Biology Chapter 27: Prokaryotes Quiz

Prokaryotes Overview

• Earth's first organisms are prokaryotes.
• Prokaryotic cells exhibit three common shapes: spheres (cocci), rods (bacilli), and spirals.

Cell Structure

• Nearly all prokaryotic cells possess a cell wall, which maintains shape, offers protection, and prevents bursting in hypotonic environments.
• Bacteria specifically have peptidoglycan in their cell walls, distinguishing them from other domains.

Domains and Organelles

• The domain Eukarya features membrane-bound organelles and nuclear envelopes, which prokaryotes lack.

Peptidoglycan and Staining

• Peptidoglycan is a composite of protein and sugar, crucial for bacterial structure.
• The Gram stain is used to classify bacteria based on cell wall composition, identifying Gram positive (thicker peptidoglycan) and Gram negative (thinner peptidoglycan) bacteria.

Survival Mechanisms

• Endospores are tough, dormant structures that can survive extreme conditions for centuries.
• Taxis refers to the movement of prokaryotes toward or away from stimuli, with chemotaxis being specifically directed toward chemical stimuli.

Flagella

• Bacterial flagella are composed of three parts: motor, hook, and filament.
• Evolutionarily, flagella proteins are modified versions of other bacterial proteins.

Genetic Exchange

• Horizontal gene transfer allows genes to move among individuals of different species, enhancing genetic diversity.
• Transformation involves prokaryotic cells incorporating foreign DNA from their environment.

Gene Transfer Methods

• Transduction is the transfer of genes between bacteria via bacteriophages.
• Conjugation is the transfer of genetic material between two bacterial cells connected by a sex pilus, facilitated by the F factor, which enables the formation of sex pili.

Reproduction and Diversity

• Prokaryotes reproduce asexually through binary fission, leading to rapid population growth every 1-3 hours, with most offspring being genetically identical.
• Key factors for genetic diversity in prokaryotes include rapid reproduction, mutations, and genetic recombination.

Metabolism Types

• Autotrophs require only inorganic compounds like CO2 for carbon.
• Heterotrophs need organic nutrients, like glucose.
• Chemoheterotrophs can function as decomposers in ecosystems.

Oxygen Requirements

• Obligate aerobes need oxygen for cellular respiration.
• Obligate anaerobes are poisoned by oxygen and rely on fermentation or anaerobic respiration.
• Facultative anaerobes can switch between aerobic and anaerobic conditions.

Nitrogen and Symbiotic Relationships

• Nitrogen fixation converts atmospheric nitrogen to ammonium.
• Symbiosis is an ecological relationship where two species exist closely, including types like commensalism (one benefits, the other is unaffected), parasitism (one benefits at the host's expense), and mutualism (both benefit).

Antibiotic Resistance

• Genes responsible for antibiotic resistance are commonly found in plasmids, small rings of DNA in bacteria.
• All genomes consist of DNA, except for certain viruses which have RNA genomes.

Test your knowledge on the two domains of prokaryotes: Bacteria and Archaea. This quiz covers key concepts including the shapes of prokaryotic cells and essential features like cell walls. Perfect for students seeking to understand the fundamental differences between these microorganisms.