Microbiology and Parasitology MCC-4 PDF

MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN INTRODUCTION PROKARYOTES MICROBIOLOGY AND PARASITOLOGY...

MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN INTRODUCTION PROKARYOTES MICROBIOLOGY AND PARASITOLOGY Structures external to cell wall Cell Wall itself Designed to assist students in the study of important Structures internal to cell wall microorganisms and parasites. It explains the physiology DNA in a prokaryote is not membrane bound. In and pathogenic properties of bacteria, fungi and viruses other words, there is no nucleus. as an introduction to causation, their biology, the Unlike eukaryotes, which generally have multiple infections they cause, host response to these infections linear chromosomes, prokaryotes have one and their mode of transmission, prevention, treatment circular chromosome and nursing responsibilities. The laboratory experiences Prokaryotes do not have membrane-bound provide specimen collection, handling and processing of organelles specimens for isolation and identification of The cell walls of prokaryotes almost always microorganisms and parasites involved in the infectious contain a structure called peptidoglycan. processes. Prokaryotes divide by binary fission. MICROBIOLOGY STRUCTURES EXTERNAL TO CELL WALL Micro-very small, minute Prokaryotes have three different types of appendages: Biology- Study of life 1. Flagella for motility 2. Fimbriae for attachment The study of the biology of microscopic organisms. 3. Pili for DNA transfer (viruses, bacteria, algae. fungi, slime molds, and protozoa.) Prokaryotes use only flagella for motility. However, keep in mind that not all prokaryotes are motile. PROKARYOTE VS. EUKARYOTE The term prokaryote comes from the Greek (pro), meaning "before" and (karyon) meaning "nut" or “kernel" which means "pre-nucleus" or "before nucleus". The word eukaryote comes from the Greek eu, well and karyon "nut or kernel," which is a common scientific word forming element that's used to talk about the nurse cells. This means "true nucleus” Flagella can be arranged 4 different ways in Prokaryotes: PROKARYOTE EUKARYOTE 1. Peritrichous, meaning the flagella are distributed Unicellular Multi-cellular over the entire cell, much like cilia would be on a Binary Fission, Mitosis, Meiosis eukaryotic cell. budding fragmentation 2. Monotrichous, meaning single polar flagellum. DNA storage in DNA storage in 3. Lophotrichous, meaning two or more flagella at Cytoplasm nucleus one pole (or end of the cell) No nucleus With nucleus 4. Amphitrichous, meaning tuft of flagella at each No organelles With organelles end of cell Size of cell is small Size of cell is large (0.2 um x 2-8 um) (10 to 100 pan in diameter) MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN Fimbriae are hair-like appendages used for attachment. There are generally many of them that surround the cell. Again, not all prokaryotes have fimbriae. Neisseria gonorrhoeae uses fimbriae to colonize mucous membranes. It is the organism responsible for gonorrhoea. Pili sometimes fimbriae and pili used Flagella is located outside of cell wall interchangeably in some textbooks Filament made of chains of flagellin usually longer than fimbriae and number only 1 Attached to a protein hook or 2 per cell. Anchored to the wall and membrane by the long hollow tubes that can attach one cell to basal body. another for a brief period of time Flagella proteins are H antigens. join bacterial cells in preparation to transfer DNA from one cell to another (also referred to as sex Flagella pili) prokaryotes move in a circular motion like a the Pilus is the actual tube through which the propeller instead of the whip- like motion used by DNA is transferred eukaryotic flagella. Like in eukaryotes, prokaryotes can have a glycocalyx. Motility Prokaryotes consists of “runs” and “tumbles”, Again the glycocalyx is a sticky substance that surrounds swims, swarms, glides, twitch or floats. the cells and is used for attachment. Motility enables the microbe to move towards The glycocalyx is a fuzzy, gel-like, sticky layer favorable conditions or away from unfavorable made up mainly of proteins and sugars. It conditions. surrounds the outermost cellular membrane of Don’t be fooled though. Microbes are not cells. “thinking” entities. They move as a result of chemical messages that the cell