1. Cell
Biology

3. Structural and functional unit of life.
• Robert Hooke, an English microscopist who, at
age 27, was awarded curator of the Royal Society
of London, England’s foremost scientific academy.
Hooke had observed the empty cell walls of dead
plant tissue, walls that had originally been
produced by the living cells they surrounded.
The word cell is derived from the Latin word
cellula, which means small compartment. Hooke
published his work in his famous work,
Micrographia.
Anton van Leeuwenhoek was the first person who
observed living cells under a microscope and
named them animalcules, meaning little animals.

5. Cell theory

6. According to this theory all living
things are made up of cells and
cell is the basic structural and
functional unit of life. In 1855,
Rudolf Virchow proposed an
important expand this cell theory
that all living cells arise from pre-
existing cells (omnis cellula e
cellula)

7. The modern cell theory
All cellular organisms are made up of one or
more cells (Unicellular and Multicellular).
Cells arise from pre-existing cells by division.
Energy flow occurs within cells.
Cells contain hereditary information (DNA) which
is passed from cell to cell.
All cells have mostly the same chemical
composition.
The modern cell theory

8. first culture of human cells was
started by George and Martha
Gey in 1951. The cells were
obtained from a malignant tumour
(Capacity of division higher than
normal cells) and named HeLa
cells (donor, Henrietta Lacks).
Basic Properties of Cells

9. Cells Are Very Complex and Organized
Cells Have a Genetic Program and the Means to Use It
Cells Are Capable of Making More of Themselves
Cells Acquire and Utilize Energy
Cells Carry Out a Variety of Chemical Reactions
Cells Engage in Mechanical Activities
Cells Are Able to Respond to Stimuli
Cells Are Capable of Self-Regulation
Basic Properties of
Cells

10. CYTOPLASM
Cell
membrane
Mitochondria
Nucleous
DNA Endoplasmic
reticulum
Lysosome
Ribosome
Golgi
apparatus
cytoplasm
Ribosome
Nucleoid
Plasmi
d
Plasma membrane
Cell wall
Flagella

13. Nuclear interchange
experiment

15. Bacterial cell walls
 Bacterial cell walls peptidoglycan (also called murein), polysaccharide chains
 The cell wall of bacteria is also distinct from that of Archaea because they do not
contain peptidoglycan.
 The antibiotic penicillin is able to kill bacteria by preventing
the cross-linking of peptidoglycan and this causes the cell
wall to weaken and breakable. The lysozyme enzyme can
also damage bacterial cell walls.
• The antibiotic penicillin is able to kill bacteria by preventing
the cross-linking of peptidoglycan and this causes the cell
wall to weaken and breakable

16. Plasma membrane
Peptidoglycan cell wall
Outer
membrane
Capsule
Porin
Lipopolysaccharide
Gram - negative Gram - positive
 Gram-positive bacteria have a thick cell wall comprising many layers of peptidoglycan
and teichoic acids. In contrast, gram-negative bacteria have a relatively thin cell wall
consisting of a few layers of peptidoglycan surrounded by a second lipid membrane
containing lipopolysaccharides and lipoproteins.
 Glycocalyx is present in many bacteria external to the cell wall the term capsule and
slime layer describe about glycocalyx. Possession of capsules makes some
pathogenic bacteria resistant to phagocytosis and enhance their virulence.

17. Plasma membrane
It is composed of protein and phospholipids just like eukaryotic cell. only
major difference is sterol, sterol is absent in bacteria but in mycoplasma
sterol present. In many bacteria hopanoids are present its role and structure
are like sterol. An invagination of the plasma membrane in the shape of
vesicles, tubules, or lamellae called as mesosome. Mesosome are play
important role in chromosome replication and formation of cross wall during
division in bacteria. They are more important in the gram positive

19. Bacterial
cell

21. Bacterial cell walls
are made
of peptidoglycan (a
lso called murein)
• The antibiotic penicillin can
kill bacteria by preventing the
cross-linking of peptidoglycan
and this causes the cell wall to
weaken and breakable.
The lysozyme enzyme can also
damage bacterial cell walls.
Fimbriae

22. There are broadly speaking two different types of cell wall in bacteria, called gram-
positive and gram-negative
Gram-positive bacteria have a thick cell wall comprising many layers of peptidoglycan
and teichoic acids. In contrast, gram-negative bacteria have a relatively thin cell wall
consisting of a few layers of peptidoglycan surrounded by a second lipid membrane
containing lipopolysaccharides and lipoproteins.

