The document discusses cell structure and taxonomy, differentiating between prokaryotic and eukaryotic cells, their components, functions, and reproduction methods. It explains the significance of metabolism and classification in biology along with the historical contributions of various scientists. Additionally, it outlines the five kingdoms of classification and modern classification systems, emphasizing the structural and reproductive differences between cells.

1. Chapter III :
Cell Structure
and Taxonomy
REGIE L. MAGALLANES, LPT, M.ED
Microbiology and Parasitology -
Instructor

2. At the end of the unit, the student
should be able to:
1. Describe the parts and functions of
eukaryotic and prokaryotic cells.
2. Differentiate the contributions of Hooke,
Schleiden and Schwann, and Virchow to the
study of cells.
3. Compare and contrast animal and bacterial
cells.

3. Introduction
to
Microorganis
ms

4. A. Definitions

5. Cell
• is defined as the
fundamental unit of
any living organism.
• exhibits the basic
characteristics of
life.

6. Cell
• It obtains food
(nutrients) from
the environment to
produce energy for
metabolism and
other activities.

7. Classification
1. Prokaryotes
2. Eukaryotes

8. Prokaryot
es
• Do not have
complex
system of
membranes
and
organelles
• Bacteria

9. Eukaryote
s
• More complex cells,
containing true
nucleus and many
membrane bound
organelles.
• Algae, Protozoa, fungi,
plants, animals, and
humans

10. Metabolism
• Refers to all the chemical
reactions that occur within a cell.
Importance of metabolism –
growth, reproduction, and
irritability

11. Mutation
•Accidental changes in genetical
material.

12. B. Eucaryotes

13. Eucaryotes

14. Eucaryotes
• From a Greek word meaning
“true nucleus”.
•DNA is enclosed by a nuclear
membrane.
•Eucaryotic cells reproduce either
by mitosis or meiosis.

15. Mitosis
•Refers to nuclear division – the equal
division of one nucleus into two
genetically identical Nuclei.
•Chromosomes are copied and allocated
equally two daughter cells.
•The genosomes of the offspring are
identical to the parent’s genome.
•Either haploid or diploid cells can divide

17. Meiosis
•Two parents give rise to offspring that
have unique combinations of genes
inherited from both parents.
•Only diploid cells can undergo meiosis.
•Diploid cells are changed into haploid
cells.
Ex: Human diploid cells – 46 chromosomes
Human haploid cells – 23

19. Eucaryotic
Cell Structure

20. Cell Membrane
• Is like a “skin” around the cell, separating
the contents of the cell from the outside
world.
•Regulates the passage of nutrients, waste
products, and secretions into and out of
the cell. – selective permeability. (only
certain substances may enter and leave
the cell)

22. Nucleus
• “Command center” of the cell because it unifies, controls,
and integrates the functions of the entire cell.
Three components: Nucleoplasms, Chromosomes, Nuclear
membrane
a. Nucleoplasm – a type of protoplasm that is the
gelatinous matrix or base material of the nucleus.
b. Chromosomes – are embedded or suspended in the
nucleoplasm.
c. Nuclear membrane – the “skin” around the nucleus; it
contains holes (nuclear pores) through which large
molecules can enter the nucleus.

24. Nucleolus
•Where rRNA molecules are
manufactured.
•The rRNA molecules then become
part of the structure of
ribosomes.

26. Cytoplasm
•It is where most of the cell’s
metabolic reactions occur.
•Where we can find insoluble
storage granules and cytoplasmic
organelles (ER, ribosomes, golgi
complex, mitochondria,
centrioles, etc.)

28. Endoplasmic Reticulum
• is a highly convulated system of
membranes that are
interconnected and arranged to
form a transport network of
tubules and flatened sacs within
the cytoplasm.

30. Ribosomes
• Consist mainly of ribosomal RNA (rRNA) and protein.
• Plays an important role in the synthesis
(manufacture) of essential proteins.
• Two subunits: 60S subunit & 40S subunit. –
produced in the nucleus.
• The subunits are then transported to the cytoplasm
where they remain separate until such time as they
join together with a messenger RNA (mRNA)
molecule to initiate protein synthesis. When united,
the 60S and 40S form an 80S ribosome.

32. Golgi Complex
•Connects or communicate with ER.
•It completes the transformation of newly
synthesized CHONs into mature
functional ones and packages them into
vesicles for storage within the cell or
export outside the cell.
•Referred to as “packaging plants”.

34. Lysosomes
•Small vesicle that originate at the GC.
They contain lysozyme that breakdown
foreign material taken into the cell by
phagocytosis.
•Lysozyme also aid in breaking down worn
out parts of the cell and may destroy the
entire cell by autolysis.

36. Peroxisomes
•It is where hydrogen peroxide is both
generated and broken down.
•It contains the enzyme catalase which
catalyzes the breakdown of H2O2 into
H2O and O2.

38. Mitochondria
• “Power plants” ; “Power houses” or
“Energy factories”.
•It is where most of the ATP molecules are
formed by cellular respiration.
ATP- Adenosine Triphosphate (energy
necessary for cellular function.