receives from There are two forms the glycocalyx can take: the environment. Capsule- is a sugar coat that is thick and gummy that surrounds the cell. A capsule is generally an indicator of virulence in bacteria and aids in attachment and colonization of the host Slime layer- a loose shield around the bacteria that helps prevent water and nutrient loss. Slime layers also help form biofilms (layers of bacteria that are impenetrable by antibiotics and other chemicals) Cell Wall Almost all organisms have cell walls: - (Mycobacteria is an exception) MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN The function of the cell wall in prokaryotes is to Next is a thin layer of peptidoglycan that is prevent the cell from rupturing when the pressure loosely attached to the inside of the outer inside cells is greater than pressure outside the membrane. cell. Surrounding the peptidoglycan on the top and bottom is the periplasmic space The cell wall is composed of 2 main molecules: Forms the periplasm between the outer 1. N-acetylmuramic acid (NAM) membrane and the plasma membrane. 2. N-acetylglucosamine (NAG)- also known as Protection from Phagocytes, complement, peptidoglycan antibiotics. O polysaccharide antigen. (e.g. E. Coli O157:H7) Many disease causing bacteria can be grouped into one Lipid A is endotoxin of two categories based on their cell wall structure: Porins (proteins) form channels through the 1. Gram positive (G+) membrane. 2. Gram negative (G-). Gram-negative bacteria have cell walls with thin layers of peptidoglycan (10% of the cell wall) Gram Positive Cell Wall and high lipid (fatty acid) content. This causes them to appear red to pink under a Gram stain G + bacteria have a very thick and rigid cell wall; it is composed of a very thick layer of Gram-negative organisms include: peptidoglycan. Neisseria gonorrhoeae and Neisseria meningitidis Peptidoglycan (90%) is made up of repeating Gonorrhea units of NAG and NAM bound together and Moraxella species: layered on top of each other. - Escherichia coli (E. coli)- UTIs and food Teichoic acids poisoning ○ Lipoteichoic acid links to plasma - Pseudomonas species membrane - Proteus species- UTIs ○ Wall teichoic acid links to peptidoglycan - Klebsiella species- pneumonia bloodstream infections, wound or May regulate movement of cations. surgical site infections and bacterial Polysaccharides provide antigenic variation. meningitis Gram-Positive Organisms Includes: GRAM STAINING Streptococcus species- bacterial pneumonia Corynebacterium species Gram stain (Gram staining or Gram's method), is a Clostridium species- Food poisoning method of staining used to classify bacterial species into Listeria species- Food poisoning two large groups: gram-positive bacteria and Staphylococcus species- bacterial pneumonia gram-negative bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) and It may also be used to diagnose a fungal toxic shock syndrome. infection. The name comes from the Danish bacteriologist Hans Christian Gram, who Gram Negative CELL WALL developed the technique in 1884. It differentiates bacteria by the chemical and G- bacteria have a more complex cell wall physical properties of their cell walls. structure. It is composed of an outer membrane Gram-positive cells have a thick layer of (lipid bilayer) that contains LPS peptidoglycan in the cell wall that retains the (lipopolysaccharide) on the outside of the outer primary stain, crystal violet. membrane and phospholipids on the inside of Gram-negative cells have a thinner the outer membrane. peptidoglycan layer that allows the crystal violet to wash out in addition to ethanol. They are stained pink or red by the counterstain, MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN commonly safranin or fuchsine. Lugol's iodine membrane fluidity, permeability, and membrane solution is always added after addition of crystal protein functions. violet to strengthen the bonds of the stain with the cell membrane Archaea GRAM STAINING MECHANISM Wall-less, or Walls of pseudomurein (lack NAM and D amino Crystal violet-iodine crystals form in a cell. acids). N-acetyltalosaminuronic acid Gram-positive Pseudopeptidoglycan (also known as Alcohol dehydrates pseudomurein) is a major cell wall component of peptidoglycan some archaea that differs from bacterial CV-I crystals do not peptidoglycan in chemical structure, but