Fungi vs. Plants Quiz

Medical Important Fungi

• Fungi are diverse, saprophytic (feeding on dead organic matter) and parasitic eukaryotic organisms.
• Previously classified with plants, they are now in their own kingdom, Mycota.
• They can be aerobic or facultatively anaerobic.
• Chemoheterotrophic, deriving nourishment from organic matter.
• About 200,000 fungal species exist, but only approximately 100 are clinically significant in terms of human infections.

Structure and Classification of Fungi

• Fungi can be unicellular or multicellular.
• Some fungi, like mushrooms, can be harmful if ingested.
• Some fungi produce toxins that can cause a variety of illnesses.
• Some molds and yeasts can be seen with the naked eye.
• Some produce toxins that can cause cancer, and/or other illnesses.

Overview

• Fungi have cell walls made of chitin.
• Unlike plants, they do not contain chlorophyll.
• Some fungi can grow in environments without oxygen.

Mycoses

• Human fungal diseases (mycoses) are classified based on the body location of infection.
• Cutaneous mycoses—limited to epidermis (outer skin layer).
• Subcutaneous mycoses—penetrated down through the skin.
• Systemic mycoses—spread throughout the body.
• Mycoses can be true pathogens or opportunistic pathogens.

Fungal Growth in the Human Body

• Fungi primarily infect skin, hair and nails (superficial mycoses).
• Fungi can also infect deeper layers of skin (subcutaneous mycoses).
• Or spread through the body (systemic mycoses).

Other Medical Importance

• Fungi produce and secrete diverse metabolic products; some are highly toxic when ingested.
• Poisoning from ingestion can be fatal in humans and animals.
• Lastly, fungal spores are critical for dispersal and transmission.

Pathogenic Fungi

• True Pathogens: Cause disease in healthy individuals.
• Opportunistic Pathogens: Typically cause disease only in those with weakened immune systems.

Major Fungal Groups

• Fungi are distinguished from bacteria and viruses because they are eukaryotic.
• Fungi lack chlorophyll and chloroplasts.
• Distinguishing features like structural characteristics, habitats and growth methods are applied to classify different fungal groups.

Comparison of Fungi and Bacteria

• Fungi are usually larger and eukaryotic compared to bacteria.
• Bacteria are typically prokaryotic and much smaller.

Fungi Compared to Other Kingdoms

• Fungi have a chemoheterotrophic nutritional type (obtaining energy and carbon from organic sources).
• Algae, protists, and helminths have different nutritional types.
• Their presence within body systems may cause various illnesses in individuals and/or animals.

Modes of Fungal Growth

• Most fungi exist as either filamentous molds or unicellular yeasts.
• Some fungi have dimorphic capabilities.
• Filamentous fungi are composed of threads called hyphae. Hyphae may be septate or aseptate.
• Budding yeasts reproduce through asexual budding.
• These types of fungi may cause illness in individuals.

Filamentous (Mold-like) Fungi

• The vegetative body or thallus of a mold is a mass of branching threads called mycelium.
• The threads are called hyphae, which are tubular cells that may be septate or nonseptate.

Yeast-like Fungi

• Yeast-like fungi exist as single, unconnected spheroid cells.
• 10 times larger than bacteria.
• Reproduce either by budding or fission.

Dimorphic Fungi

• Some fungal species can switch between yeast and mold forms.
• The form depends on factors like temperature and carbon dioxide levels.
• Environmental factors affect morphology.

Fungal Life Cycle

• Fungi reproduce asexually and/or sexually.
• The reproduction methods depend on the fungus species.

Cutaneous Mycoses

• These are infections of the skin, hair and nails caused by dermatophytes (group of fungi).
• Dermatophytes fall into three genera.
• Each genus includes many species.

Subcutaneous Mycoses

• Fungi infect the dermis, subcutaneous tissue and bones.
• Causative organisms live in soil and decaying vegetation.
• Fungi that commonly cause illness.

General Properties of Subcutaneous Infections

• Subcutaneous infections are generally acquired through trauma such as lacerations or puncture wounds.

Sporotrichosis

• A subcutaneous mycosis.
• Characterized by a granuloma at the infection site.
• Secondary lesions along lymphatic channels.
• The causal agent, Sporothrix schenckii, is a dimorphic fungus. (Sporothrix schenckii exists in both a yeast and mycelial form).

Chromomycosis

• Caused by various fungi.
• Characterized by skin lesions.

Mycetoma

• Characterized by subcutaneous lesions that can lead to bone infection.

Systemic Mycoses

• Infect normal healthy individuals.
• May infect immunocompromised individuals.
• Several types of systemic mycoses exist; they may cause death.

Opportunistic Mycoses

• Primarily affect individuals with immune deficiencies.
• The use of immunosuppressants for organ and cancer treatment increases the prevalence of fungal infections.

Nosocomial Infections

• Fungal infections acquired during treatment in hospitals, frequently in intensive care units (ICUs).
• Candida species are a common cause.

Candidiasis

• Caused by Candida albicans and other Candida species.
• Commonly found as normal body flora on skin, mouth, vagina and intestines.
• Most fungi are opportunistic pathogens.
• Can form a true mycelium.

Mucous Membranes

• Oral thrush (oral candidiasis)—characterized by white plaques in the mouth and throat.
• Vaginal candidiasis—characterized by itching and burning, with possible white vaginal discharge.
• Other Candida infections involving the esophagus are also possible.

Systemic Candidiasis

• A potentially life-threatening infection.
• Occurs in immunocompromised patients.

Cryptococcosis

• Caused by Cryptococcus neoformans yeast.
• Often found in soil containing bird droppings(especially pigeons' droppings).
• Can cause meningitis.

Aspergillosis

• Caused by several species of Aspergillus, usually A. fumigatus.
• Can infect lungs.
• More commonly found in immunocompromised individuals.

Pneumocystis jiroveci

• Caused by P. jiroveci (formerly P. carinii) a yeast-like fungus.
• Causes pneumonia.

Test your knowledge on the differences between fungi and plants with this quiz. Explore the characteristics, classifications, and functions of fungi, including their role in mycoses and pathogenic potential. Discover unique aspects of fungal structure and reproduction in various genera.