ch 27
Overview of Protists
Seventh Week Discussion: Continuing with the study of protists, a diverse group of eukaryotic microorganisms.
Upcoming Quiz: Quiz on protist material from the book is scheduled for Sunday night.
Upcoming Lab: Live demonstrations of protists will be conducted in the lab, showcasing their unique movements and behaviors.
Eukaryotic Classification
Tree of Life: Divided into three domains: Bacteria, Archaea, and Eukaryotes.
Bacteria and Archaea: Simple, single-celled organisms.
Eukaryotes: Complex cells with compartments and organelles (e.g., nucleus, mitochondria).
Unique Characteristics: Eukaryotic cells are larger and have intricate shapes and structures, making their classification challenging.
Defining Protists
General Definition: Protists are eukaryotic organisms that are not classified as plants, animals, or fungi.
Characteristics:
Need for Water: Most protists require moist environments to live.
Diversity in Structure and Function: Includes various feeding methods and reproductive strategies.
Major Groups of Protists
1. Amorphians, Amoeboids, and Apicomplexa
Amoeboid Motion: Characterized by pseudopodia for movement (e.g., amoebas).
Interesting Life Cycles: Examples include slime molds that form slugs and engage in complex behaviors.
Apicomplexans: Notable for being parasites that can cause diseases in humans (e.g., Plasmodium causing malaria).
2. Archaeoplastida
Connection to Plants: These protists are the ancestral relatives to plants.
Algae Types: Includes red algae, green algae, which are essential for photosynthesis on Earth.
Carophytes: A type of green algae that contributes significantly to biofuel production.
3. SAR Group
Components: Incorporates Straminopiles, Alveolates, and Rhizarians.
Species Diversity: Contains a vast number of protist species with varied living styles and lifecycles.
A. Straminopiles
Morphological Features: Characterized by two flagella, primarily found in reproductive cells.
Subgroups:
Diatoms: Important photosynthetic organisms with silica cell walls, contributing significantly to ocean photosynthesis.
Oomycetes: Water molds that resemble fungi but belong to protists, exhibit fuzzy appearance.
B. Alveolates
Characteristics: Defined by the presence of alveoli (sac-like structures).
Subgroups: Includes dinoflagellates, ciliates, and apicomplexans.
Ciliates: Use cilia for movement, possess complex feeding mechanisms and multiple nuclei.
Dinoflagellates: Some are bioluminescent and can cause harmful algal blooms (red tides).
C. Rhizarians
Unique Features: Characterized by their amoeboid shape and typically have a hard outer shell called a test.
Formaminifera: Famous for their shells made of calcium carbonate, contribute to limestone formation.
4. Excavates
Characteristics: Often parasites lacking typical mitochondrial functions.
Subgroups:
Metamonads: Parasites like Giardia causing gastrointestinal infections.
Euglenozoids: Organelle-rich protists capable of photosynthesis or heterotrophy; includes Euglena.
Learning Challenges
Complexity of Classification: The sheer diversity and complexity of the protist groups make them challenging to study and categorize.
Learning Strategy: Consistent review and recall of protist characteristics and classifications is essential for navigating the upcoming exam topics.
Practice: Recommended to create study tools and engage with material frequently leading up to exams.
Preparation for Exam
Exam Format: Approximately one-third of the questions will relate to protists, with a focus on classifying them correctly into their respective groups.
Study Recommendations: Develop a study grid or flashcards to aid in memorization of protists and their characteristics, beneficial for both quizzes and the exam.