leave. resembles eubacterial peptidoglycan in morphology, function, and physical structure. Gram-negative Alcohol dissolves N-acetyltalosaminuronic acid outer membranes acid is a uronic acid and leaves hales in component of pseudopeptidoglycan, a peptidoglycan. structural polymer found in the cell walls in some CV-I crystals washes types of Archaea out DAMAGE TO CELL WALLS Lysozyme is a protein that plays an important role in the innate immunity, providing protection against bacteria, viruses, and fung It attacks the protective cell walls of bacteria. I digests disaccharide in peptidoglycan. Penicillin inhibits peptide bridges in peptidoglycan. Penicillin kills bacteria through binding of the ATYPICAL BACTERIA beta- lactam ring to DD-transpeptidase, inhibiting its cross-linking activity and preventing Are bacteria that do not get colored by gram-staining new cell wall formation. Without a cell wall, a but rather remain colorless: they are neither bacterial cell is vulnerable to outside water and Gram-positive nor Gram-negative. molecular pressures, which causes the cell to quickly die Mycoplasmas Lack cell walls Protoplasts Sterols in plasma membrane is a wall-less gram-positive cell bacterial cells lacking a cell wall without an outer Sterols membrane. are isoprenoid-derived lipids with essential roles in cell structure, function, and physiology. As Spheroplasts important components of biological membranes, is a wall-less gram-negative cell. Bacterial cells sterols interact with phospholipids and proteins lacking a cell wall with an outer membrane and within the membrane. thereby regulating a plasma membrane. MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN L forms 3. Osmosis- movement of water across a selectively bacterial variants that lack a cell wall and divide permeable membrane from an area of high by a variety of processes involving membrane water concentration to an area of low water blebbing, tubulation, vesiculation and fission. concentration. are wall-less cells that swell into irregular shapes. 4. Osmotic Pressure- The pressure needed to stop Protoplasts and Spheroplasts are susceptible to the movement of water across the membrane.\ osmotic lysis. 5. Active Transport – of substances requires a transporter protein and ATP. PLASMA MEMBRANE 6. Group Translocation – requires a transporter protein and the structure of protein is altered., “Cell Membrane (cytoplasmic membrane)/ Plasma energy is supplied by phosphoenolpyruvic acid, Membrane” addition of phosphate to internalize glucose to Encloses the cytoplasm of the cell. Like form phosphorylated glucose. eukaryotes, the cytoplasm contains a lot of water, unlike eukaryotes it does not have microtubules or microfilaments It is a typical phospholipid bilayer Phospholipid bilayer is a two-layered arrangement of phosphate and lipid molecules that form a cell membrane. The hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward. Also called: lipid bilayer. STRUCTURES INTERNAL TO CELL WALL The function of the cell membrane is to selectively allow Cytoplasm: substance w/in cell membrane (selective permeability) materials such as It is 80% water. nutrients and wastes to enter and exit. It contains the nuclear area/nucleoids This is also the cite of Cellular Respiration (ATP (remember there are no membrane bound production). organelles inside a prokaryotic cell). Alcohols, quaternary ammonium (detergents), It contains ribosomes. and polymyxin antibiotics damage the It contains inclusions. membrane and cause leakage of cell contents. contains proteins, CHO, lipids, inorganic ions. FLUID MOSAIC MODEL Nuclear area (Nucleoids) The nuclear area contains the single circular Used to describe cell membranes chromosome found in prokaryotes. It states that the membrane is viscous as an olive Single, long, continuous, circular oil or fluid. It allows the proteins within the 20% volume of bacteria membrane to move throughout the Carry antibiotic resistance genes phospholipids freely. Can be transferred from one to another Proteins move to function. bacterium. Phospholipids rotate and move laterally. Sometimes plasmids are also found in the nuclear area. MOVEMENT ACROSS MEMBRANES Plasmids 1. Simple diffusion- movement of a solute from an are small, circular pieces of DNA that contain area of high concentration to an area of low extra genes that the cell can