 22
# Brief Explanations:
When a transport vesicle from the rough ER arrives at the Golgi apparatus, the vesicle fuses with the Golgi membrane. The contents (proteins, etc.) are then modified, sorted, and packaged. The Golgi modifies the proteins (e.g., adding sugars), then sorts them into new vesicles. These vesicles are sent to other organelles, the cell membrane, or for secretion.
# Answer:
The transport vesicle fuses with the Golgi apparatus. Its contents (e.g., proteins) are modified (e.g., glycosylation), sorted, and repackaged into new vesicles. These vesicles are then transported to destinations like the cell membrane (for secretion), other organelles, or for lysosomal delivery.

### Question 23
# Brief Explanations:
A lysosome is a membrane - bound organelle. It contains hydrolytic enzymes (like proteases, lipases, nucleases) that can break down macromolecules. The pH inside a lysosome is acidic, typically in the range of 4.5 - 5.0.
# Answer:
- Lysosome: A membrane - bound organelle in eukaryotic cells.
- Contents: Hydrolytic enzymes (proteases, lipases, nucleases, etc.) that can digest macromolecules.
- pH range: Approximately 4.5 - 5.0 (acidic environment).

### Question 24
# Brief Explanations:
1. **Digestion process**: A phagocytic cell (e.g., macrophage) engulfs a particle (like a bacterium) to form a phagosome. The phagosome then fuses with a lysosome, forming a phagolysosome. The hydrolytic enzymes in the lysosome break down the engulfed particle into smaller molecules, which can be used by the cell or excreted.
2. **Human cells with phagocytosis**: Macrophages (in blood, tissues), neutrophils (white blood cells), and dendritic cells carry out phagocytosis.
# Answer:
- **Digestion process**: A phagocytic cell engulfs a particle (e.g., pathogen) to form a phagosome. The phagosome fuses with a lysosome to form a phagolysosome. Lysosomal hydrolytic enzymes break down the particle into smaller, usable or excretable molecules.
- **Human cells**: Macrophages, neutrophils, dendritic cells.

### Question 25
# Brief Explanations:
In autophagy, a double - membrane vesicle (autophagosome) forms around damaged or unnecessary cellular components (e.g., old organelles). The autophagosome then fuses with a lysosome, forming an autophagolysosome. The lysosomal enzymes break down the enclosed components. The resulting small molecules (like amino acids, lipids) are recycled and used by the cell for new biosynthesis or energy production.
# Answer:
In autophagy, a double - membrane autophagosome encloses damaged/unneeded cellular components (e.g., organelles). The autophagosome fuses with a lysosome (forming an autophagolysosome). Lysosomal enzymes digest the components, and the breakdown products are recycled for the cell's use.

### Question 26
# Brief Explanations:
In Tay - Sachs disease, there is a genetic mutation that causes a deficiency of the lysosomal enzyme hexosaminidase A. This enzyme is needed to break down gangliosides (a type of lipid) in nerve cells. Since the enzyme is missing, gangliosides accumulate in lysosomes of nerve cells. The accumulation of gangliosides disrupts nerve cell function, leading to neurodegeneration, developmental delays, and eventually death (usually in early childhood). Lysosomes in Tay - Sachs are unable to properly digest gangliosides, so the lipids build up, causing the lysosomes to swell and the nerve cells to malfunction.
# Answer:
- **Tay - Sachs disease process**: A genetic mutation causes a lack of hexosaminidase A (a lysosomal enzyme). Gangliosides (lipids) accumulate in nerve cell lysosomes as they can't be broken down. This leads to nerve cell dysfunction, neurodegeneration, developmental issues, and early death.
- **Lysosome role**: Lysosomes normally break down gangliosides, but in Tay - Sachs, the lack of the required enzyme means lysosomes can't perform this digestion, leading to lipid accumulation and cell damage.

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