Transcript fungi

Three Domain System
Carl R. Woese
 Based on Ribosomes
 Ribosomes are in all cells but they are not
all alike.
 Three Domains:

1. Eukaryotes
2. Bacteria- Prokaryotes (pathogenic bacteria
and bacteria that live in soil and water)
3. Archaea- Prokaryotes (bacteria without
peptidoglycan; methanogens, halophiles, and
Figure 10.1 The Three-Domain System.
Eukarya
Fungi
Origin of mitochondria
Bacteria
Origin of chloroplasts
Animals
Amebae
Mitochondria
Slime molds
Cyanobacteria
Proteobacteria
Chloroplasts
Archaea
Methanogens
Plants
Extreme
halophiles
Ciliates
Green
algae
Dinoflagellates
Diatoms
Hyperthermophiles
Gram-positive
bacteria
Euglenozoa
Thermotoga
Horizontal gene transfer
occurred within the
community of early cells.
Giardia
Mitochondrion degenerates
Nucleoplasm grows larger
Taxonomic Hierarchy
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Figure 10.5 The taxonomic hierarchy.
All organisms
Eukarya
Archaea
Bacteria
Fungi
None assigned for archaea
None assigned for bacteria
Ascomycota
Euryarcheota
Proteobacteria
Hemiascomycetes
Methanococci
Gammaproteobacteria
Saccharomycetales
Methanococcales
Enterobacteriales
Saccharomycetaceae
Methanococcaceae
Enterobacteriaceae
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Saccharomyces
S. cerevisiae
Baker’s yeast
Methanothermococcus
M. okinawensis
Methanococcus
Escherichia
E. coli
E. coli
FUNGI
Fungi
Kingdom
Fungi
Nutritional Type
Chemoheterotroph
Multicellularity
All, except yeasts
Cellular Arrangement
Unicellular, filamentous,
fleshy
Food Acquisition Method
Absorptive
Characteristic Features
Sexual and asexual spores
Mycology: the study of fungi
Table 12.1 Selected Features of Fungi and Bacteria Compared.
Vegetative Growth

Molds
◦ The fungal thallus consists of hyphae; a mass
of hyphae is a mycelium

Unicellular fungi
◦ Fission yeasts divide symmetrically
◦ Budding yeasts divide asymmetrically

Dimorphism
◦ Pathogenic dimorphic fungi are yeastlike at
37°C
and moldlike at 25°C
Figure 12.2 Characteristics of fungal hyphae.
Cell wall
Pore
Nuclei
Spore
Septum
Septate hypha
Coenocytic hypha
Growth of a hypha from a spore
Figure 12.3a Aerial and vegetative hyphae.
Aerial hyphae
Aspergillus niger
Figure 12.4 A budding yeast.
Bud
Parent cell
Bud scar
Figure 12.5 Fungal dimorphism.
Yeastlike growth
Moldlike growth
Life Cycle

Spores- reproductive fungal product
◦ Asexual- formed by one organism; genetically
identical to parent
◦ Sexual- formed by the fusion of 2 nuclei from
2 organisms; genetic characteristics of both
parents
◦ Most are asexual.
Conidiospore
Sporangiospore
Unicellular or multicellular
 Spores are not enclosed in
a sac.
 Spores are released one at
a time.



Has a sporangium(sac) that
encloses the spores.
More than one spore is
released at one time.
ASEXUAL SPORES
Figure 12.6a Representative asexual spores.
Conidia
Conidiophore
Figure 12.6e Representative asexual spores.
Sporangiospores
Sporangiophore
Sexual Spores
Zygospore: fusion of haploid cells
produces one zygospore
 Ascospore: formed in a sac (ascus)
 Basidiospore: formed externally on a
pedestal (basidium)

Nutritional Adaptations
pH-5
 Aerobes(molds) and facultative
anaerobes(yeast)
 Can grow in high salt and sugar
environment and low moisture
environments.
 Grow on a WIDE variety of substances.

Fungal Diseases (Mycoses)
Systemic mycoses: deep within body
 Subcutaneous mycoses: beneath the skin
 Cutaneous mycoses: affect hair, skin, and
nails
 Superficial mycoses: localized, e.g., hair
shafts
 Opportunistic mycoses: caused by normal
microbiota or environmental fungi

MEDICALLY
IMPORTANT FUNGI
Aspergillus sp.
Opportunistic
 Found in decaying
vegetation
 Usually affects
immunocompromised
or people with other
lung infections
 Causes pulmonary
aspergilliosis; cough,
wheezing, fever

Microsporum
Cutaneous/Superficial
 Ringworm
 Circular patches are
affected
 Transmitted with
fomite contact

Stachybotrys
Opportunistic
 Found in water damaged walls of buildings
 Can lead to pulmonary problems

Candida albicans
Subcutaneous
 Normal flora of the genitourinary tract
and mouth
 Dimorphic
 Overgrows when other normal flora is
suppressed by antibiotics.
 Thrush and vaginitis(yeast infection)

Figure 21.17 Candidiasis.
Chlamydoconidia
Pseudohyphae
Blastoconidia
Candida albicans
Oral candidiasis, or
thrush
Pneumocystis jirovecii
Systemic
 Causes pneumonia in people who are
immunocompromised especially AIDS and
cancer patients.

