Describe the structure of the following withthe help of labelled diagrams. (i) Nucleus (ii) Centrosome

Question

Sadika · Accepted Answer

(i) Nucleus:

The nucleus is a membrane-bound organelle found in eukaryotic cells, housing the genetic material (DNA) and serving as the control center for cellular activities. Here's a description of its structure along with a labelled diagram:

Structure:

Nuclear Envelope: The nucleus is surrounded by a double membrane called the nuclear envelope, which consists of an outer nuclear membrane and an inner nuclear membrane. The nuclear envelope is perforated by nuclear pores that regulate the exchange of molecules between the nucleus and the cytoplasm.
Nuclear Lamina: Inside the nuclear envelope, there is a network of protein filaments known as the nuclear lamina, which provides structural support to the nucleus and helps maintain its shape.
Nucleoplasm: The interior of the nucleus, called the nucleoplasm or nuclear matrix, is a gel-like substance containing chromatin, nucleolus, and various nucleoproteins.
Chromatin: Chromatin consists of DNA molecules wrapped around histone proteins. It represents the genetic material of the cell and contains the instructions for cellular activities.
Nucleolus: The nucleolus is a prominent structure within the nucleus responsible for the assembly of ribosomal RNA (rRNA) and the formation of ribosomes.

Labelled Di

agram of Nucleus:

________________________
| |
| Nuclear Envelope |
|________________________|
|
|
___________V___________
| |
| Nucleoplasm |
|______________________|
/ \
______|_ _|______
| | | |
| Chromatin Nucleolus|
|__________________________|

(ii) Centrosome:

The centrosome is a microtubule-organizing center found in animal cells, playing a crucial role in cell division and organization of the cytoskeleton. Here's a description of its structure along with a labelled diagram:

Structure:

Centrosome Matrix: The centrosome contains a central region called the centrosome matrix or centrosome core, which consists of protein complexes.
Centrioles: The centrosome contains a pair of cylindrical structures known as centrioles, which are composed of microtubules arranged in a 9+0 pattern. Each centriole consists of nine triplets of microtubules arranged in a circular fashion.
Pericentriolar Material: Surrounding the centrioles, there is a region called the pericentriolar material, which contains proteins involved in microtubule nucleation and anchoring.

Labelled Diagram of Centrosome:

________________________
| |
| Centrosome Matrix |
|________________________|
|
__________V___________
| |
| Centrioles |
|______________________|

The centrosome plays a crucial role in organizing microtubules during cell division, forming the mitotic spindle apparatus, and facilitating chromosome segregation. Additionally, it serves as a point of origin for the growth of microtubules involved in intracellular transport and cell shape maintenance.

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Describe the structure of the following withthe help of labelled diagrams. (i) Nucleus (ii) Centrosome

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