Organelles
You previously learned the basics of cellular structure, including the compartmentalization of eukaryotes into organelles. Organelles are defined as discrete subunits of cells adapted to perform specific functions. You are expected to understand the organelles include:
- Nucleus
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondria
- Chloroplasts
- Vacuoles
- Vesicles
- Ribosomes
- Plasma membrane
Note that the cell wall, cytoskeleton, and cytoplasm are not considered organelles as they are structural components that do not necessarily perform specific functions.
Compartmentalization
Remember that compartmentalization refers to the separation of organelles from the rest of the cell to localize specific functions in one area. In the cytoplasm, this has several advantages:
Metabolites and enzymes can be concentrated into specific organelles and can be kept there, not affecting the other organelles.
The vacuole is an example of this, as it is hypertonic and contains many metabolites required to retain water via osmosis. This would not be possible if it was not separated by a membrane.
Incompatible biochemical processes can be separated so that the enzymes are not affected by other enzymes and vice versa.
The lysosome is an example of this, as its digestive enzymes are fantastic for digestion of endocytosed materials, but if present in the cytoplasm would digest the cell from the inside.
Additionally, separation of the nucleus from the cytoplasm is worth discussing. This is advantageous because:
- It protects the DNA from external factors and enzymes present in the cytoplasm.
- It separates transcription from translation, allowing for post-transcriptional modification.
Without this separation, DNA is more susceptible and easily altered, increasing the rate of mutation, and alternative splicing cannot occur, reducing the number of proteins that can be produced from one gene.