Figure 24.20 The life cycle of Pneumocystis jirovecii, the cause of Pneumocystis pneumonia.
Mature
cyst
Cyst
Intracystic
bodies
Each trophozoite
develops into a
mature cyst.
The mature cyst
contains 8 intracystic bodies.
The cyst ruptures,
releasing the
bodies.
Trophozoite
The trophozoites divide.
The bodies
develop into
trophozoites.
Trophozoite,
note
extensions
for feeding on
tissue.
Economic Effects of Fungi
Saccharomyces cerevisiae: bread, wine, HBV
vaccine
 Can control pests.

ALGAE
Algae
Kingdom
Protista
Nutritional Type
Photoautotroph
Multicellularity
Some
Cellular Arrangement
Unicellular, colonial,
filamentous, tissues
Food Acquisition Method
Diffusion
Characteristic Features
Pigments
Figure 12.12a Algae and their habitats.
Sublittoral
zone
SURFACE
Unicellular green algae,
diatoms, dinoflagellates
Green algae,
Littoral cyanobacteria,
zone
euglenoids
LAND
Red 𝛌
Multicellular
green algae
Orange 𝛌
Brown algae
Yellow 𝛌
Violet 𝛌
Blue 𝛌
Algal habitats
Red algae
Life Cycle

Sexual and Asexual- fragments can
become a new algae
Rhodophyta





Red algae
Cellulose cell walls
Most are
multicellular
Store glucose
polymer
Harvested for
agar(media plates)
Dinoflagellates- Plankton
Cellulose in plasma
membrane
 Unicellular
 Store starch
 Neurotoxins cause
paralytic shellfish
poisoning

Protozoans
Protozoa
Kingdom
Various
Nutritional Type
Chemoheterotroph
Multicellularity
None
Cellular Arrangement
Unicellular
Food Acquisition Method
Absorptive; ingestive
Characteristic Features
Motility; some form cysts
Characteristics of Protozoa

Two Morphological forms:
◦ Trophozoites- vegetative form; oval to
irregular shape
◦ Cysts-some produce; resistant form; round
shape
Characteristics of Protozoa

Means of Motility
◦ Flagella
◦ Cilia
◦ Pseudopods
Giardia lamblia
No mitochondria
 Multiple flagella
 Adheres to the
intestinal wall.
 Causes diarrhea

Figure 25.17 The trophozoite form of Giardia lamblia, the flagellated protozoan that causes giardiasis.
Insert Fig 25.17
Mark left by
ventral sucker
Trichomonas vaginalis





No mitochondria
Multiple flagella
No cyst
Vagina and male
urinary tract
STD- greenish yellow
discharge
Trypansoma brucei
Hemoflagellate- lives
in the bloodstream
 Tsetse fly
 African Sleeping
Sickness- causes
headache and fever
that progress to
coma

Plasmodium sp.






Nonmotile
Intracellular parasites
Complex life cycles
Female Anopheles
mosquito
Blood and liver are
affected
Merozoites-infect
RBCs, reproduce and
the RBC ruptures 48
hours later

Chills, fever, headache
and vomiting.
Alternating periods.

Estimated 200-400
million people are in
infected
Figure 23.26 Malaria.
RBCs
Merozoites
RBCs
Merozoites being
released from lysed
RBCs
Ring forms
Malarial blood smear;
note the ring forms.
Entamoeba histolytica
Pseudopods
 Causes cell lysis of
the intestinal tissue
which leads to
bloody and mucoid
diarrhea.
 Transmitted through
feces.

Figure 25.19 Section of intestinal wall showing a typical flask-shaped ulcer caused by Entamoeba
histolytica.
Normal mucosa
Ulcer
Insert Fig 25.19
Toxoplasmosis gondii
Nonmotile
 Carried in a cat’s gut
 Transmission:

◦ Ingesting undercooked
meat
◦ Contact with cat feces

People with healthy
immune systems may
have mild cold-like
symptoms or none at
all

Congenital infection
◦ Stillbirth
◦ Neurological damage
Figure 23.24 The life cycle of Toxoplasma gondii, the cause of toxoplasmosis.
5
1
Cat ingests
bradyzoites in tissue
cysts of animals,
usually mice.
Immature oocyst is shed in cat feces.
Immature
cyst
Definitive host
4
Sporozoites from
ingested oocysts
invade animal tissue
and develop into
bradyzoites within
tissue cysts or into
tissue-invading
tachyzoites.
Sporogony
Bradyzoites
Tachyzoites
in tissue cyst
Sporocysts
If humans eat undercooked meat
containing tissue cysts, they may
become infected.
Sporozoite
2
Intermediate
hosts
3
If a pregnant woman
accidentally ingests oocysts
(contacted when changing a
cat litter box), prenatal
infection of the fetus may
occur.
Mature oocyst
(10–13 μm x 9–11 μm)
Mature oocysts
develop by
sporogony and
contain two
sporocysts, each
with four infective
sporozoites.
Oocysts can
infect many hosts,
including mice,
domestic animals,
and humans, via
ingestion.
Balatidium coli
Cilia
 Trophozoites secrete proteases that
destroy cells of the large intestine.
 Causes severe dysentery.
 Transmitted through fecal contamination
of water

