1. The document discusses the morphology and classification of bacteria and other microorganisms. It describes the different shapes bacteria can take and how they are classified into kingdoms. 2. Key characteristics of bacteria are described, including their size, structures like the cell wall and flagella, and differences between prokaryotic and eukaryotic cells. 3. Different types of medically important bacteria are mentioned, as well as some common diseases they can cause. The document also provides brief summaries of archaea, algae, slime molds, protozoa and helminths.

1. Cell morphology
Course : B.Sc. Biotechnology, Biochemistry
Sem II
Sub: Basic Microbiology
Unit 3.1

2. Introduction
• In microbiology, the term morphology means
cell shape. Several morphologies are known
among prokaryotes.
• Among the major characteristics of bacterial
cells are their size, shape, structure and
arrangement. These characteristics constitute
the morphology of the cell.

3. BACTERIA

4. 1. Classified into two kingdoms:
-- Eubacteria (true bacteria)
-- Archaebacteria (Ancient Bacteria).
2. are microscopic Prokaryotes. (“before nucleus”)
3. Adapted to living in all environments (even some
extreme) – they exist EVERYWHERE
4. Bacteria are much larger in size than viruses.
BACTERIA

5. 3 common shapes
Some unusual shapes also:
1

6. 1. Cell wall – keeps cell from bursting or collapsing due to osmotic changes
(changes in water)
2. Flagella is used for movement
3. Pilli (Fimbrae) help bacteria cling to surfaces
4. Prokaryotes do not have organelles or a membrane bound nucleus
5. Nucleoid region contains a circular loop of DNA
6. Plasmids are rings of DNA, used in reproduction
7. Ribosomes in cytoplasm synthesize proteins
a. The cell wall may also be surrounded by an organized capsule
called a glycocalyx and/or by a loose jelly-like sheath called a
slime layer.
b. In parasitic forms, these outer coverings protect the cell from
host defenses.

7. 2

8. 7. Kingdom Archaebacteria
• Quite different than other bacteria
• They have unusual lipids (fats) in their cell membranes
• They have no peptidoglycan (a carbohydrate found in cell
walls)
• They are sometimes called “extremophiles”
• Live in extreme environments

9. Thermoacidophiles
• Live in extremely acidic environments such as hot springs (up
to 230 F)
• Live near volcanic vents
• Thrive in areas where the pH is less than 2
• Live in areas that leak scalding acid water at the bottom of the
ocean

10. Halophiles
• Salt-loving bacteria
• Found in areas with high salt concentrations
• Great Salt Lake, Dead Sea, etc
• Use salt to generate ATP

11. Methanogens
• Convert hydrogen and carbon dioxide to
methane gas
• Can only live in anaerobic conditions
• Found in “swamp mud” and sewage
• Found in the gut of animals
• Produce “gas” methane

12. 8. Kingdom Eubacteria
• “Stereotypical” bacteria
• Can be classified by shape and by staining
• By shape:
• Bacillus (plural: Bacilli) = rod-shaped
• Coccus (plural: Cocci) = sphere-shaped
• Spirillum (plural: Spirilla) = spiral-shaped
• “Streptococci” = cocci occur in chains
• “Staphylococci” = cocci occur in clusters

13. Classification based upon staining
Gram Positive vs
Gram Negative
Hans Christian Gram -- 1884
-- Crystal violet
Gram positive structure
-- thick layer of peptidoglycan
Gram negative structure
-- inner vs outer membranes
-- lipopolysaccharides and endotoxins

14. 9. Bacterial Reproduction
• Sexual reproduction called “conjugation”
• Asexual reproduction called “binary fission”
• Results in genetically similar/identical bacteria
• Can occur very, very quickly

15. 10. Common Bacteria & Problems
• “Staph” infections….often found on skin. Acne, skin
lesions/sores, etc
• “Strep” infections….strep throat, scarlet fever, impetigo, etc.
• Food Poisoning - Escherichia coli infections
• Pathogens

16. Harmful :
a. human diseases –
strep throat, tuberculosis,
tooth decay and bad
breath, anthrax, plague,
tetanus, food poisoning

17. Harmful :
a. human diseases –
strep throat, tuberculosis,
tooth decay and bad
breath, anthrax, plague,
tetanus, food poisoning
b. food spoilage and poisoning – caused by
Salmonella and Staphylococcus
c. Treated with antibiotics – Some bacteria are able
to survive in presence of antibiotics that kill
other bacteria – antibiotic resistant bacteria
Note: This is why doctors tell you to take the entire amount of
medicine given even if you start to feel better because if not, bacteria
will have the chance to evolve and become antibiotic resistant.

18. D. Importance:
1. Beneficial
a. breakdown dead matter to recycle
nutrients into ecosystem -
decomposers
Example:
a. Compost piles need microorganisms (ex. bacteria) to
decompose (breakdown) matter.
b. dairy industry - bacteria inyogurt, sour cream and
cheese
c. Oil spills - bacteria can digest small oil spills

19. d. symbiotic relationship - E. coli and our
intestines-both organisms benefit
Example: E. coli in intestines helps us digest food and make
vitamins (such as Vitamin K and B-complex) In
return, human intestines provide food and
shelter for bacteria.
(This strain of E. coli is different from the E. coli strain
that causes food poisoning.)