use. concentration. Sometimes they carry genes for antibiotic 2. Facilitated diffusion- solute combines with a resistance or for toxins transporter protein in the membrane. MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN They are also used very frequently for genetic engineering because they are easily manipulated and can be easily moved into a cell. Ribosomes Ribosomes in prokaryotes are free. Like ribosomes in eukaryotes, they are the site for protein synthesis. There is a difference in the structure and mass of the ribosomes in eukaryotes and prokaryotes. This is important to know because it helps to treat bacterial infections. Inclusions Storage for reserve nutrients Polysaccharide granules: store glycogen and starch SHAPE AND ARRANGEMENT OF BACTERIAL CELLS Lipid inclusions - energy reserves Sulfur granules – energy reserves Carboxysomes: store enzymes for carbon fixation Bacterial cells come in all kinds of shapes and sizes and from carbon dioxide arrangements. Gas vacuoles: control buoyancy to receive sufficient oxygen, light and nutrients Coccus, single ball shaped cell (cocci, many ball Magnetosomes: store iron oxide, act like magnet shaped cells) to reach attachment sites - Diplococci, two ball shaped cells connected together. ENDOSPORES - Streptococci, chains of ball shaped cells. - Tetrads, four ball shaped cells bound together. - Sarcinae, groups of eight ball shaped cells Some bacteria, such as Bacillus and Clostridium, connected together form resting cells called endospores upon - Staphylococci, balled shaped bacteria depletion of nutrients in the environment. connected together in what look like grape Endospores are essentially highly durable clusters dehydrated cells, similar to a plant seed. It contains all the genetic information of the Bacillus (bacilli) is rod shaped bacteria original cell and will form a living cell again once - Diplobacilli, two rods connected together. the environmental conditions are right. - streptobacilli, chains of rods connected end to Endospores are formed inside the cell and then end. released into the environment when the cell dies. - Coccobacilli, short fat rods that look similar to Upon release, endospores can survive extreme cocci. heat, lack of water, exposure to many toxic - (Bacillus has to meanings. Bacillus, the genus chemicals, and radiation name of bacteria and bacillus, the cellular shape Sporulation is the process of endospore of a bacterium.) formation. Germination is the process where the endospores Other shapes returns to its vegetative state (living cell). - Vibrio, comma shape. Sporulation does not increase the number of cells - Spirilla, spirochetes and others but rather preserves the genetic information of the parent cell until conditions are right for it to EUKARYOTIC CELLS grow again MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN Like a prokaryotic cell, a eukaryotic cell has a plasma FLAGELLA OVERVIEW membrane, cytoplasm, and ribosomes. However, unlike prokaryotic cells, eukaryotic cells have: Flagella are hair-like structures emerging through the cell a membrane-bound nucleus surface. They help in locomotion in prokaryotic and numerous membrane-bound organelles eukaryotic cells. (including the endoplasmic reticulum, Golgi apparatus, chloroplasts, and mitochondria) Flagella are of three types: several rod-shaped chromosomes Bacterial flagella Archaeal flagella Eukaryotic flagella- they beat back and forth to bring movement. E.g., sperm cells. The structure is similar to motile cilia, but length and functions differ. The core of eukaryotic flagella is called an axoneme, which comprises microtubules with a 9+2 arrangement. The nine doublets surround the 2 central singlets. EUKARYOTIC CELL WALL A cell wall is a rigid structure present outside the plant cell. It is, however, absent in animal cells. It provides shape to the cell and helps in cell-to-cell interaction. It is a protective layer that protects the cell from any injury or pathogen attacks It is composed of cellulose, hemicellulose, pectins, proteins, etc. Plant and algae- cellulose Fungi- chitin (NAG) Yeast – glucan, mannan Glycocalyx The glycocalyx is a system of protein -linked ( glycoproteins) and lipid -linked carbohydrates CILIA OVERVIEW that span the plasma membrane of a eukaryotic cell forming a slimy layer. Cilia are short hair-like structures present in large numbers in eukaryotic