Microbiology exam part 2

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Questions and Answers

What is one of the main functions of S-layers in bacteria?

Water storage

Energy production

Protection from host defenses (correct)

Enhancing photosynthesis

Fimbriae are used exclusively for gene transfer in bacteria.

False

What do flagella allow bacteria to do?

Move or swim

Pili can be used for ______ as well as attachment.

gene transfer Signup and view all the answers

Match the following bacterial appendages with their primary functions:

Flagella = Locomotion Fimbriae = Attachment to surfaces Pili = Gene transfer Capsules = Protection against phagocytosis Signup and view all the answers

Which of the following environments can biofilms grow on?

Solid surfaces Signup and view all the answers

Bacterial capsules provide a barrier against osmotic stress.

True Signup and view all the answers

What protein composes flagella?

Flagellin Signup and view all the answers

Bacteria can exhibit movement called ______ using their flagella.

taxis Signup and view all the answers

Which type of bacteria structure is primarily involved in protection from harsh environmental conditions?

Capsules Signup and view all the answers

Which of the following statements correctly describes prokaryotic cells?

Prokaryotic cells lack organelles and have a peptidoglycan cell wall. Signup and view all the answers

Eukaryotic cells grow faster than prokaryotic cells.

False Signup and view all the answers

What term is used for the network of polysaccharides extending from the surface of a prokaryotic cell?

glycocalyx Signup and view all the answers

Prokaryotic cells reproduce through __________.

binary fission Signup and view all the answers

Match the following prokaryotic cell shapes with their descriptions:

Cocci = Spherical Bacilli = Rod-shaped Vibrio = Bent rod Spirilla = Rigid helices Signup and view all the answers

Which component of the prokaryotic cell is responsible for its shape?

Cell wall Signup and view all the answers

Prokaryotes can have histones associated with their DNA.

False Signup and view all the answers

Name the two main groups of bacteria.

Gram positive and Gram negative Signup and view all the answers

The types of arrangements formed by prokaryotic cell division include pairs called , chains called , and clusters called __.

diplococci, streptococci, staphylococci Signup and view all the answers

What component is found in prokaryotic cells but not in eukaryotic cells?

Peptidoglycan cell walls Signup and view all the answers

Study Notes

Prokaryotic vs. Eukaryotic Cells

Prokaryotic cells, derived from Greek "prenucleus," differ from eukaryotic cells, which mean "true nucleus."
Prokaryotes contain one circular chromosome that is not membrane-bound, while eukaryotes have paired chromosomes enclosed in a nuclear membrane.
Eukaryotic cells have histones, organelles, and cell walls composed of polysaccharides, unlike prokaryotes.
Prokaryotes reproduce through binary fission, whereas eukaryotes undergo mitosis and possess a mitotic spindle.

Advantages of Small Cell Size

Smaller cells have a higher surface-to-volume (S/V) ratio, promoting better nutrient and waste exchange.
They tend to grow more rapidly than larger cells and accumulate mutations faster, leading to quicker evolutionary changes. Eukaryotic cells adapt more slowly.

Prokaryotic Cell Structure

Prokaryotic cells are characterized by a lack of internal membrane systems and are classified into two domains: Bacteria and Archaea.
Bacteria can be further categorized based on their Gram stain reaction into Gram-positive and Gram-negative.

Major Shapes of Prokaryotic Cells

Cocci: spherical shape.
Bacilli: rod-shaped.
Vibrio: bent rods.
Spirilla: rigid helices.
Spirochetes: flexible helices.
Mycelium: network of long filaments.
Pleomorphic: lacking a defined shape.

Division and Arrangement of Prokaryotic Cells

Cells can divide along one plane to form pairs (diplococci) or chains (streptococci).
Division along two or three planes results in cubical packets (Sarcina) or clusters (Staphylococcus).

Glycocalyx

Glycocalyx refers to a network of polysaccharides on the cell surface, including capsules and slime layers.
Capsules are well-organized, composed of polysaccharides, and not easily removed; slime layers are less organized and easily detachable.
S-layers are complex layers of glycoprotein found in some bacteria and Archaea.

Functions of Glycocalyx

Provides protection against host defenses and harsh environmental conditions.
Facilitates attachment to surfaces, forming biofilms and interacting with host receptors.
Shields against viral infections, predation, and environmental chemicals.

Biofilms

Dense masses formed by microbes adhering to solid surfaces, such as rocks, pipes, and medical implants.

Microbial Appendages

Flagella are responsible for locomotion; fimbriae facilitate attachment and movement.
Pili come in different types, such as sex pili for genetic exchange, attachment, and secretion.

Fimbriae and Pili Characteristics

Fimbriae are short, thin, hair-like structures with up to 1,000 per cell, crucial for surface attachment.
Pili are tubular structures with fewer than 10 per cell, serving roles in attachment and gene transfer.

Flagella Structure and Function

Flagella consist of chains of the protein flagellin and are anchored to the cell wall and membrane by a basal body.
Motility is achieved through rotation, allowing movement toward or away from stimuli (taxis). Flagella proteins act as H antigens.

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Description

Explore the fascinating world of bacterial structures such as capsules, slime layers, and S-layers. This quiz will test your knowledge on their roles in protection against environmental challenges and host defenses. Delve into the significance of biofilms and their attachment mechanisms.