Structural organization of life

1. Chapter#2
Structural Organization Of Life

2. Cell
• The cell (from Latin cella, meaning "small room" is the basic
structural, functional, and biological unit of all known organisms.
A cell is the smallest unit of life. Cells are often called the
"building blocks of life"

3. Salient Features of Cell Theory
All living organisms are made
up of one or more cells.
1
The cell is the smallest, basic
structural and functional unit
of all living organisms.
2
New cells
are formed by the divisions of
pre-existing cells.
3

4. Microscope

5. Light
Microscope
Illuminating source is the
Light.
Wavelength of light is 400-
700nm.
Lenses are used.
Maximum resolution
is 200nm

6. Electron Microscope
Illuminating source is
the beam of
electrons.
Wavelength of beam
of
electrons is 0.005nm.
Electromagnets are
used.
Maximum resolution
is 0.5nm

7. Comparison between Prokaryotic and
Eukaryotic cells
Prokaryotic Cell
• Prokaryotes are organisms made up of
cells that lack a cell nucleus or any
membrane-encased organelles.
• Examples are Bacteria and Cyanobacteria
Eukaryotic Cell
• Eukaryotes are organisms made up of
cells that possess a membrane-bound nucleus
that holds genetic material as well as
membrane-bound organelles.
• Examples are animals, plants and fungi

8. Basic Structure of
Cell

9. Structure
of Cell
• There are many different
types, sizes, and shapes of
cells in the body.

10. Cell
Membrane
• Every cell in the body is
enclosed by a cell
(Plasma) membrane.
• The cell membrane separates
the material outside the cell,
extracellular, from the material
inside the cell, intracellular
• It is a thin , elastic, delicate and
self-repairable to some extent.
• It is composed of lipid bilayer
and proteins.

12. Cell Wall • It is present in plant, fungal
and bacterial cells.
• It is a non-living structure.
• It is tough and rigid in
structure.
• It is composed of
cellulose fibrils.

14. Nucleus • It is the most important and
distinct part of the cell.
• Discovered by Robert Brown.
• In animal cell it is present in the
center while in the plant cell it is
pushed in the side.
• It is surrounded by a membrane
called nuclear membrane.
• It controls all activities of cell.
• It is filled with a gel like
substance called nucleoplasm.
• The nucleoplasm
contains nucleoli and chromatin

16. Cytoplasm
• The cytoplasm is the gel-like fluid inside
the cell.
• It is the medium for chemical reaction.
• It provides a platform upon which other
organelles can operate within the cell. All
of the functions for cell expansion, growth
and replication are carried out in the
cytoplasm of a cell.
• Within the cytoplasm, materials move
by diffusion, a physical process that can
work only for short distances.

17. Cytoplasmic
organelles
• Cytoplasmic organelles are
"little organs" that
are suspended in the
cytoplasm of the cell.
• Each type of organelle has a
definite structure and a
specific role in the function of
the cell.
• Examples of cytoplasmic
organelles
are mitochondrion, ribosomes,
endoplasmic reticulum, golgi
apparatus, and lysosomes.

19. Endoplasmic
Reticulum
• A network of membranous tubules within the cytoplasm of
a eukaryotic cell, continuous with the nuclear membrane.
• It usually has ribosomes attached and is involved in
protein and lipid synthesis.
• The endoplasmic reticulum (ER) is a type
of organelle made up of two subunits – rough
endoplasmic reticulum (RER), and smooth
endoplasmic reticulum (SER)
• RER having ribosomes which are involved in
protein synthesis.
• SER without ribosomes

21. Golgi
apparatus
• Golgi apparatus, also called Golgi
complex or Golgi body, membrane-
bound organelle of eukaryotic cells that
is made up of a series of flattened,
stacked pouches called cisternae.
• The Golgi apparatus is responsible for
transporting, modifying, and
packaging proteins and lipids into vesicl
es for delivery to targeted destinations.
• It is located in the cytoplasm next to
the endoplasmic reticulum and near
the cell nucleus.

