Biology Chapter 20 Prokaryotes Flashcards

Classification of Prokaryotes

• Prokaryotes belong to two domains: Bacteria and Archaea.
• They are the smallest and most abundant microorganisms.

Structure and Composition

• Prokaryotes are unicellular and lack a nucleus.
• Bacterial cell walls are composed of peptidoglycan, a polymer made of sugars and amino acids.

Unique Characteristics of Archaea

• Archaea thrive in extreme environments, such as high salt levels, extreme temperatures, and areas with little or no oxygen.

Diversity in Prokaryotes

• Prokaryotes exhibit variation in size, shape, motility, and energy acquisition.
• Different shapes include bacilli (rod-shaped), cocci (spherical), and spirilla (spiral/corkscrew).

Reproduction

• Prokaryotes reproduce asexually through a process called binary fission, which involves duplication of DNA and cell division.

Endospores

• Endospores are protective structures formed by some prokaryotes, containing DNA and cytoplasm, enabling survival in harsh conditions.

Evolutionary Processes

• Prokaryotic evolution relies on mutations or conjugation, despite asexual reproduction limiting genetic variation.

Genetic Exchange: Conjugation

• Conjugation involves the formation of a bridge between two bacterial cells for the transfer of genetic material, usually in the form of plasmids.

Ecological Roles

• Prokaryotes play crucial roles in ecological balance, acting as decomposers, producers, and nitrogen fixers.

Decomposition and Nutrient Recycling

• Prokaryotic decomposers break down dead organisms, recycling raw materials essential for the survival of living organisms.

Importance of Algae

• Algae, a photosynthetic prokaryote, contribute significantly to food chains and are vital producers of food and biomass.

Nitrogen Fixation

• Nitrogen fixers convert atmospheric nitrogen into ammonia, which is then transformed into nitrates for plant use or attached to amino acids for general utilization by various organisms.

Human Utilization of Prokaryotes

• Prokaryotes have practical applications in human industry, including yogurt production and the synthesis of pharmaceuticals through genetic engineering.

Explore the classification and characteristics of prokaryotes through these informative flashcards. Learn about their classification into Bacteria and Archaea, their unique cellular structures, and more. Perfect for studying microbiology concepts effectively.