Week 11 Flashcards

Question

During asexual reproduction in zygomycetes, hyphae produce which of the following?

Answer 1

They form arbuscular mycorrhizae. They do not undergo sexual reproduction.

Answer 2

A zygosporangium

Answer 3

Flagellated spores

Answer 4

The spores swim.

Answer 5

sporangiophores

Answer 6

They have a haplodiplontic life cycle. They produce zoospores.

Answer 7

Mycorrhizae

Answer 8

They are anaerobic. They produce zoospores with multiple flagella

Answer 9

Haplodiplontic life cycle; zoospore with a single flagellum

Answer 10

Neocallimastigomycota

Answer 11

They parasitize animal cells.

Answer 12

mushrooms truffles etc Cultivated mushrooms: Agaricus bisporus Also processed foods made using fungi, either as a food or to process other foods

Answer 13

--Worth £350 million p.a. in the UK --Straw and manure composted (microbial fermentation…)- Manure richer in nitrogen. --Pasteurised --“Spawned” inoculated using grain on which mycelium has developed

Answer 14

allow the fungus to grow through compost

Answer 15

Capping – cover compost with peat/chalk mix to induce fruiting

Answer 16

Harvest – in flushes every 7 days

Answer 17

Requires controlled temperature and humidity

Answer 18

---Grow microbe on a solid substrate:closest to natural growth condition --Mushrooms (harvest just the fungus) --Very variable and difficult to control but low-tech so not expensive. Breads Cheeses Soybean & rice products etc

Answer 19

- ---Saccharomyces cerevisiae (yeast) - ---Aerobic respiration of the free sugars in bread, releases CO2, putting bubbles in the dough. - --Limited enzyme secretion alters the proteins responsible for the texture of the dough - --Yeast cells give additional flavour - --Too much salt/too cold stops yeast from growing and gives a hard flat bread!

Answer 20

---Fungal rinds on cheeses: digest the cheese from the edge to the centre: Brie, Camembert etc: Penicillium camembertii

Answer 21

---The fungus secretes proteases: digests the casein, liquefying the cheese. ---Lipases to alter the lipid profile of the milk fats Alters the taste and texture ----Stilton/blue cheeses: (P. roquefortii) grows within the cheese – inoculated as veins,low oxygen levels – slow growth,metabolite production and digestionof milk solids - altered taste

Answer 22

Salami and “moldy” sausages High salt content and low water levels reduce microbial growth Fungal rind helps prevent infection from the outside (as it does on maturing cheeses)

Answer 23

are in the dikaryotic group and are typically thought of being mushrooms and toadstool but there is far more diversity. -- Within the Basidiomycetes you also have more microscopic forms e.g the jelly fungus which is commonly found on things like dead bits gorse or other timbers. The whole of the outside of the fungus is the reproductive SA highly folded up giving it more SA from where it can sporulate.

Answer 24

have a central stalk which is known as a stipe on top of this is the cap- usually circular. The cap gives a big surface area from which gills can hang underneath. Circular (ish) cap – pileus Supported by a stalk – stipe

Answer 25

Bracket fungi are within the Basidiomycetes it is a fungus that usually grows in standing timber- woods of different sorts. The fungus fruiting body is growing out from the timber getting a big surface area from which it can hang its gills and so produce spores. Usually growing out of standing timber Stipe not always present Indicate a heart rot in the tree!

Answer 26

have cylindrical shaped fruiting bodies on a stalk and the spores are made inside that chamber. If you touch the structure of the puff ball it sends a shock wave through the structure which puffs millions or even billions of spores out of the fruiting body. Massively productive in releasing spores. Central cavity has a sponge-like texture, with basidia all over the exposed surfaces.Produces BILLIONS of basidiospores. Any disturbance leads to a puff of spores out of the fruiting body .

Answer 27

The earthstars have an outer casing around the spherical fruiting body.

Answer 28

The casing peals back showing the spherical structure in the middle. Typically grow in the leaf litter. Often found in the autumn.

Answer 29

are plant pathogenic fungi, there are no large fruiting bodies made, they are single celled fruiting bodies.

