Fungi, Yeasts, Parasites, and Epidemiology

What are the two forms of fungi and their cellular characteristics?

The two forms of fungi are unicellular (yeasts) and multicellular (molds).

Define mycelium and hyphae.

Mycelium is the network of fungal filaments, while hyphae are the individual filaments that make up the mycelium.

What is the difference between vegetative hyphae and aerial hyphae?

Vegetative hyphae are involved in nutrient absorption and growth, while aerial hyphae are involved in reproduction and spore production.

What is a fungal spore, and where are they located on a mold?

A fungal spore is a reproductive structure that can develop into a new organism; they are typically located at the tips of aerial hyphae.

How do fungal spores function similarly to bacterial endospores, and how are they different?

Fungal spores can survive harsh conditions, aid in reproduction, disperse to new locations, and germinate when conditions are favorable; they differ in that they are not as resistant to extreme conditions as bacterial endospores.

What are the three ways molds can cause disease in humans?

Molds can cause disease through allergic reactions, infections, and mycotoxin production.

What are the two types of yeast and how do they differ?

The two types of yeast are pathogenic yeasts (e.g., Candida) which can cause disease, and non-pathogenic yeasts (e.g., Saccharomyces) which are generally safe and used in food production.

What are true yeasts used for by humans?

True yeasts are used in baking, brewing, and fermentation processes.

Define the terms pathogen, primary pathogen, and opportunistic pathogen.

A pathogen is any organism that causes disease; a primary pathogen can cause disease in healthy individuals, while an opportunistic pathogen causes disease primarily in immunocompromised individuals.

Why are dimorphic yeasts called 'dimorphic'?

Dimorphic yeasts are called 'dimorphic' because they can exist in two forms: yeast form and mold form.

Where are Candida yeasts normally found in the body, and why are they considered opportunistic pathogens?

Candida yeasts are normally found in the human microbiota, particularly in the mouth and intestines; they are considered opportunistic pathogens because they can cause infections when the immune system is weakened.

What are the three kinds of mycoses and where do those infections occur in the body?

The three kinds of mycoses are superficial (skin), subcutaneous (under the skin), and systemic (internal organs).

What are the two ways we define parasite in microbiology?

Parasites can be defined as organisms that live on or in a host and derive nutrients at the host's expense.

What are the two major types of microbial parasites?

The two major types of microbial parasites are protozoa and helminths.

Why do parasites tend to live in warmer or tropical environments?

Parasites tend to live in warmer environments due to favorable conditions for reproduction and survival; those in colder places have adaptations to withstand harsh conditions.

What are the two kinds of life stages that parasites have and their purposes?

Parasites typically have a reproductive stage for propagation and a feeding stage for nutrient absorption.

Define the term infective stage and identify it for each parasitic disease discussed in class.

The infective stage is the life cycle stage of a parasite that can invade a host; specific stages vary by parasite.