20. Algae

21. Algae
• Simple, eukaryotic phototrophs that carry out
oxygenic photosynthesis using chlorophyll a
• Have sexual reproductive structures
– Every cell becomes a gamete
• Differ widely in distribution, morphology,
reproduction, and biochemical traits

22. Algae
• Distribution of Algae
– Most are aquatic
• Live in the photic zone of fresh, brackish, and saltwater
– Accessory photosynthetic pigments that trap
energy of light and pass it to chlorophyll a
• Morphology of Algae
– Unicellular, colonial, or have simple multicellular
bodies (thalli)

23. II. ALGAE
Vegetative Structures of multicellular algae:
– Thallus: Body. Lacks conductive tissue.
– Holdfasts: Anchor alga to rock.
– Stipes: Hollow, stem-like structures. Does not support
weight.
– Blades: Leaf-like structures.
– Pneumatocyst: Floating, gas-filled bladder.
DIVISIONS OF ALGAE
Green algae: May be unicellular or multicellular.
• Have cellulose cell walls, contain chlorophyll a and b, and
store starch like plants. Most are microscopic. Live close to
water surface. Believed to be the ancestors of terrestrial plants.
• Sexual & Asexual production.

24. Brown Algae or Kelp: Macroscopic (up to 50 m
long). Most are found in coastal waters, at
intermediate depths. Rapid growth. Can be
harvested regularly.
Red Algae: Live at greater ocean depths than other
algae. Red pigments allow them to absorb blue
light that penetrates deepest into ocean. Agar is
extracted from many red algae. Some produce
lethal toxins.

25. DIVISIONS OF ALGAE (Continued)
 Diatoms: Unicellular or filamentous algae with complex cell
walls with silica or calcium.
– Two parts of cell wall fit together like Petri dish.
Distinctive patterns are used for identification. Store
energy in form of oil.
– Some diatoms can cause neurological disease (memory
loss and diarrhea) in people who eat mussels, due to
domoic acid intoxication.
– Fossil deposits of diatoms (diatomaceous earth) are used
as filtering agents and abrasives in several industries.

26. Dinoflagellates (Plankton): Unicellular free-floating algae.
Rigid structure due to cellulose in plasma membrane.
 Some dinoflagellates produce neurotoxins, which kill
fish, marine mammals, and humans.
– Paralytic shellfish poisoning: Consumption of clams and mussels that
have eaten dinoflagellates (Gonyaulax) that produce neurotoxin.
– Red Tide: Caused by large concentrations of (Gonyaulax).
Euglenoids: Unicellular, flagellated algae. Semi-rigid plasma
membrane (pellicle). Most have anterior red eye spot.
Frequently studied with protozoa, because lack a cell wall.

27. Euglenoids are Flagellated, Unicellular Algae
3

28. • Reproduction in Algae
– Unicellular algae
• Asexual reproduction involves mitosis followed by cytokinesis
• Sexual reproduction forms zygotes from individual gametes
– Zygote undergoes meiosis
– Multicellular algae
• Reproduce asexually by fragmentation
• Reproduce sexually with alternation of generations
© 2012 Pearson Education Inc.

29. LICHENS
Combination of a green alga (or cyanobacterium) and a fungus.
Mutualistic relationship in which each partner benefits.
– Alga: Provides nutrients by photosynthesis to fungus.
– Fungus: Provides attachment and protection from desiccation.
20,000 species of lichens occupy unique habitats, in which either
fungi or algae could not survive alone: rocks, cement, rooftops,
trees, and newly exposed soil.
Grow very slowly, secreting acids that break down rocks.
Accumulate nutrients needed for plant growth.
Sensitive to air pollution.
Major food source for tundra herbivores (caribou and reindeer).

30. Ecological Importance of Algae
Important part of the food chain in aquatic ecosystems
because they fix carbon dioxide into organic molecules that
can be used by heterotrophs.
80% of the earth’s oxygen is believed to be produced by
planktonic algae.
Algal blooms are indicators of water pollution.
– Grow rapidly in water with high concentrations of organic material
(sewage or industrial waste).
Petroleum and natural gas reserves were formed primarily
from diatoms and plankton.
Many unicellular algae are symbionts in animals.

31. IV. SLIME MOLDS
Have both fungal and animal characteristics.
– Amoeboid stage
– Produce spores like fungi
Eukaryotic, classified as protists.
Cellular and plasmodial (acellular) slime molds.
Life Cycle of Cellular Slime Molds:
– Amoeba stage: Germinate from a spore.
– Slug stage: Many amoebas aggregate and sheath forms. Migration.
– Fruiting body: Releases spores which germinate into amoebas.
Plasmodial (Acellular) Slime Molds
– Mass of protoplasm with many nuclei (plasmodium).
– Capable of sexual reproduction.