Answer 30

Start of with hyphae in the soil coming from basidiospores. This single cell basidiospore will germinate that will give you a hypha that will be haploid. Those haploid hyphae will grow perfectly happily in the soil and can grow for a long time but if they bump into a sexually transmitting strain then mating will take place. You get fusion of the cytoplasm of the two hyphae giving you a dikaryotic mycelium. A mycelium where the two pairs of spores will grow together, staying together all the way through that mycelium. You don't get nuclei fusion at that point so the cytoplasm fuse but the nuclei are maintained in pairs in this growing mycellium. When the conditions are right that fertile mycellium can then form a fruiting body and you get get a slight formation of a mushroom. And up grows the mushroom so all the mycellium in this mushroom are dikaryotic, that is they have two different nuclei inside each cellular compartment. It then produces the gills and on the surface of the gills on teh very most outer surface of the gills is where the two nuclei will fuse together and so you have this basidium outer cell in which the two haploid nuclei will fuse giving you the diploid nucleus. Goes through meiosis giving four nuclei inside that basidium cell. The nuclei then get pushed out the make spores on the outside of the body of the basidium. So you have four basidium spores made on the outside of the basdium. These basidious spores will get released into the air to spread around and start another colony. Sexual progany is made externally to the parent cell. Whereas in the ascomyocye the sex progany stayed inside the parent cell.

Answer 31

The spores on the outside have an active release mechanism there's a tiny little drop of water that rushes from one side of the stalk to the other and that momentum of the water drop moving across the spore is enough to lift the spore off of the stalk and move it into the air space between the gills and the mushroom so that they can then fall out under the power of gravity. Are some basidium like yeast that can shoot out their spores several cm using a active shooting method because of water drops moving across the spores.

Answer 32

you get this septum structure where you get some membranes around the septum, which has some sort of structures on either side of the pore that will regulate movement of things.

Answer 33

Typically the Basidiomycetes don't have nuclei freely migrating through the septa. These septa don't usually allow nuclei transmission through them and so you have membrane structures that can surround the septum again regulating movement through the septa.

Answer 34

Septum with septal pore swellings around it. Both the pore and the membrane can regulate movement so how nutrients and things move through the fungus

Answer 35

so you have a dikaryon you often see things like clamp connections and these connections are swellings that remains on the side of the hypha when its going through its vegetative growth. You have a dikaryotic hyphae with two distinct nuclei inside. When these are going to divide they form the next cellular compartment a swelling starts coming out of the side of the hyphae. The two nuclei both go through mitosis at the same time and you get a complicated pattern nuclei movement where you have to nuclei in the hyphae tier, one nucleus in the side shoot and one in the main stalk in the fungus and then the wall dissolve away. By dissolving away they can move into the compartment together. Maintaining two nuclei in the stalk area and 2 in the hyphal tip. This grows and results in another clamp connection being formed.

Answer 36

Fungus grows on two different plant hosts, much of its lifecycle is done on wheat. Other parts of its lifecycle happen on barberry. Start with a diakaryotic spore which lands on the surface and grows in through the stomata and can give rise to pastures that have these rust spores. As it gets to late spring or autumn the fungus changes its behaviour. Instead of uredospores it produces teliospores. In these teliospores there are two cells and in each cell the two nuclei fuse together to form a diploid nucleus. These teliospores are effectively Basidiomycetes for the fungus and can survive adverse conditions and when they germinate they give rise to 4 basidious spores. This is where meiosis has taken place. These basidiospores can not infect wheat but can infect barberry. So they land on barberry and penetrate into the plant and produce another sporulating structure and in this case its spermagonia. The fungus has different mating types and the small spores being made here can fertilise the receptive hypha of other spermagonia. Allowing the dikaryotic to form and when it forms the fungus grows from the surface of the leave typically down to the lower part of the leaf where it produced a fruiting body called a aecium. And the aecium which gives rise to dikaryotic spores. Those spores land on a wheat leaf going through the stomata and then will start the asexual cycle in the uredospores again. You have five different spore types- uredospores, teliospores, basidiospores, spermatia and aeciospores. And its growing on two different species of plant. One on wheat and one on barberry.

