Lecture Notes: Evolution of Prokaryotic Domains

Introduction to Prokaryotic Domains

• First organisms on Earth from two prokaryotic domains.
• Likely sequence of evolution:
  • Domain Bacteria likely evolved first; DNA analysis supports this.
  • Domain Archaea and eukaryotes are closer relatives.
• Prokaryotes evolved around 3.5 billion years ago.

Characteristics of Prokaryotic Domains

• Initially grouped in Kingdom Monera due to shared features.
• General Characteristics:
  • Unicellular organisms; can grow in colonies.
  • No membrane-bound organelles; some have internal membranes.
  • Single circular chromosome.
  • Size ranges from 0.5 to 5 micrometers.

Differences Between Bacteria and Archaea

• Cell Wall Composition:
  • Both have cell walls, but compositions differ.
  • Domain Bacteria: Cell walls made of peptidoglycan (polysaccharides + polypeptides).
  • Domain Archaea: Diverse cell wall constructions.

Lecture Notes: Prokaryotic Organism Classification

Overview of Prokaryotic Species

• Over 6 million species identified; only about 10,000 cultured in labs.
• DNA differences are key in identification.
• An estimated 1 trillion prokaryotic species globally.

Classification Characteristics

• Shape:
  • Cocci: Spherical
  • Bacilli: Rod-shaped
  • Spirilla: Corkscrew

Gram Staining

• Developed by a Danish physician to identify bacterial infections.
• Stains peptidoglycan cell walls.
• Stain Colors:
  • Gram Positive: Dark purple
  • Gram Negative: Lighter pink

Differences in Gram Staining

• Gram Positive Bacteria:
  • Expose peptidoglycan cell wall to the environment.
• Gram Negative Bacteria:
  • Additional outer membrane inhibits staining.

Lecture on Prokaryotic Movement and Taxis

Introduction to Prokaryotic Movement

• Approximately half of prokaryotic species can move using flagella.

Mechanism of Flagella Movement

• Flagella move by spinning; anchored by an "axle and wheel".

Directionality and Environmental Influence

• Movement influenced by environmental heterogeneity.

Taxis: Movement Toward/Away from Stimuli

• Types of Taxis:
  • Chemotaxis: Response to chemical stimuli.
  • Phototaxis: Response to light stimuli.
  • Magnetotaxis: Response to magnetic fields.

Detailed Explanation of Magnetotaxis

• Detected through iron particles acting as a compass.

Prokaryotic External Characteristics and Classification

Importance of Adherence

• Adherence allows prokaryotes to remain in favorable environments.

Capsules and Slime Layers

• Allow adherence to surfaces; composed of proteins and polysaccharides.
• Capsules: More organized structure.
• Slime Layers: Less organized.

Fimbriae (or Pili)

• Short appendages for adherence; enhance survival and reproduction.

Lecture: Characteristics of Prokaryotes

Internal Structures of Prokaryotes

Internal Membranes

• Some prokaryotes have internal membrane structures similar to mitochondria or chloroplasts.

Energy Acquisition

• Photosynthesis and aerobic respiration methods.

Nucleoid Region

• Contains genetic material; functions include replication and RNA synthesis.

Plasmids

• Additional genes; beneficial in certain conditions like antibiotic resistance.

Survival Mechanisms

Endospores

• Resistant structures formed to survive harsh conditions.

Prokaryotic Nutritional Diversity

Introduction

• Prokaryotes can occupy diverse niches and use various energy sources.

Autotrophic Growth

• Autotrophs derive energy and carbon from non-organic sources.

Heterotrophic Growth

• Heterotrophs obtain carbon and energy from organic sources.

Lecture Notes on Systematics of Bacteria and Archaea

Introduction

• Biologists are subdividing Bacteria and Archaea into kingdoms.

Challenges in Classification

• Polytomies Present: Difficulty in discerning evolutionary history.
• Molecular Basis: Many described based on DNA sequences.

Ecological Roles of Prokaryotes

• Primary Producers: Base of the food web.
• Chemical Recycling: Key roles in recycling chemicals and decomposing matter.

Prokaryotes in New Eco Niches

• First to explore and exploit new niches post-extinction events.

Symbiotic Relationships for Prokaryotes

Definition of Symbiotic Relationships

• Types: Mutualistic, commensalistic, parasitic.

Examples of Symbiotic Relationships

Mutualistic Relationships

• Nitrogen Fixing Prokaryotes and Plants: Benefits both.

Commensalistic Relationships

• Bacteria and Pine Trees: Bacteria provide growth benefits to trees.

Pathogenic Prokaryotes

• Some bacteria cause diseases like gonorrhea and syphilis.

Antibiotic Resistance

• Misuse leads to resistance; judicious use needed.

Lecture Notes on Protists

Introduction to Protists

• Protists: Eukaryotic, non-multicellular organisms.
• No common evolutionary ancestry.

Characteristics of Protists

• Eukaryotic with membrane-bound organelles and complex cytoplasmic organization.

Diversity in Nutritional Methods

• Autotrophic Protists: Photosynthetic.
• Heterotrophic Protists: Decomposers and ingestive heterotrophs.
• Mixotrophic Protists: Photosynthesis with ingestion/absorption.

Reproductive Cycles

• Variation in reproductive strategies among Protists.

