Prokaryotes and Eukaryotes Quiz

Prokaryotes vs. Eukaryotes

• Prokaryotes:
  • Cell walls typically contain peptidoglycan.
  • Nuclear division occurs without a nuclear membrane.
  • Chromosome is not enclosed in a membrane.
  • Asexual reproduction is common; sexual reproduction (in some bacteria).
  • Flagella, when present, lack a 9+2 structure.
  • Some can fix nitrogen (e.g., bacteria and blue-green algae).
• Eukaryotes:
  • Cell walls lack peptidoglycan.
  • Nuclear division usually occurs via mitosis or meiosis.
  • Chromosomes are enclosed within a nuclear membrane.
  • Sexual reproduction is common.
  • Flagella, when present, have a characteristic 9 + 2 structure (9 outer and 2 inner).
  • Most cannot fix nitrogen (e.g., all other plants and animals).

Algae Characteristics

• Algae diversity ranges from tiny unicellular microalgae to large seaweeds.
• Algae are photosynthetic organisms.
• They can be unicellular or multicellular.
• Algae lack specialized roots, stems, and vascular bundles.
• Algae lack a diploid embryo stage and surrounding sterile tissues.
• Zygote development uses mitosis or meiosis, not embryo formation.

Rhodophyta (Red Algae)

• Abundant and diverse in warm tropical and subtropical areas.
• Found in temperate and polar seas (some in hot springs).
• Critical to coral reef building (encrusting, calcified corallines).
• Involved in carbon storage—carbonate deposits containing calcium carbonate in cell walls.
• Deepest photosynthetic eukaryotes (over 210 meters in the Bahamas).
• Some species are parasitic on other macroalgae.
• About 6,000 species; mostly marine, some freshwater, and very few terrestrial.
• Color comes from pigments like phycoerythrin and phycocyanin (pinkish in marine, bluish in freshwater).

Batrachospermum sp.

• Found in clear, cold running fresh water streams.
• Deep water species are dark violet or reddish.
• Shallow water species are olive green.

Red Algae Thallus

• Thallus (body) of red algae is delicate compared to brown algae.
• Motile forms are absent, even reproductive cells are non-flagellated.

Red Algae Morphology

• Most red algae have multicellular, macroscopic, and diverse thallus forms.
  • Uniaxial: Axis formed by a single row of filaments.
  • Multiaxial: Axis formed by more than one row of filaments.

Cell Wall Structure

• Plant cell walls contain two main parts:
  • Fibers of cellulose: Rigid, glucose polymer.
  • Gels of polysaccharides: Flexible, sugar polymer.

Red Algae Plastids

• Red algae plastids come in two general types:
  • Axial/Stellate: Examples are Porphyridium with a large, central plastid.
  • Parietal/Discoidal: Examples are Audouinella with multiple small plastids.

Floridean Starch

• Red algae store carbohydrates as floridean starch.
• It is different from starch in land plants (Lacks amylose; branched structure called amylopectin).

Pit Connections

• Most cells in red algae do not completely divide.
• The open region is eventually plugged with proteins.
• These are considered ordinal level taxonomic characters (core and cap morphology).
• There are primary and secondary pit connections.

Red Algae Reproduction

• Red algae reproduce vegetatively (cell division, fragmentation) or asexually (monospores).
• Many red algae taxa exclusively rely on vegetative and/or asexual reproduction.

Test your knowledge on the differences between prokaryotes and eukaryotes, focusing on their cellular structures and reproductive processes. Additionally, explore the diverse world of algae, including their characteristics and classifications. This quiz will help reinforce essential concepts in cell biology.