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The History of Eukaryotes

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Presentation on theme: "The History of Eukaryotes"— Presentation transcript:

1 The History of Eukaryotes
Eukaryotic Cells The History of Eukaryotes They first appeared approximately 2 billion years ago. Evidence suggests evolution from prokaryotic organisms by symbiosis. Organelles originated from procaryotic cells trapped inside them. -> Endosymbiosis

2 Endosymbiosis Algae

3 Eukaryotic Organisms in Microbiology
Eukaryotic Cells Eukaryotic Organisms in Microbiology

4 Form and Function of the Eukaryotic Cell
Eukaryotic Cells Form and Function of the Eukaryotic Cell

5 Form and Function of the Eukaryotic Cell
Eukaryotic Cells Form and Function of the Eukaryotic Cell

6 Eukaryotic Cells External Structures Locomotor appendages Flagella
Cross section -> arrangement of proteins Locomotor appendages Flagella -> long, sheathed cylinder containing microtubules in a 9+2 arrangement -> covered by an extension of the cell membrane -> 10X thicker than prokaryotic flagella -> function in motility Longitudinal section Locomotor pattern

7 Eukaryotic Cells External Structures Locomotor appendages Cilia
-> similar in overall structure to flagella, but shorter and more numerous -> found only on a single group of protozoa and certain animal cells -> function in motility, feeding and filtering Structure Locomotion

8 Eukaryotic Cells External Structures Glycocalyx
an outermost boundary that comes into direct contact with environment - usually composed of polysaccharides - appears as a network of fibers, a slime layer or a capsule - functions in adherence, protection, and signal reception - beneath the glycocalyx -> Fungi and most algae have a thick, rigid cell wall. -> Protozoa, a few algae, and all animal cells lack a cell wall and have only a membrane.

9 External Boundary Structures
Eukaryotic Cells External Boundary Structures Cell wall rigid, provides structural support and shape > Fungi have thick inner layer of polysaccharide fibers composed of chitin or cellulose and a thin layer of mixed glycans. > algae – varies in chemical composition; substances commonly found include cellulose, pectin, mannans, silicon dioxide, and calcium carbonate

10 External Boundary Structures
Eukaryotic Cells External Boundary Structures Cytoplasmic (cell) membrane typical bilayer of phospholipids and proteins sterols confer stability serves as selectively permeable barrier in transport Eucaryotic cells also contain membrane-bound organelles that account for 60-80% of their volume.

11 Eukaryotic Cells Internal Structures

12 Eukaryotic Cells Internal Structures Nucleus
compact sphere, most prominent organelle of eukaryotic cell nuclear envelope composed of two parallel membranes separated by a narrow space and is perforated with pores - contains chromosomes nucleolus – dark area for rRNA synthesis and ribosome assembly

13 Eukaryotic Cells Internal Structures Nucleus Cell division
-> Mitosis Replication of Chromosomes Separation of replicated Chromosomes into 2 cells

14 Eukaryotic Cells Internal Structures
Endoplasmic reticulum – two types: Rough endoplasmic reticulum (RER)– originates from the outer membrane of the nuclear envelop and extends in a continuous network through cytoplasm; rough due to ribosomes; proteins synthesized and shunted into the ER for packaging and transport; first step in secretory pathway Smooth endoplasmic reticulum (SER)– closed tubular network without ribosomes; functions in nutrient processing, synthesis and storage of lipids, etc. Rough Endoplasmic reticulum

15 Eukaryotic Cells Internal Structures Golgi apparatus
consists of a stack of flattened sacs called cisternae closely associated with ER Transitional vesicles from the ER containing proteins go to the Golgi apparatus for modification and maturation. Condensing vesicles transport proteins to organelles or secretory proteins to the outside. -> The secretary pathway

16 Eukaryotic Cells Internal Structures Lysosomes
> vesicles containing enzymes that originate from Golgi apparatus used for breaking down material -> Trash bin of the cell !!! > involved in intracellular digestion of food particles and in protection against invading microbes (Phagocytosis) and absorbing any material (molecules) from outside (Endocytosis)

17 Eukaryotic Cells Internal Structures Mitochondria
consists of an outer membrane and an inner membrane with folds called cristae - Cristae hold the enzymes and electron carriers of aerobic respiration. - divide independently of cell - contain DNA and procaryotic ribosomes - function in energy production

18 Eukaryotic Cells Internal Structures Chloroplast
found in algae and plant cells outer membrane covers inner membrane folded into sacs, thylakoids, stacked into grana larger than mitochondria contain photosynthetic pigments convert the energy of sunlight into chemical energy through photosynthesis - primary producers of organic nutrients for other organisms

19 Eukaryotic Cells Internal Structures Ribosomes
composed of rRNA and proteins 40S and 60S subunits form 80S ribosomes larger than procaryotic ribosomes (70S) - function in protein synthesis 30S 50S 70S

20 Eukaryotic Cells Internal Structures Cytoskeleton
flexible framework of proteins -> microfilaments and microtubules form network throughout cytoplasm involved in movement of cytoplasm, amoeboid movement (motility), transport, and structural support

21 Eukaryotic Cells Eukaryotic Microbes -> Fungi -> Algae
-> Protozoa -> Parasitic worms

22 Eukaryotic Cells Kingdom Fungi 100,000 species divided into 2 groups:
-> macroscopic fungi (mushrooms, puffballs, gill fungi) -> microscopic fungi (molds, yeasts) Majority are unicellular or colonial; a few have cellular specialization

