Question

Short / Long answer type questions.
Explain the following terms rough and smooth endoplasmic reticulum, cisterna, vesicle, cristae, stroma lamella, granum thylakoid, proplastid, polyribosome, tonoplast, nuclear envelope, chromatin, and chromosome.

Answer 1

• The rough endoplasmic reticulum is a series of connected flattened sacs that are found in the cytoplasm. They are continuous with the nuclear envelope and are covered with ribosomes. Its major function is protein synthesis.
• The smooth endoplasmic reticulum is also a series of connected flattened sacs that are found in the cytoplasm. They are continuous with the nuclear envelope and are not covered with ribosomes. The major function of the smooth endoplasmic reticulum is the detoxification of the body from drugs consumed and metabolic wastes produced.
• Cisternae are the folds of the ER and Golgi apparatus membranes.
• A vesicle is a large structure that could either be intracellular or extracellular and usually contains a fluid enclosed in a lipid bilayer.
• Cristae are the fold of the inner membrane of the mitochondria.
• Stroma lamellae are lamellae that are present in the stroma.
• Granum thylakoid is the granum present in the thylakoids or the disc-like flattened structures involved in photosynthesis.
• Proplastids are organelles that are found in the meristematic regions of a plant. It is colourless and small and these are the structures from which the plastids are derived.
• Polyribosomes can be described as a cluster of ribosomes found in the cytoplasm.
• Tonoplast is the membrane which surrounds the chief vacuole of a plant.
• The nuclear envelope is a membrane that surrounds the nucleus of a cell.
• Chromatin is a mass of genetic material located in the nucleus of our cells that are composed of DNA and proteins that condense to form chromosomes during eukaryotic cell division.
• The major function of the chromosomes in terms of inheritance is the transfer of information (about genes in the form of alleles or traits) from one generation to the next.