B2.2.1 Organelles as discrete subunits of cells that are adapted to perform specific functions
Organelles are specialized structures within a cell that perform distinct functions necessary for the cell’s survival and proper functioning. They are like tiny “organs” inside the cell, each designed to carry out specific tasks. Organelles are found in both prokaryotic and eukaryotic cells, although eukaryotic cells have more complex and membrane-bound organelles.
Organelles with double membrane are:
- Nuclei
- Mitochondria
- Chloroplasts
- Amyloplasts
- Chromoplasts
- In Eukaryotes: keeps chromosomes inside nucleus, safeguards DNA and allows mRNA to be modified after transcription and before translation (post-transcriptional modification)
- In Prokaryotes : no nucleus so DNA and ribosomes together in cytoplasm, translation happens directly after transcription
B2.2.2—Advantage of the separation of the nucleus and cytoplasm into separate compartments
Advantages of separating the nucleus and cytoplasm in eukaryotic cells:
- DNA Protection: Keeping chromosomes within the nucleus safeguards the DNA.
- Post-transcriptional Modification: Separation allows for mRNA processing (e.g., splicing, capping, polyadenylation) before translation, which is not possible in prokaryotes where transcription and translation occur simultaneously.
B2.2.3—Advantages of compartmentalization in the cytoplasm of cells
Advantages of compartmentalization in cytoplasm are:
- Enzymes/substrates are more concentrated for processes.
- Substances that could cause damage to cell kept inside membrane organelle, eg. digestive enzyme in lysosome
- Conditions (pH) maintained at ideal level for particular processes.