23 Microscopic fungi Slime mold Yeast

24 Macroscopic fungi

25 Eukaryotic Cells Microscopic fungi Exist in two morphologies:
-> yeast – round ovoid shape, asexual reproduction, unicellular -> hyphae – long filamentous fungi or molds Some exist in either form – dimorphic: mold-like at low temperature, yeast like at 37 degrees C, characteristic of some pathogenic molds

26 Macroscopic and Microscopic view – Molds/fungi
Eukaryotic Cells Macroscopic and Microscopic view – Molds/fungi Mixed cultures of mold Hyphal structures Structural types of hyphae

27 Macroscopic and Microscopic view - Yeast
Eukaryotic Cells Macroscopic and Microscopic view - Yeast Morphology of yeast

28 Eukaryotic Cells Fungal Nutrition
Mycellium growing on raspberries Fungal Nutrition -> All are heterotrophic (org. Carbon Source) -> Majority are harmless saprobes living off dead plants and animals -> Some are parasites, living on the tissues of other organisms, mycoses – fungal infections -> Growth temperature 20o-40oC -> Extremely widespread distribution in many habitats Fungus growing on skin

29 Eukaryotic Cells Fungal Organization
-> Most grow in loose associations or colonies -> Yeast – soft, uniform texture and appearance -> Filamentous fungi – mass of hyphae called mycelium; cottony, hairy, or velvety texture - hyphae may be divided by cross walls – septate - vegetative hyphae – digest and absorb nutrients - reproductive hyphae – produce spores for reproduction

30 Eukaryotic Cells Fungal Organization

31 Fungal Reproduction - Asexual
Eukaryotic Cells Fungal Reproduction - Asexual -> All Fungi have asexual reproduction !!! -> Primarily through spores formed on reproductive hyphae -> Asexual reproduction – spores are formed through budding or mitosis; conidia or sporangiospores

32 Fungal Reproduction - Sexual
Eukaryotic Cells Fungal Reproduction - Sexual -> Sexual reproduction – spores are formed following fusion of male and female strains and formation of sexual structure -> Sexual spores and spore-forming structures are one basis for classification.

33 Fungal Reproduction – sexual
Eukaryotic Cells Fungal Reproduction – sexual -> Zygospores– diploid spores (2n) are formed following fusion of male and female strains zygospore germinates -> meiosis occurs -> haploid vegetative cells are released. -> Ascospores – haploid spores (n), formed following fusion of male and female strains in fungal sac -> ascus zygote (fused) cells undergo meiosis -> formation of haploid spores

34 Fungal Reproduction – sexual
Eukaryotic Cells Fungal Reproduction – sexual -> Ascospores in a fruit body Ascomycetes -> Penicillium

35 Fungal Reproduction – sexual
Eukaryotic Cells Fungal Reproduction – sexual -> Basidiospores – haploid sexual spores in a fruit body Basidiomycetes Fruit body

36 Fungal Classification
Eukaryotic Cells Fungal Classification Subkingdom Amastigomycota – terrestrial -> inhabitants including those of medical importance: Fungi perfecti (sexual + asexual spores): -> Zygomycota – zygospores; sporangiospores and some conidia -> Ascomycota – ascospores; conidia -> Basidiomycota – basidiospores; conidia Fungi imperfecti (just asexual cycle know until now): -> Deuteromycota – majority are yeasts and molds; no sexual spores known; conidia

37 Eukaryotic Cells Roles of Fungi -> Adverse impact
- mycoses, allergies, toxin production destruction of crops and food storages -> Beneficial impact - decomposers of dead plants and animals - sources of antibiotics, alcohol, organic acids, vitamins - used in making foods and in genetic studies

38 Eukaryotic Cells Roles of Fungi

39 Eukaryotic Cells Kingdom Protista -> Algae -> Protozoa Ameba
Diatoms -> silica cell wall

40 Eukaryotic Cells Kingdom Protista Algae -> Photosynthetic organisms
-> Contain chloroplasts with chlorophyll and other pigments -> Produce large proportion of atmospheric O2 -> Most are free-living in fresh and marine water – plankton. -> Provide basis of food web in most aquatic habitats -> Classified according to types of pigments and cell wall -> Kelps, seaweeds, euglenids, green algae, diatoms, dinoflagellates, brown algae, and red seaweeds -> Dinoflagellates can cause red tides and give off toxins that cause food poisoning with neurological symptoms. -> Used for cosmetics, food, and medical products

41 Eukaryotic Cells Kingdom Protista Protozoa -> 65,000 species
-> Vary in shape, lack a cell wall -> Most are unicellular; colonies are rare -> Feed by engulfing other microbes and organic matter -> Most have locomotor structures – flagella, cilia. -> Many can enter into a resting stage when conditions are unfavorable for growth and feeding – cyst. -> Most are harmless, some are animal parasites Pathogen Protozoa -> Malaria (Plasmodium falciparum/vivax/ovale/malariae), Toxoplasmosis (Toxoplasma gondii)

42 Eukaryotic Cells Kingdom Protista Cycle of Infection - Protozoa

43 Parasitic Helminths (Worms)
Eukaryotic Cells Parasitic Helminths (Worms) -> 50 species parasitize humans. -> Acquired though ingestion of larvae or eggs in food; from soil or water; some are carried by insect vectors -> Multicellular animals, organs for reproduction, digestion, movement, protection Major Groups: 1. Flatworms 2. Roundworms

44 Parasitic Helminths (Worms)
Eukaryotic Cells Parasitic Helminths (Worms) Life cycle of roundworms

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