Answer 37

mating types

Answer 38

n the rusts it is typically just two mating types A x alpha. When these mate the progeny that you get back will all be the same mating type to the parents. If the parents mates with an alpha the four progeny you get back will have two A and two alpha. In other Basidiomycetes, in the smuts and the true mushrooms you can have much more complicated systems. Where two different genetic loci are responsible for determining the mating type, so you can have an A locus and a B locus. To be able to mate the compatible partner has to be genetically different to both of those loci. So it has to have a different A allele and a different B allele. If A1B1 mated with A2B2 we can get 4 genotypes for the mating types of the resulting progeny. You get the two parental types A1B1 and A2B2 and then you get to the other mating types of A1B2 and A2B1. this is helpful in reducing certain mating because one of these will only be sexually compatable with one third of the other progeny. So the A1B1 wont be able to mate with the A1B2 because it has the A1 locus in common and wont be able to mate with the A2B1 because it has the same B locus in common. It will only be able to mate with A2B2 so it can produce sibling matings. But it gets more complicated because you can have over 30,000 different mating types. As long as they have different alleles at the A and B locus they will be able to mate. It means that if a fungus bumps into another unrelated individual it is likely able to mate as it is likely to meet something with completely different mating types.

Answer 39

many different ways

Answer 40

The gill tissue that is hanging down from the mushrooms have vertical hyphae in the middle of the gills as you get to the edge the hyphae become a little bit less regular and on the outer membrane. On the outer membrane you have the Basidium and has spores on the end. There are also cystidium- a sterile cell that help maintain the structure of the space between the gills.

Answer 41

Mushrooms can detect light will grow into the direction of light and once it has found it it will grow straight. They can also detect gravity. That matters because you want the gills vertically underneath the cap. By having vertical gills all the spores and released and nothing is lost. As soon as the gill is no longer vertical for example by 5 degrees 50% of the spores are lost

Answer 42

Some mushrooms dont have gills, some have spikes but its the same idea, the spikes have a very large surface area. The cap is the fruiting body and the teeth hang down beneath and give rise to spores. Puffballs make their spores inside- its a shock wave that makes them come out.

Answer 43

associations with trees and are often found under them. Basidiomycetes forming those associations makes ectomycorrhizae where the hyphae stay mostly a sheaf around the outside of the root with a few hyphae penetrating into the root and a lot of hyphae penetrating into the environment. The roots in this circumstance are small, if the hyphae are growing out into the soil that take up nutrients they need to have complex root hair structures for this.

Answer 44

Biggest challenge that fungi cause is around the way they access their food. They have a rigid cell wall so they cant physically engulf things such as food, they have to get their food from absorption. This means that the nutrients have to be small and soluble so they can diffuse through the wall of the fungus to get to the membrane and be taken up. A fungus digests food outside its own body. So the fungus secretes its digestive enzymes into its surrounding environment and then bathes in this nutrient rich soup where the nutrients make there way back into the fungus. The enzymes are typically secreted are enzymes that depolymerase the macromolecules usually found in nature. So there will be protease to break down proteins etc. nutrient uptake is via absorption and there is a massive production of degrading enzymes that is secreted outside the fungus that cause many of the problems associated with fungus.

Answer 45

Fungi can eat pretty much anything that is of biological origin, so organic waste which can be recycled by a fungus they can access the carbon, sulphur locked up in these molecules. Because this digestion happens outside of the fungus other organisms competing in the natural environment might also access these molecules. When a fungus colonises a new niche. Secondary colonisers use starch and proteins which secrete enzymes into their environment accessing the easy to digest compounds. As those simple polymers start to run out- we have tertiary colonisers these are the fungi that use really complex things. Macromolecules like cellulose and lignins are harder to break down. It takes a much longer time but they are using polymers that primary and secondary colonisers couldnt really access.

Answer 46

all contain proteins so they provide a very valuable nutrient in the environment because nitrogen is quite limiting to growth. So these compounds are really beneficial if something can metabolise them. If they get wet that is what happens, the fungus can start to break down proteins in wool or leather or bone. Degrading these things and protease they make break up the protein chains.

Answer 47

lignin - radical chemistry to break down lignin as its harder to break.

Answer 48

each line has been occupied by fungus and where it meets a competitor fungus it marks down this dark lines as a way to mark their territory

Answer 49

Fungi can also rot away many man made products because these are originally from nature.they can also infect food and storage of food. We can control this sort of thing by drying etc cooling- fungi cant grow as fast.

