Cell Biology: Functions of Lysosomes

Questions and Answers

What is the function of lysosomes in a cell?

To synthesize proteins

To store genetic information

To provide energy to the cell

To digest and break down various molecules and substances (correct)

What does the root 'lys' in lysosome mean?

To synthesize

To cut or digest (correct)

To store

To provide energy

What is the process called when lysosomes digest molecules that are part of the cell itself?

Mitosis

Crinophagy

Phagocytosis

Autophagy (correct)

What happens to the broken-down molecules after lysosomes finish digesting them?

They are released into the cytoplasm Signup and view all the answers

What is an example of autophagy in the immune system?

Macrophages engulfing bacteria and viruses Signup and view all the answers

What is crinophagy?

The digestion of excess secretory products Signup and view all the answers

What is broken down into individual amino acids by lysosomes?

Proteins Signup and view all the answers

What is the ultimate fate of the broken-down molecules by lysosomes?

They are reused by the cell Signup and view all the answers

What is the primary function of the acidic environment within a lysosome?

To activate the acid hydrolases Signup and view all the answers

What would happen if many lysosomes were to burst simultaneously in a cell?

The cytoplasm would become more acidic Signup and view all the answers

What is the main function of peroxisomes in liver cells?

To detoxify chemicals and drugs Signup and view all the answers

What is the by-product of certain cellular enzyme activities that peroxisomes isolate?

Hydrogen peroxide Signup and view all the answers

What is the enzyme responsible for breaking down hydrogen peroxide in peroxisomes?

Catalase Signup and view all the answers

What is the pH of the cytoplasm in a cell?

7.4 Signup and view all the answers

Why is the acidic environment of lysosomes a safety mechanism for the cell?

It prevents the acid hydrolases from digesting organelles Signup and view all the answers

What is the result of the breakdown of hydrogen peroxide by catalase in peroxisomes?

Water and oxygen Signup and view all the answers

Study Notes

Lysosomes

Lysosomes are membrane-bound organelles that digest various molecules and substances within a cell.
The root "lys" means "to cut or digest".
Lysosomes have two main functions: Autophagy and Crinophagy.

Autophagy

Autophagy means "self-eating" and involves the digestion of molecules that are part of the cell itself or other cells.
Examples of autophagy include:
- Breaking down non-functional organelles, such as old mitochondria.
- Digesting engulfed bacteria and viruses in macrophages of the immune system.

Crinophagy

Crinophagy involves the digestion of excess secretory products.
Example: Breaking down excess hormones produced by a cell.
In both Autophagy and Crinophagy, the lysosomes release the broken-down molecules into the cytoplasm as building blocks, which can be reused by the cell.

Environment in Lysosomes

The enzymes in lysosomes, known as acid hydrolases, require an acidic environment to work properly.
The pH inside a lysosome is approximately 5, which acts as a safety mechanism for the cell.
If a lysosome were to burst, the acid hydrolases would not function properly in the cytoplasm due to its higher pH (approximately 7.4).

Peroxisomes

Peroxisomes are membrane-bound organelles responsible for various metabolic activities.
They are similar to lysosomes but have different functions.
Examples of peroxisome functions include:
- Lipid break down in some cells.
- Detoxifying chemicals and drugs in liver cells.
Peroxisomes contain enzymes, including catalase, which breaks down hydrogen peroxide into water and oxygen.
Hydrogen peroxide is a by-product of certain enzyme activities and is dangerous to the cell if not isolated and broken down.