Micro Chap 4
Two types of Cilia
motile cilia and non-motile, or primary cilia, which typically serve as sensory organelles.
Pathogen classifications
opportunistic (causing disease if the host's defenses are compromised in some way) or primary (causing disease even if the host's defenses are intact.)
All living organisms can be divided into ___ & ___
prokaryotes and eukaryotes
Virulence genes can be regulated by
quorum sensing
Peroxisomes
Organelles found in virtually all eukaryotic cells. They are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, D-amino acids, polyamines, and biosynthesis of plasmalogens, i.e. ether phospholipids critical for the normal function of mammalian brains and lungs. They also contain approximately 10% of the total activity of two enzymes in the pentose phosphate pathway, which is important for energy metabolism.
Prokarytic cells & Eukaryotic cells: intracellular structures: Ribosomes
P: 70S; E: 80S in cytoplasm & on endoplasmic reticulum, 70S in mitochondria
Prokarytic cells & Eukaryotic cells: Extracellular structures: cell wall
P: Peptidoglycan, LPS & Teichoic acid; E: none in most eukaryotic cells; chitin in fungal cells
Prokarytic cells & Eukaryotic cells: Genetic structure: Histones
P: absent; E: present
Prokarytic cells & Eukaryotic cells: Genetic structure: Nucleolus
P: absent; E: present
Prokarytic cells & Eukaryotic cells: intracellular structures: Golgi
P: absent; E: present
Prokarytic cells & Eukaryotic cells: intracellular structures: Lysosomes
P: absent; E: present
Prokarytic cells & Eukaryotic cells: intracellular structures: Mitotic spindle
P: absent; E: present
Prokarytic cells & Eukaryotic cells: intracellular structures: Peroxisomes
P: absent; E: present
Prokarytic cells & Eukaryotic cells: intracellular structures: cytoskeleton
P: absent; E: present
Prokarytic cells & Eukaryotic cells: intracellular structures: endoplasmic reticulum
P: absent; E: present
Prokarytic cells & Eukaryotic cells: Extracellular structures: cilia
P: absent; E: present in certain cell types
Prokarytic cells & Eukaryotic cells: reproduction: reproduction mode
P: asexual; E: sexual or asexual
Prokarytic cells & Eukaryotic cells: intracellular structures: Respiration (ATP)
P: at cell membrane; E: in mitochondria
Prokarytic cells & Eukaryotic cells: reproduction: cell division
P: binary fission; E: mitosis or meiosis
Prokarytic cells & Eukaryotic cells: Extracellular structures: external layer
P: capsule or slime layer; E: None in most eukaryotic cells; pellicle or shell in certain parasites
Prokarytic cells & Eukaryotic cells: Genetic structure: Extracrhomosomal DNA
P: in plasmids; E: in mitochondria & plasmids
Prokarytic cells & Eukaryotic cells: intracellular structures: Plasma membrane
P: lacks sterols; E: contains sterols
Prokarytic cells & Eukaryotic cells: genetic structure: location of genetic material
P: nuclear region; E: membrane-enclosed nucleus
Prokarytic cells & Eukaryotic cells: intracellular structures: internal membranes
P: only in photosynthetic organisms; E: numerous membrane-enclosed organelles
Prokarytic cells & Eukaryotic cells: Extracellular structures: Pili
P: present; E: absent
Prokarytic cells & Eukaryotic cells: Extracellular structures: Flagella
P: present; E: present in certain cell types
Prokarytic cells & Eukaryotic cells: genetic structure: genetic material
P: usually found in single circular chromosome; E found in paired chromosomes
Virulence
Virulence refers to how harmful a given pathogen is to a host. There are virulence genes that are carried on the bacterial chromosome or on extrachromosomal pieces of DNA called plasmids.
___ can assist in the infectious process by inhibiting the exposure of bacteria to antibiotics and other molecules toxic to bacteria
biofilm
Negative differential stains
stains background and allows bacterial capsules to be seen
Infection by pathogen requires
the pathogen get in, stay in, defeat the host defense, damage the host, and be transmissible.
