Ch 4

Eukaryotic

Cells and Microorganisms

SLOs for Culturing of Microorganisms

• List the types of eukaryotic microorganisms, and denote which are

unicellular and which are multicellular.

• Review the structure of a model eukaryotic cell and explain the functions of all the organelles. (See BIO 30)

• List two detrimental and two beneficial activities of fungi (from the viewpoint of humans).

• Explain some general features of fungal anatomy.

• Differentiate among the terms heterotroph, saprobe, and parasite.

• List three means of locomotion exhibited by protozoa.

• Explain why a cyst stage might be useful to a protozoan.

• Give an example of a disease caused by each of the four types of

protozoa.

• List the two major groups of helminths, and provide examples

representing each body type.

• Summarize the stages of a the Enterobius vermicularis life cycle.

Microbiology covers protozoa, miccroscopic algae and fungi, and helminth (because they have a microscopic stage).

Structure and Function of Eukaryotic Cells

Review on your own if necessary!

See BIO 30

Fig 4.1

•Chemoheterotrophs, mostly saprobes/saprophytes _______________, some parasites

• 300 species are human pathogens. # of serious fungal infections

•Hyphae: Cell filaments, mostly septate

•Mycelium: Mass of hyphae.

The Study of Fungi: ___________

Fig 4.11

Morphology:

•Molds: mostly filamentous, aerobic

•Yeasts: non-filamentous, unicellular, facultatively anaerobic

•Dimorphic fungi: yeast-like at 37C, mold-like at 25C.

Mycoses: Fungal infections esp. in immunocompromised (_____, cancer, DM)

Allergies and Intoxications e.g.: Alfatoxin

Study of Fungi cont.

Fig 4.12

Reproductive Strategies and Spore Formation

• Fungi can reproduce

through outward

growth of hyphae

• 1 reproductive mode:

Spores

Not to confuse with

ES in ______________?

• Spores – can be dispersed through air, water, and living things

– will germinate upon finding favorable substrate.

• Systemic mycosis: infection deep within body, affects many tissues and organs. Histoplasmosis and coccidiomycosis.

• Cutaneous mycosis = Dermatomycosis: affects keratin-containing tissues (hair, nails, skin).

• Opportunistic mycoses: Caused by normal microbiota of fungi that are not usually pathogenic. E.g.:

– Candidiasis

– Pneumocystis pneumonia

Preview: Fungal Diseases – Mycoses nib

Economic Effects of Fungi The good:

• Saccharomyces cerevisiae: Bread, wine, HBV vaccine

• Trichoderma: Cellulase for clear fruit juice

• Taxomyces: Taxol

The bad:

• Mold spoilage

The ugly:

nib

Medical Moments:

1. Vaginal Candidiasis

1. Toxoplasmosis and Pregnancy Radiolab start at 49 mins

The Protozoa

Unicellular, eukaryotic chemoheterotrophs. Large and diverse group. Few are pathogenic.

Found in soil and water and as normal microbiota in animals.

Trophozoite: Vegetative form (feeding and growing stage).

Some protozoa can produce a cyst. Dormant stage during adverse environmental conditions. Reminiscent of?

Asexual reproduction mitotic cell division or schizogony (multiple fission)

Sexual reproduction in most

Fig 4.14

General Lifecycle of Protozoa

2

3

6 7

8

Major Pathogenic Protozoan: Apicomplexa, not mobile, intracellular

Plasmodium and Toxoplasma,

Plasmodium vivax Life Cycle

The Helminths (Parasitic Worm)

• Kingdom: Animalia

– Phylum: Platyhelminthes (flatworms)

• Class: Trematodes (flukes)

• Class: Cestodes (tapeworms)

– Phylum: Nematoda (roundworms)

• Few are human parasites

• Anatomy and life cycle modified for parasitism

• Adult stage in definitive host.

• Each larval stage in specific intermediate host.

Life Cycle of Helminths

1. Hermaphroditic: Male and female reproductive systems in one animal

2. Separate male and female

3. Asexual reprodution: Mitotic cell division

or multiple fission.

Egg larva(e) adult Depending on species either egg or larvae can be infective

Male Eggs

Mouth

Cuticle

Mouth

Fertile

egg

Swallowed

(self-infection) Copulatory

spicule

Scratching

contaminates

hands.

Eggs emerge

from anus.

Eggs transferred

to new host

(cross-infection). Female Anus

Fig. 4.17

A Helminth Cycle: Pinworm / Enterobius vermicularis

Diagnosing Pinworm Disease

Do test immediately after waking up. Several samples might need to be examined. Since scratching of the anal area is common, samples taken from under the fingernails may also contain eggs.

pinworm paddle

• Case File: Puzzle in the Valley

Deadly Bite: Malaria

Who will present?

Inside the Clinic