Microbiology exam 3

What is a chemoheterotroph?

Organisms that have to consume to get energy

What is a mass of hyphae called?

Mycelium

What are the jobs of vegetative hyphae and aerial hyphae?

Vegetative obtains nutrients

Aerial is involved in reproduction

Coenocytic hyphae (non septate)

Does not contain septa (cross walls)

Septate hyphae

Contains cross walls

Features of yeasts

No filamentous and unicellular

How do budding yeasts divide?

Unevenly

How do fission yeasts divide?

Evenly

What is dimorphic fungi?

Yeast like at 37*C and moldlike at 25*C

Are fungi haploid or diploid?

Haploid

Is mitosis or meiosis responsible for asexual fungi reproduction?

Mitosis

Is mitosis or meiosis responsible for sexual fungi reproduction?

Meiosis

What are anamorphs?

FunginOnly capable of asexual reproduction.

Name these parts

A - sporangium

B - sporangiospore

C - sporangiophore

Arthrospores

A - macroconidia

B- microconidia

Porospores

Phialospore

A - chlamydospores

B - blastospores

What are telomorphs

Sexual spores by fusion of two nuclei from opposite mating strains

What are the 3 phases of sexual reproduction of telomorphs?

Plasmogamy

Karyogamy

Meiosis

Plasmogamy

Haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (-)

Karyogamy

(+) and (-) nuclei fuse and form diploid zygote

Meiosis in telomorphs

Diploid nucleus produces haploid nuclei (sexual spores)

Which fungi are known as the sac fungi?

Ascomycota

Define mycosis (mycoses).

Fungal infection singular or plural

Systemic mycosis

all throughout/deep within the body.

Subcutaneous mycoces

Beneath the skin

Cutaneous mycoses

Affects hair, skin and nails.

Superficial mycoses

Localized and non-destructive. Typically cosmetic affects

Opportunistic mycoses

Fungi is harmless in normal habitat but pathogenic in compromised hosts. Can be introduced with things like implanted prosthetic devices and catheters.

What pathogen causes yeast infections? What type of pathogen is it?

Candida. Opportunistic pathogen.

What are the 3 types of organisms can cause dermatophytoses (infections of skin, hair and nails)?

Dermatophytes:
Geophilic (found in soil, ocassional pathogens)
Zoophilic (animal parasites transferred to humans)
Anthropophilic (human to human)

What kind of fungi causes coccidioidomycosis?

Ascomycota.

Which fungi is dimorphic encouraged by the nitrogen in bird and bat droppings?

Coccidiodes immitis and coccidiodes posadasii

Which phylum is Aspergillus in?

Ascomycota.

What are included in Kingdom Protista?

Algae and protozoans.

Protist

any eukaryotic unicellular or colonial organism that lacks true tissues

Features of protozoa

1. Habitats are mostly fresh and marine water, soil, plants and animals

2. Unicellular with some complex life cycles

3. Most are harmless but a few species are responsible for disease

What is a free-living protozoa?

Scavenge dead plant or animal debris or graze on live cells of bacteria and algae

What is a parasitic protozoa?

Lives on the fluids of the host such as plasma and digestive juices. May actively feed on tissues.

Trophozoite

Motile feeding stage of a protozoan. Requires ample food and moisture to remain active.

Cyst (protozoa)

Dormant resting stage. Formed when conditions become unfavorable for growth and feeding.

Conjugation

Form of genetic exchange between two cells

Classification of Protozoans that use flagella to move

1. Flagella alone or flagella and amoeboid motion

2. Single nucleus

3. Sexual reproduction by syngamy

4. Form cysts and are free-living

Classification of Protozoans that use amoeboid motion to move

1. Primarily amoeba

2. Use pseudopods for locomotion

3. Asexual reproduction by fission

4. Mostly uninucleate

5. Usually encyst

   1. Free-living and not infectious

Classification of protozoans that use cilia to move

1. Have cilia in tufts for feeding and attachment

2. Most develop cysts

3. Have macro and micronuclei

4. Division by transverse fission

5. Most have definite mouth and feeding organelle

6. Free-living and harmless

Classification of protozoan that have no motility (sporozoa)

1. Motility absent

2. Complex life cycles with well-developed asexual and sexual stages

3. Special spore-like cells (sporozoites)

4. Entire group is parasitic

What is the only human parasite? What does it cause?

Balantidium coli (causes dysentery)

How is toxoplasmosis transmitted? What type of infections can it cause?

By cats. Can cause fetal infections.

What is the definitive host of toxoplasmosis and what is the intermediate host

Definitive = cat

Intermediate = prey animals (birds, rodents etc)

Intermediate Host

Host where sexual reproduction does not occur.

Definitive host

Where sexual reproduction occurs.

Dead-end host

A host that harbors a pathogen but does not transmit it to another host, often limiting the spread of the disease.

What is the organism that causes malaria?

Plasmodium

What 2 hosts are requires for malaria transmission?

Mosquito and human

Which host is definitive and which is intermediate in malaria transmission?