Gram stain is used
to classify bacteria on the basis of their cell wall structure.
Endospore
A dormant, tough, and non-reproductive structure produced by certain bacteria from the Firmicute phylum. The name 'endospore' is suggestive of a spore or seed-like form (endo means within), but it is not a true spore (i.e., not an offspring). It is a stripped-down, dormant form to which the bacterium can reduce itself.
Keratin
A family of fibrous structural proteins. Keratin is the key structural material making up the outer layer of human skin. It is also the key structural component of hair and nails.
Pinocytosis
A form of endocytosis in which large particles are brought into the cell, forming an invagination, and then suspended within small vesicles (pinocytotic vesicles) that subsequently fuse with lysosomes to hydrolyze, or to break down, the particles. This process requires a lot of energy in the form of adenosine triphosphate, the chemical compound is mostly used as energy in the majority of bacteria cells. Pinocytosis is used primarily for the absorption of extracellular fluids (ECF), and, in contrast to phagocytosis, generates very small amounts of Adenosine Tri-phosphate from the wastes of alternative substances such as lipids (fat).
Ubiquitin
A small regulatory protein that has been found in almost all tissues (ubiquitously) of eukaryotic organisms. It directs proteins to compartments in the cell, including the proteasome which destroys and recycles proteins. Ubiquitin can be attached to proteins and label them for destruction.
Quorum sensing
A system of stimulus and response correlated to population density. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In similar fashion, some social insects use quorum sensing to determine where to nest.
Bacilli
A taxonomic class of bacteria. It includes two orders, Bacillales and Lactobacillales, which contain several well-known pathogens like Bacillus anthracis (the cause of anthrax).
Ziehl-Neelsen acid fast differential stain
Acid-fast organisms retain red of carbolfuchsin; non acid-fast organisms are colored blue with methylene blue. The stains distinguishes members of genera mycobacterium and Nocardia
Receptor-mediated endocytosis
Also called clathrin-dependent endocytosis, is a process by which cells internalize molecules (endocytosis) by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being internalized.
Biofilm
An aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS). Biofilm EPS, which is also referred to as slime (although not everything described as slime is a biofilm), is a polymeric conglomeration generally composed of extracellular DNA, proteins, and polysaccharides.
Endoplasmic reticulum
An organelle of cells in eukaryotic organisms that forms an interconnected network of membrane vesicles.The lacey membranes of the endoplasmic reticulum were first seen by Keith R. Porter, Albert Claude, and Ernest F. Fullam in the year 1945. . According to the structure the endoplasmic reticulum is classified into two types, that is, rough endoplasmic reticulum and smooth endoplasmic reticulum. The rough endoplasmic reticulum is studded with ribosomes on the cytosolic face.
Eukaryote
An organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is carried.
Chromosome
An organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.
Parts of eukaryotic host cell
cilium, microtubule, microvillus, microfilament, rough endoplasmic reticulum, nucleus, nucleolus, ribosome, mitochondrion, plasma membrane, secretory vesicle, peroxisome, lysome, Golgi complex, Cytoplasm, centriole, smooth endoplasmic reticulum
Flagella differential stain
Dies or silver used to build up layers on flagella allows the flagella to be seen
Parts of a host cell involved in infectious process
cilium, microtubule, microvillus, microfilament, rough endoplasmic reticulum, nucleus, ribosome, plasma membrane, lysome, cytoplasm,
Pathogenicity island
(PAIs), as termed in 1990, are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer. Pathogenicity islands are found in both animal and plant pathogens. Additionally, PAIs are found in gram postive and gram negative bacteria.
Development of biofilm
1. bacteria can accumulate on device & absorbed into it 2. bacteria can detach from device service & move into surrounding liquid 3. biofilm can form tenacious gelatinous mass that's resistant to host defenses 4. large pieces of biofilm can detach from device surface & spread to other locations. (some cases may cause fatal thromboembolisms (clots))
Motility
A biological term which refers to the ability to move spontaneously and actively, consuming energy in the process. Most animals are motile but the term applies to unicellular and simple multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs, in addition to animal locomotion. Motile marine animals are commonly called free-swimming.
