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1. CELL- STRUCTURE AND
FUNCTIONS
MADE BY: ANAM
CLASS:VIII-A

2. Discovery of the cell
 The andy was first discovered by Robert Hooke in 1665, which can be
found to be described in his book Micrographia. In this book, he gave 60
‘observations’ in detail of various objects under a coarse, compound
microscope .One observation was from very thin slices of bottle cork.
Hooke discovered a multitude of tiny pores that he named "andys".This
came from the Latin word Cella, meaning ‘a small room’ like monks lived
in and alsoCellulae, which meant the six sided cell of a honey comb.
However, Hooke did not know their real structure or function. Before, it
had been thought that cells shared walls and the fluid passed between
them this way.

3. Cell theory
 In biology, cell theory is a scientific theory which describes the properties of cells.
These cells are the basic unit of structure of all organisms and also the basic unit of
reproduction.With continual improvements made to microscopes over time,
magnification technology advanced enough to discover cell in the 17th century.This
discovery is largely attributed to Robert Hooke, and began the scientific study of cell,
also known as cell biology.Cell theory has become the foundation of biology and is
the most widely accepted explanation of the function of cells.
 The three tenets to the cell theory are as described below:
 All living organisms are composed of one or more cells
 The cell is the most basic unit of life.
 All cells arise from pre-existing, living cells.

4. Parts of a cell

5. All cells, whether they are
prokaryotic or eukaryotic, have some
common features.
 The common features of prokaryotic and eukaryotic cells are:
 1. DNA, the genetic material contained in one or more
chromosomes and located in a nonmembrane bound nucleoid
region in prokaryotes and a membrane-bound nucleus in
eukaryotes
2. Plasma membrane, a phospholipid bilayer with proteins that
separates the cell from the surrounding environment and functions
as a selective barrier for the import and export of materials
3. Cytoplasm, the rest of the material of the cell within the plasma
membrane, excluding the nucleoid region or nucleus, that consists
of a fluid portion called the cytosol and the organelles and other
particulates suspended in it
4. Ribosomes, the organelles on which protein synthesis takes
place

7. Cell diversity
 Living organisms include unicellular organisms living as only one
cell, and multicellular organisms whose bodies are made of
many cells.Various kinds of unicellular organisms exist, from
bacteria such as the 1-2-μm-long Escherichia coli (E. coli) to
protists such as the 200-μm-long paramecia Multicellular
organisms, e.g., humans, are made of a great variety of cells.
Cells have various shapes, including flat cells (e.g., skin epithelial
cells), disc-shaped cells (e.g., red blood cells), and long, narrow,
extended cells (e.g., nerve cells). Cell sizes vary from a diameter
of about 7 am in red blood cells to a dendrite length of up to 1 m
in nerve cells. Plant cells also have a variety of shapes and sizes,
including rectangular compartmentalized cells (e.g., cork cells),
cells resembling jigsaw puzzle pieces (e.g., spongy cells), and
cells elongated from a few millimeters to several dozen
centimeters in length (e.g., pollen tube cells).

9. Cell division
 Cell division is the process by which a parent cell divides into two
or more daughter cells.Cell division usually occurs as part of a
larger cell cycle. In eukaryotes, there are two distinct type of cell
division: a vegetative division, whereby each daughter cell is
genetically identical to the parent cell (mitosis), and a reductive
cell division, whereby the number of chromosomes in the
daughter cells is reduced by half, to produce
haploid gametes (meiosis). Meiosis results in four haploid
daughter cells by undergoing one round of DNA replication
followed by two divisions: homologous chromosomes are
separated in the first division, and sister chromatids are
separated in the second division. Both of these cell division
cycles are in sexually reproducing organisms at some point in
their life cycle, and both are believed to be present in the last
eukaryotic common ancestor Prokaryotes also undergo a
vegetative cell division known as binary fission, where their
genetic material is segregated equally into two daughter cells.
All cell divisions, regardless of organism, are preceded by a
single round of DNA replication.

11. Animal cell

12. Plant cell

13. THANK YOU FOR WATCHING.. 