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In this chapter of AS/A-level Biology, we will learn about the structures and functions of organelles inside a cell.
Membrane-bound organelles in Eukaryotic cells
Nucleus
- Surrounded by double membrane called nuclear envelope which contains pores. The nuclear envelope separates the contents of the nucleus from the rest of the cell.
Nucleolus
- is within the nucleus, and contains RNA.
- Ribosome are made in here.
Rough Endoplasmic Reticulum
- System of membranes contains fluid-filled cavities (cisternae). Ribosome on its surface. Provides large surface area for ribosome
Smooth Endoplasmic Reticulum
- System of membranes contains fluid-filled cavities (cisternae). Contains enzymes that catalyse reactions involved with lipid metabolism.
Golgi apparatus
- Consists of heap of membrane-bound flattened sacs. Vesicles bring materials to and from. Proteins are modified e.g. by adding sugar molecules to make glycoproteins. The proteins are packaged into vesicles.
Mitochondrion
- Surrounded by double membranes with fluid-filled space between them. The inner membrane folded into cristae. The outer membrane is a fluid-filled matrix. It is the site of ATP (energy currency) production during aerobic respiration. They are self-replicating. They are abundant in cells where much metabolic activity takes place e.g. lives cells
Chloroplasts
- Found only in plants cells and in some protoctists. Surrounded by double membrane. Inner membrane has flattened sacs called thylakoids which contain chlorophyll. Contains loop of DNA and starch grains. The fluid-filled matrix is called stroma. it is the site of photosynthesis
Vacuole
- Formed from the Golgi apparatus. Each surrounded by single membrane. Contain hydrolytic (digestive) enzymes. Abundant in phagocytic cells. Keep powerful hydrolytic enzymes from the rest of the cell. Can engulf old cell organelles and foreign matter.
This is the end of this topic!
