Pertemuan 4 Microbiology & Parasitology

Microbiology & Parasitology:
Cell Structure, Fuction & The

Gram Stain
M. Ali Azis Hasan Rizki, M.Sc
Prokaryote vs Eukaryote Cells
Prokaryote Eukaryote
DNA is not enclosed within a membrane and is DNA is found in the cell’s nucleus, which is
usually a singular, circularly arranged chromosome. separated from the cytoplasm by a nuclear
membrane, and the DNA is found in multiple
chromosomes.
DNA is not associated with histones; other proteins DNA is consistently associated with chromosomal
are associated with the DNA. proteins called histones and with nonhistones.
Generally lack organelles. Advances in microscopy Have a number of membrane-enclosed organelles,

reveal a few membrane-enclosed organelles (for including mitochondria, endoplasmic reticulum,
example, some inclusions). Golgi complex, lysosomes, and sometimes
chloroplasts.
Cell walls almost always contain the complex Cell walls, when present, are chemically simple.
polysaccharide peptidoglycan.
Usually divide by binary fission. Cell division usually involves mitosis.
General
Structure of
Bacterial Cells
The Cell Surface
Structures on cell surface protecting the cell from

external hazard and maintains cell’s integrity.
On the other hand, they also must enable transport

of large molecules into and out of the cell.
The structures and their composition can vary

between organisms
Capsules
01 02 03
True capsules: Less discrete Glycoclayx: thin layer
discrete layer of structure called slime of tangled
polysaccharides layer or biofilm: polysaccharide fibers
(and/or polypeptide) polysaccharides on cell surface,
deposited outside matrix where cells cannot be detected
the cell wall embeded visually
Capsules
Capsules composition
Bacterium Capsule composition Structural subunits
Gram-positive Bacteria
Bacillus anthracis polypeptide (polyglutamic acid) D-glutamic acid
Bacillus megaterium polypeptide and polysaccharide D-glutamic acid, amino sugars, sugars
Streptococcus mutans polysaccharide (dextran) glucose
Streptococcus pneumoniae polysaccharides sugars, amino sugars, uronic acids
Streptococcus pyogenes polysaccharide (hyaluronic acid) N-acetyl-glucosamine and glucuronic acid
Gram-negative Bacteria
Acetobacter xylinum polysaccharide (cellulose) glucose
Escherichia coli polysaccharide (colonic acid) glucose, galactose, fucose glucuronic acid
Pseudomonas aeruginosa polysaccharide mannuronic acid
Azotobacter vinelandii polysaccharide glucuronic acid
Agrobacterium tumefaciens polysaccharide (glucan) glucose
Capsules Functions
Mediate attachment of cells to surfaces.
Protect bacterial cells from engulfment or from

antimicrobial agents
Protect cells from drying or desiccation  soil

bacteria.
Carbohydrate reserves  dextrans.

B. antrachis
Fimbriae and Pili
Fimbriae (sing.: fimbria)
• Short hair-like projection, composed of protein called pilin,

found numerous on cell surface
• Play role in adherence of cells on surfaces or other cells, forming
biofilm
• Commonly found in Gram-negative bacteria
Pili (sing.: pilus)
• Longer than fimbriae, also composed of pilin, but only one or

two per cell
• Involved in motilities (twitching and gliding motility) and DNA
transfer (conjugation, or sex, pili)
Some fimbriae and pili properties
Bacterial species where observed Typical number on Distribution on cell Function

cell surface
Escherichia coli (F or sex pilus) 1-4 uniform stabilizes bacteria during transfer of DNA
during conjugation
Escherichia coli (common pili or Type 1 surface adherence to epithelial cells of the
fimbriae) 100-200 uniform GI tract
surface adherence to epithelial cells of the
Neisseria gonorrhoeae 100-200 uniform urogenital tract
Streptococcus pyogenes (fimbriae plus ? uniform adherence, resistance to phagocytosis;
the M-protein) antigenic variability
Pseudomonas aeruginosa 10-20 polar surface adherence
Sulfolobus acidocaldarius
(an archaic) ? ? attachment to sulfur particles
Flagella (sing.: flagellum)
The base part of the

Long and thin (20nm)
Helical structure flagella called hook which
whiplike appendages that
composed of protein connects flagella with its
attached to cell at one
monomers called flagellin motor which called basal
end
body
Flagella (sing.: flagellum)
Bacterial cell wall
Essential structure for viability
Composed of unique components found nowhere else in nature.
One of the most important sites for attack by antibiotics.
Provide ligands for attachment and receptor sites for drugs or viruses.
Cause symptoms of disease in animals.
Provide for immunological distinction and immunological variation among strains of bacteria.
Cell Wall:
Bacteria
Peptidoglycan
Gram Positive
vs
Gram Negative
Cell Membrane
Composed of 40 % phospholipid and 60 %

protein.
Phospholipids are amphoteric molecules

with a polar hydrophilic glycerol "head"
attached via an ester bond to two
nonpolar hydrophobic fatty acid tails.
Protein molecules dispersed inside the

phospholipid bilayer
Cell Membrane: Function
Bacterial Cell Membrane
Membrane Transport
Bacterial DNA
• Chromosomal DNA
• Mostly circular, placed in nucleoid, one each cell
• Some bacteria have linear chromosome, some other have two
chromosomes (Vibrio cholerae)
• Plasmid
• Circular, much smaller than chromosome, can be many each
cell
Infrequent in fungi
Saccharomyces cerevisiae:
• Plasmid found in the nucleus
Plasmids • Circular, dsDNA, 2 µm, 6200bp

