All GRE Subject Test: Biology Resources
Example Questions
Example Question #91 : Gre Subject Test: Biology
Which of the following is not a common destination for proteins translated by membrane-bound ribosomes?
Cytosol
Lysosomes
Plasma membrane
Secretory vesicles
Cytosol
Membrane-bound ribosomes are found on the surface of the rough endoplasmic reticulum. Proteins synthesized by membrane-bound ribosomes are translocated into the endoplasmic reticulum while they are being translated.
These proteins generally undergo modification in the rough endoplasmic reticulum and are packaged into vesicles by the Golgi apparatus. Vesicles from the Golgi apparatus then interface with the plasma membrane of the cell or the membranes of other organelles. Proteins from the interior of the vesicle can be released into the extracellular space or interior of other organelles. Proteins in the membranes of the vesicle become embedded in the plasma membrane of the cell or the organelle.
Proteins synthesized on free ribosomes commonly remain in the cytosol and are modified by different processes than protein synthesized on the rough endoplasmic reticulum.
Example Question #92 : Gre Subject Test: Biology
Which organelle is used to create triglycerides and other lipids?
Golgi apparatus
Smooth endoplasmic reticulum
Ribosome
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
The smooth endoplasmic reticulum serves several different purposes in the cell, one of which is lipid synthesis. This structure is responsible for producing phospholipids and cholesterol, as well as some steroid hormones and other lipid molecules. It also helps to eliminate foreign toxins from the cell.
The rough endoplasmic reticulum houses ribosomes that synthesize proteins that are destined for the membrane or extracellular environment. The Golgi apparatus is responsible for packaging proteins in vesicles, allowing for transport out of the cell. Ribosomes are involved in protein synthesis (translation).
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