Organelles within a eukaryotic cell are small, membrane-bound packages that have certain tasks that help overall survival and function of the cell. Therefore, I will explain the functions of several organelles below:
1. Ribosomes and the endoplasmic reticulum help to make proteins. Proteins are required for almost every major function of cellular life. For example, enzymes are proteins that help to speed up chemical reactions, proteins build the structure of many cell parts, and receive signals from outside the cell that then alert intracellular responses. Proteins also act as selective channels within the cell membrane that let good things into the cell and keep harmful things out.
2. Mitochondria undergo cellular respiration, which the process of using glucose and oxygen to make water, carbon dioxide, and ATP (adenosine triphosphate). The cell, and organism, use this ATP as an energy source.
3. Lysosomes clean up toxins within the cell. This is easy to remember because lysosome sounds like the common household cleaner called Lysol.
This is by no means a comprehensive list, but I hope it gets you started!