MICR501 Final

Which of the following statements on fungal replication is FALSE?

Asexual reproduction involves spores, while sexual reproduction does not

Which of the following statements on Leucoagaricus gongylophorus, which are farmed by leafcutter ants, is TRUE?

They produce ‘gongylidia’ which are hyphal swellings that are cultivated by the ants

Which of the following best describes the process of 'fragmentation', a form of fungal reproduction?

A form of asexual reproduction where parts of the mycelia break off and grow into a separate mycelium

Which of the following statements on fungal metabolism is FALSE?

All fungi get their nutrients from the extracellular digestion of decaying organic matter

Which of the following is an important structure that divides hyphal cells?

Septum

Ophiocordyceps unilateralis, also known as the zombie ant fungus, is an example of a parasitic fungus. Explain the effect this fungus has on the host ant and describe the infection/reproduction cycle

• Infected host ant driven to find forest area with suitable temperature and humidity

• Attaches self to underside of leaf to remain and die

• Fungus undergoes reproductive stage

  • Fruiting body grows from ant’s head, ruptures and releases spores

  • 4–10 days from infection to spore release

Describe the sexual reproduction cycles in fungi, including the different structures involved and the implications for taxonomic assignment

• Plasmogamy: merging of protoplasms

• Karyogamy: merging of nuclei

• Meiosis: division reducing number of chromosome sets

• Teleomorph: sexual stage, often a fruiting body

• Anamorph: asexual stage, often mould-like

• Holomorph: whole fungus incl. prev.

List four enzymes involved in fungal metabolism and their functions

• Protease: breaks down proteins into amino acids

• Lipase: breaks down lipids into fatty acids and glycerol

• Amylase: breaks down starch into simple disaccharides

• Cellulase: breaks down cellulose into glucose

Describe what hyphae are. Include in your answer a description of the structure and function of the Spitzenkörper organelle

Hyphae: vegetative growth of filamentous fungi

• branching filamentous structures

• one or more cells surrounded by tubular cell wall

• divided into cells by septa

Spitzenkorper: organising centre for hyphal growth

• intracellular organelle associated with tip growth

Describe what mycorrhizal fungi are and the importance of them to plant growth.

• Type of root fungus with mutalistic symbiosis with plant roots

• Ectomycorrhizae = fungal cells that form extensive sheath around root exterior with little penetration into tissue

• Endomycorrhizae = fungal mycelium embedded in root tissue

• Symbiosis provides plants with nutrients and increases tolerance to stresses and defence against pathogens and herbivores

List THREE benefits and THREE limitations of mycelium-based leather compared to traditional cowhide derived leather

Benefits: shorter production time, smaller space required, can be grown on waste products

Limitations: scalability, inconsistent/unpredictable growth, still mixed with plastics to increase strength

Explain the role of Brettanomyces in the production of wine. Include in your answer the common sources of the organism, the impact on the wine, and how the presence of the organism can be controlled

Brettanomyces = yeast commonly found in wineries

• Saccharomycetaceae family

• From grape, barrel, equipment, possibly bottle

• Produces volatile phenol compounds = wine spoilage

• Sulfur dioxide prevents contamination

• Filtration and dimethyl dicarbonate for removal

Define cilia

Specialised hair-like organelles, shorter + more numerous + different undulating pattern than eukaryotic flagella

Define contractile vacuole

Vacuole in some protists (ciliates) for osmotic pressure regulation

Define dinokaryon

Form of dinoflagellate nucleus where the chromosomes are attached to the nuclear membrane

Define endocytosis

Engulfing of materials by invagination of cell membrane

Define polyphyletic

Derived from more than one common evolutionary ancestor

What term describes the protist phylogeny?

Polyphyletic

What was the most recent common ancestor of the protists?

A unicellular eukaryote

Which of these statements about ciliates is FALSE?

Give an example of a unicellular protist, a multicellular protist, and a protist which can have both unicellular and multicellular cell types, and the implications for studying the evolution of multicellularity

Unicellular: Amoeba, Diatoms

Multicellular: 

Both: Algae, Volvox,

Which viral evolution theory states that viruses arose from nucleic acids and proteins on early Earth and evolved alongside cellular life?

‘Virus Early’ theory

Which of the following statements is FALSE?

Negative (-) sense RNA viral genomes can be immediately translated by the host cell

Which of the following statements on viral replication is TRUE?

The replication cycle of animal viruses starts with penetration, when the virion enters or injects its nucleic acid into the host cell

During which stage of bacteriophage replication does the viral DNA integrate into the host genome?