23. Mitochondria
• Mitochondria are known as the
powerhouses of the cell.
• They are organelles that act like a
digestive system which takes in
nutrients, breaks them down, and
creates energy rich molecules for the
cell.
• The biochemical processes of the
cell are known as cellular
respiration.
• Many of the reactions involved in
cellular respiration happen in the
mitochondria.
• Mitochondria are the working
organelles that keep the cell full of
energy.

25. Plastids
• Plastids are a group of
phylogenetically and physiologically-
related organelles found in all types
of plants and algae
• In the cells, plastids are primarily
involved in the manufacture and
storage of food
• They are therefore involved in such
processes as photosynthesis,
synthesis of amino acids and lipids
as well as storage of various
materials among a few other
functions.
•

27. Types of Plastids
• Chloroplast
• Chromoplast
• Leucoplast

29. Centrosomes
and
centrioles
• Both centrioles and centrosome
s are complicated cell structures
that are essential for cell division
• The centrosome directs the
movements of the chromosomes
when a cell divides, and
the centrioles help create the
spindle of threads along which the
duplicated chromosomes
separate into the two new cells.

31. Ribosomes
• Ribosomes are the protein
builders or the
protein synthesizers of the cell
• Ribosomes are special because
they are found in both prokaryotes
and eukaryotes.
• Endoplasmic reticulum with
attached ribosomes is called
rough ER

33. Vacuole
• Vacuoles are storage bubbles
found in cells
• They are found in both animal and
plant cells but are much larger
in plant cells.
• The structure of vacuoles is fairly
simple. There is a membrane that
surrounds a mass of fluid called
tonoplast.
• In plant cells, the vacuoles are
much larger than in animal cells.

35. Animal Cell
And Plant
Cell

36. Home Task
• Define cell.
• Write down the salient features of the cell theory.
• Differentiate between electron microscope and light microscope.
• Differentiate between prokaryotes and eukaryotes.
• Differentiate between animal cell and plant cell
• Define plastids with its types.
• Draw animal cell and plant cell

37. Cell Division

38. Cell
Division
• Cells reproduce by division.
• Nucleus divides first.
• Nuclear division is
called Karyokinesis.
• Two main types of cell division:
• Mitosis and meiosis

39. Mitosis
A type of cell division that results in two daughter cells each
having the same number and kind of chromosomes as the parent
nucleus, typical of ordinary tissue growth.

41. Stages of
Mitosis

42. Prophase
1
During prophase, the
complex of DNA and proteins
contained in the nucleus,
known as chromatin,
condenses.
2
The chromatin coils and
becomes increasingly
compact, resulting in the
formation of visible
chromosomes.
Chromosomes are made of a
single piece of DNA that is
highly organized.
3
The replicated chromosomes
have an X shape and are
called sister chromatids. The
sister chromatids are pairs of
identical copies of DNA
joined at a point called the
centromere.
4
Then, a structure called the
mitotic spindle begins to
form. The mitotic spindle is
made of long proteins called
microtubules that begin
forming at opposite ends of
the cell.
5
The spindle will be
responsible for separating
the sister chromatids into two
cells

44. Metaphase
Chromosome
arranges itself on
the equator of the
spindle.
Each chromosome
is attached
to separate spindle
fiber by its
centromere.

46. Anaphase

47. Telophase

48. Significance of mitosis
• It is responsible for growth and development.
• Helps in asexual reproduction.
• It produces new somatic cells.
• Heals wound, repair of wear, and tear within organism.

49. Homework
Define
Define Mitosis.
Describe
Describe mitosis and its
stages in detail with the
help of a
labelled diagram .
Write
Write significances of
Mitosis.

50. Meiosis

51. Definition
• A type of cell division that results in four daughter cells each with
half the number of chromosomes of the parent cell, as in the
production of gametes and plant spores.

52. Meiosis
Meiosis I
Prophase I
Metaphase
I
Anaphase I
Telophase
I
Meiosis II