Here are the functions of the endoplasmic reticulum, Golgi apparatus, chloroplast, and mitochondria:

Endoplasmic reticulum
The endoplasmic reticulum is like a pathway or road of the cell. It gives way to the chemical compounds such as lipid components of the cell membrane, proteins, and other materials within the cell.

Golgi apparatus
The Golgi apparatus is the organelle that prepares, modifies, and sorts proteins from the endoplasmic reticulum.

Chloroplast
The chloroplast contains the chlorophyll, which is the green pigment found in plants. This organelle is mainly responsible for capturing the sunlight and use it for photosynthesis.

Mitochondria
The mitochondrion is the powerhouse of the cell. Its main job is to convert the chemical energy from the food into an energy that used by the cells for its activities.

The nucleus found in the cell is similar to the function of a person’s brain. The nucleus controls most of the cell’s growth and activity. It contains the genetic material of the cell, which is coded with the instructions needed for protein synthesis to produce chromosomes and other important molecules.

The cytoskeleton gives shape to a cell which is similar to the function of a human skeleton. This supporting structure is mainly responsible for the cell’s internal organization. In addition, it is also involved in the movement of the cell, as well as the movement of organelles within the cytoplasm.

A cell is compared to the way how a factory works. In factories, there are workers designated for each specific task but they all work together as a system. Similarly, a cell contains organelles that perform a specific function. For example, the nucleus is the control center of the cell, which works like an Officer-in-Charge in a factory. The nucleus controls and oversees the cell activities. On the other hand, the plasma membrane regulates what comes in and out of the cell, which is similar to the way how a shipping or receiving department works. The cytoplasm serves like a factory floor because it houses all the organelles and the cell activities. Ribosomes act like factory workers as they build the proteins inside the cell. In general, these organelles, together with the other cell structures work altogether and operate like a system.

Chloroplasts, which contain chlorophyll, are organelles found in plant cells and eukaryotic algae. These organisms, also known as autotrophs, can absorb sunlight and use it to produce their own energy through the process of photosynthesis. Therefore, the unknown cell is either from a plant or an algae.