Endosymbiotic Hypothesis and Eukaryotic Cells
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Endosymbiotic Hypothesis and Eukaryotic Cells

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Questions and Answers

What type of chromosomes are present in the mitochondria of Saccharomyces cerevisiae?

  • No chromosomes
  • Linear chromosomes
  • Fragmented chromosomes
  • Circular chromosomes (correct)

    • The hypothesis of endosymbiosis suggests that eukaryotic nuclei contain genes derived from archaea.

    False

    Name the two subunits of eukaryotic ribosomes.

    40s and 60s

    The first cells to appear on Earth were __________.

    <p>prokaryotes</p> Signup and view all the answers

    Match the type of ribosome with its classification:

    <p>Eukaryotic ribosome = 40s and 60s Prokaryotic ribosome = 30s and 50s Bacterial ribosome = 70s Mitochondrial ribosome = Varies from 40s to 70s</p> Signup and view all the answers

    Which of the following does tigecycline inhibit?

    <p>Bacterial protein translation</p> Signup and view all the answers

    The transition of prokaryotic to eukaryotic cells involved the discovery of asexual reproduction.

    <p>False</p> Signup and view all the answers

    What is the main function of the mitochondria in eukaryotic cells?

    <p>Energy production</p> Signup and view all the answers

    What is the primary function of tigecycline as described in the context?

    <p>Targeting human 55S mitoribosomes</p> Signup and view all the answers

    Tigecycline binds to human 80S ribosomes at physiological concentrations.

    <p>False</p> Signup and view all the answers

    What are the two types of endosymbiosis discussed?

    <p>Primary and Secondary Endosymbiosis</p> Signup and view all the answers

    The last eukaryotic common ancestor (LECA) is a key concept in understanding ________.

    <p>Eucariogenesis</p> Signup and view all the answers

    Match the following concepts with their descriptions:

    <p>Primary Endosymbiosis = Origin of mitochondria and chloroplasts within eukaryotic cells Secondary Endosymbiosis = Incorporation of chloroplasts from other species LECA = Last eukaryotic common ancestor Eucariogenesis = Evolution of eukaryotic cells from prokaryotic predecessors</p> Signup and view all the answers

    Which of the following organisms are included in the secondary endosymbiosis?

    <p>Dinoflagellates</p> Signup and view all the answers

    The divergence of red and green algae indicates they share a common ancestor.

    <p>False</p> Signup and view all the answers

    Name the two major hypotheses discussed about the origin of eukaryotes.

    <p>Endosymbiotic Hypothesis and Eucariogenesis</p> Signup and view all the answers

    What type of organism is Giardia intestinalis?

    <p>Diplomonad</p> Signup and view all the answers

    Trichomonas vaginalis is a disease caused by a waterborne infection.

    <p>False</p> Signup and view all the answers

    Name one characteristic of Parabasalids.

    <p>Presence of a parabasal body</p> Signup and view all the answers

    The _____ is responsible for the mobility of Trichomonas.

    <p>flagella</p> Signup and view all the answers

    Match the following groups with their correct descriptions:

    <p>Diplomonads = Two equal-sized nuclei Parabasalids = Support the Golgi complex Cinetoplastids = Aquatic environments and some pathogens Euglena = Photosynthetic or chemotrophic</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Euglena?

    <p>Pathogenic</p> Signup and view all the answers

    All dinoflagellates are non-toxic and safe for marine life.

    <p>False</p> Signup and view all the answers

    Which of the following is a characteristic of ciliates?

    <p>The presence of cilia for movement and feeding</p> Signup and view all the answers

    What is the primary role of alveoli in alveolates?

    <p>Their function is unknown but may help maintain osmotic balance.</p> Signup and view all the answers

    Toxoplasma and Eimeria are classified as dinoflagellates.

    <p>False</p> Signup and view all the answers

    What is the function of the micronucleus in Paramecium?

    <p>Genetic recombination</p> Signup and view all the answers

    Dinoflagellates are known to produce _____ that can be highly toxic.

    <p>neurotoxins</p> Signup and view all the answers

    Match the following groups with their characteristics:

    <p>Ciliates = Use cilia for movement and feeding Dinoflagellates = Produce neurotoxins and can cause red tides Apicomplexans = Obligate parasites of animals Stramenopiles = Include both photosynthetic and chemosynthetic microorganisms</p> Signup and view all the answers

    Which of the following are included in the Stramenopiles group?

