GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Lysosomes
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #51 : Cellular Structures And Functions
What are acid hydrolases?
Protein designed to create acids
Proteins commonly found in lysosomes and designed to function at low pH
Proteins designed to break apart acids using water
Proteins that break apart molecules using acid catalysts
Proteins commonly found in lysosomes and designed to function at low pH
Acid hydrolases are proteins that are specifically designed to function at acidic pH, particularly at levels that would typically denature other proteins. They are commonly found in lysosomes where they aid in the digestion of various cellular wastes and materials.
Though acid hydrolases use water to break apart molecules, acids are not used as reactants, products, or catalysts in these reactions.
Example Question #2 : Lysosomes
Which of the following organelles has an acidic internal pH?
Mitochondria
Nucleus
Golgi apparatus
Lysosomes
Lysosomes
An acidic environment is not suitable for the cell as a whole, so the low pH is sequestered in a specific organelle: the lysosome. This low pH in the lysosome activates the hydrolytic enzymes in the lysosome, and allows them to degrade macromolecules that enter the organelle.
Example Question #1 : Lysosomes
Which cell organelle is tasked with collecting and recycling cytoplasmic debris?
Lysosome
Ribosomes
Endoplasmic reticulum
Mitochondria
Nucleus
Lysosome
A lysosome is a cell organelle that is part of the intracellular digestive system. Inside its limiting membrane there are hydrolytic enzymes capable of breaking down proteins and carbohydrates. Lysosomal enzymes contribute to the digestion of pathogens phagocytosed by a cell, and also to the tissue damage that accompanies inflammation. In short, they swallow up dead cells and debris, breaking down these compounds and recycling their components.
The mitochondria are frequently referred to as "powerhouses" because they are the site of the reactions of anabolic metabolism and most ATP synthesis. The nucleus is considered the "brain" of the cell because it controls the cell and contains the cell's genetic material. The ribosomes and endoplasmic reticulum are the sites of protein synthesis; smooth endoplasmic reticulum also synthesizes lipids and digests toxins.
Example Question #2 : Lysosomes
Which of the following is not a function of the lysosome within the cell?
Degradation of RNA and DNA into monomeric subunits to be recycled.
Degradation of cellular components that have become too old to function properly.
Contain an acidic, aqueous lumen for efficient destruction of components.
Uptake of organelles through autophagy.
Detoxification of ethanol through oxidation reactions.
Detoxification of ethanol through oxidation reactions.
The lysosome can be considered the "garbage man" of the cell. Old cellular parts that are no longer very useful to the cell are taken up by lysosomes and broken down into more fundamental molecules. Each of the functions listed above has been associated with the lysosome, except for the detoxification of ethanol, which is a specific function of the peroxisome.
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