Organelles and Their Functions

2.3. a) Eight main organelles and their functions:

Nucleus-this organelle is the most prominent feature of an eukaryotic cell. It can be found both in plants and animals. Some cells contain multiple nuclei, such as skeletal muscle, while some do not have any, such as red blood cells. The functions of the nucleus are to:

·           act as a control centre through the production of mRNA and protein synthesis

·         retain genetic material of the cell in the form of DNA   /chromosomes

·         manufacture rRNA and ribosomes

·         start the process of cell division;

Chloroplasts can be found only in plant cells and some protists. The main function of the chloroplast is to:

·         trap light energy and convert it into the chemical bond energy of sugar.

Sugar is used as a primary energy source. The chloroplast has an outer membrane and an inner membrane. Within the chloroplast is a cavity called the stroma where a third set of membranes is located. These innermost membranes, called thylakoids, are arranged in stacks called grana. Most of photosynthesis occurs along the thylakoid membranes with the help of the pigment chlorophyll.

Vacuole   is another organelle mainly found in plant cells. It helps the cell by:

·         isolating harmful materials so they do not affect the cell. Vacuole does that by containing and exporting waste products

·         containing water solution

·         maintaining internal hydrostatic pressure so cell maintain it’s shape

Mitochondrion   is responsible for energy rich ATP molecules from carbohydrates. Therefore, the number of these organelles, their size and the number of cristae all increase in cells that have a high level of metabolic activity and as a result need a lot of energy. Such cells include those of muscles and liver.

Endoplasmic reticulum is three-dimensional system of sheet like membranes. This organelle is important for a cell as it:

·         provides a large surface...