cells. PLASMA MEMBRANE Cilia are of two types: The plasma membrane separates the cell from non-motile the outside environment. motile It comprises specific embedded proteins, which help in the exchange of substances in and out of The motile cilia are found in the respiratory tract and the cell. fallopian tubes of the human body. where they sweep ○ Selective permeability mucus in the airways and facilitate the movement of ova ○ Simple diffusion from the ovary to the uterus, respectively. ○ Facilitated diffusion Non-motile cilia are also known as sensory cilia or primary ○ Osmosis cilia. They act as sensory organelles. They receive signals ○ Active Transport from nearby cells and act as antennae for the cells. E.g. cilia present on olfactory neurons and hair cells. MICROBIOLOGY AND PARASITOLOGY MCC-4 bY: STEPHANIE E. MASIADO, SN Endocytosis- a cellular process in which substances are Endoplasmic Reticulum - It is a transport network of small, brought into the cell. The material to be internalized is tubular structures that divides the cell surface into two surrounded by an area of cell membrane, which then parts: luminal and extraluminal. buds off inside the cell to form a vesicle containing the ingested material. Endoplasmic Reticulum is of two types: Phagocytosis (from φαγεῖν 'to eat', and κύτος Rough Endoplasmic Reticulum – associated with 'cell') is the process by which a cell uses its ribosomes; makes secretory and membrane plasma membrane to engulf a large particle (≥ proteins. 0.5 μm), giving rise to an internal compartment Smooth Endoplasmic Reticulum – makes lipids called the phagosome. “to eat” Pinocytosis is the method by which a cell absorbs Golgi Complex – Golgi apparatus or Golgi Body, is small particles outside the cell and brings them the packaging of materials for secretion. The Golgi inside. A process by which liquid droplets are apparatus is the major collection and dispatch station of ingested by living cells. “To drink”. protein products received from the ER. The Golgi apparatus is also involved in lipid transport and lysosome Cytoplasmic membrane - is a biological membrane that formation. separates and protects the interior of a cell from the outside environment (the extracellular space). Lysosomes - is a membrane-bound cell organelle that contains digestive enzymes. Lysosomes are involved with Cytosol – is the liquid found inside the cells. It is the various cell processes. They break down excess or water-based solution in which organelles, proteins, and worn-out cell parts. They may be used to destroy invading other cell structures float. viruses and bacteria. Cytoskeleton - is present inside the cytoplasm, which Vacuole - helps in storage of salts, minerals, pigments and consists of microfilaments, microtubules, and fibers to proteins within the cell. It isolates metabolic waste that provide perfect shape to the cell, anchor the organelles, might be harmful to the cell. It maintains turgor pressure. It and stimulate the cell movement. facilitates endocytosis and exocytosis. Mitochondria- Mitochondria are membrane-bound cell Cytoplasmic streaming – also called protoplasmic organelles (mitochondrion, singular) that generate most streaming and cyclosis. Is the flow of cytoplasm inside the of the chemical energy needed to power the cell's cell, driven by forces from the cytoskeleton. biochemical reactions. Chemical energy produced by the mitochondria is stored in a small molecule called ORGANELLES adenosine triphosphate (ATP). Nucleus - nucleus houses the cell's DNA and directs the Chloroplast - is a type of plastid (a saclike organelle with synthesis of proteins and ribosomes, the cellular a double membrane) that serves as the site of organelles responsible for protein synthesis. photosynthesis, the process by which energy from the Sun is converted into chemical energy for growth. The nucleus stores chromatin (DNA plus proteins) in a Chloroplasts contain the pigment chlorophyll to absorb gel-like substance called the nucleoplasm. The nucleolus light energy. is a condensed region of chromatin where ribosome synthesis occurs.The boundary of the nucleus is called the nuclear envelope. It consists of two phospholipid bilayers: an outer membrane and an inner membrane. The nuclear membrane is continuous with the endoplasmic reticulum. Nuclear pores allow substances to enter and exit the nucleus.