32. Protozoa

33. Protozoa
• Diverse group defined by three characteristics
– Eukaryotic
– Unicellular
– Lack a cell wall
• Motile by means of cilia, flagella, and/or
pseudopodia
– Except subgroup, apicomplexans
© 2012 Pearson Education Inc.

34. Unicellular, chemoheterotrophic, eukaryotic organisms of
kingdom Protista (3-2000 mm).
Protozoan - “first animal”.
20,000 species, only a few are pathogens.
Most are free-living organisms that inhabit water and soil.
Some live in association with other organisms as parasites or
symbionts.
Reproduce asexually by fission, budding, or schizogony.
Some exhibit sexual reproduction (e.g.: Paramecium).
Trophozoite: Vegetative stage which feeds upon bacteria
and particulate nutrients.
Cyst: Some protozoa produce a protective capsule under
adverse conditions (toxins, scarce water, food, or oxygen).

35. V. PROTOZOA (Continued)
Nutrition
 Most are heterotrophic aerobes. Intestinal protozoa can
grow anaerobically.
Some ingest whole algae, yeast, bacteria, or smaller
protozoans. Others live on dead and decaying matter.
Parasitic protozoa break down and absorb nutrients from
their hosts.
Some transport food across the membrane.
Others have a protective covering (pellicle) and required
specialized structures to take in food.
– Ciliates take in food through a cytostome.
Digestion takes place in vacuoles.
Waste may be eliminated through plasma membrane or an
anal pore.

36. Medically Important Protozoa
1. Amoeboflagellates (Phylum Sarcomastigophora)
Move using pseudopods (false feet) or flagella.
A. Amoebas (Subphylum Sarcodina)
Move by extending blunt, lobelike projections
(pseudopods).
Amoebas engulf food with pseudopods and phagocytize it.
Several species cause amoebic dysenteries of varying
degrees of severity.
– Entamoeba hystolytica: Feeds on red blood cells. Produces
dysentery and extraintestinal cysts.
– Dientamoeba fragilis: Found in 4% of humans. Usually commensal.
Can cause chronic, mild diarrhea.
Other diseases include:
– Meningoencephalitis: Caused by Naegleria fowleri. Penetrate
nasal mucosa of swimmers in warm waters. Mortality rate almost
100%.
– Keratitis: Caused by Acanthamoeba. Can cause blindness.
Associated with use of contact lenses.

37. B. Flagellates (Subphylum Mastigophora)
Move by one or more whiplike flagella. Some parasitic
flagellates have up to eight flagella.
Most are spindle shaped with flagella projecting from
anterior end.
Outer membrane is a tough pellicle. Food is ingested
through an oral groove or cytosotome.
 Important pathogens:
– Trichomonas vaginalis: Causes genital and urinary infections. Has
undulating membrane. Lacks a cyst stage. Transmitted sexually or
by fomites.
– Giardia lamblia: Causes a persistent intestinal infection (giardiasis)
with diarrhea, nausea, flatulence, and cramps. In U.S. most
common cause of waterborne diarrhea. About 7% of U.S.
population are healthy carriers.
– Trypanosoma brucei gambiense: Hemoflagellate (blood parasite).
Causes African sleeping sickness.
– Trypanosoma cruzi: Hemoflagellate that causes Chaga’s disease, a
cardiovascular disease common in Texas and Latin America.

38. V. PROTOZOA (Continued)
Nutrition
 Most are heterotrophic aerobes. Intestinal protozoa can
grow anaerobically.
Some ingest whole algae, yeast, bacteria, or smaller
protozoans. Others live on dead and decaying matter.
Parasitic protozoa break down and absorb nutrients from
their hosts.
Some transport food across the membrane.
Others have a protective covering (pellicle) and required
specialized structures to take in food.
– Ciliates take in food through a cytostome.
Digestion takes place in vacuoles.
Waste may be eliminated through plasma membrane or an
anal pore.

39. Medically Important Protozoa (Continued)
3. Ciliates (Phylum Ciliophora)
Move and obtain food using cilia.
Only known human pathogen is Balantidium coli, which
causes a severe intestinal infection in pigs and humans.
4. Microsporans (Phylum Mycrospora)
Obligate intracellular parasites, lack mitochondria and
microtubules.
Discovered in 1984 to cause chronic diarrhea and
conjunctivitis, mainly in AIDS patients.

40. VI. HELMINTHS (WORMS)
Characteristics
Eukaryotic, multicellular animals that usually have
digestive, circulatory, nervous, excretory, and reproductive
systems.
Worms with bilateral symmetry, head and tail, and tissue
differentiation (endoderm, mesoderm, and ectoderm).
Parasitic helminths spend most or all of their lives in host
and usually have the following specializations:
– May lack a digestive system. Absorb nutrients from host’s food,
body fluids, or tissues.
– Have a reduced nervous system.
– Means of locomotion is reduced or absent.
– Complex reproductive system. Individuals produce many eggs that
can infect another host.