Lysogenic cycle

In the lysogenic cycle, what triggers the switch from lysogeny to the lytic cycle?

Environmental factors or stress

Name and describe TWO different types of viral morphology

Icosahedral: spherical appearance, 20 triangular faces, highly efficient and stable

Helical: rod-like, capsomeres spiral around genome

Complex: elaborate, head and tail regions

Bacteriophage replication mnemonic

A Pretty Russian Ate Raisins

Attachment Penetration Replication Assembly Release

Name and describe the steps of bacteriophage replication

1. Attachment of bacteriophage to surface receptor on host bacterium

2. Penetration of phage genetic material into host cell

3. Replication of genetic material using host resources

4. Assembly of phage particles

5. Release of phage via cell lysis

Viral replication cycle for animal viruses mnemonic

Acrobatic Playboys Can Never Attain Relief

Attach Penetrate Coat Nucleic Assembled Released

Describe the viral replication cycle for animal viruses

1. Virus attaches to host cell

2. Virus penetrates host cell

3. Protein coat removed, naked nucleic acid enters

4. Nucleic acid replicated, proteins synthesised

5. Virus assembled

6. Mature virus released

Which of the following is the correct order of the soil horizons from surface down?

O A B C R

Organic, organic + mineral, sand + silt/clay, parent rock, unweathered parent material

Which of the following best describes the Baltimore classification system?

A system used to classify viruses based on their genome type and replication strategy

Which of the following statements on Zooxanthellae is FALSE?

They all belong to the genus Symbiodinium

Which of the following best defines assisted evolution?

The intentional acceleration of evolutionary processes thorugh human intervention to improve resilience or performance

Provide a definiton for ‘Reverse transcription’

A process used by some viruses to conver RNA to DNA using reverse transcriptase

List FOUR features of ciliates

1. Hair-like organelles (cilia)

2. Have two nuclei

• micronucleus for reproduction

• macronucleus for metabolism, cell regulation, etc.

3. Can perform conjugation

4. Feed through phagocytosis

Scenedesmus sp. is an example of what type of organism?

An alga commonly used for biofuel production

Which of the following is NOT a suitable way to increase the effectiveness of Phage therapy

Using a single, highly specific strain of phage

Which of the following is the correct description of an endomycorrhizal fungus?

A mutualistic symbiosis between most terrestrial plant roots and fungi where the fungal mycelia embed in root tissue

What role does Brettanomyces have in wine making?

It is commonly associated with wine spoilage as it produces volatile phenol compounds which lead to a characteristic, unpleasant taste

Which of the following statements on why fungal hyphae make a good leather alternative is FALSE?

Their growth is consistent between different batches

What is a plasmodium in the context of plasmodial slime moulds?

A single, large cell with multiple nucelid that moves and engulfs food

Describe the relationship between Zooxanthellae and corals and how assisted evolution is being explored to support this dynamic

• Zooxanthellae = photosynthetic protists forming symbiotic relationships with marine life

• Mutualistic symbiosis between zoo and corals

• Zoo lives inside coral cells, provides coral with 90% of energy needs via photosynthesis

• Corals provide safe home and compounds necessary for photosynthesis

• Corals expel zoo when stressed

• Heat tolerance largely determined by zoo

  • Manipulating zoo may enhance endurance of corals

Explain how biofuels can be created by algae

• Biofuel = renewable energy source derived from biomass

• Created by algae, commonly Scenedesmus sp.

1. Cultivation (ponds or bioreactors)

2. Harvesting (water removes via filtration/centrifugation)

3. Oil extraction (energy-rich oils extracted by breaking down cell structures)

4. Conversion into usable fuel (transesterification or distillation and cracking)

Open system = pond (cheap, evaporation and contamination

Closed system = photobioreactor w panels (expensive, controlled and efficient)

Describe the structure and function of the Spitzenkörper organelle

‘Organising centre’ for hyphal growth

Intracellular organelle associated w tip growth

Aggregation of membrane-bound vesicles containing cell wall components

In the context of Fungi, provide a definiton for ‘Septum’

Internal cell wall dividing hyphae into cells

Describe the secual reproduction cycles in fungi, and one structure that is involved

1. Plasmogamy: fusion of parent cell protoplasms

2. Karyogamy: fusion of two nuclei

3. Meiosis: cell division reducing chromosome sets to 1

Ascospore: sexual spores formed in ascus

Basidiospre: sexual spores formed on basidium

Provide a definition for ‘Terroir’

A term encompassing environmental factors (e.g. soil, climate, elevation) that influence whine characteristics, typically involved in wild yeast