23. Most bacteria have the gram-negative cell wall and only
the Firmicutes and Actinobacteria (previously known as the low GC and high GC gram-
positive bacteria, respectively) have the alternative gram-positive arrangement. These
differences in structure can produce differences in antibiotic susceptibility, for
instance vancomycin can kill only gram-positive bacteria and is ineffective against gram-
negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa
 Glycocalyx (glycocalyx is a carbohydrate-enriched coating that covers the outside of
many eukaryotic cells and prokaryotic cells) is present in many bacteria external to the
cell wall the term capsule and slime layer describe about glycocalyx. Possession of
capsules makes some pathogenic bacteria resistant to phagocytosis and enhance
their virulence.

24. Plasma membrane
only major difference is sterol,
sterol is absent in bacteria but in
mycoplasma sterol present. In
many bacteria hopanoids are
present its role and structure are
like sterol. An invagination of the
plasma membrane in the shape of
vesicles, tubules, or lamellae called
as mesosome. Mesosome are play
important role in chromosome
replication and formation of cross
wall during division in bacteria.
They are more important in the
gram positive.

25. Cytoplasm
In the bacterial cytoplasm inclusion bodies are present which is part of
many organic and inorganic reserve granules. (glycogen, cyanophycean
granules, phosphate granules etc.)
Carboxysomes are also found in cytoplasm which is responsible for CO2
fixation in bacteria because this inclusion bodies contain RUBP (ribulose-
1,5-biphosphate).

26. Filament is made up of flagellin protein.
A Basal body, a hook and a filament.
basal body contain four ring (L, P, MS and
C-ring) and rod which is located just above
the Ms-ring and connected to the proximal
region of the hook. the C-ring consist of 3
protein FliG, FliM and FliN. with the motor
complex the most directly involved in the
rotation of the flagella among the C-ring
protein as it interacts with the motor
complex (Mot A and B).

28. Nucleoid
It contains bacterial chromosome. It lacks membrane. Bacterial chromosome is mostly
circular dsDNA molecules. Basic Histone protein absent but relates to polyamines
(Polyamines are polycations that interact with negatively charged molecules such as
DNA, RNA and proteins). E. coli contain single circular DNA molecules as a
chromosome. In some bacteria like Vibrio cholerae contain two circular chromosomes.

29. Plasmid
Plasmid term coined by J.
Lederberg. It is autonomous self -
replicating molecules of DNA that
are maintained as distinct, extra
chromosomal genetic elements in
bacteria. it is a self-replicating
molecule of the nucleic acid).
plasmids are mostly DNA
molecules. RNA plasmids are
very rare and reported in few the
plants fungi and even animals.
bacterial plasmids are usually
much smaller than the bacterial
chromosome.
Fimbriae

30. Bacterial cell walls are composed of a sugar and amino acid
polymer called peptidoglycan.

31.  Primary Cell Wall (cellulose, pectic polysaccharides and structural proteins)
 The Middle Lamella (pectin’s, lignin and proteins)
 The secondary cell wall (cellulose lignin)
Plant cell wall 3 layers and composed of carbohydrates, like pectin, cellulose,
hemicellulose and other smaller amounts of minerals,

32.  The plant cell wall provides definite shape, strength, rigidity
 It also provides protection against mechanical stress and physical shocks
 It helps to control cell expansion due to the intake of water
 Also helps in preventing water loss from the cell
 It is responsible for transporting substances between and across the cell
 It acts as a barrier between the interior cellular components and the
external environment

33. 1972. Jonathan singer and garth Nicolson proposed fluid mosaic model
which is not the most accepted model.

34. Proteins
The cell is made up of two
different types, or “classes”, of
proteins. Integral proteins are
nestled into the phospholipid
bilayer and stick out on either
end. Integral proteins are
helpful for transporting larger
molecules, like glucose, across
the cell membrane. They have
regions, called “polar” and
“nonpolar” regions, that
correspond with the polarity of
the phospholipid bilayer.