Lysosomes and Vacuoles

Question 1

What is the structure of a Lysosome? What are the contents of a lysosome?

Answer 1

• Lysosomes are simple, tiny spherical sac like structures. They are bound by a single membrane.
• they are rich in hydrolytic enzymes (aka hydrolases for eg.: Lipases, Proteases, Carbohydrases).

Question 2

How are Lysosomes formed? Where are they found?

Answer 2

• Lysosomes are formed by the process of packing in the Golgi Apparatus.
• They are found evenly distributed in the cytoplasm.

Question 3

Lysosomes are active (ideally) at the acidic pH. How and why?

Answer 3

• Acidic conditions are maintained inside a lysosome by the pumping of H⁺ ions into them.
• Due to this the enzymes are capable of digesting carbohydrates, proteins, lipids, nucleic acid.

Question 4

The lysosome shows Polymorphism. On the basis of morphology, their contents and functions, lysosomes are divided into 4 forms.

Answer 4

1. Primary Lysosome
2. Secondary Lysosome/ Heterophagosomes/ Digestive Vacuoles
3. Residual Bodies
4. Autophagic Vacuoles/ Suicide Bags

Question 5

What are Primary Lysosomes?

Answer 5

They are produced in the Golgi Apparatus at trans face. They contain inactive enzymes. These are small, vesicle like newly formed structures.

Question 6

What are Secondary Lysosomes?

Answer 6

These are formed when phagosomes fuse with pre-existing Primary L. These contain enzymes that act against the material to be digested.

Question 7

What is the process by which larval organs disappear during metamorphosis?

Answer 7

Autolysis

Question 8

Vacuoles are aka

Answer 8

Sap Vacuoles

Question 9

Where are Vacuoles found? What are their contents?

Answer 9

-They are found in the cytoplasm.

-They contain- water, sap, excretory products and other materials not useful for the cell.

Question 10

A Vacuole is a membrane bound space. Why is the concentration of ions and other materials higher in the Vacuole?

Answer 10

• It has a single, semi permeable membrane called tonoplast.
• This membrane facilitates the transport of a number of ions and other materials against the concentration gradient (lower to higher) into the vacuole.

Question 11

What are Residual Bodies?

Answer 11

These are Secondary L. containing undigested substances. They pass outwardly, come in contact with the cell membrane and throw their contents to the outside by the process ephagy/ exocytosis

Question 12

What are Autophagic Vacuoles?

Answer 12

They are formed by the union of many Primary L. around old/ dead organelles. This surrounds them with vacuolar membrane. They are then digested by the process of autolysis/ autodigestion.

Question 13

What are the types of Vacuoles and where are they found?

Answer 13

1. Contractile Vacuole: Found in Ameoba, it helps in excretion.
2. Food Vacuole: Found in cells like protists, formed by engulfing of food particles.
3. Gas Vacuoles/ Pseudovacuoles: Found in prokaryotes, they are membraneless vacuoles and provide buoyancy.