Answer 50

Fungi have to prevent competition so they most commonly produce toxins that will act against different microbes or different organisms in their natural environment. They also produce these large fruiting structures in the case of mushrooms. As that is the reproductive part of the tissue then they will also protect that tissue from being eaten by other things.

Answer 51

There can be fungi that look just like the common mushroom. The yellow stainer that looks just like the field mushroom but when it gets bruised you get this yellow discolouration. If you cut the stem you often get this yellow discolouration in the stem. Yellow stainer produces a toxin in the fruiting body. The toxin is stable through cooking. Orellanin is highly poisonous, it will attack your liver or kidneys. Sweating, stomach cramps but not all people!

Answer 52

They also have other alarming effects apart from making you ill. The liberty cap for example this grows quite commonly in grassland which has been grazed by sheep. If a larger mammal eats the liberty cap the effects are alarming but not life threatening compared to smaller organisms.

Answer 53

has an outer membrane all the way around the fruiting body as well as the inner membrane that covers over the gills. This outer membrane gives this valva structure at the base of the fruiting body. These are deadly poisonous. The mushrooms contain two different toxins alpha-amanitin and phalloidin. Phalloidin can be destroyed by cooking but the alpha-amanitin is pretty serious. Toxins are normally ingested the toxin gets quickly taken up through the stomach. Your body will recognise that something is going wrong and it will trigger violent vomiting. The toxin causes degradation of RNA in the liver cells, by destroying RNA it halts protein synthesis. So you cant produce any proteins or destroy any toxins. Toxin is reabsorbed by the kidney so it doesnt get secreted out into the urine. There are antibodies that bind to the toxin.  Produces -amanitin and phalloidin  Toxins easily ingested  Violent vomiting 6-24hrs post ingestion  Causes nuclear RNA degradation in liver cells – halting protein synthesis  Reabsorbed by the kidney and causes damage to convoluted tubules  Causes liver failure 10-14 days post ingestion  Mortality of 50-90%

Answer 54

various mycotoxins

Answer 55

Fungi from many different groups can cause disease. Powdery mildew- common disease of cereals and under a microscope the white patches consist of conidia. Chains of asexual spores that spread around and get blown around in the wind. This fungus can go through a sexual cycle. The small black patches are the fruiting bodies of the fungus. Becasue the fungus a sexual cycle that genetic reassortment means that if one strain is resistant to one fungicide and a different strain is resistant to another if they mate two different fungicide resistances can get into the same fungus. Therefore it is difficult to control a fungus that goes through sexual reproduction because they are able to continually reassort resistance mechanisms that they have.

Answer 56

Plant disease is often controlled by things like making sure the seed is cleaned before you plant it. They can sometimes be heat treated to try and eliminate pathogens from the seed. It is controlled by things like hygiene measures, crop rotation where you grow different crop in the field each year so you don't build up soil residence in the pathogens as they are typically host specific. We breed plants so we can select resistant varieties which are resistant to the fungi that are out there. But the fungi to evolve over time to resist the fungicides. Can also use fungicides which are sprayed onto the crops to try and eradicate the disease.

Answer 57

Animals can also get fungal disease, common ringworm, the fungus that can cause this in dogs can also cause this on people. The fungal hyphae can get onto your skin. It is not a worm it is one fungal colony which starts and the middle and is slowly moving outwards and is getting bigger with massive irritation around the outside.. Its in the fungus interest to make you itch as you will loosen flakes of skin and those flakes will have hyphae that can transmit the infection. Most fungi that can infect humans are very mild and the typical things you will get is allergies, skin diseases, localised infections.

Answer 58

yeast that can cause things thrush, can cause oral infection in babies. Pink eye.

Answer 59

the fungus here is living in dead material the outer layers of the skin and the outer layers of the toe nail. Because the fungus is secreting enzymes they diffuse through the tissue and you have an immune response in the proteins which causes the itching.

Answer 60

Most fungi dont have the ability to penetrate through the skin so infections tend not to happen very easily. But if the skin is damaged that has pushed a fungal spore under the skin then the fungus has got past your main barrier and into a nutrient rich environment. Providing that the fungus can cope with your body temperature, a few can, that fungus can then start growing and metabolising. You will have a white blood cell response and will engulf the fungal hyphae and will eventually eradicate it. More common to get in tropical areas.