40. Plastids
• Energy- producing organelle in plant
cells.
•Sites of photosynthesis- conversion of
light energy into chemical energy.

42. Cytoskeleton
• Three types of cytoskeletal fibers: microtubules,
microfilaments, intermediate filaments.
• Serve to strengthen, support, and stiffen the cell and
give the cell its shape.
• Microtubules and microfilaments are essential for
cell division, contraction, motility, and the movement
of chromosomes within the cell.
• Microtubules are composed of spherical protein
subunits called tubulins.

44. Cell Wall
• External structure that provides rigidity, shape, and
protection.
• Simpler in structure in eukaryotic cells and may
contain cellulose, pectin, lignin, chitin, and some
mineral salts.
• Cell walls of algae and plants – contain a
polysaccharide, cellulose.
• Cell walls of fungi – contain a polysaccharide, chitin.

46. Flagella & Cilia
a.Flagella – responsible for
motility
b.Cilia – are also organelles of
locomotion.
c.Eukaryotic flagella and cilia are
structurally more complex than
bacterial flagella.

48. C. Procaryotes

49. Procaryotes
•From a Greek word meaning
“prenucleus”.
•Are about 10 times smaller than
Eukaryotes.
•Possess no membranes other than
the cell membrane that encloses the
cytoplasm.

50. Procaryotes

51. Binary Fission
The parent cell (one cell) in half to
become two daughter cells. DNA
replication (duplication of
chromosomes) must occur prior to the
actual splitting of the parent cell so
that each daughter cell will possess the
same genetic information as the
parent cell.

53. Procaryotic
Cell Membrane

54. Cell Membrane
• Encloses the
cytoplasm.
• Consists of proteins
and phospholipids.
• It controls which
substances may enter
or leave the cell.

55. Chromosome
• Consists of a single, long,
supercoiled, circular DNA
molecule which serves as
the control center of the
bacterial cell.
• Capable of duplicating
itself, guiding cell
division, and directing
cellular activities.

56. Plasmids
• Extrachromosomal DNA.
• Small, circular molecules of
double-stranded DNA that
are not part of the
chromosome.
• It may contain from fewer
than 10 to several hundreds
of genes.

57. Cytoplasm
• Consist of water, enzymes,
dissolved oxygen, waste
products, essential nutrients,
CHONs, CHO, and lipids.
• Complex mixture of
materials required by the cell
for its metabolic functions.

58. Cytoplasmic
Particles
• Ribosomes – sites
of CHON synthesis;
7OS

59. Cytoplasmic Particles
•Cytoplasmic
Granules – consist
of starch, lipids,
sulfur, iron, & other
stored substances.

60. Bacterial Cell
Wall
•It defines the shape
of bacterial cells.
•It provides rigidity,
strength, and
protection.
•Main constituent:
Peptidoglycan.

61. Bacterial Cell Wall
Cell walls of bacteria:
“Gram-Positive bacteria” – have thick
layer of peptidoglycan combined with
teichoic acid and lipoteichoic acid
molecules.
“Gram-Negative bacteria” have
thinner layer of peptidoglycan, but this
layer is covered with a complex layer of

63. Bacterial Cell
Wall
•Genus Mycoplasma
– do not have cell
walls.

64. Glycocalyx (slime
layer & capsules)
•A slimy, gelatinous
material produced
by the cell
membrane and
secreted outside of
the cell wall.

65. Glycocalyx (slime layer & capsules)
A. Slime Layer- is not highly organized
and is not firmly attached to the cell
wall.
- enable certain bacteria to glide or
slide along solid surfaces.
ex: Pseudomonas sp. – produce a slime
layer that plays a role in the disease
that it cause.

67. Glycocalyx (slime layer & capsules)
B. Capsule – is highly organized and firmly attached
to the cell wall.
- Consist of polysaccharides, which may be combined
with lipids and proteins, depending on the bacterial
species.
ex: H. influenza, K. pneumonia, N. meningitides, S.
pneumonia.
- capsules serve an antiphagocytic function.
- can be detected using a negative stain whereby the
bacterial cell and background become stained.

69. Flagella
- Are thread-like protein (flagellin)
appendages that enable bacteria to move
(motile).
The number and arrangement of flagella
can be used for classification and
identification purposes.
ex: Salmonella sp.

70. Flagella
Flagellar Arrangement
1. Monotrichous – one
flagellum.
2. Amphitrichous – one or
more flagella at each end.
3. Lophotrichous – a tuft
of flagella at one end.
4. Peritrichous – flagella
all over the surface.

71. Flagella
Test for motility:
a. Wet mount and Hanging drop method –
differentiates true motility from Brownian
movement.
b. growth in a semi-solid medium
Motile- growth of bacteria is away from the
inoculation line.
Non- Motile – growth of bacteria is confined
along the inoculation line.