Cytoskeleton
A cellular scaffolding or skeleton contained within a cell's cytoplasm. The cytoskeleton is present in all cells; it was once thought to be unique to eukaryotes, but recent research has identified the prokaryotic cytoskeleton. It has structures such as flagella, cilia and lamellipodia and plays important roles in both intracellular transport (the movement of vesicles and organelles, for example) and cellular division.
Cilia
A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body.
Infectious disease
A complex process that involves both the pathogen and the host.
Microtubule
A component of the cytoskeleton, found throughout the cytoplasm. These tubular polymers of tubulin can grow as long as 25 micrometres and are highly dynamic. The outer diameter of microtubule is about 25 nm while the inner diameter is about 12 nm.
Prokaryotes
A group of organisms whose cells lack a cell nucleus (karyon). The organisms whose cells do have a nucleus are called eukaryotes. Most prokaryotes are unicellular organisms, although a few such as myxobacteria have multicellular stages in their life cycles or create large colonies like cyanobacteria.
Bacteria
A large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria can be classified by genus and species. Further classification can be based on size, shape, & arrangement
Actin
A lobular multi-functional protein that forms microfilaments. It is found in all eukaryotic cells (the only known exception being nematode sperm), where it may be present at concentrations of over 100 μM. Actin is roughly 42-kDa in size and it is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. It can be present as either a free monomer called G-actin or as part of a linear polymer microfilament called F-actin both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division.
Mitochondrion
A membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometer (μm) in diameter. Mitochondria are sometimes described as 'cellular power plants' because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.
Nuclear membrane
A nuclear membrane, nucleolemma or karyotheca, is the double lipid bilayer membrane which surrounds the genetic material and nucleolus in eukaryotic cells. The nuclear membrane consists of two lipid bilayers-the inner nuclear membrane, and the outer nuclear membrane. The space between the membranes is called the perinuclear space, a region contiguous with the lumen (inside) of the endoplasmic reticulum.
Pathogen
A pathogen or infectious agent (colloquially known as a germ) is a microorganism-in the widest sense, such as a virus, bacterium, prion, or fungus-that causes disease in its host. The host may be an animal (including humans), a plant, or even another microorganism.
Gram-positive bacteria
Bacteria that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain (safranin or fuchsine) and appearing red or pink. Gram-positive organisms are able to retain the crystal violet stain because of the high amount of peptidoglycan in the cell wall.
Gram-negative bacteria
Bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain (commonly safranin) is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color. This is because of the existence of an outer membrane preventing the penetration of the stain.
Cell membrane
Biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. The basic function of the cell membrane is to protect the cell from its surroundings.
Lysosome
Cellular organelles that contain acid hydrolase enzymes that break down waste materials and cellular debris. They can be described as the stomach of the cell. They are found in animal cells, while their existence in yeasts and plants are disputed.
Intermediate filaments
Cytoskeletal components found in metazoan cells. They are composed of a family of related proteins sharing common structural and sequence features. Intermediate filaments have an average diameter of 10 nanometers, which is between that of 7 nm actin (microfilaments), and that of 25 nm microtubules, although they were initially designated 'intermediate' because their average diameter is between those of narrower microfilaments (actin) and wider myosin filaments found in muscle cells.
Endospore
Endospores retain malachite green color while cell counterstained with safranin is red. Stain is used to identify endospores present in bacteria cells
Gram Differential stains
Gram-positive (purple); gram-negative (pink); gram-intermediate (intermediate or mixed); gram non-reactive (stain poorly or not at all).
Ribosome
Large and complex molecular machine, found within all living cells, that serves as the primary site of biological protein synthesis. Ribosomes link amino acids together in the order specified by messenger RNA (mRNA) molecules. Ribosomes consist of two major subunits--the small ribosomal subunit reads the mRNA, while the large subunit joins amino acids to form a polypeptide chain.
Types of simple stains
Methylene blue (blue), safrainin (red), crystal violet (purple); Shows size, shape, and multicell arrangement
Tubulin
One of several members of a small family of globular proteins. The most common members of the tubulin family are α-tubulin and β-tubulin, the proteins that make up microtubules. Each has a molecular weight of approximately 55 kiloDaltons.