41. VI. HELMINTHS (Continued)
Two main groups (phyla)
Platyhelminths (Flatworms)
Nematoda (Roundworms)
Life Cycle
Extremely complex
Intermediate hosts harbor larval (developmental) stage.
Definitive host harbors adult stage.
Sexual reproduction strategies:
– Dioecious: Male and female reproductive organs are found in
separate individuals.
– Monoecious (Hermaphroditic): One animal has both male and
female sex organs. Most hermaphrodites copulate with other
animals, a few copulate with themselves.

42. VI. HELMINTHS (Continued)
II. Nematodes (Roundworms)
Cylindrical body tapered at each end.
Have a complete digestive system: mouth, intestine, and
anus.
 Body is covered by tough cuticle that resists drying and
crushing.
Most species are dioecious: separate males and females.
– Males are smaller than females and have one or two spicules on
posterior end.
Over 90,000 known species. Most are free-living. Only
about 50 are human parasites.
Life cycle of parasitic nematodes is simpler than that of
flatworms.
Infections can be caused by eggs or larvae.

43. II. Nematodes (Roundworms) Continued
Infectious eggs
– Pinworm (Enterobius vermicularis): Spends entire life in human
host. Adults live in large intestine. Female lays eggs in perianal
region which causes itching. Up to 90% of children are infected
through contaminated clothes or bedding. Infection usually
disappears after a few years.
– Ascaris (Ascaris lumbricoides): Large nematode, up to 30 cm.
Dioecious with sexual dimorphism. Live in small intestines of
humans, horses, and pigs. Eggs can survive in soil for long time.
Infectious larvae
– Adult Hookworm (Necator americanus): Live in small intestine of
humans, eggs are excreted in feces. Enter host by penetrating skin.
Enters bloodstream, travels to lungs, swallowed in sputum.
Avoided by wearing shoes.
– Trichinosis (Trichinella spiralis): Reproduce sexually in small
intestine of humans. Obtained from eating undercooked pork.
Larvae enter blood vessels and form cysts throughout body.
– Anisakines (Wriggly worms): Infected fish and squid. Killed by
freezing and cooking.

44. Pinworm (Enterobius vermicularis)
Source: http://www.biosci.ohio-state.edu/~parasite/a-h.html
4

45. Ascaris (Ascaris lumbricoides)
Source: http://www.biosci.ohio-state.edu/~parasite/a-h.html
5

46. Head of Ascaris (Ascaris lumbricoides)
Notice three lips characteristic of Ascaris
Source: www. soton.ac.uk/~djab/ascaris.html
6

47. Insects are Arthropods with Six Legs
Source: www. soton.ac.uk/~djab/ascaris.html
Tse-tse Fly: Host Vector of
African Sleeping Sickness
7

48. Crustaceans are Arthropods with Four
Antennae
8

49. Fungi

50. Fungi
• Chemoheterotrophic
• Have cell walls typically composed of
chitin
• Do not perform photosynthesis
– Lack chlorophyll
• Related to animals

51. Fungi
• The Significance of Fungi
– Decompose dead organisms and recycle their
nutrients
– Help plants absorb water and minerals
– Used for food and in manufacture of foods and
beverages
– Produce antibiotics
– 30% cause diseases of plants, animals, and humans
– Can spoil fruit, pickles, jams, and jellies

52.  I. FUNGI (Mycology)
 Diverse group of heterotrophs.
– Many are ecologically important saprophytes
– Others are parasites.
 Most are multicellular, but yeasts are unicellular.
 Most are aerobes or facultative anaerobes.
 Cell walls are made up of chitin.
 Over 100,000 fungal species identified.
 Only about 100 are human or animal pathogens.
– Most human fungal infections are nosocomial and/or occur in
immunocompromised individuals.
 Fungal diseases in plants cause over 1 billion dollars/year in losses.

53. CHARACTERISTICS OF FUNGI
1. Yeasts
 Unicellular fungi, nonfilamentous, typically oval or spherical cells.
Reproduce by mitosis:
– Fission yeasts: Divide evenly to produce two new cells
(Schizosaccharomyces).
– Budding yeasts: Divide unevenly by budding (Saccharomyces).
Budding yeasts can form pseudohypha, a short chain of undetached
cells.
Candida albicans invade tissues through pseudohyphae.
 Yeasts are facultative anaerobes, which allows them to grow in a
variety of environments.
– When oxygen is available, they carry out aerobic respiration.
– When oxygen is not available, they ferment carbohydrates to produce ethanol
and carbon dioxide.

