Bio Exam 2 Flashcards
- History of Protist Phylogeny
Organism that do not fit into any categories (plant animal fungi)
studies have now placed them across multiple eukaryotic supergroups, showing they are not a single monophyletic group but rather a paraphyletic one, containing diverse lineages with complex evolutionary histories.
Major Differences Between Prokaryotes and Eukaryotes
Prokaryotes lack membrane-bound organelles, while eukaryotes contain organelles like nuclei, mitochondria, and chloroplasts.
Genetic Material: Prokaryotes do not have nucleus
Cell Size and Complexity: Eukaryotic cells are typically larger and more complex than prokaryotic cells.
Endosymbiosis in Eukaryotic Evolution
Mitochondria came first
After the heterotrophic eukaryotes engulfed cyanobacteria so they could photosynthesis
secondary is when these new photosynthesis eukaryote were engulfed by the heterotrophic eukaryotes
Diversity among protist
Can reproduce asexually or sexually
Nutritional Modes: Protists can be autotrophic, heterotrophic, or mixotrophic (capable of both autotrophy and heterotrophy).
Most or unicellular but can be in colonies
Life Cycles: Protist life cycles vary, with some being predominantly haploid, others diploid, and some alternating between these stages
- Life Cycles: Diplontic, Haplontic, and Diplohaplontic
Haploid: A cell or organism has one set of chromosomes.
Diploid: A cell or organism has two sets of chromosomes.
Mitosis and Meiosis: Mitosis results in identical cells, while meiosis produces haploid gametes.
Diplontic Life Cycle: The organism spends most of its life in the diploid stage (e.g., animals).
Haplontic Life Cycle: The organism spends most of its life in the haploid stage, and the only diploid cell is the zygote (e.g., many fungi and some algae).
Diplohaplontic Life Cycle: Alternation between multicellular haploid (gametophyte) and diploid (sporophyte) stages, common in plants and some algae.
- Four Major Eukaryotic Supergroups
Excavata: Characterized by unique flagellar structures; includes organisms like Euglena and Trypanosoma.
SAR (Stramenopiles, Alveolates, Rhizarians): Stramenopiles have hairy flagella (e.g., diatoms), Alveolates have alveoli beneath their cell membranes (e.g., Plasmodium), and Rhizarians are amoeboid with filamen
tous pseudopodia (e.g., foraminiferans).
Archaeplastida: Includes red algae, green algae, and plants, characterized by primary plastids from primary endosymbiosis.
Unikonta: Defined by a single posterior flagellum, includes fungi, animals, and related protists like Choanoflagellates.
Protists can be parasitic or mutualistic
Protists can engage in mutualistic or parasitic relationships. Example: Trichonympha lives in the guts of termites and helps digest cellulose, a mutualistic relationship. Plasmodium, on the other hand, is parasitic and causes malaria in humans
Protists as Primary Producers and Their Ecological Impact
Many protists, particularly photosynthetic ones like phytoplankton, are primary producers in aquatic ecosystems, forming the base of the food web. Their presence supports a wide array of marine life and contributes significantly to global carbon cycling and oxygen production
Plastid Organelle
Allow prokaryote to photosynthesis
Benefits of living on land and some challenges. How it helps other organism
better light,access to oxygen, CO2, Soil is rich in nutrients. Challenges Desiccation (waterloss)
Plant provides food to other organism, plant supply oxygen, habitat
Closest living clade to plant
Algae, they also contain chloroplasm - Charophytes in the supergroup Archaeoplastids
Sporopollenin
Durable layer that protects zygotes algae to dry out (also found in spores and pollen to protect from drying out)
5 key derived traits
Alternation of Generation
Multicellular, dependent embryos
Spores in the Sporangia
Multicellular gametangia
Apical Meristems
Name the Haploid Spores Specialized Organs
Sporangia
