Chapter 20, Problem 1CQ

To determine

Different membranous organelles found in a eukaryotic cell and function of each of them.

Answer to Problem 1CQ

Eukaryotic cells have a well-defined nucleus and organelles. Each part of a eukaryotic cell performs a specific and well-defined function. There are certain membrane-bound organelles present in the eukaryotic cells that together constitute “endomembrane system”. Organelles that are the part of the endomembrane system are Endoplasmic Reticulum (ER), Golgi apparatus, and Lysosomes. Some of the other membrane-bound organelles found in the eukaryotic cells are vacuoles, peroxisomes, mitochondria, chloroplast, and contractile vacuoles.

Explanation of Solution

Cells are having a well-defined membranous nucleus and other cell organelles are called eukaryotic cells. In these types of cells, each organelle is distinct and has its own function. Some of the organelles in eukaryotic cells are membrane-bound, and together they form the endomembrane system. Golgi apparatus, endoplasmic reticulum, and lysosomes form the endomembrane system in the eukaryotic cells. Vacuoles, peroxisomes, mitochondria, and chloroplast are some of the other membrane-bound organelles that can be found in eukaryotic cells. The functions performed by each of these organelles are as follows:

(i) Endoplasmic Reticulum: They form the basic skeletal framework for the cells. Transportation of cellular material from one cell to the other is also carried out by endoplasmic reticulum. One of the most important functions of the ER is to mediate protein synthesis. In the liver, ER performs the function of detoxification of substances that can be harmful to the body.

(ii) Golgi apparatus: Golgi bodies are mainly associated with the process of modification, packaging, and transport of cellular materials. It is also related to the activation of enzymes in the cell.

(iii) Lysosomes: Lysosomes are sacs that keep the strong digestive enzymes separated from other parts of the cell; thus preventing their digestion. In unicellular organisms, they are associated with the digestion of food.

(iv) Vacuoles: Vacuoles are associated with storage of different materials in the cell. In plant cells, vacuoles also provide turgidity and rigidity to the cell.

(v) Mitochondria: Mitochondria are the site for the production of energy molecules in eukaryotic cells. Aerobic respiration also takes place in the mitochondria.

(vi) Chloroplast: Chloroplasts are found in plant cells and perform the function of capturing light energy from the sun and converting it into a biologically useful form. The process of photosynthesis takes place in the chloroplast.

(vi) Peroxisomes: Peroxisomes are associated with the metabolism of fat in the body. They contain many different enzymes that help in the digestion of fat molecules in the body.