Helminths
Helminths
Kingdom
Animalia
Nutritional Type
Chemoheterotroph
Multicellularity
All
Cellular Arrangement
Tissues and organs
Food Acquisition Method
Ingestive; absorptive
Characteristic Features
Elaborate life cycles
Helminths (Parasitic Worms)

Kingdom: Animalia
◦ Phylum: Platyhelminthes (flatworms)
 Class: trematodes (flukes)
 Class: cestodes (tapeworms)
◦ Phylum: Nematoda (roundworms)
Characteristics of Helminths
Reduced digestive system
 Reduced nervous system
 Reduced locomotion
 Complex reproduction

Life Cycle of Helminths

Monoecious (hermaphroditic)
◦ Male and female reproductive systems in one
animal

Dioecious
◦ Separate male and female

Egg  larva(e)  adult
Question

Why are the drugs used to treat parasitic
helminths often toxic to the host? 12-14
Platyhelminths- Trematodes
Also called flukes
 Absorb food through a cuticle

Schistosoma mansoni
Tissue damage
(granulomas) in
response to eggs
lodging in tissues
 African, Middle
East, South
America,
Caribbean
 2nd only to malaria
in the # of people it
kills or disables

Granuloma
Figure 23.28 Schistosomiasis.
8
Cercariae travel
through circulatory
system to intestinal
blood vessels,
where they mature
into adults.
1
Definitive
host
Adult
flukes
Adult female
flukes lay
eggs.
Male
Mouth
Female
(size:
15–20 mm)
Eggs
Sucker
Female
Mouth
Male
7
Free-swimming
cercariae penetrate
human skin,
losing tail.
(a) Male and female
Cercaria
(0.13 mm)
2
Eggs reach
body of
water after
being excreted
in human
feces or
urine.
Egg
(0.15 mm)
Cercaria
(0.33 mm)
Intermediate
host
6
3
Cercariae are released
from the snail.
5
Miracidium reproduces
in snail, forming
several cercariae.
4
Miracidium
penetrates
snail.
Miracidium
(0.2 mm)
schistosomes. The
female lives in a groove
on the ventral (lower)
surface of the male
schistosome
(“split-body”), is
continuously fertilized,
and continuously lays
eggs. The sucker is used
by the male to attach to
the host.
Eggs hatch into free-swimming
larvae (miracidia).
(b) Life cycle of Schistosoma,
cause of schistosomiasis.
Platyhelminths- Cestodes
Also called a
tapeworm
 Scolex- head with
suckers or hooks
 Absorb foods
through cuticle
 Proglottidssegments; contains
both female and male
reproductive parts

Taenia saginata
Found in cattle (beef tapeworm)
 Human ingest the proglottids found in the
meat
 Abdominal distress

Nematoda
Roundworms
 Complete digestive system
 Male and female
 Some are free living in soil
 Most common helminth infection

Nector americanus
Hookworm
 Attaches and feeds
on blood and tissue
 Leads to anemia and
lethargic behavior

Ascaris lumbricodes
Common in the SE US
 Absorb partially ingested
food
 Can cause lung problems
or blockages in the
intestines, liver or
pancreas
 Can come out of the
anus, mouth, nose or
navel

Enterobius vermicularis
Most common in the US
 Females lay their eggs around the anus
and this causes itching.
 Eggs get transmitted by hands and close
contact
 Scotch-Tape test diagnosis

Figure 12.29 The pinworm Enterobius vermicularis.
Mouth
Intestine
Mouth
Ovary
Genital
pore
Anus
Genital
pore
Intestine
Testis
Spicules
Egg
(55 μm
long)
Anus
Adult
pinworm
Female
(8–13 mm
long)
Male
(2–5 mm long)
Larva
Pinworm egg
Arthropods as Vectors
May transmit diseases (vectors)
 Kingdom: Animalia

◦ Phylum: Arthropoda (exoskeleton, jointed
legs)
 Lice, fleas, mosquitoes
 Mites and ticks
Arthropods as Vectors
Mechanical transmission
 Biological transmission

◦ Microbe multiplies in vector

Definitive host
◦ Microbe’s sexual reproduction takes place in
vector
Figure 12.31 Mosquito.
Figure 12.32 Tick.
Figure 12.33 Arthropod vectors.
2.5 mm
2.5 mm
2 cm
Insert Fig 12.33
1 cm
Human louse
Rat flea
Deer fly
Kissing bug