• Can be up to 100 copies per cell
Kluyveromyces fragilis
• Two linear dsDNA with different

lengths
Chromosome of
Bacteria
Ribosomes
• Same function as eukaryotic ribosomes: protein
synthesis
• Two subunits: Large 50S and Small 30S
General Structures Eukaryote
Eukaryotic microorganisms
Algae
Fungi
Protista
• Flagella: long projections, few in number
Flagella and cilia • Cilia: Short projections, numerous
• Both made of microtubules
Fungal Cell Wall
• Mainly made of chitin: linear

polymer of N-acetyl-glucosamine
• Also found: mannan & glucan
• Zygomycetes: additional chitosan
Fungal Cell Wall
Hyphal Septa
• Ascomycota and Basidiomycota hyphae contain septum made of
chitin
• The septa has pore to permit passage of nuclei and cytoplasmic
stream
The plasma membrane
• Selective barrier (selective permeability)
• Cell to cell recognition
• Crossing the membrane:
• membrane transport (small molecules)
• Endocytosis in animal cells (large molecules)
Cytoplasm
• All substances inside plasma membrane and outside nucleus
• Liquid portion of cytoplasm called cytosol
• Cytoskeleton:
• made of microfilament, intermediate filament, and microtubules
• provides support, shape, and assistance in transporting substances through
the cell
Ribosomes
• Place of protein synthesis
• Ribosome molecule in eukaryote is 80S ribosome
consists of:
• a large 60S subunit containing 3 molecules of rRNA
• a smaller 40S subunit with 1 molecule of rRNA.
• Free ribosomes: unattached to any structure, synthesize
protein used inside cell
• Bound ribosomes: attached to nuclear membrane or
endoplasmic reticulum, synthesize membrane protein
and excreted protein
• Mitochondrial/chloropast ribosomes: 70S ribosome,
synthesize protein used by mitochondria or chloroplast
• Enveloped by double membrane with pores
• Contains hereditary information (DNA)
The Nucleus • Nucleoli: actually condensed regions of chromosomes where ribosomal RNA
is being synthesized.
Eukaryotic Chromosomes
Endoplasmic Reticulum (ER)
• Flattened membranous sacs or tubules called cisternae,
continuous with nuclear membrane
• Rough ER: attached by ribosomes, processing place of
protein
• Smooth ER: unattached by ribosomes, synthesized
phospholipids, fats, and sterols
• Consists of 3 to 20 cisternae stacked togather
Golgi Complex • Place of molecule processing and transport
Energy Factory: Mitochondria
• Smaller than chloroplast

• Contain ribosomes and their own DNA
• Surrounded by a double membrane
• Inner membrane surrounds the matrix and is convoluted (folds) to form cristae.
• Matrix – Inner semifluid containing respiratory enzymes
• Break down carbohydrates
• Involved in cellular respiration
• Produce most of ATP utilized by the cell
Bound by a double membrane
organized into flattened disc-like
sacs called thylakoids
Carbohydrate Chlorophyll and other pigments
s Factory: capture solar energy
Chloroplast
Enzymes synthesize carbohydrates
Lysosome, Peroxisome, Vacuole
• Derived from Golgi Complex

• Lysosome: single membrane-enclosed sphere consists up to 40 types of strong digestive enzymes
• Peroxisome: similar to lysosome but smaller, consists enzymes to oxidize substances specially toxic substances
such as alcohol and hydrogen peroxide
• Vacuole:
• temporary storage organelles for substances such as proteins, sugars, organic acids, and inorganic ions.
• has roles in endocytosis
• store metabolic wastes and poisons
• take up water to increase cell in size and also providing rigidity to leaves and stems.

Pertemuan 4 Microbiology & Parasitology

Uploaded by

Copyright:

Available Formats

Pertemuan 4 Microbiology & Parasitology

Uploaded by

Document Information

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Pertemuan 4 Microbiology & Parasitology

Uploaded by

Copyright:

Available Formats

Microbiology & Parasitology:

Cell Structure, Fuction & The

Generally lack organelles. Advances in microscopy Have a number of membrane-enclosed organelles,

Structures on cell surface protecting the cell from

On the other hand, they also must enable transport

The structures and their composition can vary

Mediate attachment of cells to surfaces.

Protect bacterial cells from engulfment or from

Protect cells from drying or desiccation  soil

Carbohydrate reserves  dextrans.

• Short hair-like projection, composed of protein called pilin,

Pili (sing.: pilus)

• Longer than fimbriae, also composed of pilin, but only one or

Bacterial species where observed Typical number on Distribution on cell Function

The base part of the

Composed of unique components found nowhere else in nature.

One of the most important sites for attack by antibiotics.

Cause symptoms of disease in animals.

Composed of 40 % phospholipid and 60 %

Phospholipids are amphoteric molecules

Protein molecules dispersed inside the

• Plasmid found in the nucleus

Plasmids • Circular, dsDNA, 2 µm, 6200bp

• Two linear dsDNA with different

• Mainly made of chitin: linear

• Smaller than chloroplast

• Derived from Golgi Complex

You might also like