Answer 61

biological control

Answer 62

Challenge with controlling fungal disease is that we are often dealing with a eukaryotic host, so it is harder to kill fungi than bacteria. Fungi are also very closely related to animals so having a drug that will kill the fungus and not you is also quite difficult.

Answer 63

 Many edible species:  Mushrooms, truffles etc  Cultivated mushrooms: Agaricus bisporus  Also processed foods made using fungi, either as a food or to process other foods

Answer 64

 Soy beans are rather indigestible  Ferment with Rhizopus oligosporus  Degrades Trypsin Protease Inhibitor-making the proteins more digestible for us  Degrades polysaccharides, reducing flatulence!  Alters fatty acid and lipid profile  Improves flavour

Answer 65

 Soy beans soaked and inoculated with Aspergillus sojae, A. awemori and A. oryzae.  Indigestible proteins degraded to release free amino acids, starches to sugars (more flavour)  Add salt, yeast, and lactic acid bacteria  Ferment for several years

Answer 66

 Yeast cannot degrade starch, so how do you get from starch to sugar to produce alcohol?  Rice is soaked then inoculated with Aspergillus oryzae or Aspergillus awemori  These fungi secrete amylase enzymes to degrade the starch  After 2-3 days, there is sufficient enzyme secreted to move on to yeast-based fermentation, flood the culture inhibiting filamentous fungi growth but enzymes still active and add yeast.

Answer 67

 Grow a microbe in liquid media  Needs a suitable container  What nutrient source  Aeration?  Contamination?  Alcohol production by Saccharomyces cerevisiae – anaerobic fermentation of glucose to give ethanol  Wines and Ciders from natural sugars in the ripe fruit.  Yeast cannot use starch so needs MALTING/MASHING for cereals – or another “pre-fermentation”

Answer 68

 Carbon source: corn steep liquor | Nitrogen source: ammonium

Answer 69

costs low but quality control is important

Answer 70

 Starter culture-lab grown  Plate → flask → small fermenter  Inoculate main fermenter and grow  Commence harvest when at desired density  Continuous culture for ~16 weeks–Add fresh media and harvest fungus at a dilution rate of 1 fermenter volume per 5-6 hours

Answer 71

```  Fungally produced toxins  Produced on cereals and oil-rich seeds  Non-transmissible, seasonal  Liver damage  Carcinogenic ```

Answer 72

```  Aspergillus flavus, A. parasiticus etc  Toxins Fluoresce under UV light  Occurs on cereals and peanuts  Present in milk and meat from animals fed on contaminated feeds  Highly Carcinogenic ```

Answer 73

 Aspergillus ochraceus, Penicillium verrucosum  Kidney and liver damage T2 toxin:  Fusarium sporotrichoides  Poisoned thousands in WW2 (1942/43) in Russia – unharvested crops

Answer 74

 Citric acid – Aspergillus niger 400,000 T pa  Vitamins and amino acid supplements: from various fungi e.g., riboflavin from Ashbya sp. Antibiotics:  Penicillin (Flemming 1928) Penicillium notatum, grown in shallow trays  Penicillium chrysogenum – submerged culture, NRRL 1951 from a mouldy canteloupe melon  Initially 2U/ml, now 70,000U/ml

Answer 75

 Cephalosporins: -lactam antibiotics from Cephalosporium acremonium  Cyclosporin: Immunosuppressant from Tolypocladium inflatum – an 11 aminoacid ring made from a gene of 48.5kb  Griseofulvin: antifungal from Penicillium griseofulvum – topical application only  Echinocandin: antifungal from Aspergillus sp., inhibitor of  1-3 glucan synthesis  “Statins”: anticholesterol drugs

Answer 76

 Amylases, glucanases, invertases– to get sugars from starches  Pectinases for clearing fruit juices  Proteases for washing powders  Rennets for vegetarian cheese  Hydrophobins for detergent additives  Medical proteins: insulin, factor VIII etc.

Answer 77

```  Most fungi are haploid – a single copy of each chromosome  Mutations show their phenotype  Excellent genetic models  Crosses  Transformation, Knockouts etc ```  Yeast: First eukaryote sequence (1996)  Full set of gene knockouts commercially available