72. Pili (Fimbriae)
- Are hair-like structures, most
often observed on Gram (-)
bacteria.
- Composed of protein called
pilin.
- Much thinner than flagella,
have a rigid structure and are
not associated with motility.

73. Spores (Endospores)
•Sporulation- process of spore formation-
resistant to heat, cold, drying and most
chemicals.
•When dried spore lands on a moist,
nutrient-rich surface, it germinates, and a
new vegetative bacterial cell emerges.
ex: Bacillus sp., Clostridium sp.

75. Spores (Endospores)
Location of spores within the cell:
a. Central – spore is produced at the
center of cell.
b. Terminal – spore is produced at the
very end of cell.
c. Subterminal - spore is produced
elsewhere in the cell.

76. Spores (Endospores)
Location of spores within the cell:
a. Central – spore is produced at the
center of cell.
b. Terminal – spore is produced at the
very end of cell.
c. Subterminal - spore is produced
elsewhere in the cell.

77. D. Comparison
Between Eucaryotic
and Procaryotic Cells

79. E. Prokaryotic Cell
Reproduction

81. Prokaryotic Cell Reproduction
•Prokaryotic cells reproduce by binary
fission.
• One cell (parent cell) splits into half to
become two daughter cells.
• Before a prokaryotic cell can divide into
half, its chromosomes must be
duplicated.
• Generation time- varies from one

82. F. Eukaryotic Cell
Reproduction

83. Eukaryotic Cell Reproduction
• Eukaryotic cell reproduce in a process
called mitosis.
•Mitosis the type of division that gives rise
to daughter cells for the purpose of tissue
growth, regeneration or asexual
(vegetative) reproduction.

84. G. Taxonomy

85. Taxonomy
• Taxonomy is the science of classification
of living organism.
Consists of 3 but interrelated areas:
1. Classification- arrangement of
organisms into taxonomic groups
(taxa).
2. Nomenclature- assignment of names.
3. Identification- process of determining

86. H. Microbial
Classification

87. Microbial
Classification
Carolus Linnaeus- established
the binomial nomenclature.
genus + specific epithet
Genus- capitalize the first letter
Specific epithet- not capitalized
“sp.”- single specie, “spp.”- more
than one specie.

88. I. Taxonomic
Hierarchies

89. Taxonomic Hierarchies
• Species- group of related organism/strains
• Genus- collection of related species
• Family- collection of similar genera
• Order- collection of similar families
• Class- collection of similar orders
• Phylum/Division- collection of similar classes
• Kingdom- collection of similar phyla/divisions
• Domain- collection of similar kingdoms

90. Fried
Kingdom – Animalia
Phylum – Chordata
Class – Aves
Order – Galliformes
Family – Phasianidae
Genus – Gallus
Species - domesticus

92. Ensalada Solanum melongena
with Mangifera indica.

94. BAHAY KUBO
Bahay-kubo, kahit munti
Ang halaman doon ay sari-sari
Pachyrhizus erasus at Solanum melongena Psophocarpus
tetragonolobus at Arachis hypogaea Vigna unguiculata spp.
sesquipedalis, purpureus), Phaseolus lunatus Benincasa hispida
, Luffa acutangula, Lagenaria sinceraria Cucurbita maxima At tsaka
mayro’n pang Raphanus sativus, Brassica juncea Allium cepa,
Lycopercum esculentum, Allium sativum at Zingiber officinale
Sa paligid-ligid ay puno ng Sesamum indicum

95. J. Examples of
Bacteria Named after
the Diseases That

96. Taxonomic Hierarchies

97. K. The 5 Kingdom
Classifications

98. The 5 Kingdom
Classifications
Founded in 1969 by
Robert H. Whittaker.

99. The 5 Kingdom Classifications
• Bacteria and archaeans are in the Kingdom Prokaryotes (or
Monera).
• Algae and Protozoa are in the Kingdom Protista (organisms
in this kingdom are reffered to as protists).
• Fungi are in the Kingdom Fungi.
• Plants are in the Kingdom Plantae.
• Animals are in the Kingdom Animalia.
• Viruses are not included in the Five-Kingdom System of
Classification because they are acellular.

101. Modern Classifications
• In 1978, Carl R. Woese proposed
elevating the three cell types to a level
above kingdom, called DOMAIN.
Cells are classified into three types:
1. ARCHAEBACTERIA
2. EUBACTERIA
3. EUKARYA

103. Let’s
Recap!

104. •Structural Differences
•Prokaryotic cells are simpler and smaller than
eukaryotic cells, lacking a nucleus and membrane-
bound organelles.
•Eukaryotic cells have a complex structure with a
true nucleus and various organelles performing
specific functions.

105. •Reproduction Methods
•Prokaryotic cells reproduce quickly through
binary fission.
•Eukaryotic cells can reproduce both asexually
(mitosis) and sexually (meiosis), allowing for
genetic diversity.

106. •Taxonomy Principles
•The hierarchical system of classification helps in
organizing and understanding the relationships
among different organisms.
•Accurate identification and naming are crucial for
the study and communication of biological
research.