Proteasome
Protein complexes inside all eukaryotes and archaea, and in some bacteria. In eukaryotes, they are located in the nucleus and the cytoplasm. The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds.
Receptor
Protein molecules, embedded in either the plasma membrane (cell surface receptors) or the cytoplasm or nucleus (nuclear receptors) of a cell, to which one or more specific kinds of signaling molecules may attach. Receptors are protein molecules, embedded in either the plasma membrane (cell surface receptors) or the cytoplasm or nucleus (nuclear receptors) of a cell, to which one or more specific kinds of signaling molecules may attach.
Stains used to identify structures associated with the bacteria cell
Several stains such as the capsule, glagella, and endospore stains.
Nucleoplasm
Similar to the cytoplasm of a cell, the nucleus contains nucleoplasm or karyoplasm. The nucleoplasm is one of the types of protoplasm, and it is enveloped by the nuclear membrane or nuclear envelope. The nucleoplasm is a highly viscous liquid that surrounds the chromosomes and nucleoli.
Two types of stains
Simple stains which use one dye, and differential stains which use more than one dye.
Pseudopodia
Temporary projections of eukaryotic cells or unicellular protists. Cells that possess this faculty are generally referred to as amoeboids. Pseudopodia extend and contract by the reversible assembly of actin subunits into microfilaments.
Golgi apparatus
The Golgi apparatus, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the cellular endomembrane system, the Golgi apparatus packages proteins inside the cell before they are sent to their destination; it is particularly important in the processing of proteins for secretion. (so large it was one of the first organelles to be discovered and observed)
Pathogenicity
The ability of a pathogen to produce an infectious disease in an organism. It is often used interchangeably with the term 'virulence', although virulence is used more specifically to describe the relative degree of damage done by a pathogen, or the degree of pathogenicity caused by an organism. A pathogen is either pathogenic or not, and is determined by the pathogen's ability to produce toxins, its ability to enter tissue and colonize and its ability to spread from host to host.
Stain to confirm identity of mycobacterium species
The acid-fast stain
Exocytosis
The durable process by which a cell directs the contents of secretory vesicles out of the cell membrane and into the extracellular space. These membrane-bound vesicles contain soluble proteins to be secreted to the extracellular environment, as well as membrane proteins and lipids that are sent to become components of the cell membrane. However, the mechanism of the secretion of intra-vesicular contents out of the cell is very different from the incorporation of ion channels, signaling molecules, or receptors at the cell membrane.
Cytoplasm
The gel-like substance residing within the cell membrane holding all the cell's internal sub-structures (called organelles), outside the nucleus. All of the contents of the cells of prokaryote organisms (such as bacteria, which lack a cell nucleus) are contained within the cytoplasm. Within the cells of eukaryote organisms the contents of the cell nucleus are separated from the cytoplasm, and are then called the nucleoplasm.
Cristae
The internal compartments formed by the inner membrane of a mitochondrion. They are studded with proteins, including ATP synthase and a variety of cytochromes. The maximum surface for chemical reactions to occur is within the mitochondria.
Cytosol
The liquid found inside cells, that is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into compartments. The contents of a eukaryotic cell within the cell membrane (excluding the cell nucleus), is referred to as the cytoplasm.
Endosymbiotic theory
The theory that argues that mitochondria, plastids (e.g. chloroplasts), and possibly other organelles of eukaryotic cells, originate through symbiosis between multiple microorganisms. According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts. Mitochondria developed from proteobacteria (in particular, Rickettsiales, the SAR11 clade, or close relatives) and chloroplasts from cyanobacteria.
Microfilaments
The thinnest filaments of the cytoskeleton, a structure found in the cytoplasm of eukaryotic cells. These linear polymers of actin subunits are flexible and relatively strong, resisting buckling by multi-piconewton compressive forces and filament fracture by nanonewton tensile forces. Microfilaments are highly versatile, functioning in cytokinesis, amoeboid movement, and changes in cell shape.
