L20 - Fungal Cell Biology

Question 1

What is yeast?

Answer 1

Simplest form of fungi (grows similarly to bacteria, not filamentous

Question 2

What is the kingdom hierarchy for fungi

Answer 2

Prokaryota, eukaryota, kingdom fungi

Question 3

Based on the universal phylogenetic tree, are fungi more related to animals or plants

Answer 3

Animals

Question 4

What are cellular slime moulds

Answer 4

Aggregation of amoebae differentiate into spore-bearing fruiting structures

Question 5

What happens when amoeba is exposed to cAMP

Answer 5

Infection of micropipetted cAMP causes signalling and the induced pseudopod induces chemotaxis and amoeba grows towards it

Question 6

What are plasmodial slime moulds

Answer 6

difference: instead of being individual cells it is one massive cell

• single cell but exists as plasmodium
• millions of nuclei
• can grow the size of a pizza
• they move around
• in soil to degrade organic matter

Question 7

What is yeast and describe the structure of it as its dividing

Answer 7

• simplest form of fungus
• diagram shows a budding years (like a balloon)
• nucleus divides
• daughter nucleus is pulled in and separated by cleavage

Question 9

What is the species name of a budding yeast

Answer 9

Saccharomyces cerevisiae

Question 10

Describe the yeast cell cycle

Answer 10

• spindle pole duplication
• bud emergence
• SPB separation
• nuclear migration
• nuclear division
• cytokinesis
• cell separation

Question 12

Describe how fission yeast divides

Answer 12

Instead of budding they divide by fission (crossbow and breaks into 2 pieces)

Question 13

What word is used to describe filamentous fungal cell?

Answer 13

Hypha is derived from the Greek word meaning web and is used to describe a filamentous fungal cell. A network composed of multiple interconnected hyphae is termed mycelium

Question 14

What are some characteristics of tip growth? What does growth include?

Answer 14

Tip growth = polarised extension in which increase in cell length is restricted to a narrow region of a few micrometers at the cell tip

Growth involves
- fungal hyphae
- pollen tubes
- root hairs
- algal and fern rhizoids
- moss cell filaments

Question 15

Describe the spore germination

Answer 15

Germ tubes are specialised hyphae which emerge during spore germination and are involved in colony stablishment

Question 16

What conditions can spores survive in

Answer 16

Extended periods and extreme conditions such as:
- freezing temperatures
- vacuum
- electron beam/radiation

Question 17

What are rhizomorphic mycelium

Answer 17

Hyphae aggregates that form thick strands of hyphae which have adhered. Helps fungus cover area, grow quickly through substrates and establish a feeding network

Question 18

Describe the diagrammatic representation of fungal hyphae. What is AVC and where is it located?

Answer 18

tip = AVC (apical vesicle cluster): where most secretory vesicles are located and they continuously bind with plasma membrane and brings enzyme synthase secretory enzymes

Question 19

Definition of spitzenkorper

Answer 19

A multi-component organelle assemblage predominated by vesicles. Responses to stress include cessation of growth or retraction of the spitzenkorper

Question 20

What happens when hypha bursts?

Answer 20

When hypha bursts possibly due osmotic stress, cytoplasm stains and all the matter is released into external environment

Question 21

Hyphae posses septa that are cross walls with spores. How was it formed and what does it allow?

Answer 21

Septum formation is like a cell cleavage during the mitotic division of animal cell. It allows passage of organelles and cytoplasm between adjacent hyphal compartments

Septal pores are blocked if hyphae become damaged so septal pores can also be blocked in old hyphae

Question 22

Mitochondria are present in hyphae,. How do we visualise them? What are the drawbacks of teh 2 ways

Answer 22

• 2 diff ways of staining mitochondria (GFP or fluorescent dyes transparent)
• difference in reporters and probes you get diff results
• sensitive to membrane potential (changes fluorescence depending on how much electricity potential)
• tips are brighter bc they are more highly charged
• GFP = staining is uniform, dont get to do comparative comparisons with mitochondria differences membrane

Question 23

What is the function of golgi cisternae in hyphae

Answer 23

Involved in glycosylation and packaging in vesicles of secreted and integral membrane proteins. In filamentous fungi they do not form golgi stacks

Question 24

Describe the vacuoles in hyphae

Answer 24

Spherical and tubular vacuoles compartments in hyphae (lysosomes)

Question 25

Describe the nuclei and how it is visualised

Answer 25

Fungal colony is a supracellular interconnecting network of multinucleate hyphae. GPF attaches to histone proteins

Question 26

Where is the nuclei not aggregated?

Answer 26

Region of hyphal extension avoids nuclei.

Question 27

Describe the development of a colony

Answer 27

Fungal mycelium is an interconnected complex network of hyphae. Increase in colony diameter occurs via hyphal tip growth in the colony periphery. Hyphal fusion and additional growth occurs in the colony interior as colony matures.

Question 28

How does hyphal fusion take place?

Answer 28

Hyphal branches grow towards each other in older parts of the fungal colony. They can sense each other and signal as a handshake if they are compatible.