Cell Structure and Function

These flashcards cover key concepts related to bacterial cell structure and function, focusing on their unique features, the processes they undergo, and how they interact with their environments.

What is Bdellovibrio bacteriovorus known for?

It is a predatory bacterium that attacks Escherichia coli.

What imaging technique was used to study Bdellovibrio bacteriovorus?

Cryo-electron tomography.

Which type of bacteria lacks a nucleus?

Prokaryotes, which include Bacteria and Archaea.

What distinguishes Gram-negative bacteria from Gram-positive bacteria?

Gram-negative bacteria have a thin cell wall covered by an outer membrane.

What composes the outer membrane of a Gram-negative bacterium?

Phospholipids and lipopolysaccharides (LPS).

Describe the structure of the bacterial cell envelope.

It includes the inner membrane, cell wall, periplasm, and outer membrane.

What is the cytoplasm primarily composed of?

A gel-like network of proteins and macromolecules.

What role does the cell wall play in bacteria?

It maintains turgor pressure and protects against osmotic shock.

What are the major components found in a bacterial cell membrane?

Phospholipids and integral membrane proteins.

What is the Z-ring's function during bacterial cell division?

It coordinates the formation of the septum and determines cell diameter.

How does bacterial DNA replication initiate?

At the origin of replication attached to the cell envelope.

What molecule is responsible for the synthesis of peptidoglycan?

Penicillin-binding proteins (PBPs).

What are carboxysomes?

Protein-covered bodies in bacteria that fix CO2 using Rubisco.

How do bacteria sense their environment?

Through chemoreceptors embedded in their membranes.

What is the purpose of pili on bacterial cells?

To anchor cells to surfaces and facilitate DNA transfer during conjugation.

What do gas vesicles do for cyanobacteria?

Increase buoyancy to keep the cell near the water surface for light exposure.

What is the function of lipopolysaccharides (LPS) in Gram-negative bacteria?

They serve as endotoxins and are key components of the outer membrane.

Describe the role of MreB in bacterial cells.

It is a cytoskeletal protein that guides peptidoglycan elongation.

What structures make Gram-positive bacteria resistant to phagocytosis?

Thick peptidoglycan cell wall and teichoic acids.

What are the advantages of having a capsule in bacteria?

It protects against phagocytosis and aids in adherence.

What structure do some bacteria use for motility?

Flagella.

What is chemotaxis?

The movement of bacteria toward or away from chemical stimuli.

What does the term 'nucleoid' refer to in bacterial cells?

The region in the cytoplasm where the bacterial chromosome is located.

How do bacteria perform cell division?

By orchestrating DNA replication with the growth of the cell envelope and septation.

What triggers the formation of the septum during bacterial division?

Completion of DNA replication leads to formation of the Z-ring, triggering septum growth.

How do bacteria maintain their structural integrity under osmotic stress?

By having a rigid cell wall that can withstand turgor pressure.

What is the significance of ribosomal RNA (rRNA) in bacteria?

It plays a crucial role in protein synthesis and is a component of ribosomes.

How do bacteria share genetic material?

Through a process called conjugation, facilitated by sex pili.

What is the bacterial cytoskeleton composed of?

Proteins such as FtsZ, MreB, and crescentin.

What is the function of the ATP synthase protein complex in bacterial membranes?

It synthesizes ATP using the proton motive force generated by ion gradients.

What are specialized structures found in certain taxa for carbon fixation?

Carboxysomes.

How can environmental conditions affect bacterial cell size?

Nutrient availability can lead to variations in cell growth rates and sizes.

What is the role of the inner membrane in Gram-negative bacteria?

It serves as the plasma membrane separating the cytoplasm from the external environment.

What is the purpose of mechanical forces like those provided by the Z-ring?

To regulate and complete the division process of bacterial cells.

How do polar aging and differential cell division manifest in bacteria?

Older poles may accumulate damaged proteins and affect the cell's proliferative capacity.

What are endospores and their significance to bacteria?

Asymmetric cell division produces endospores, which are resilient to harsh conditions.

What do intercellular nanotubes facilitate between bacterial cells?

They enable the direct transfer of proteins and nutrients between cells.

What is the structure of the peptidoglycan layer in bacteria?

It is composed of disaccharides cross-linked by peptides.

How does a bacteria's morphology affect its function?

Morphological traits contribute to nutrient uptake efficiency and environmental adaptability.

How does the ability to form biofilms benefit bacteria?

It provides protection, nutrient capture, and enhanced survival in hostile environments.

What happens when bacteria face oxidative stress?

They can release membrane vesicles to protect and share resources with other bacteria.

What are thylakoids, and what function do they serve in phototrophic bacteria?

Thylakoids are folded membranes that house chlorophyll for photosynthesis.

Name some factors that influence bacterial cell differentiation.

Environmental cues, nutrient availability, and genetic regulation.

What is a filamentous structure in bacteria responsible for swimming?

Flagella, which rotate to propel the cell forward.