54. CHARACTERISTICS OF FUNGI (Continued)
2. Molds and Fleshy Fungi
Multicellular, filamentous fungi.
Identified by physical appearance, colony characteristics,
and reproductive spores.
– Thallus: Body of a mold or fleshy fungus. Consists of many hyphae.
– Hyphae (Sing: Hypha): Long filaments of cells joined together.
Septate hyphae: Cells are divided by cross-walls (septa).
Coenocytic (Aseptate) hyphae: Long, continuous cells that are
not divided by septa.
Hyphae grow by elongating at the tips.
Each part of a hypha is capable of growth.
Vegetative Hypha: Portion that obtains nutrients.
Reproductive or Aerial Hypha: Portion connected with
reproduction.
– Mycelium: Large, visible, filamentous mass made up of many
hyphae.

55. CHARACTERISTICS OF FUNGI (Continued)
Dimorphic Fungi
Can exist as both multicellular fungi (molds) and yeasts.
Many pathogenic species.
– Mold form produces aerial and vegetative hyphae.
– Yeast form reproduces by budding.
Dimorphism in pathogenic fungi typically depends on
temperature:
– At 37oC: Yeast form.
– At 25oC: Mold form.
Dimorphism in nonpathogenic fungi may depend on other
factors: Carbon dioxide concentration.

56. NUTRITIONAL ADAPTATIONS OF FUNGI
Fungi absorb their food, rather than ingesting it.
Fungi grow better at a pH of 5, which is too acidic for most
bacteria.
Almost all molds are aerobic. Most yeasts are facultative
anaerobes.
Fungi are more resistant to high osmotic pressure than
bacteria.
Fungi can grow on substances with very low moisture.
Fungi require less nitrogen than bacteria to grow.
Fungi can break down complex carbohydrates (wood,
paper), that most bacteria cannot.

57. Fungi• Nutrition of Fungi
– Acquire nutrients by absorption
– Most are saprobes
– Haustoria allow some to derive nutrients from
living plants and animals
– May use ionizing radiation as energy source

58. Fungi
• Reproduction in Fungi
– All have some means of asexual reproduction involving
mitosis and cytokinesis
– Most also reproduce sexually
– Budding and asexual spore formation
• Yeasts bud in manner similar to prokaryotic budding
• Pseudohypha
– Series of buds that remain attached to one another and to
parent cell
• Filamentous fungi produce lightweight spores that disperse
over large distances

59. LIFE CYCLE OF FUNGI
Filamentous fungi can reproduce asexually by
fragmentation of their hyphae.
Fungal spores are formed from aerial hyphae and are
used for both sexual and asexual reproduction.
1. Asexual spores: Formed by the aerial hyphae of one organism.
New organisms are identical to parent.
Conidiospore: Unicellular or multicellular spore that is not
enclosed in a sac.
Chlamydospore: Thick-walled spore formed within a hyphal
segment.
Sporangiospore: Asexual spore formed within a sac
(sporangium).
2. Sexual spores: Formed by the fusion of nuclei from two opposite
mating strains of the same species. New organisms are different
from both parents.

60. Fungi
• Classification of Fungi
– Division Zygomycota
– Division Ascomycota
– Division Basidiomycota
– Deuteromycetes

61. IMPORTANT DIVISIONS OF FUNGI
2. Zygomycota (Conjugation Fungi)
Also known as bread molds.
Saprophytic molds with coenocytic hyphae
Asexual Reproduction: Used most of the time.
Sporangiospore: Asexual spore enclosed within a
sporangium or sac at the end on an aerial hypha.
Sexual Reproduction: Occurs through conjugation, the
joining of hypha of two different strains (plus and minus).
Zygospores: Sexual spores which are enclosed in a thick,
resistant wall.
 Generally not pathogens.
– Rhizopus nigricans: Common black bread mold. May cause
opportunistic infections in diabetes patients

62. IMPORTANT DIVISIONS OF FUNGI
3. Ascomycota (Sac Fungi)
Molds with septate hyphae and some yeasts.
Asexual Reproduction: Conidiospores not enclosed in a sac.
Become airborne easily. Form chains (broom-like structures).
 Sexual Reproduction: Ascospores enclosed in a sac-like
structure.
Include common antibiotic producing fungi and yeasts, and
several human pathogens.
– Penicillium notatum (Produces penicillin)
– Saccharomyces (Brewer’s yeast)
– Trychophyton (Athlete’s foot)
– Aspergillus (Carcinogenic aflatoxin in peanuts),
– Blastomyces (Respiratory infections)
– Histoplasma capsulatum (Respiratory and systemic infections)

63. IMPORTANT DIVISIONS OF FUNGI
4. Basidiomycota (Club Fungi)
Have septate hyphae.
Include mushrooms, toadstools, rusts, and smuts.
Sexual Reproduction: Produce basidiospores: Spores
formed externally on a club shaped sexual structure or base
called basidium.
 Asexual Reproduction: Through hyphae.
 Examples:
– Cryptococcus: Causes opportunistic respiratory and CNS infections in
AIDS patients.
– Amanita: Mushroom produces lethal toxins to humans.
– Claviceps purpurea: Produces ergot toxin in wheat and rye.

