Question

Sketch and describe in your own words, the animal cell

Answer 1

An animal is made of following components.

1. Cell membrane or plasma membrane : It forms the limiting boundary of the cell. It encloses the cytoplasm and cell organelles. Its function is to selectively allow the movement of substances into and outside the cell.
2. Cytoplasm - It a semifluid substance present within the cell membrane. It has various cell organelles and inclusions dispersed in it. The cytoplasm helps in the movement of substance between organelles and to the cell membrane. The movement is regulated by proteins present in the cytoplasm that form the cytoskeleton.
3. Nucleus - It is the most important organelle of the cell. It consists of genetic material dispersed in the nucleoplasm enclosed by a nuclear envelope. The envelope has multiple pores for exchange of substances between the nucleoplasm and the cytoplasm. It also contains a nucleolus. The major function of the nucleus is to control all the activities of the cell.
4. Endoplasmic Reticulum : It is a system of single membrane bound tubules called cisternae and vesicles. The ER system may be in continuation with the outer membrane of the nucleus, and is of two types - Rough and Smooth

• The RER: Has ribosomes transiently attached to the external surface of membrane and performs the function of protein synthesis.
• The SER : Has a smooth external surface with no ribosomes attached to it. Its function is to synthesize fats.

The proteins and fats synthesized by ER are trasported to the Golgi Apparatus in vesicles

5. Golgi apparatus : It also consists of cisternae and vesicles. It receives vesicles from the ER, modifies the fats, proteins and sugars, tags them tranports them to their respective organelles or to the cell membrane to be secreted outside by packing them in vesicles.

6. Mitochondria: It is a sausage shaped double membraned structure. The inner membrane is folded to form cristae, that contains respiratory particles. Mitochondria contains respiratory enzymes for formation of ATP from glucose.

7. Lysosome : They are single membrane bound organelles, containing hydrolytic enzymes. They digest unwanted cellular components and pathogens.

8. Centrosome: Centrosome is a clear space, closer to the nucleus and contains a pair of centrioles. The function of centrioles is formation of spindle fibres and aster during cell division.