Microbiology Chapter on Bacterial Structures

A small, circular DNA molecule found in bacteria. Plasmids can be gained or lost without harming the cell and may contain genes for antibiotic resistance, toxin production, or other beneficial traits.

The site of protein synthesis in bacteria, composed of a large and small subunit made of protein and ribosomal RNA (rRNA).

Reserve deposits of nutrients that bacteria store for times of low resource availability. Examples include metachromatic granules, polysaccharide granules, lipid inclusions, sulfur granules, carboxysomes, gas vacuoles, and magnetosomes.

Resistant, dormant bacterial cells formed when essential nutrients become scarce. Endospores are highly resistant to heat, chemicals, and radiation and are responsible for diseases like anthrax, gangrene, tetanus, and botulism.

The process by which bacteria form endospores.

The area where a bacterium's chromosome attaches to the plasma membrane. It is involved in DNA synthesis and partitioning during binary fission.

A process of cell division in bacteria, where a single parent cell divides into two identical daughter cells.

A rigid cell wall found in most bacteria, providing structural support and protection. Peptidoglycan is a major component of the bacterial cell wall.

A Gram-positive bacterial cell where the cell wall has been destroyed, but the cell is still alive and functional. It has lost its peptidoglycan layer.

The process by which cells break down glucose to release energy in the form of ATP.

A Gram-negative bacterial cell that has lost both its outer membrane and peptidoglycan layer.

The site of cellular respiration in eukaryotic cells, responsible for generating ATP.

The two layers that surround a mitochondrion, each composed of a phospholipid bilayer and proteins.

Wall-less bacterial cells that can swell into irregular shapes, but can still live, divide, and potentially regain their cell wall.

The space between the outer and inner mitochondrial membranes.

A process where cells without a cell wall (like protoplasts and spheroplasts) burst due to the influx of water.

The inner layer of the mitochondrial membrane, folded into cristae to increase surface area for ATP production.

The outer membrane of Gram-negative bacteria acts as a barrier, preventing penicillin from reaching the peptidoglycan layer.

A structure within bacteria responsible for transporting substances into and out of the cell.

The space enclosed by the inner mitochondrial membrane, containing enzymes and other molecules involved in respiration.

The process by which mitochondria use a proton gradient to generate ATP. It occurs in the inner mitochondrial membrane.

A type of protein embedded within the plasma membrane, spanning its entire width.

The model describing the structure of the plasma membrane, which is fluid and allows movement of its components.

Tiny organelles within mitochondria that are involved in protein synthesis, suggesting mitochondria were once independent organisms.

Mitochondria are organelles found in eukaryotic cells responsible for producing energy (ATP) through cellular respiration. They have their own DNA, suggesting their evolution from ancient bacteria.

Mitochondria have a unique structure with compartments that carry out specific functions. These include the outer membrane, intermembrane space, inner membrane, cristae, and matrix.

The number of mitochondria in a cell can vary depending on the organism, tissue, and cell type. For example, red blood cells have no mitochondria, while liver cells can have thousands.

Mitochondria have their own independent genome, separate from the cell nucleus, which is similar to bacterial DNA.

Mitochondria are involved in cellular respiration, a process that converts energy from food into ATP, the cell's energy currency.

Mitochondria play a role in apoptosis, or programmed cell death, by releasing proteins that trigger this process.

The mitochondrial proteome, the collection of proteins in mitochondria, varies depending on the tissue and species.

Mitochondrial defects, such as problems with their proteins or DNA, can contribute to a range of diseases, including neurodegenerative disorders and muscle diseases.

The endoplasmic reticulum (ER) membrane is structurally similar to other cellular membranes like the plasma membrane, nuclear membrane, and Golgi apparatus.

The ER membrane is continuous with other cellular membranes, forming an interconnected network within the cell.

The internal space of the ER, called the lumen, serves as a pathway for transporting secretory products within the cell.

Ribosomes attached to the ER give it a rough appearance. These ribosomes synthesize proteins destined for secretion or integration into membranes.

Smooth ER lacks ribosomes and appears smooth. It is involved in lipid synthesis and detoxification.

The RER is especially prominent in cells actively producing proteins for secretion, such as pancreatic acinar cells, plasma cells, and goblet cells.

The ER membrane contains various enzymes that participate in diverse metabolic activities, including lipid synthesis, steroid hormone production, and detoxification.

The smooth ER in liver cells plays a crucial role in detoxifying hydrophobic chemicals by converting them into water-soluble forms for excretion.

Ribosomes are classified based on their sedimentation coefficient, a measure of their size and density. 70S ribosomes are found in prokaryotes, while 80S ribosomes are found in eukaryotes.

70S ribosomes are smaller, have a sedimentation coefficient of 70S, and are found in prokaryotic cells like bacteria and blue-green algae, as well as in mitochondria and chloroplasts of eukaryotic cells.

80S ribosomes are larger, have a sedimentation coefficient of 80S, and are found in eukaryotic cells, which include plants and animals.

Ribosomes are composed of two subunits, a larger subunit and a smaller subunit. These subunits are made up of rRNA (ribosomal RNA) and proteins.

The number of ribosomes in a cell varies depending on the cell type and its metabolic activity. E.coli cells have about 10,000 ribosomes, while mammalian cultured cells can contain 10 million ribosomes.

The chemical composition of ribosomes includes RNA and proteins as their primary components. The relative proportions of RNA and proteins can vary depending on the type of ribosome.

Ribosomal RNA (rRNA) comprises a significant portion of a ribosome's mass. 70S ribosomes contain three types of rRNA: 23S, 16S, and 5S. The 23S and 5S rRNA are located in the larger subunit, while the 16S rRNA resides in the smaller subunit.