64. IMPORTANT DIVISIONS OF FUNGI
1. Deuteromycota
Not known to produce sexual spores.
Reproduce asexually.
 Catch-all category for unclassified fungi:
– Pneumocystis carinii: Causes pneumonia in AIDS
patients. Leading cause of death in AIDS patients.
Originally classified as a protozoan.
– Candida albicans: Causes yeast infections of vagina in
women. Opportunistic infections of mucous
membranes in AIDS patients.

65. FUNGAL DISEASES
Mycosis: Any fungal disease. Tend to be chronic because fungi grow
slowly.
Mycoses are classified into the following categories:
I. Systemic mycoses: Fungal infections deep within the body. Can
affect a number if tissues and organs.
 Usually caused by fungi that live in the soil and are inhaled. Not
contagious.
 Examples:
– Histoplasmosis (Histoplasma capsulatum): Initial infection in lungs.
Later spreads through blood to most organs.
– Coccidiomycosis (Coccidioides immites): Resembles tuberculosis.

66. FUNGAL DISEASES (Continued)
III. Subcutaneous mycoses: Fungal infections beneath the skin.
Caused by saprophytic fungi that live in soil or on vegetation.
Infection occurs by implantation of spores or mycelial
fragments into a skin wound.
Can spread to lymph vessels.
IV. Superficial mycoses: Infections of hair shafts and superficial
epidermal cells. Prevalent in tropical climates.

67. FUNGAL DISEASES (Continued)
Opportunistic mycoses: Caused by organisms that are
generally harmless unless individual has weakened
defenses:
– AIDS and cancer patients
– Individuals treated with broad spectrum antibiotics
– Very old or very young individuals (newborns).
 Examples:
– Aspergillosis: Inhalation of Aspergillus spores.
– Yeast Infections or Candidiasis: Caused mainly by Candida albicans.
Part of normal mouth, esophagus, and vaginal flora.

68. ECONOMIC IMPORTANCE OF FUNGI
25-50% of harvested fruits and vegetables are damaged by
fungi.
Fungal infections of plants are commonly called rots, rusts,
blights, wilts, and smuts.
– Phytophthora infestans: Caused great potato famine in mid-1800s.
Over 1 million people died from starvation in Ireland. Many
immigrated to the U.S.
 Beneficial fungi:
– Candida oleophila: Prevents fungal growth on harvested fruits.
– Saccharomyces cerevisiae: Used to make bread and wine.
– Genetically engineered yeast strains are used to make proteins
(Hepatitis B vaccine).
– Taxomyces: Produces anticancer drug taxol.
– Trichoderma: Produces cellulase. Used to make fruit juice.

70. Viruses
Viruses:
• are noncellular infectious agents
Virology:
• study of viruses
Virologists:
• scientists who study viruses

71. General features of Viruses
Viruses are infectious agents with both living
and nonliving characteristics.
1. Living characteristics of viruses
a. They reproduce at a fantastic rate, but only
in living host cells.
b. They can mutate.

72. …General features of Viruses
2. Nonliving characteristics of viruses
• They are acellular, that is, they contain no
cytoplasm or cellular organelles.
• They carry out no metabolism on their own
and must replicate using the host cell's
metabolic machinery.

73. …General features of Viruses
– Virus particles contains either DNA or RNA
(not both)
–Nucleic Acid is surrounded or coated by a
protein shell (capsid)
–Some viruses possess a membrane-like
envelope surrounding the particle

74. …General Properties of viruses
–Consists of 1 molecule of DNA or RNA
enclosed in coat of protein
–May have additional layers
–Cannot reproduce independent of living
cells nor carry out cell division as
procaryotes and eucaryotes do
• An intact viral particle is called a virion.

75. The Size and Morphology of
Selected Viruses
9

76. Generalized Structure of Viruses
Viral components
– Nucleic acids
– Capsid
– Envelope
10

77. The Structure of Viruses
Virion size range is ~10-400 nm
virions : nucleocapsid
Some viruses : only of a nucleocapsid, others
have additional components
Envelopes
virions having envelopes = enveloped
viruses
virions lacking envelopes = naked viruses

78. Introduction – Structure – Replication – Virology – Medicine - Review
A VIRUS is either DNA or RNA, that is protected by a protein coat called a
CAPSID.
DNA CAPSID
VIRUS
11

79. How Do Viruses Differ From Living Organisms?
 Viruses are not living organisms because they are incapable of
carrying out all life processes.
 Viruses
– are not made of cells
– can not reproduce on their own
– do not grow or undergo division
– do not transform energy
– lack machinery for protein synthesis
Images: Eukaryotic living organism named Kayla, T. Port; H1N1
Influenza Virus, Public Health Image Library (PHIL) #11702

80. What Are Viruses Made Of?
 Nucleic acid, proteins, and sometimes, lipids.
 Nucleic acid surrounded by a protective protein coat, called a Capsid.
 An outer membranous layer, called an Envelope. made of lipid and protein,
surrounds the capsid in some viruses.

