Mic CH 3

1. Define the term pleomorphic, and discuss how this property may impact an organism's ability to cause infection.

meaning it can take on different forms This enhances its survival, and appears to be important for transmission to a new human host. Makes it hard to do Biofilms.

1. Describe the basic structure and function of the prokaryotic cytoskeleton.

A dynamic and responsive intracellular network of protein fibers that maintains cell shape, facilitates movement, protects against external forces that may otherwise deform the cell, and directs transport of vesicles, organelles, and other cellular cargo; it also coordinates cell division by moving chromosomes and organelles to developing daughter cells; eukaryotes and prokaryotes have a cytoskeleton.

1. Define the term nucleoid.

A somewhat centralized region of a prokaryotic cell, though its boundaries are not distinct, since it isn't membrane enclosed. In addition to containing prokaryotic DNA, the region also includes some RNA and proteins.

1. Explain the basic structure and function of endospores and discuss why they present challenges in healthcare settings.

Are metabolically inactive structures that allow certain cells to enter a dormant state. Once the endospore is released, it is simply called a spore. Bacterial spores are highly resistant to environmental stress such as starvation, heat, drying, freezing, radiation, or various chemicals The capacity to make endospores allows dangerous pathogens like Clostridium tetani (the causative agent of tetanus), Clostridium botulinum (the causative agent of botulism), Clostridium perfringens (the causative agent of gas gangrene), and Clostridium difficile (the causative agent of a severe diarrhea) to survive for extended periods on surfaces, even in healthcare facilities that work hard to eradicate them.

1. Name two prokaryotic domains and state one way that these domains differ and one way they are alike.

Bacteria and Archaea. They both are unicellular and lack a nucleus along with other membrane bound organelles. Archaea have not been linked to human diseases like Bacteria

1. Discuss the role of inclusion bodies and provide examples of them.

Bacteria typically build inclusions in times of excess, such as when grown on nutrient-rich media. The stored materials can then be used in leaner times for a variety of tasks, including metabolic processes. Glycogen is a commonly stored molecule; in times of need, cells break it down one glucose molecule at a time to make ATP. Another commonly stored substance is the polymer poly-β-hydroxybutyrate (PHB), which acts as a carbon and energy reserve for times when more preferable nutrients like glucose run low. Certain prokaryotes, such as cyanobacteria, fix carbon and help sustain life on Earth by serving as major participants in the carbon cycle.

1. Outline the types of passive and active transport mechanisms that exist in cells.

Diffusion: The movement of molecules from an area of higher concentration to an area of lower concentration without an energy investment Simple: does not require assistance from transporters or carriers. Small noncharged molecules, gases, and lipid-soluble substances tend to enter and exit cells by simple diffusion. Facilitated: The transport proteins that mediate facilitated diffusion are specific for the substances they transport. Examples include channels that span the membrane and protein transporters that can flip-flop in the cell membrane Osmosis: The net movement of water from an area of low solute (salt, sugar, or other dissolved substance) concentration to an area of higher solute concentration across a selectively permeable membrane. It does not require energy to occur. Cells experience osmotic stress when they are placed in environments where their water balance is disrupted. Active Transport: Active transport requires energy to transport specific substances through specific channels or carrier proteins. Active transport can move substance along or against a concentration gradient. Most cellular transport mechanisms are active transport mechanisms.

1. Describe the function of prokaryotic ribosomes and discuss how their structural features support the endosymbiotic theory.

Essential organelles for making proteins; eukaryotic ribosomes, like prokaryotic ribosomes, are made up of protein and ribosomal RNA (rRNA); ribosomes build proteins by linking together amino acids. Prokaryotes have 70S ribosomes while eukaryotes have 80S ribosomes. Interestingly, the ribosomes of two eukaryotic organelles—chloroplasts and mitochondria—are 70S, just like prokaryotic ribosomes. This observation further supports endosymbiotic theory, which hypothesizes that eukaryotic cells developed from prokaryotic cells that lived symbiotically with an ancient shared ancestor.

1. Discuss the roles of flagella, fimbriae, pili, and glycocalyx structures.

Flagella: Tail-like structures used by some cells for motility; while eukaryotic microbes tend to have only one flagellum located at a single pole of the cell, prokaryotes can have single or multiple flagella with diverse arrangements. Fimbriae: Short, bristle-like structures that extrude from the cell surface; only found on prokaryotic cells; made of protein, they tend to be numerous and cover the cell; their adhesive properties help prokaryotes stick to surfaces or to each other for establishing biofilms or for invading a host. Pili: Similar to fimbriae, except that they tend to be longer, more rigid, and less numerous. They are used to adhere to surfaces, move, and aid in gene transfer through conjugation. Glycocalyx : A sticky extracellular layer made of carbohydrates; found in prokaryotes and eukaryotes; in prokaryotes this can be loosely or tightly associated with the cell wall.

1. Compare L-forms to Mycoplasma bacteria.

L-forms had a cell wall and lost it. Mycoplasma never had one to begin with

1. Identify various flagella arrangements and discuss how periplasmic flagella differ from regular flagella.

Monotrichous A term that describes cells with a single flagellum (mono = one). Lophotrichous A term applied to cells with a tuft or cluster of flagella at one pole (end) of the cell (lopho = tuft). Amphitrichous A term that describes cells with one or more flagella present at each end (pole) of the cell. Peritrichous A term that describes cells that have flagella distributed all over the cell surface. Periplasmic flagella Flagella located in the space between the plasma membrane and the cell wall. These unique flagella allow spirochetes to move with their distinct corkscrew motion.

1. Name two acid-fast genera, state what makes them so, and explain why the acid-fast stain is clinically useful.

Nocardia and Mycobacterium. Have a waxy lipid called mycolic acid in their cell walls. Clinically speaking, the acid-fast stain is especially important for identifying the causative agents of leprosy (Mycobacterium leprae) and tuberculosis (Mycobacterium tuberculosis). Nocardia species typically live in soil and may cause skin infections, or in the case of immune-compromised patients, lung infections.

1. Discuss structural and functional features of prokaryotic plasma membranes.

Selectively permeable: H2O, gases, and small non-charged substances can go through without resistance. Larger charged substances cannot. Two lipid bilayers make a sandwich.: hydrophilic side loves water and hydrophobic fatty acids are in the middle and hate water. proteins serve as transporters, anchors, receptors, and enzymes.(glycoproteins or lipoproteins) fluidity enables proteins to relocate to areas of the membrane where they are most needed. Maintaining a certain level of membrane fluidity is essential to the cell and can impact its physiological functions (warm increase, cold decreases)

1. Compare bacteria and archaea plasma membranes and cell walls.

The chemical linkages in bacterial plasma membranes differs from those in archaea. This is actually one of the ways we distinguish bacteria from archaea. In bacteria, phospholipids are built from generally linear fatty acids, while archaea use long-branched lipids called isoprenoids instead of fatty acids. Certain archaea that live in extreme heat build lipid monolayers as opposed to lipid bilayers. These monolayer membranes contain unique lipids (called tetraether lipids) that are basically long lipid molecules capped on either end with a polar head group. These unique membrane adaptations help archaea thrive in harsh environments.