Biology Chapter 4 Flashcards

Bacterial Appendages

• Bacterial cells can have various appendages for movement and attachment, including flagella, fimbriae, and sex pili; however, they do not have cilia.
• Spirochetes use periplasmic flagella for their twisting and flexing movement.
• Fimbriae are short and abundant appendages that help bacteria adhere to surfaces.
• Sex pili are tubular appendages used for genetic material transfer during bacterial conjugation.

Bacterial Structures and Functions

• Every bacterial cell contains a chromosome, which is organized within a region called the nucleoid.
• The presence of flagella allows bacteria to exhibit chemotaxis, directing movement toward chemicals in their environment.
• Capsules are protective structures that shield bacteria from being engulfed by immune cells.

Cell Wall Characteristics

• The Gram stain classification is based on differences in bacterial cell wall composition; gram-positive bacteria have thick peptidoglycan layers, while gram-negative bacteria have an outer membrane containing lipopolysaccharides.
• Peptidoglycan is a unique macromolecule found exclusively in bacterial cell walls, crucial for structural integrity.

Endospores

• Bacterial endospores serve as a protective mechanism for genetic material during adverse conditions; they are resistant to heat, radiation, and chemicals.
• Calcium dipicolinic acid presence indicates the presence of endospores, which are metabolically inactive during dormancy.

Shape and Arrangement of Bacteria

• Bacteria are classified by their shapes: cocci (spherical), rods (bacilli), spirilla (spiral), and specific arrangements like sarcinae (cuboidal packets).
• Coccobacillus refers to short and plump rod-shaped bacteria.

Biofilms and Evolution

• Biofilms are complex communities of microbes that cooperate and adapt, playing roles in ecological recycling and medical device colonization; they are difficult to eliminate with antimicrobials.
• The similarity in nitrogen base sequences of rRNA is an essential criterion for determining evolutionary relatedness among bacteria.

Phyla of Bacteria

• Bacterial phyla include Gracilicutes (gram-negative), Firmicutes (gram-positive), and Actinobacteria, which feature unique characteristics like waxy cell walls.
• Cyanobacteria are notable for their photosynthetic capabilities and presence of thylakoids for light absorption.

Miscellaneous Knowledge

• Lysozyme, found in tears, defends against bacteria by hydrolyzing peptidoglycan in cell walls.
• The mordant in Gram staining is iodine, which stabilizes the dye within the cell wall.
• Plasmids are crucial vectors in genetic engineering techniques due to their role in gene transfer among bacteria.
• Certain microorganisms thrive in extreme environments; for instance, Archaea can survive in highly acidic and hot habitats.

Mismatches in Classification

• Identifying mismatches in characteristics can clarify misconceptions; for example, Coxiella burnetti is associated with Q fever, not cowpox.
• Similarly, while Actinobacteria have waxy acid-fast walls, they differ from typical gram-positive structures.

Properties of Living Cells

• Living cells exhibit key characteristics such as boundary formation and ability to replicate; however, the presence of a nucleus is not a property exclusive to all living things, particularly in prokaryotic cells.

Test your knowledge on bacterial appendages with these flashcards covering key concepts from Chapter 4. Each card presents different types of appendages found in bacteria and their functions, helping you to reinforce your understanding of microbiology.