(i) Nucleus (ii) Centrosome
Solution:
i) The nucleus is a double-membraned structure with an oval or spherical shape that contains the genetic material. The nuclear envelope, nuclear matrix, nucleoplasm, nucleolus, and chromatin are the five components.
Nuclear envelope – The nuclear pore, a double membrane nuclear envelope with microscopic pores in the membrane that act as a route for things to flow in and out of the nucleus, confines the nucleus. The outer membrane, which also includes the ribosomes, is attached to the endoplasmic reticulum.
Nucleoplasm – It is the fluid that fills the nucleus and contains enzymes, nucleosides, proteins, and other components that help the genetic material work. The chromatin filaments and nucleolus are also embedded.
Chromatin – They are a fine network of thread-like structures found inside the nucleus that hold DNA and a few basic proteins such as histones, RNA, and non-histone proteins. During cell division, these chromatin fibres condense to create the chromosomes.
Nucleolus – They are spherical, lightly uneven, naked structures that manufacture ribosome subunits and are connected to the chromatin. Proteins are produced by them.
(ii) Centrosome
- Is made up of two cylindrical structures called centrioles that are perpendicular to one another and grouped in the shape of a cartwheel.
- Engirdled by amorphous pericentriolar materials
- Consists of 9 tubulin protein peripheral fibrils that are uniformly spaced, each of which is a triplet with neighbouring triplets joined together.
- The centriole’s centre is a proteinaceous hub that is connected to the triplets by radial spokes.
- It is critical during cell division as it organizes the spindle fibres and astral rays