    <p>All of the above</p> Signup and view all the answers

    Apicomplexans have chloroplasts that are fully functional.

    <p>False</p> Signup and view all the answers

    What is an example of a ciliate mentioned in the content?

    <p>Balantidium coli</p> Signup and view all the answers

    Which of the following is a characteristic of Gimnamebas?

    <p>They utilize pseudopodia for movement.</p> Signup and view all the answers

    Entamoeba histolytica is known for its role as a free-living protist.

    <p>False</p> Signup and view all the answers

    What do mucilaginous fungi produce for reproduction?

    <p>Spores</p> Signup and view all the answers

    The color of red algae is primarily due to the presence of __________.

    <p>phycoerythrin</p> Signup and view all the answers

    Match the following algae with their characteristics:

    <p>Red algae = Contain phycoerythrin, lack flagella Green algae = Have chloroplasts with chlorophyll a and b Cyanidium = Unicellular red algal species Chara = Macroscopic green algal species</p> Signup and view all the answers

    Which of the following is NOT a type of amoebozoan?

    <p>Polysiphonia</p> Signup and view all the answers

    All green algae are unicellular.

    <p>False</p> Signup and view all the answers

    Name one characteristic that distinguishes mucilaginous fungi from other fungi.

    <p>They can move on solid surfaces.</p> Signup and view all the answers

    Study Notes

    Origin of Eukaryotic Cells

    • The first cells that appeared were prokaryotes (before the nucleus).
    • Originated 1500 to 2000 million years ago.
    • Evolutionary transition involved morphological complexity, incorporating genomes, discovering sexual reproduction, and leading to multicellular organisms.

    Endosymbiotic Hypothesis

    • The eukaryotic nucleus contains genes derived from bacteria.
    • Ribosomes, organelles and their phylogeny suggest a shared origin with prokaryotic ribosomes.
    • Antibiotic specificity supports the theory.

    Endosymbiotic Hypothesis: Antibiotic Specificity

    • Tigecycline is an antibiotic used to treat bacterial infections.
    • It inhibits bacterial protein translation by blocking the ribosomal A-site.
    • While cytotoxic to human cells, its mechanism of inhibition is unclear.

    Endosymbiotic Hypothesis: Hidrogenosomas

    • Phylogenetic analyses associate them with prokaryotes.

    Primary and Secondary Endosymbiosis

    • Primary Endosymbiosis: A cell of Eukarya acquires a mitochondrion and a nucleus.
    • Secondary Endosymbiosis: A cell from a cyanobacterial lineage of Bacteria acquires a chloroplast from red algae, leading to:
      • Dinoflagellates
      • Apicomplexans
      • Stramenopiles.
    • A cell from a green algae lineage acquires a chloroplast from green algae leading to:
      • Green Algae
      • Euglenida
      • Chlorarachniophytes.

    Eucariogenesis

    • Eukaryotes originated from a prokaryotic ancestor.
    • LECA (Last Eukaryotic Common Ancestor) is a key point in eukaryotic evolution.
    • Debates on the origin of LECA from Bacteria or Archea.
    • Monophyletic origin of Eukaryotes.

    Eucariogenesis: Phylogeny

    • A comparison of 3D and 2D phylogenetic trees shows the relationship between Bacteria, Archaea, and Eukarya.

    Diplomonads and Parabasalids

    • Diplomonads:
      • Two nuclei of the same size.
      • Mitosomes.
      • Compact genome with few introns.
      • Giardia intestinalis causes diarrheal disease transmitted through water.
    • Parabasalids:
      • Parabasal body supporting the Golgi complex.
      • Hidrogenosomas.
      • Found in the gastrointestinal and urogenital tracts.
      • Trichomonas vaginalis is a sexually transmitted disease.

    Trichomonas

    • Trichomonas is a flagellated protozoan with a parabasal body and hidrogenosomas.
    • It's a human pathogen that causes sexually transmitted infections.

    Euglenozoa

    • A diverse group of unicellular flagellated eukaryotes.
    • They can be free-living or parasitic.
    • Some are pathogenic and have a kinetoplast (DNA in the unique mitochondrion).
    • Euglenids are mobile, non-pathogenic, and phototrophic or chemotrophic.

    Euglenozoa: Kinetoplastids and Euglenids

    • Kinetoplastids:
      • Kinetoplast.
      • Unique mitochondrion.
      • Aquatic environments. Some are pathogenic (e.g., Trypanosoma brucei, T. cruzi, Leishmania).
    • Euglenids:
      • Non-pathogenic.
      • Chemo- or phototrophic.
      • Found in freshwater or saltwater environments.
      • Phagotrophic (feeding on bacteria by phagocytosis).

