Unit 5- Eukaryotic Pathogens

Question 1

What are the four ecological roles of fungi?

Answer 1

• Saprobes
• Symbionts
• Commensals
• Parasites

Fungi play diverse roles in ecosystems, including decomposition and forming beneficial relationships with other organisms.

Question 2

Human pathogenicity in fungi has evolved multiple times across which major lineages?

Answer 2

• Ascomycota
• Basidiomycota

Pathogenic species are found in several major fungal lineages, with adaptations allowing some fungi to infect humans.

Question 3

True or false: Fungal and human cells are both prokaryotic.

Answer 3

FALSE

Both fungal and human cells are eukaryotic, which complicates the development of selective antifungal treatments.

Question 4

What are the main components of the fungal cell wall?

Answer 4

• Chitin
• β-glucans
• Mannoproteins

These components provide structural support, protection, and facilitate host interactions.

Question 5

Why is ergosterol an important target for antifungal drugs?

Answer 5

It is unique to fungi, allowing selective targeting without harming human cells

Antifungal drugs exploit ergosterol by inhibiting its synthesis or disrupting membrane integrity.

Question 6

Fill in the blank: Dimorphism refers to a fungus’s ability to exist in two different __________.

Answer 6

morphological forms

This includes switching between yeast and filamentous forms, which is crucial for pathogenicity.

Question 7

What are the key mechanisms through which fungi cause disease (mycosis)?

Answer 7

• Adhesion and colonization
• Tissue invasion
• Immune evasion
• Biofilm formation
• Toxin production

Fungal pathogenesis relies on a combination of these mechanisms to establish infections.

Question 8

What are the key structural characteristics of medically important protozoa?

Answer 8

• Unicellular eukaryotes
• Heterotrophic
• Lack of cell wall
• Motility structures
• Diverse life cycles

These characteristics enable protozoa to adapt and thrive in various environments.

Question 9

Differentiate between the trophozoite and cyst stages of protozoan parasites.

Answer 9

• Trophozoite: Active, feeding, motile form
• Cyst: Dormant, non-motile, infectious form

The trophozoite is responsible for disease symptoms, while the cyst stage aids in transmission.

Question 10

What is the life cycle of Giardia lamblia?

Answer 10

• Transmission via cysts
• Excystation in the small intestine
• Colonization by trophozoites
• Pathogenesis leading to symptoms
• Encystation in the large intestine

The cycle involves both active and dormant stages, impacting transmission and infection.

Question 11

Define definitive host and provide an example.

Answer 11

The organism in which the parasite undergoes sexual reproduction

Example: In malaria, the female Anopheles mosquito is the definitive host for Plasmodium.

Question 12

How does malaria cause disease through red blood cell destruction?

Answer 12

• Infection by Plasmodium species
• Multiplication inside RBCs
• Rupture of RBCs releasing merozoites
• Causes cyclical fevers and anemia

Severe malaria can lead to serious complications, especially in vulnerable populations.

Question 13

What are the challenges in malaria prevention and treatment?

Answer 13

• Drug resistance
• Mosquito resistance
• Stalled progress due to COVID-19

These challenges hinder efforts to control and eliminate malaria effectively.

Question 14

What are the steps of bacterial infection establishment?

Answer 14

• Adhesion
• Colonization
• Invasion

Each step is crucial for bacteria to successfully infect a host and establish a population.

Question 15

What are the immune evasion strategies used by bacteria?

Answer 15

• Capsules
• Antigenic variation
• Inhibition of complement activation
• Destruction of immune cells

These strategies help bacteria avoid detection and destruction by the host immune system.

Question 16

What is the role of biofilms in persistent infections?

Answer 16

• Physical barrier against antibiotics
• Metabolic diversity
• Communication via quorum sensing

Biofilms contribute to chronic infections, making them difficult to treat.