Definitive = mosquito

Intermediate = human

What kingdom are helminths in?

Kingdom Animalia

What two categories are helminths divided into?

Flatworms (thin, segmented bodies) like flukes
Roundworms (long and round, unsegmented bodies) like nematodes

4 features of helminths

1. Reproductive tract is most developed

2. Primitive digestive, excretory, nervous and muscular systems

3. Thick cuticles for protection

4. Mouth glands for breaking down the host’s tissue

3 stage life cycle of helminth

1. Fertilized egg (embryo)
   Transmission of egg or larva to the body of another host, either a different or the same species

2. Larval stage
   Intermediate (secondary) host is where the larval development occurs

   1. Adult Stage
      The final mating and adulthood is done in the definitive (final) host.

How can male and female nematodes be told apart?

They have different morphologies

Trematodes

Sexes are separate or male/female organs are in the same worm (hermaphroditic)

Cestodes

generally hermaphroditic

What is the most common route of transmission for helminths?

Fecal-oral but can also be picked up by them burrowing into your feet from walking barefoot and picking one up.

What are the main biological reservoir for helminths?

Humans. Also sometimes animal or insect vectors.

Features of trematodes (flukes)

1. Flat, leaf shape

2. Ventral/oral sucker

3. Absorb food through cuticle on the outside

Monoecious

Having both male and female reproductive organs in the same organism, allowing for self-fertilization.

Dioecious

Having distinct male and female individuals within a species, requiring cross-fertilization.

Scolex

The highly specialized anterior end of a tapeworm, equipped with hooks and suckers for attachment to the host's intestine.

Proglttids

Segments of a tapeworm that contain both male and female reproductive structures, allowing for reproduction.

What are the definitive hosts for cestodes (tapeworms)?

Humans.

Cycticerci

The larval form of tapeworms that develop in the tissues of intermediate hosts, often causing cysticercosis in humans.

What kinds of cells do the planaria have?

Entire body is stem-cells that can differentiate into other cells.

Are roundworms monoecious or dioecious?

Dioecious

Where is the infection infestation of pinworms located?

Large intestines

What is the transmission mode for pinworms?

Fecal-oral/fomites

What are the cell walls of fungi made of?

Chitin

Features of fungi (6)

-Unicellular or multicellular

-Haploid

-Eukaryotes

-Chitin cell walls

-Heterotrophs

-Can reproduce sexually or asexually

General Characteristics of Viruses (8)

-Obligatory intracellular parasites

-Small

-Ubiquitous

-Contain DNA or RNA (never both)

-No ribosomes

-No ATP-generating mechanism

-Contain a protein coat (capsid)

-Resistant to antibiotics

-Some viruses enclosed by an envelope

-Some viruses have spikes

-Host specificity

Virus Host range

The spectrum of cells a virus can infect, which can vary from a single species to multiple species within a family.

Virion Structure

-Nucleic acid

-Capsid

RNA Plus (sense)

makes sense to the ribosome so it can be translated
5’ to 3’

RNA minus (antisense)

Doesn’t make sense to the ribosome so it must be transcribed firstinto a complementary strand before translation.
3’ to 5’

Types of virus DNA

Double stranded (dsDNA) - can be read directly

Single stranded (ssDNA) - often requires second strand to be synthesized

What is the name of the System used for viral classification?

The Baltimore System

Function and Structure of Capsid (protein coat)

-Prevents degradation and helps with transmission

-Capsomeres (protein unit)

-Nucleic acid + capsid protein= nucleocapsid that protects viral genetic material

Virus envelope

Enveloped versus nonenveloped (can come from other membranes)

Spikes (virus)

Can be used for attachment (both to the capsid and the host cell)

Polyhedral virus shape

Viruses with symmetrical geometry include those with icosahedral and helical structures, characterized by a uniform arrangement of proteins that form their capsid.

Icosahedral virus

A type of virus shape characterized by a polyhedral structure with 20 equilateral triangular faces. This arrangement provides a highly symmetrical and stable configuration for the viral capsid.

Helical virus shape

Aka filamentour

Capsid monomers form a helical tube around helical nucleic acid

Can be very long

Complex virus shape

Combination of polyhedral and helical structures (like bacteriophage)

Unusual arrangements

5 Steps of Lytic Cycle

1. Attachment

2. Penetration (entry)

3. Biosynthesis (makes viral proteins)

4. Maturation (assembles viruses)

5. Release (cell bursts = lysis)

5 steps of lysogenic cycle

1. Attachment

2. Penetration (entry)

3. Integration of viral DNA into host (becomes prophage)

4. Replication with host DNA

5. Can later enter lytic cycle

Prophage

Viral DNA inside host’s genome

6 steps of replication of an animal virus

1. Attachment

2. Entry

3. Uncoating

4. Biosynthesis

5. Assembly

6. Release

Acute viral infection

Quick illness, virus cleared (like the flu)

Latent viral infection

Virus hides in host cells and can reactivate later.