Lysosomes, vacuoles and peroxisomes Flashcards
What is the main function of lysosomes?
Intracellular digestion using hydrolytic enzymes
Lysosomes digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.
What pH do lysosomal enzymes operate at?
pH 5
The acidic environment protects the cytosol from degradative enzymes.
What is autophagy?
The process of breaking down old cells
It involves the digestion of excess or worn-out organelles.
How do lysosomes contribute to cell healing?
By fusing with the plasma membrane to seal digested areas
This process helps patch the cell membrane.
True or False: Lysosomes can be referred to as ‘suicide bags’.
True
They can lead to cell death through autolysis.
What are peroxisomes?
Membrane-bound organelles involved in the metabolism of fatty acids and detoxification
They contain enzymes like catalase that break down hydrogen peroxide.
What is the primary enzyme found in peroxisomes that deals with hydrogen peroxide?
Catalase
Catalase converts toxic hydrogen peroxide into water and oxygen.
What are the two main functions of peroxisomes?
- Participate in fatty acid metabolism
- Detoxify harmful substances
They oxidize substrates and rid cells of toxic peroxides.
What is Zellweger’s syndrome?
A condition where children have ‘empty’ peroxisomes due to failure in importing enzymes
This leads to toxin buildup and typically results in early death.
What do vacuoles do?
- Remove unwanted structural debris
- Isolate harmful materials
- Maintain internal hydrostatic pressure
- Store food and other materials
Vacuoles play a major role in autophagy.
What type of vacuole is involved in phagocytosis?
Food vacuoles
These vacuoles are used by some protists and macrophages.
What is the role of the central vacuole in plant cells?
To maintain turgor pressure against the cell wall
Turgor pressure helps in cellular elongation and keeps chloroplasts closer to light.
What are the two types of endocytosis?
- Phagocytosis
- Pinocytosis
Phagocytosis involves solid materials, while pinocytosis involves liquid solutions.
What is a plasmalogen?
A type of lipid synthesized in peroxisomes
Plasmalogens are essential for the myelination of nerve cells.
What is the tonoplast?
The membrane surrounding vacuoles
It regulates the internal environment of the vacuole.
What happens to turgor pressure when water is lost from a plant cell?
Turgor pressure declines and the cell plasmolyzes
This can lead to wilting in plants.
What is the function of contractile vacuoles?
To pump excess water out of the cell
This prevents cytolysis or osmotic lysis.
Fill in the blank: Peroxisomes participate in the metabolism of fatty acids through _______.
Beta-oxidation
Fatty acids are broken down into acetyl-CoA.
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