The document discusses the processes of cell division through mitosis and meiosis. It explains that mitosis produces two identical daughter cells and occurs in somatic cells, while meiosis produces four haploid daughter cells and occurs in germ cells to create gametes. Both processes go through similar stages of prophase, metaphase, anaphase and telophase, but meiosis involves two cell divisions to separate homologous chromosomes and then sister chromatids, resulting in four daughter cells each with half the number of chromosomes. The key difference is that mitosis maintains genetic variation, while meiosis increases it through independent assortment and crossing over.

1. B Y - N I H A R I K A V E R M A
CYTOLOGY

2. CYTOLOGY
 The human body develops from a single cell called
the ‘Zygote’- the result of the fusion of ovum and
sperm.
 All cells, tissues organs and systems of our body
originate from a Zygote Cell is a smallest living
structural unit in the body.
 Cell is the structural and functional unit of life
because whole body is made up of cell.
 The cell is a Latin word for a ‘little room’.
 Discovered by Robert Hook (1665).

3. CELL
 The cell is the structural and functional unit of all known
as living organisms.
 It is the smallest unit of an organism that is classified as
living, and is often called the building block of life.
 Some organisms, such as most bacteria, are unicellular
(consists of a single cell).
 Other organisms, such as human, are multicellular.
 It consists of : minerals, carbohydrates, lipids, and
proteins (amino acids)
 The protoplasm is surrounded by fine membrane (Wall)
of protein threads and lipids.

5. CELL FORMATION
 Female – ovum
 Male – sperm Fusion
Single cell (ZYGOTE) unit of
human  Tissue  Organ  Organ System
• Human- animal cell
• Nuclic acid – Protein
• Living cell – Protoplasm (non color jelly like fluid).

7. PROTOPLASM
 Different substances that make a cells are collectively
called Protoplasm.
 Protoplasm is composed of :
1. Water – 70-80% is present in cell.
2. Carbohydrates
3. Lipids
4. Proteins
5. Electrolyte – Sodium (Na+), Potassium (K+),
Magnesium (Mg2+), Calcium (Ca2+), Phosphate,
Chloride (C1-1), and Bicarbonate (HCo3-).

8. CELL DIVISION
 Cell divide  Daughter Cell
|
Mitosis – division of somatic cells.
life long [genes thread like structure in the bundle
called Chromosomes (DNA)].
|
Meiosis – creation of new sex cells.
46 Pair  23 Father : 23 Mother
(exceptional cases – 24:23)

9.  SOMATIC CELL- A body cell- a cell whose genes will
not be passed on to future generations.
 GERM CELL- A cell that is destined to become a
gamete (egg or sperm), a cell whose a genes can be
passed on to future generations.

10. AEROBIC RESPIRATION
ANAEROBIC
RESPIRATION
 It is the process of
breakdown of food in
the presence of oxygen.
 Its end products are
CO2 and H2O.
 It takes longer time to
energy.
 It is the process of
breakdown of food in
the absence of oxygen.
 End products can be
lactic acid or CO2 and
alcohol.
 It is a fast process as
compared to aerobic
respiration.

11. ANAEROBIC
RESPIRATION
 It produces large
amount of energy.
 Example : Occurs
mostly in plants and
animals.
 It produce small
amount of energy as
compared to aerobic
respiration.
 Example : Yeast,
Bacteria, Human
muscle, Cells, etc.
AEROBIC RESPIRATION

12. MITOSIS
 4 stages in total (plus
interphase)
 Happens in somatic cells.
 Purpose is cellular
proliferation.
 Produces 2 diploid
daughter cells.
 Chromosome number
remains the same
 Genetic variation doesn’t
change.
MEIOSIS
 8 stages in total (plus
interphase).
 Happens in germ cells.
 Purpose is sexual
reproduction.
 Produces 4 haploid
daughter cells.
 Chromosome number is
halved in each daughter
cell.
 Genetic variation
increased.

13. MITOSIS AND MEIOSIS (SAME)
 Produce new cells.
 Similar basic steps.
 Start with a single parent cell.

14. MITOSIS
 Mitosis is a process where a single cell divides into
two identical daughter (cell division).
During mitosis one cell divides once to form two
identical cells
The major purpose of mitosis is for growth and to
replace worn out cells.
If not corrected in time, mistakes made during
mitosis can result in changes in the DNA that can
potentially lead to genetic disorders.

15. MITOSIS IS DIVIDED INTO FIVE PHASES:
1. INTERPHASE
2. PROPHASE
3. METAPHASE
4. ANAPHASE
5. TELOPHASE

16. Interphase
 The DNA in the cell is copied in preparation for cell
division, this results in two identical full sets of
chromosome.
 Outside of the nucleus are two centrosome, each
containing a pair of centrioles, these structures are
critical for the process of cell division.
 During interphase, microtubes extend for these
centrosomes.

17. Prophase
 The chromosome condense into X-shaped structures that
can be easily seen under a microscope.
 Each chromosome is composed of two sister chromatids,
containing identical genetic information.
 The chromosome pair up so that both copies of
chromosome are together, both copies of chromosome 2
are together, and so on.
 At the end of prophase the membrane around the
nucleus in the cell dissolves away releasing the
chromosomes.
 The mitotic spindle. Consisting of microtubules and
other proteins, extends across the cell between the
centrioles as they move to opposite poles of the cell.

18. Metaphase
 The chromosomes line up nearly – to – end – along
the centre (equator) of the cell.
 The centrioles are now at opposite poles of the cell
with the mitotic spindle fibers extending from them.
 The mitotic spindle fibers attach to each of the sister
chromatids.

19. Anaphase
 The sister chromatids are thin pulled apart by the
mitotic spindle which pulls one chromatid to the
opposite pole.

20. Telophase
 At each pole of the cell a full set of chromosomes
gather together.
 A membrane forms around each set of chromosome
to create two new nuclei.
 The single cell then pinches in the middle to form
two separate, daughter cells each containing full set
of chromosomes within a nucleus.
 This process is known as Cytokines.

22. MEIOSIS
 Meiosis , on the other hand, is used for just one
purpose in the human body.
 The production of gametes, sex cells, or sperm and
eggs. It goal is to make daughter cells with exactly
half as many chromosome as the starting cell.
 To put that another way, meiosis in humans is a
division process that takes us from a diploid cell, one
with two sets of chromosomes to haploid cells, ones
with a single set of chromosome.

23. PHASES OF MEIOSIS
 In many ways, meiosis is a lot like mitosis. The cell
goes through similar stages and uses similar
strategies to organize and separate chromosome. In
meiosis, however, the cell has a more complex task.
It still needs to separate sister chromatids (the two
halved of a duplicated chromosome) as in mitosis.
But it must also separate homologous chromosomes,
the similar but non identical chromosomes pairs an
organism receives from its two parents.
 These goals are accomplished in meiosis using a two-
step division process.

24.  Homologue pairs separate during a first round of cell
division, called Meiosis I, sister chromatids separate
during a second round, called Meiosis II.ng cell can
 Since cell division occurs twice during meiosis, one
starting cell can produce four gametes (egg or
sperm). In each round of division, cells go through
four stages : PROPHASE, METAPHASE,
ANAPHASEM AND TELOPHASE.