Lysosomes Flashcards
What are lysosomes?
Lysosomes are membrane-bound organelles that contain digestive enzymes.
True or False: Lysosomes are involved in cellular digestion.
True
What are the functions of lysosomes?
-hydrolases
-enzyme activators/protective factors
-transport proteins
Which type of enzymes are found in lysosomes?
Hydrolytic enzymes
Multiple Choice:
What pH level do lysosomes typically maintain for optimal enzyme activity?
A) 4.5-5
B) 7-9
C) 10-12
A) 4.5-5
True or False: Lysosomes can also play a role in apoptosis (programmed cell death).
True
What is the origin of lysosomes in the cell?
Lysosomes originate from the Golgi apparatus.
Fill in the blank: Lysosomal storage diseases occur due to __________ of lysosomal enzymes.
deficiency
Which cellular process do lysosomes participate in for recycling cellular components?
Autophagy
Multiple Choice: Which of the following is NOT a function of lysosomes? A) Digestion of macromolecules B) Energy production C) Recycling of cellular components
B) Energy production
What happens to lysosomes during cellular stress?
They can release their enzymes and contribute to cell death or inflammation.
True or False: Lysosomes are only found in animal cells.
False
What is the role of lysosomal membranes?
Lysosomal membranes protect the rest of the cell from the digestive enzymes inside.
Fill in the blank: The process of breaking down old or damaged organelles by lysosomes is called __________.
autophagy
Which disease is associated with a malfunction of lysosomal enzymes?
Tay-Sachs disease
Multiple Choice: Which of the following structures is involved in the formation of lysosomes? A) Ribosomes B) Golgi apparatus C) Nucleus
B) Golgi apparatus
True or False: Lysosomes can fuse with other organelles to aid in their function.
True
What is the typical size range of lysosomes?
0.1 to 1.2 micrometers in diameter.
Fill in the blank: Lysosomes contain __________ that help break down various biomolecules.
Hydrolytic enzymes
What is the significance of the acidic environment within lysosomes?
It activates the hydrolytic enzymes for digestion.
True or False: Lysosomes can degrade both proteins and lipids.
True
Multiple Choice: Which of the following is a characteristic of lysosomes? A) They contain ribosomes B) They are involved in protein synthesis C) They contain digestive enzymes
C) They contain digestive enzymes
What is the potential consequence of lysosomal dysfunction?
Accumulation of waste materials and cellular damage.
Fill in the blank: Lysosomes are part of the __________ system of the cell.
endosomal-lysosomal
What are some examples of lysosome related organelles?
1) melanocyte
2) platelet
3) neutrophil
4) T cell
5) neuron
What are extracellular and intracellular substrates?
Extracellular- molecules that exist out of the cell
Intracellular- molecules that exist in the cells
What are extracellular and intracellular substrates?
Extracellular- molecules that exist out of the cell
Intracellular- molecules that exist in the cells
What is endocytosis?
Endocytosis- cells take extracellular substrates by engulfing membranes.
What is endocytosis?
Endocytosis- cells take extracellular substrates by engulfing membranes.
What is invagination?
Invagination- plasma membrane bends inwards to punch off to create intracellular vesicle.
What is invagination?
Invagination- plasma membrane bends inwards to punch off to create intracellular vesicle.
Explain extracellular substrates: endocytosis?
-fluid phase endocytosis of molecules and lipoproteins
-phagocytosis of particles above 0.5 micrometres
Explain intracellular substrates
- Microautophagy (invagination of the lysosomal membrane)
- Macroautophagy (cytosol or organelles wrapped in ER membrane which then fuses with lysosomes)
Explain key features of fluid phase endocytosis?
Cells randomly engulf extracellular fluid into vesicles
1) Non specific uptake
2) Mechanism:
The plasma membrane detaches, forming a vesicle filled with extracellular liquid.
3) Vesicle formation:
Vesicle formed are usually uncoated.
These vesicles fuse with early endosomes where internalised fluid is sorted/recycled back into the plasma membrane.
4) Volume regulation:
-cells use fluid-phase endocytosis to help regulate the volume of internal fluid and maintain osmotic balance
Explain the stages in the receptor mediated endocytosis
1) Ligand binding:
Specific ligands bind to receptors on cell surface
2) Receptor- ligand complex formation
Once the ligands bind, the receptors cluster together in specialised regions of the plasma membrane.
3) Invagination and vesicle formation:
The clathrin-coated put invaginated and pinches off the membrane
4) Uncoating of vesicles
After vesicle is internalised, the clathrin coat is removed by specialised proteins
5) Fusion of early endosome
The uncooked vesicle fuses with an early endosome
Acidic environments causes ligands to dissociate from their receptors
6) Sorting of contents
Recycling, degradation, transport.
What is the process of phagocytosis?
1) the phagocytes are attracted to the pathogen and moves towards it.
2) phagocytes receptors attach to the chemicals on the surface of the pathogen
3) lysosomes move towards the phagosome and engulf it
4) lysosomes release lysozymes into phagosome to hydrolyse bacterium
5) hydrolysis products are absorbed.
Explain the definition of Macroautophagy
Macroautophagy- viral cellular process where cells degrade and recycle their own components
Explain the definition of Macroautophagy
Macroautophagy- viral cellular process where cells degrade and recycle their own components
What is enclosed in a autophagosome?
Cellular components enclosed in a double membrane vesicle called an autophagosome
What is enclosed in a autophagosome?
Cellular components enclosed in a double membrane vesicle called an autophagosome
What does the autophagosome fuse with?
Autophagosome fuses with lysosomes—-> the contents are degraded by lysosomal enzymes.
What is the role of vacuolar ATPase?
Vacuolar ATPase- transports protons into lysosomes and related organelles whilst generating ATP.
What is the role of vacuolar ATPase?
Vacuolar ATPase- transports protons into lysosomes and related organelles whilst generating ATP.
What term is used to describe the cellular uptake of material through vesicles?
Endocytosis
What is the principal lipid component of low density lipoprotein (LDL)?
Cholesteryl ester
What do we call the process by which intracellular organelles are delivered to- digested in- lysosomes?
Autophagy