81.  Protein coat provides protection for viral nucleic acid and means of attachment to
host’s cells.
 Composed of protein subunits called capsomeres.
 Some capsids composed of single
type of capsomere; others
composed of multiple types.
The Viral Capsid
What Are Viruses Made Of?
The Viral Envelope
 Acquired from host cell during viral replication or release; envelope is
portion of membrane system of host.
 Envelope’s proteins and glycoproteins often play role in host recognition.

82. Helical viruses
• resemble long rods that may be rigid or
flexible.
• The viral nucleic acid is found within a hollow,
cylindrical capsid that has a helical.
• viruses - cause rabies and Ebola hemorrhagic
fever are helical viruses.

83. Polyhedral Viruses
• Many animal, plant, and bacterial viruses –
polyhedral viruses.
• The shape of capsid -icosahedron, a regular
polyhedron with 20 triangular faces and 12
corners .
• capsomeres of each face -equilateral triangle.
• example –adenovirus, poliovirus.

84. Complex Viruses
• bacterial viruses – complicated structures : called
complex viruses.
• One example -bacteriophage.
• Some bacteriophages : capsids to which additional
structures are attached.
• capsid (head): polyhedral and the tail sheath is helical.
• head - the nucleic acid.
• example - poxviruses, which do not contain
• clearly identifiable capsids but have several coats
around the nucleic acid.

85. • tail :hollow tube through which the nucleic acid passes
during infection
• T4 -largest phage.
• T4 tail - surrounded by a contractile sheath, which
contracts during infection of the bacterium.
• end of the tail, phages : base plate and one or more tail
fibers attached to it.
• The base plate and tail fibers - involved in the
• binding of the phage to the bacterial cell.
• Not all phages have base plates and tail fibers.

86. VIRAL ENVELOPES
Envelopes vary in:
–Size
–Morphology
–Complexity
–Composition

87. ENVELOPE GLYCOPROTEINS
• They are firmly embedded in the envelope
bilayer.
• This is facilitated by domains of host
membrane proteins called spanners.
• They can form spikes or other structures on the
outside of the virion.
• These can be used to attach to a host cell.

88. Let’s look at the Defining Properties
of Viruses
• Viruses are parasites that invade cells
• Viruses have either DNA (Deoxyribose Nucleic
Acid) or RNA (Ribonucleic Acid)
• Viruses direct the synthesis of new virus within
a host cell.
• Newly made viruses infect other cells.
Introduction – Structure – Replication – Virology – Medicine - Review

89. Cell Biology
Let's review a little cell biology since viruses cannot multiply without the help
of cells. The viruses enter the cell and forces the cell to make more viruses.
The cell has three main zones:
Introduction – Structure – Replication – Virology – Medicine - Review
Cytoplasm – this is the “factory”
where biochemical reactions
occur.
Membrane – this double layer protects
the cell and allows the cell to
communicate with the outside
environment.
Nucleus – this holds the DNA
or genetic information
about the cell.

90. Genetic Material of Viruses
 Show more variety in nature of their genomes than do cells.
 Like cells, viral genome is a nucleic acid., but can be _____ or ____; never
both.
 Primary way scientists categorize and classify viruses.
 Can be dsDNA, ssDNA, dsRNA, ssRNA.
 May be linear and composed of several segments or single and circular.
 Much smaller than genomes of cells.
What Are Viruses Made Of?

91. DNA/RNA
DNA, deoxyribonucleic acid, is
the double-stranded molecule
that encodes genetic
information (e.g. your hair color,
height, etc.) in the nucleus of
cells. The complete set of DNA
in a cell is called the genome.
RNA, ribonucleic acid, is typically
single stranded so that it can be read
to make proteins.
Introduction – Structure – Replication – Virology – Medicine - Review
DNA or RNA code for genes that defines who we are.
12

92. GENOMIC PACKAGING
• Genome packaging has an important role in
the infection.
• Viral genomes are packaged in one of three
ways:
• Directly in the capsid-inner side of the
protein coat
• Enclosed in special proteins-nucleic acid
binding protein
• Enclosed in proteins from the host cell

93. Bacteriophage
Introduction – Structure – Replication – Virology – Medicine - Review
Bacteriophage is a virus that infects bacteria.
13

94. Enveloped Viruses
Introduction – Structure – Replication – Virology – Medicine - Review
Enveloped viruses are viruses which have a membrane coat surrounding the
protein coat or capsid. These viruses are common in animal viruses, but are
uncommon in plant viruses.
Herpes Simplex Virus.
A membrane (made of proteins)
surrounds the capsid (also made of
proteins) which surrounds the viral DNA.
14

95. DISEASE VIRUSES
AIDS HIV
Wart
Herpes Simplex
Virus
Flu Influenza
Measles Morbillivirus
Cancer Hepatitis B
Introduction – Structure – Replication – Virology – Medicine - Review
Examples of some viral diseases:

