Inner Morphology of Eukaryotic Cells:
- Nucleus:
This is the central organelle that houses the genetic material (DNA). It is separated from the cytoplasm by a double-membraned nuclear envelope.
The nuclear envelope contains nuclear pores that regulate the transport of molecules between the nucleus and the cytoplasm. The DNA is organized into chromosomes, which are complexed with proteins to form chromatin.
There are two types of chromatin:
- A) heterochromatin, which is densely packed and inactive, and
- B) euchromatin, which is more loosely packed and active.
The nucleolus is a subdomain of the nucleus where ribosomal RNA (rRNA) is synthesized and assembled into ribosomal subunits.
- Cytoplasm:
The gel-like substance where cellular activities occur. It contains organelles, the cytoskeleton, and various molecules.
- Endoplasmic Reticulum (ER): A network of membranes involved in protein and lipid synthesis. There are two types of ER:
- A) rough ER, which has ribosomes attached to its surface, and smooth ER, which lacks ribosomes. Rough ER is involved in the synthesis of proteins that are destined for secretion or insertion into the cell membrane.
- B) Smooth ER is involved in the synthesis of lipids and steroids, and it also plays a role in detoxification and calcium storage.
- Golgi Apparatus:
A stack of membranes that modifies, sorts, and packages proteins for secretion or transport within the cell. Proteins synthesized in the rough ER are transported to the Golgi apparatus, where they are modified by the addition of sugars or other molecules. The Golgi apparatus then sorts the proteins and packages them into vesicles, which are transported to their final destinations.
- Mitochondria:
Most eukaryotic cells house mitochondria for energy production through cellular respiration. Mitochondria are often elongated structures. They contain their own DNA and ribosomes, and they are thought to have evolved from bacteria that were engulfed by ancestral eukaryotic cells.
- Lysosomes:
Lysosomes are membrane-bound organelles that contain enzymes that break down waste materials and cellular debris. They are specifically involved in the manufacture of lysosomal enzymes.
- Cytoskeleton:
The cytoskeleton is a network of protein filaments that provides support and shape to the cell, and it also plays a role in cell movement and intracellular transport. There are three main types of protein filaments in the cytoskeleton: microtubules, microfilaments, and intermediate filaments.
- Inclusions:
Inclusions are cytoplasmic structures or deposits filled with stored macromolecules. They are not present in all cells.