    Alveolates

    • Characterized by alveoli, cytoplasmic sacs below the plasma membrane.
    • Alveoli may help maintain osmotic balance.
    • Three main groups:
      • Ciliates (e.g., Paramecium)
      • Dinoflagellates (photosynthetic, some toxic; e.g., Gonyaulax - red tide)
      • Apicomplexans (e.g., Toxoplasma, Plasmodium, Eimeria).

    Alveolates: Ciliates, Dinoflagellates and Apicomplexans

    • Ciliates:
      • Have cilia at some point.
      • Use them for movement and feeding.
      • Have a food vacuole.
      • Micronucleus for genetic recombination.
      • Macronucleus for basic cell functions.
      • Examples: Balantidium coli, Paramecium
    • Dinoflagellates:
      • Phototrophic freshwater organisms.
      • Secondary endosymbiosis.
      • Flagella with spinning motion.
      • Free-living or symbiotic.
      • Some produce neurotoxins (e.g., Gonyaulax, Pfiesteria).
    • Apicomplexans:
      • Non-phototrophic.
      • Obligate parasites of animals.
      • Produce sporozoites, the transmission stage of the parasite.
      • Apicomplexan refers to their specialized organelles at the sporozoite's end.
      • Degenerate chloroplasts (fatty acids, isoprenoids, heme group).
      • Examples: Plasmodium, Toxoplasma, Eimeria (coccidia).

    Paramecium

    • Micronuclei function in genetic recombination.
    • The macronucleus controls cellular activities.
    • Specialized cellular structures: Contractile vacuole, Anal pore, Pellicle, Oral groove, Digestive vacuole, Trichocyst, Fibrils, Alveolus, Cilium, Cilia, Alveoli.

    Stamenopiles

    • 'Stramen' refers to the straw-like hairs (pili) on their flagella.
    • Includes chemotrophs (heterotrophs) and phototrophs (autotrophs), from micro- to macro- organisms.

    Stamenopiles: Diatoms, Oomycetes, Crisophytes and Brown Algae

    • Diatoms:
      • Unicellular, photosynthetic.
    • Oomycetes:
      • Aquatic fungi.
      • Filamentous and coenocytic (multinucleate) growth.
    • Crisophytes:
      • Chrysophytes or golden-brown algae.
    • Brown Algae:
      • Large and multicellular.

    Amoebozoa

    • Gymnamoebas:
      • Free-living protozoa.
      • Use pseudopods (false feet) for movement (e.g., Amoeba)
    • Entamoebas:
      • Parasites of vertebrates and invertebrates.
      • Found in the oral cavity or gastrointestinal tract.
      • Entamoeba histolytica is a human parasite.
    • Slime Molds:
      • Form fruiting bodies with spores.
      • Mobile, moving over solid surfaces.
      • Two types:
        • Plasmodial (multinucleate)
        • Cellular (individual cells)

    Amoebozoa: Amoeba, Slime Molds and Entamoeba

    • Amoeba
    • Slime Molds
    • Entamoeba

    Red and Green Algae: General Properties

    • Photosynthetic.
    • Contain chlorophyll a.
    • Red algae:
      • Do not have chlorophyll b.
      • Contain phycobiliproteins, giving them a reddish color due to phycoerythrin.
      • Lack flagella.
      • Used in agar and sushi production.
      • Some live acid hot springs.
    • Green algae:
      • Have chlorophyll a and b, giving their characteristic green color.
      • Closely related to plants.
      • Unicellular (e.g., Chlamydomonas, Dunaliella, Ostrococcus tauri) or macroscopic (e.g., Chara, Volvox).

    Red and Green Algae: Organisms

    • Red algae:
      • Polysiphonia
      • Cyanidium
      • Galdiera
    • Green algae:
      • Chlamydomona
      • Dunaliella
      • Ostrococcus tauri
      • Chara
      • Volvox

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    Eukaryotic Cells: Assembling the Cell PDF

    Description

    Explore the origin of eukaryotic cells and the endosymbiotic hypothesis in this quiz. Learn about the evolutionary transition from prokaryotes to complex multicellular organisms and how antibiotic specificity supports this theory. Delve into the significance of ribosomes and organelles in understanding cellular evolution.

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