Organelles

Question 1

Intro of vacuoles

Answer 1

• Found in plants and fungi
• In plants, 90% of the volume is occupied by a single membrane-bound, fluid-filled central vacuole.

Question 2

Explain the structure of vacuole

Answer 2

• Membrane of vacuole is called tonoplast.
• Tonoplast contains active transport pumps that influx ions into the vacuolar compartment to maintain higher conc.
  eg) V type proton pump
• Increased ionic strength also attracts water inside. This maintains turgor pressure for strength, support and shape

Question 3

What are the functions of vacuoles

Answer 3

• cell’s solutes and macromolecules (ions, sugars, protein and polysaccharide) are stored temporarily in the vacuole.
  -They also store a host of secondary metabolites for planet defence
  eg) Digitalis, cyanide containing compounds
  -Sites for intracellular digestion- have hydrolytic enzymes
  -Substitute excretory system in plants

Question 4

What is contractile vacuole?

Answer 4

Protozoans have them.
A contractile vacuole takes up water from cytosol and unlike a plant vacuole, periodically discharges its content through fusion with the plasma membrane
Maintains osmolarity of the cell

Question 5

What is lysosomes?

Answer 5

• Animal cell’s digestive organelles with at least 50 digestive enzymes.
• Acidic pH of the lysosomal lumen is maintained by V type proton pumps in the lysosomal membrane.
• Shape is variable and not very distinct.
• Main function is to breakdown materials brought into cell from extracellular environment. Resulting nutrients pass through lysosomal membrane into the cytosol.

Question 6

Relation btw lysosomes and phagocytosis

Answer 6

• Ingested bacteria is inactivated by low pH of lysosomes and the digested enzymatically
• Peptides produced by digestive process are posted on the cell surface where they alert the immune system about the presence of a foreign agent.

Question 7

What are hydrolytic enzymes?

Answer 7

Enzymes- acid hydrolases that work at a pH of 4-5 of lysosomal compartment.

Question 8

What is autophagy?

Answer 8

• The process in which lysosome regulate destruction and replacement of cell’s own organelles.
  It plays a key role in organelle turnover.
• Helps protect an organism against intracellular threats like abnormal protein aggregates invading bacteria and parasite.
• Play a role in the prevention of certain types of cancer and slowing the body’s age process

Lipofucin granules increase in no. as an individual becomes older.

Question 9

Different LSDs

Answer 9

• TSD Tay-Sachs Disease
• Fabry disease
• Neimann Pick
• Gaucher’s Disease- skeletal disfigurement
• MLD (central nervous system)
• MPS (bones, cartilage)
• Pompe disease - damage to muscle and nerve cell

Question 24

What are importins and exportins ?

Answer 24

Active transport of large macromolecules requires mobile transport receptors, ferrying macromolecules across nuclear envelope by recognising and binding with NLS.

Importins- moving macromolecules from cytoplasm to nucleus.
Exporting- move macromolecules in the opposite direction, bind to a NES

Question 29

What is ribosomal RNA (rRNA) ?

Answer 29

• Ribosome is a ribonucleoprotein having 60%rRNA + 40%protein.
• rRNA is small subunit that help is positioning of mRNA- tRNA complex during translation
• rRNA of large subunit form a catalytic center for peptide bond formation