Lecture 14. Euglena - an Example of a Single- Celled Autotrophic Protist

Transcription

1 Lecture 14 Euglena - an Example of a Single- Celled Autotrophic Protist

2 Overview of Lecture 14 Nutrition Basic Structure Light Detection and Phototaxis Locomotion Exchanging Materials Osmoregulation

3 Nutrition Most Euglena are autotrophs? Carry out photosynthesis Contain chloroplasts

4 Nutrition heterotroph Absorbs organic molecules mixotrophic

5 Basic Structure Nucleus - largest organelle Contain chloroplasts

6 Basic Structure Contractile vacuole Two flagella tiny hair-like structures

7 Basic Structure Outermost layer is a plasma membrane pellicle

8 Light Detection and Phototaxis Light detector Phototaxis

9 Euglena moves by three types of locomotion Swimming Gliding Euglenoid movement

10 Swimming flagellum undulates Pulling the euglena Hairs (increases the surface area, steering)

11 Exchange of Materials with its environment Purpose Cell membrane

12 Exchange of Materials with its environment E.g. oxygen for cellular respiration The waste product carbon dioxide released by diffusion O2 CO2

13 Exchange of Materials with its environment Ammonia waste product of protein breakdown diffuses out at the surface of the plasma membrane NH4

14 Osmoregulation Most live in freshwater Hypertonic contractile vacuole H2O

15 Osmoregulation Rate is influenced both by temperature and the tonicity Not active transport Caused by contraction of microfilaments

16 Lecture 15 Laminaria : A Representative Autotrophic Multicellular Alga

17 Overview of Lecture Division of labour and Specialization Body form of Laminaria Life cycle of Laminaria

18 Greatest Specialization occurs in Brown Algae Body form (blade, stipe and holdfast) Brown algae have transport cells Blade Photosynthetic cells on blade Stipe Holdfast

19 Significance of Cell Wall Unlike Euglena, Laminaria has a cellulose cell wall Prevents the cell membrane from bursting in hypotonic conditions Lives in shallow water

20 Classification of Laminaria Clade Stramenopila Brown alga (phaeophyta)

21 Classification of Laminaria Stramenopila have hairy flagella on flagellated stages

22 Reproduction and Life Cycle of Laminaria Alternation of generation Sporophyte Gametophyte

23 Reproduction and Life Cycle of Laminaria Two multicellular stages in their life cycle Multicellular Sporophyte Multicellular Gametophyte

24 Multicellular Gametophyte (haploid) Reproduction and Life Cycle of Laminaria Differ in ploidy Multicellular Sporophyte (diploid)

25 Ploidy refers to the number of chromosomes in the nucleus Diploid means two complete sets of chromosomes (2n) Haploid means only one complete set of chromosomes (n) Gametophyte has only half the number of chromosomes of the sporophyte

26 Laminaria is heteromorphic Sporophyte and gametophyte are different in appearance Sporophyte Gametophyte

27 Laminaria is heteromorphic In plants sporophyte and gametophyte are also dissimilar

28 Multicellular Gametophyte (haploid) The stages are named according to their reproductive products Gametophyte produces gametes Multicellular Sporophyte (diploid) Gametes

29 Multicellular Gametophyte (haploid) The stages are named according to their reproductive products Sporophyte produces spores Multicellular Sporophyte (diploid) Spores

30 The stages are named according to their reproductive products Both male gametes and spores are flagellated Their flagellated spores are called zoospores (unusual)

31 Two differing types of cell division produce spores and gametes Mitosis produces daughter cells that have the same number of chromosomes as mother cell 2N 2N 2N

32 Two differing types of cell division produce spores and gametes Meiosis produces daughter cells that have half number of chromosomes as mother cell 2N N N N N N N

33 Mitosis and Meiosis Mitosis: 2n 2n or Mitosis: n n Meiosis: 2n n

34 Mitosis or Meiosis? Spores and gametes are both haploid Haploid gametophyte produces haploid gametes by Diploid sporophyte produces haploid spores by Growth occurs by

35 Mitosis or Meiosis? Spores and gametes are both haploid Haploid gametophyte produces haploid gametes by Mitosis Diploid sporophyte produces haploid spores by Meiosis Growth occurs by Mitosis

36 Life Cycle Spores are released by sporophyte Spores (zoospores)

37 Life Cycle Spores grow by mitosis into a multicellular gametophyte

38 Life Cycle Sporophyte meiosis spores released grow by mitosis gametophyte

39 Life Cycle Gametes are produced in gametangia of gametophyte

40 Life Cycle Sperm released into the sea Sperm swim to egg in female gametophyte Unite to form diploid zygote (syngamy)

41 Life Cycle Zygote grows by mitosis into a multicellular sporophyte

42 Life Cycle Gametophyte mitosis gametes sperm released syngamy zygote grow by mitosis sporophyte

43 Insert mitosis into life cycle