cell- definition, charcteristics, organelles

1. Cell
PRESENTED BY
MISS. SANAMBI SHAIKH
MSC NURSING (OBGY)

2. Basic terminology
 Anaplasia – structural differentiation loss within a cell or
group of cells.
 Aplasia – organ or part of organ missing
 Hypoplasia – congenital below – average number of cells,
especially when inadequate
 Hyperplasia – proliferation of cells
 Neoplasia - abnormal proliferation
 Dysplasia – change in cell or tissue phenotype
 Metaplasia – conversion in cell type

3. Cont…
Prosoplasia – development of new cell function
Desmoplasia – connective tissue growth
Atrophy – reduced functionality of an organ
Hypertrophy – increase in the volume of cells
Hypotrophy – decrease in the volume of cells
Dystrophy – any degenerative disorder resulting from
improper or faulty nutrition.
Cyanosis – bluish discoloration
Inflammation – bodies self defense mechanism

4. Introduction
• A cell is the structural and fundamental unit of life.
• Robert Hooke was the first biologist who discovered
cells.
• A cell consists of small, membrane – bound compartment
that contains all the chemicals & molecules that help to
support an organism’s life.
• All living organism are composed of cells. They may be
made up of a single cell (unicellular) or many cells
(multicellular).
• They are of a different shape & size.

5. Definition
“ A cell is defined as the smallest, basic unit of life
that is responsible for all of life’s processes.”

6. Characteristics of cells
• Cells provide structure & support to the body of an
organism.
• The cell interior is organised into different individual
organelles surrounded by a separate membrane.
• The nucleus (major organelle) holds genetic information
necessary for reproduction & cell growth.
• Every cell has one nucleus & membrane – bound
organelles in the cytoplasm.

7. Cont……
• Mitochondria a double membrane bound organelle is
mainly responsible for the energy transactions vital for
the survival of the cell.
• Lysosomes digest unwanted materials in the cell.
• Endoplasmic reticulum plays a significant role in the
internal organization of the cell by synthesising selective
molecules & processing, directing & sorting them to their
appropriate locations.

8. Types of cells
There are two main types of cells.
Prokaryotes – one - celled organisms with no membrane
bound nucleus or other organelles (cell parts) . The cell size
ranges from 0.1 to 0.5 µm in diameter.
e.g. Bacteria
Eukaryotes – multi – celled organisms with membrane bound
nucleus & other organelle (cell parts) . The cell size ranges
between 10 – 100 µm diameter.
e.g. Plants & Animal

10. Structure of cell
• The cell structure comprises individual components with
specific functions essential to carry out life’s processes.
• These components include- cell wall, cell membrane,
cytoplasm, nucleus, and cell organelles.

11. Cell Membrane / plasma membrane
• The cell membrane supports and protects the cell.
• It controls the movement of substances in and out of the cells.
• It separates the cell from the external environment.
• The cell membrane is the outer covering of a cell within which
all other organelles, such as the cytoplasm and nucleus, are
enclosed.
• The cell membrane also protects the cellular component from
damage and leakage.

12. Cell Wall
• The cell wall is the most prominent part of the plant’s cell
structure.
• It is made up of cellulose, hemicellulose and pectin.
• The cell wall is present exclusively in plant cells.
• It protects the plasma membrane and other cellular
components.
• The cell wall is also the outermost layer of plant cells.
• It is a rigid and stiff structure surrounding the cell membrane.
• It provides shape and support to the cells and protects them
from mechanical shocks and injuries.

13. Cytoplasm
• The cytoplasm is a thick, clear, jelly-like substance present
inside the cell membrane.
• Most of the chemical reactions within a cell take place in this
cytoplasm.
• The cell organelles such as endoplasmic reticulum,
mitochondria, ribosomes, are suspended in this cytoplasm.

14. Nucleus
• The nucleus contains the hereditary material of the cell, the
DNA.
• It sends signals to the cells to grow, mature, divide and die.
• The nucleus is surrounded by the nuclear envelope that
separates the DNA from the rest of the cell.
• The nucleus protects the DNA and is an integral component of
a plant’s cell structure.

15. Organelles
Endoplasmic reticulum (ER) -
It is a large, dynamic structure that serves many
roles in the cell including calcium storage, protein synthesis and
lipid metabolism .
• The ER is a series of membrane extending throughout the
cytoplasm of eukaryotic cells.
• In some places the ER is studded with microscopic bodies
called ribosomes. This type of ER called rough ER.
• In other places there are no ribosomes this type ER is called
smooth ER.
• The rough ER is the site of protein synthesis in a cell because
it contains ribosomes.
• The smooth ER lacks of ribosomes & is responsible for
producing lipids.

17. Golgi apparatus / Golgi body
• The Golgi apparatus is a series of flattened sacs, usually curled
at the edges.
• In the Golgi body the cell’s proteins and lipids are processed
and packaged before being sent to their final destination.
• To accomplish this function the outermost sac of the Golgi
body often bulges and breaks away to form drop like vesicles
known as secretory vesicles.

19. Lysosome
• An organelle called the lysosome is derived from the Golgi
body.
• It is a drop like sac of enzymes in the cytoplasm.
• These enzymes are used for digestion within the cell.
• They break down particles of food taken into the cell and make
the products available for use; they also help break down old
cell organelles.
• Enzymes are also contained in a cytoplasmic body called the
peroxisome.

21. Mitochondria
• The organelle that releases quantities of energy to form
adenosine triphosphate (ATP) is the mitochondrion (the plural
form is mitochondria).
• Because mitochondria are involved in energy release and
storage, they are called the “power houses of the cells.”

23. Cytoskeleton
• It is an interconnected system of fibers, threads and interwoven
molecules that give structure to the cell.
• The main components of the cytoskeleton are microtubules,
microfilaments and intermediate filaments.
• It is helps cells maintain their shape and internal organization
and it also provides mechanical support that enables cells to
carry out essential function like division and movement.

25. Centriole
• The centriole organelle is a cylinder like structure that occurs
pairs.
• Centrioles function in cell division.

27. THANK YOU