Fungi

1. Fungi Mycology: The study of fungi

2. Aidhm • Define the terms: saprophytic & parasitic • Explain nutrition in fungi.

3. http://www.youtube.com/watch?v=5_rprVa-RY4 Starter sheet

4. Can you list out any features of fungi (use page 251) • They do not make their own food • They are mostly multi-cellular • They are made up of threads called hyphae • Hyphae combine in masses to form a mycelium • Their walls are made of a carbohydrate called chitin • They have mitochondria. • They store glycogen instead of starch

5. Nutrition • All fungi are heterotrophs Fungi are either: • Parasitic (used to control numbers of organisms in nature) • Saprophytic (used to recycle and decompose in nature)

6. Saprophytic fungi • Most fungi are saprophytic: obtain nutrients from dead material • As they digest it minerals are released and recycled • E.g. mushrooms and moulds

7. Parasitic Fungi • Parasitic: absorb their food from live hosts • E.g. athlete’s foot • Obligate parasites • live on live hosts but do not normally kill them • Facultative parasites • May kill the host and feed on the remains

8. Some fungi e.g. form symbiotic relationships with other organisms • A lichen is an organism which is a combination of a fungus and an alga

9. Can you…. • Define the terms: saprophytic & parasitic • Explain nutrition in fungi.

10. Learning Objectives • Mention that there are Edible and Poisonous fungi • Identify and state functions for the following structures: rhizoid, sporangium, gametangium, zygospore.

11. Edible and poisonous fungi • Some fungi are edible, but many are poisonous if eaten • Edibile: field mushrooms, truffles • Poisonous: Death cap fungi, the destroying angel

12. Some key words • A Haploid cell has one set of chromosomes, ie n=23 • A Diploid has two sets of chromosomes, 2n=46 • Mitosis is where a nucleus divides into 2 nuclei • Meoisis is where a nucleus divides into 4 nuclei

13. Rhizopus

14. Rhizopus growing on agar

15. Structure of Rhizopus

16. Consists of threadlike structures called Hyphae Hypha

17. Rhizopus • Saprophytic • Composed of hyphae and mycellium • Hyphae: Thread like structures (not divided into separate cells- aseptate). Digest and absorb substrate on which they grow. • Mycelium: mass of hyphae • Rhizoids: hyphae that grow into substrate. Penetrate, digest and absorb the food source. Secrete enzymes to break down food. • Stolons: horizontal hyphae which allow Rhizopus to spread sideways and find food. • Sporangiophores: Hold sporangium • Sporangium: produce spores • Columella: Base of sporangium. Feeds spores • Apophysis: swollen area of columella

18. Structure of Rhizopus

19. Sporangium Spores Columella: swelling below sporangium (feeds spores) Apophysis: wall at base of sporangium Sporangiophore

21. Complete in your copy

22. Can you…. • Mention that there are Edible and Poisonous fungi • Identify and state functions for the following structures: rhizoid, sporangium, gametangium, zygospore.

23. Learning Objectives • State the structure & life cycle of Rhizopus

24. Life cycle of Rhizopus

25. Asexual reproduction • Sporangiophores grow up from the substrate after a number of days • Cells within the sporangium divide by mitosis to produce haploid cells • These cells develop a resistant wall. These are spores.

26. Asexual reproduction • Spores dispersed by wind. If they land on suitable substrate they germinate into a new hypha and mycelium.

28. http://bcs.whfreeman.com/thelifewire8e/content/cat_010/30040.htmlhttp://bcs.whfreeman.com/thelifewire8e/content/cat_010/30040.html

29. Sexual reproduction + Strain - Strain • Sexual reproduction in Rhizopus can only occur between a plus and a minus strain.

30. Sexual reproduction + Strain - Strain 2. Hyphae from opposite strains grow close together. Swellings grow on both strains and touch each other.

31. Sexual reproduction + Strain - Strain • 3. Nuclei from both hyphae move into these swellings which are now called progametangia.

32. Sexual reproduction + Strain - Strain 4. Cross-walls form to produce gametangia.

33. Sexual reproduction + Strain - Strain 5. The walls of the gametangiadissolve and a number of fertilisations take place producing diploidzygote nuclei.

34. Sexual reproduction + Strain - Strain 6. A tough walled, zygospore forms around these nuclei. 7. When conditions are suitable the zygospore germinates by meiosis.

35. Sexual reproduction 8. A hypha grows out of the zygospore and produces a sporangium at the tip. 9. The sporangium opens releasing many haploid spores which grow into new individuals.

36. Remember • Gametangium: used for sexual reproduction • Zygospore: for dispersal

38. Put the pictures 1-4 in order and label parts A and B 1 2 3 4

39. Can you…. • State the structure & life cycle of Rhizopus

40. Learning Objectives • Outline the structure & reproduction of Yeast • Name 2 Beneficial & 2 Harmful fungi

41. Yeast

42. Structure of yeast:Single celled • Cell wall: made of chitin • Lots of storage granules – cytoplasm appears granular.

43. Can you label this

44. Reproduction by budding in Yeast 1. A small bubble grows out from the cell wall and fills with cytoplasm 2. Divides by mitosis 3. One nucleus moves into bud 4. Bud pinches off mother cell

45. Sometimes this can happen….

46. Budding

47. Budding

48. Economic importance of fungi Beneficial fungi • Yeasts: production of alcohol (brewing) in anaerobic (no oxygen) conditions • Fungi: used as a source of food e.g. mushroom

49. Economic importance of fungi Harmful fungi • Fungi: cause crop disease e.g. potato blight • Fungi: food spoilage e.g. rhizopus grows on bread

50. Practical Activities: Investigate the growth of leaf yeasts using agar plates and controls Aseptic: Exclude unwanted organisms Sterile: All microorganisms destroyed.