Cell Biology and Structure

Plastids are similar to mitochondria in their external structure, as both have a double membrane and contain their own DNA and ribosomes. This similarity supports the endosymbiotic theory of organelle origin.

The Rough Endoplasmic Reticulum (RER) has particles called ribosomes attached to its surface, giving it a 'rough' appearance. These ribosomes are the sites of protein synthesis.

Cisterns (or cisternae) are the flattened, membrane-bound sacs that make up the Golgi apparatus. They are stacked in a parallel fashion and are involved in the processing of proteins.

Vacuoles are very large in plant cells, often occupying 50% to 90% of the cell volume. They provide structural support and maintain turgor pressure within the cell.

The stroma is the fluid-filled internal space of a plastid (specifically chloroplasts) surrounding the thylakoids. It contains the enzymes necessary for the dark reactions of photosynthesis.

The Endoplasmic Reticulum (ER) is responsible for the synthesis of essential biomolecules. Rough ER, which has ribosomes attached, manufactures proteins, while Smooth ER is the primary site for lipid and fat molecule production.

The Golgi apparatus is functionally and often physically connected to the endoplasmic reticulum. It receives proteins and lipids synthesized in the ER via transport vesicles for further processing, packaging, and distribution.

Plastids, specifically leucoplasts, serve as storage organelles in plant cells. Amyloplasts store starch, elaioplasts store oils, and aleuroplasts store protein granules.

The membrane of the endoplasmic reticulum is a phospholipid bilayer that is structurally similar to the plasma membrane. This similarity allows for the exchange of membrane components through vesicle budding and fusion.

Plastids are unique to plant cells and some algae; they are not found in animal cells. While large central vacuoles are characteristic of plants, small vacuoles can exist in animal cells, making plastids the most distinctive answer.

Plastids (like chloroplasts) and mitochondria are semi-autonomous organelles. They possess their own circular DNA and ribosomes, allowing them to produce some of their own proteins independently of the nucleus.

The Smooth Endoplasmic Reticulum (SER) contains specialized enzymes that detoxify harmful substances like drugs and poisons. This function is particularly prominent in the liver cells of vertebrates.

The Endoplasmic Reticulum is an extensive network of membrane-bound tubules and flattened sacs called cisternae. It forms a continuous transport system throughout the cytoplasm of eukaryotic cells.

In many unicellular organisms like Amoeba, contractile vacuoles are essential for osmoregulation. They collect excess water and metabolic wastes from the cell and expel them into the surrounding environment.

Chromoplasts are a type of plastid that synthesize and store carotenoid pigments. These pigments are responsible for the bright yellow, orange, and red colors seen in many flowers, fruits, and aging leaves.