Excavates Lecture Notes

Overview of Excavates

• Supergroup characterized by:
  • Use of flagella.
  • Feeding groove on cell surface.
  • Modified mitochondria.

Subgroups of Excavates

Diplomonads

• Pair of haploid nuclei; multiple flagella.

Parabasalids

• Anaerobic symbiotic organisms.

Euglenozoans

Euglenids

• Freshwater, free-living; mixotrophic.

Kinetoplastids

• Parasitic species; notable parasite is Trypanosoma.

Lecture Notes on the SAR Supergroup

Overview

• SAR Supergroup: Stramenopiles, Alveolates, Rhizarians.

Endosymbiosis Events

• Stramenopiles and Alveolates: Secondary endosymbiosis of a red algae.
• Rhizarians: Lineage from secondary endosymbiosis of a green algae.

Group-Specific Details

Stramenopiles

• Multi-cell colonies with photosynthetic behavior.

Lecture Notes: Alveolates in the SAR Supergroup

Overview of Alveolates

• Apicomplexins, Dinoflagellates, Ciliates.

Dinoflagellates

• Habitat: Freshwater and marine.

Apicomplexans

• Nutritional method: Heterotrophic, primarily parasitic.

Ciliates

• Locomotion via cilia: Aid in feeding.

Lecture on Rhizarians in the SAR Supergroup

Overview of Rhizarians

• Unique clade with evolutionary developments.

Main Groups of Rhizarians

Foraminiferins (Forams)

• External shell-like covering; pseudopodia for movement and feeding.

Radularians

• Test of silica; uses pseudopodia for nutrition.

Lecture Notes: Archaeoplastids and Eukaryotic Multicellular Kingdom

Overview of Archaeoplastids

• Closest relatives of land plants.

Key Groups within Archaeoplastids

Red Algae

• Marine species with accessory pigment phycoerythrin.

Green Algae

• Chlorophytes and Charophytes; related to land plants.

Lecture Notes: Unicots, Amoebazoans, and Slime Molds

Overview of Unicots

Epistokonts

• Contains fungal and animal kingdoms.

Amoebazoans

• Lobe-shaped pseudopodia different from thin pseudopodia of rhizarians.

Slime Molds

• Cellular and acellular types; unique in reproduction.

Land Plants and their Ancestry

Common Ancestry with Chirophytes

• Evolutionary relationship to land plants.

Evolutionary Traits in Land Plants

• Derived traits: Alternation of generations, apical meristems.

Alternation of Generation in Plants

Overview

• Alternation in life cycle between sporophyte and gametophyte.

Evolutionary Adaptations in Land Plants

Roots

• Anchoring and nutrient mechanisms.

Vascular Tissues

• Transport of nutrients and water.

Evolution of Land Plants

Major Lineages

Non-vascular plants (Bryophytes)

• Lack vascular tissue.

Vascular plants (Tracheophytes)

• Evolved vascular tissue.

Drivers for Terrestrial Evolution

• Light and CO2 availability on land.

Nonvascular Plants: Liverworts, Hornworts, and Mosses

Overview

• Bryophytes, including liverworts, hornworts, and mosses.

Life Cycle Characteristics

• Gametophyte: Dominant phase producing gametes.

Vascular Plants Lecture Notes

Introduction to Vascular Tissue

• Includes xylem and phloem for growth.

True Roots and Leaves

• Vascular tissue allows for true roots and enhanced growth.

Lecture Notes: Seedless Vascular Plants - Lycophytes and Monilophytes

Overview

• Classified into Lycophytes and Monilophytes.

Ecological Impact

• Formed the first terrestrial forests.

Seed Plants and Their Evolutionary Significance

Introduction

• Seed plants include gymnosperms and angiosperms.

Mechanisms of Seed Plant Reproduction

• Pollen dispersal via wind or animals.

Lecture Notes: Male and Female Gametophyte Development

Overview

• Development lines for male and female gametophytes.

Lecture Notes: Seed Plant Divergence - Gymnosperms vs Angiosperms

Introduction to Seed Plant Groups

• Gymnosperms: Non-flowering.
• Angiosperms: Flowering plants dominant in ecosystems.

Differences in Seed Structure

• Gymnosperms: 'Naked seeds'.
• Angiosperms: Seed protected by fruit.

Characteristics of Gymnosperms

Major Groupings

• Conifers, Cycads, Ginkgos, Nidophytes.

Life Cycle of Gymnosperms

• Dominant sporophyte; fertilization forms diploid zygote.

Lecture Notes: Characteristics of Angiosperms

Competitive Advantages of Angiosperms

Reproductive Advantages

• Flowers improve reproductive success.

Physiological Advantages

• Broad leaves increase light capture.

Flower Structure and Function

• Composed of sepals, petals, stamens, carpels.

Seed Dispersal in Angiosperms

Types of Seed Dispersal Mechanisms

• Wind, mechanical, water, animal dispersal.

Pollination and Fertilization in Angiosperms

Overview

• Process of pollination and fertilization.

Double Fertilization

• Results in both a diploid zygote and triploid endosperm.

Angiosperm Lineages Overview

Four Major Angiosperm Lineages

• Basal Angiosperms, Magnoliids, Monocots, Eudicots.

Key Differences Between Monocots and Dicots

• Flower structure, leaf structure, vascular tissue, root system.

Implications for Plant Care

• Differences in care needs based on monocot or dicot classification.