Structure of cell, their functions, mitosis, meiosis and determination of sex this all topic are cover.

1. Kamla Nehru College of Pharmacy
Butibori, Nagpur - 441108
Presented By
Ms. Monika P. Maske
(Pharmaceutical Chemistry)

2. Structure of cell

3. o The cell is the smallest unit of living tissues.
o Cells of different tissues perform different functions.
A cell is made up of following structures:
1. Cell wall :
- It is the external boundary of the living cell.
- It is three layered str. Made up of lipids & proteins.
Function :
- It provide structure, support and protection for the cell.

4. 2. Nucleus :
- It is the largest structure present almost in the centre of a cell.
- It is more or less spherical in shape.
- It is bounded by nuclear membrane.
Function :
- Control heredity characteristics of organism.
- It responsible for protein synthesis, cell division, growth and
differentiation.
- Store heredity material in the form of DNA(deoxy-ribonucleic acid).
- Controlled synthesis of particular enzymes.

5. The nucleus contain,
a) Nucleolus b) Chromatin
a) Nucleolus:
- It is highly coiled filamentous str. Present in nucleus.
- It surrounded by membrane and contains numerous granules.
b) Chromatin:
- These are fibrous threads present in the nucleus.
- They are composed of DNA(deoxy-ribonucleic acid) and proteins.
- The chromatin threads carry genetic information.

6. 3. Cytoplasm :
- It is the region lying between the cell membrane and nucleus.
- The cytoplasm contains cell organelles like endoplasmic reticulum,
Golgi apparatus, mitochondria, lysosomes.
Ribosomes :
- These are tiny spheres that contain ribosomal RNA and ribosomal proteins.
- These are the site of protein synthesis, 2 types of ribosomes-
i) Membrane bound ribosomes- these are attached to endoplasmic
reticulum.
ii) Free ribosomes- these are free in cytosol.

7. Organelles of cytoplasm :
Organelles present in the cytoplasm are,
i. Endoplasmic reticulum :
- It is the most extensive cell organelle present in cytoplasm.
- It consists of two membranes which are separated by a
space.
- Endoplasmic reticulum is of 2 types,
(a) Granular :
- It is also called as rough surface endoplasmic reticulum.
- It contain ribosomes.
- The ribosomes are the sites of protein synthesis.
(b) Agranular :
- It is also called as smooth surface endoplasmic reticulum.
- It does not contain ribosomes.
- They store and release calcium.

8. ii. Golgi apparatus :
- It is a cup shaped structure.
- It is situated between the nucleus the apex of the cell.
- The stack of Golgi sacs has two defined regions Cis and Trans.
- It stores proteins and modifying them.

9. iii. Mitochondria :
- The mitochondria generate ATP hence called as power house of cells.
- The no. of mitochondria vary from cell to cell depending on their
energy requirement.
- It consists of 2 protein membranes,
1. An outer layer which is smooth.
2. An inner layer folded into sheets of tubules called cristae.
- Both these layers enclose a central cavity called matrix.
- Mitochondria made up of proteins, phospholipids and some
ribonucleic acid.

10. iv. Lysosomes :
- They are small spherical or oval Shap bodies surrounded by a single
membrane.
- They vary in number.
- The lysosomes breakdown bacteria and cell debris engulfed by the
cell.
- The damaged intracellular organelles are also broken down and
digested by lysosomes.
v. Centrosome :
- It is a small, rod shaped body found near the nucleus.
- It plays an important role during cell division.

11. vi. Microtubules :
- They are straight, hollow cylinders in shape.
- They maintain a cell shape.
vii. Vacuoles :
- It is the storage structure in a cell.
- It can hold food for later use or waste for removal.

12. Functions of cells
1. Ingestion and assimilation :
- The cell ingests chemical sub. Like amino acids from
intercellular fluid.
- These sub. are used to build up complicated sub. Like
proteins.
2. Growth and repair :
- The ingested and assimilated materials are used to synthesise
new protoplasm.
- This leads to increase in size and growth of the cell.
3. Metabolism :
- This involves 2 processes
a) Anabolism in which the ingested and assimilated food material is
used for growth & repair.
b) Catabolism in which food material is broken down to release
energy for various function of cell.

13. 4. Respiration:
- It involves transport of oxygen from lungs through blood to the tissues
and removal of waste products like CO2.
5. Excretion :
- The cell eliminates waste products resulting from catabolism into the
interstitial fluid.
- These products are carried by blood for elimination through lungs and
kidneys.
6. Irritability and Contractility :
- The cell responds to any stimulus (physical, chemical,
thermal)by contracting.
7. Reproduction :
- After growing to - an optimum size, cell divides into daughter cells.
- Reproduction of cells occurs by mitosis or meiosis.

15. Fig. stages of mitosis
Mitosis
This occurs in 4 stages namely prophase, metaphase, anaphase and telophase.

16. It is process of reproduction which involves the fusion of
1) Spermatozoon from the male ( which contains 23 chromosomes).
2) Ovum from the female ( which contains 23 chromosomes).
- The spermatozoon and ovum also called as gametes.
- The fusion of these two ( male and female) gametes results in the formation
of a zygote which has the normal number of 46 chromosomes.
- This leads to mixing of genes from the male and female.
Meiosis

18.  One pair of chromosomes from the father and one pair from the mother are sex
chromosomes.
 These sex chromosomes determine the sex of the child.
 In the female, sex chromosomes are same and called as XX.
 In the male, they are different and called as XY.
 One chromosomes from each pair determines the sex of child.
 If child has X chromosomes from mother and X from father, it is Female (XX).
 If child has X chromosomes from mother and Y from father, it is Male (XY).
Determination of sex