96. Who do viruses infect?
• Viruses infect Bacteria
– These viruses are called bacteriophages
• Viruses infect Plants
– One example is the Tobacco Mosaic Virus
• Viruses infect Animals
– One example is the common cold
Viruses usually infect a specific host including:
Introduction – Structure – Replication – Virology – Medicine - Review

97. Replication Phases
V - Release
- Assembly of virus
DNA and protein
coat into whole
new viruses
- Leaving the cell
http://www.cat.cc.md.us/courses/bio141/lecguide/unit2/viruses/adlyt.html
Phase I
Phase II
Phase IV Phase VPhase III
Introduction – Structure – Replication – Virology – Medicine - Review
I, II, III - Viruses enter cell
- Attachment to cell membrane
- Penetration inside cell
- Losing virus protein coat
IV - Replication
- Tricks cell into making
more viral DNA
- Tricks cell into making
viral protein coat
15

98. The concept of a virus as an organism
challenges the way we define life:
* Viruses do not breathe.
* Viruses do not metabolize.
* Viruses do not grow.
* However, they do reproduce.
Introduction – Structure – Replication – Virology – Medicine - Review

99. How Viruses Multiply
• Active viruses enter cells and immediately begin to
multiply, leading to the quick death of the invaded cells.
16

100. THE INFECTION CYCLE
• The infection cycle was first worked out in
bacteriophages (bacterial viruses).
• Animal virus infections can be either lytic or
lysogenic.

101. Filters – Very small holes in material filter only
viruses through
Sedimentary Centrifugation – A sample is spun
so fast, different elements in it are separated by
density
Electron Microscope – Electrons are smaller than
light wavelengths, so viruses can be “seen” by
reflecting electrons off of them

102. Viruses Can Help Cells, Too
Introduction – Structure – Replication – Virology – Medicine - Review
- Since viruses can transport DNA and RNA into
cells, scientists are exploring Gene Therapy
- In Gene Therapy, viral genetic material is
replaced with new DNA
- In time, this could be used to cure genetic
diseases. Currently we have no cure for
these types of illnesses

103. References
Books:
1. Biology of microorganisms By M. T. Madigan, J. M. Martinko, D. A. Stahl and D. P. Clark
Images:
1. https://ramyaraj16.files.wordpress.com/2012/10/ib0461.jpg
2. http://en.docsity.com/documents/original/2013/01/17/thumbs/Prokaryotic_Cells_-_Plant_Biology_-
_Lecture_Slides_pdf.pdf.jpg
3. https://lh6.ggpht.com/CiMJmDiuXwoK9KxK0fhzjTRql-oq20kkUjtmPHshDhuql7mGSV1Lm471PwecEoXyDKQykg=s85
4. http://3.bp.blogspot.com/_Toi-rh0Nm00/TLLd4ElGLzI/AAAAAAAAGvM/g_dVIymgArw/s1600/pinworms.jpg
5. http://1.bp.blogspot.com/-8i8Q-_HlgSU/Un1bMDbKdYI/AAAAAAAAAV4/GcHOWaV1Wy4/s1600/lombriga.jpg
6. https://learnzoology.files.wordpress.com/2014/04/roundworms02.jpg?w=256&h=203
7. http://www.petualangan-aghaja.com/wp-content/uploads/2012/08/Tsetse.jpg
8. https://lh6.ggpht.com/v-se0VDueDB2DwvPRuwBme6PPXon27zfv123NfLpCV64uwEjFvg7rk_kUyFD7-gO4noOBw=s108
9. https://lh3.ggpht.com/ZFnF71d-Jk-8Lzrox3roj9ynttDnFzCob13hIVn4qp6Gi221zhYe7LiQUIvYrJIzpm61=s118
10. https://lh3.ggpht.com/zIEMb1BYMEVoFxz8xlzkN4rhTA_-_XIWaOpvRFEUZnEsDVhQTAoROfbKXbiLHrf8ld_9YQ=s97
11. https://lh6.ggpht.com/GAc1EoWlGfSwYSm5UvJBWYApshpoYNqOyRBbTkFiS24EBDIfMRUUddWAgY-
TO5Xo2x2Eww=s114
12. https://lh4.ggpht.com/HxdfAvLfngJ9_EvXU4FtA4gmqtlfvxD06rXXwkYhO4bEA7O49e6vflLh6v5uM9TC2Rg=s88
13. https://lh3.googleusercontent.com/-OBG_lFwGfAk/UlMyTOvz6RI/AAAAAAAAACo/D4VqNRWUU3w/s640/blogger-
image--814710016.jpg
14. https://lh4.ggpht.com/iGsWdNeV96W9w3ysaoTo0OOVzMPsVBE2MTFg2h6-ra4HJZdIYN4rY9JVUfOxmO3O-
81yJA=s114
15. https://lh5.ggpht.com/5llormqCVcqi_F96_HUxzQxzERwBroQu5wAA4dV6AUf84deWqNQtCDpM-dIjejawk8COVxI=s119
16. http://classes.midlandstech.com/carterp/Courses/bio225/chap13/Slide16.JPG