Opisthokonta and Fungi Overview

Flashcards covering key concepts and facts from the lecture on Opisthokonta and Fungi.

What is the Opisthokonta clade?

The Opisthokonta clade is a diverse group of eukaryotic organisms that includes animals, fungi, nucleariids, and certain protists such as choanoflagellates. It is characterized by the presence of a unique flagellum that is positioned at the rear of the organism.

What does 'Opistho' and 'Kont' refer to in Opisthokonta?

'Opistho' refers to the rearward facing flagellum present in members of this group, which is an important feature for locomotion. 'Kont' means pole, indicating the pole-like structure of the flagellum.

Who are the closest living relatives of animals?

Choanoflagellates are identified as the closest living relatives of animals, sharing a common ancestor and exhibiting similar cellular features, particularly their collar cells that resemble certain structures found in sponges.

What structures do choanoflagellates have that are similar to those found in sponges?

Choanoflagellates possess specialized structures known as collar cells (or choanocytes), which are used to trap food particles from water, similar to the filter-feeding mechanism found in sponges.

How do fungi obtain energy?

Fungi are classified as absorptive heterotrophs, meaning they obtain energy by breaking down organic materials in their environment and absorbing the resulting nutrients through their cell walls.

What is the reproductive structure of fungi called?

The fruiting body is the reproductive structure of fungi, which is involved in spore production and dissemination, often taking on various forms such as mushrooms.

What is mycelium in fungi?

Mycelium refers to the vast and intricate network of filamentous structures called hyphae that make up the vegetative part of a fungus, essential for nutrient absorption and growth.

How are fungi classified?

Fungi are classified based on the type of sexual reproductive structures they produce during their life cycle, such as zygosporangia, asci, or basidia, which are critical in the identification of various fungal groups.

What is a zygosporangium?

A zygosporangium is a specialized reproductive structure found in the phylum Mucoromycota that is responsible for producing zygotes during sexual reproduction, allowing for genetic diversity.

Give an example of an organism in Ascomycota.

An example of an organism in the Ascomycota phylum is Saccharomyces cerevisiae, commonly known as baker's yeast, which is utilized in baking and brewing due to its ability to ferment sugars.

What type of relationship do mycorrhizae represent?

Mycorrhizae symbolize a symbiotic relationship between a fungus and the roots of a plant, enhancing nutrient uptake for the plant while providing the fungus with carbohydrates produced through photosynthesis.

What layers are present in lichens?

Lichens are composed of two main layers: an outer cortex made of fungal hyphae that protects the lichen structure, and a medulla layer containing fungal tissue, with a layer of photosynthetic organisms such as cyanobacteria or algae encased within.

List the three common forms of lichens.

The three common morphologies of lichens are: 1. Crustose (crust-like) - adheres tightly to the substrate; 2. Foliose (leaf-like) - with distinct leaf-like lobes; and 3. Fruticose (branch-like) - characterized by upright, branched structures.

What is the defining feature of Cnidarians?

Cnidarians are defined by their two germ layers, the ectoderm and endoderm, along with their radial symmetry, which allows them to interact with their environment from all sides.

What are nematocysts?

Nematocysts are specialized stinging cells unique to Cnidarians, utilized for capturing prey and defense, which contain a harpoon-like structure that can inject toxins.

What are the components of a sponge's feeding system?

The sponge's feeding system comprises choanocytes that draw water through multiple ostia (pores) into a central cavity, where food particles are trapped by the microvilli collars and then transferred to amoebocytes for digestion and nutrient distribution.