Bacterial Structures And Components PDF

Bacterial Structures/Components Chapter 7  Module 1: Question Submission Please use this document to submit any questions that you have related to the Module 1 content. We will review any questions submitted on this doc in class. What would be the size...

Bacterial Structures/Components Chapter 7  Module 1: Question Submission Please use this document to submit any questions that you have related to the Module 1 content. We will review any questions submitted on this doc in class. What would be the size relevance of some of these organisms and how would they relate to each other explicitly? (More in-depth but please explain in a digestible way) “Obligate intracellular parasites survive and reproduce inside themself (need living cell to replicate)” What does this statement mean? Does it only survive when it reproduces or it needs another living cell to survive and reproduce from? Assessments Module-2 KC-1 Module-2 KC-2 Module activity Module Quiz  4 Think * Pair * Share Imagine you are a microbiologist……… What criteria could you use to group bacteria??  5 Why do we classify organisms? Arrange related organisms into groups Sets universal criteria for identifying known/new organisms Provide information on how organisms evolved Unity among scientific community  Main types of Classification Taxonomy: – Science of classification – Organize living organisms into groups based on similarities and differences Phylogenetics: – Tracking evolutionary descent of organisms through studying the genetic material Learning Objectives Describe the structure and function of the components of a bacterial cell Distinguish between the various shapes and arrangements of bacterial cells Correctly utilize binomial nomenclature to name a bacterial species Compare and contrast Gram positive vs. Gram negative bacteria Cell Shapes and Patterns Morphology: bacteria are found in several common shapes (and arrangements), which are useful in species identification ○ Bacillus, (bacilli, pl.) rod shaped ○ Coccus, (cocci, pl.) spherical ○ Curved or spiral, (vibrio, curved; spirilla, rigid helix or wavy; spirochete, flexible helix)  Classifying Organisms Carl Linnaeus (1707-78) Developed hierarchal classification system Grouped living things together based on common physical characteristics A modified version is still used today Popularized binomial nomenclature (Genus species) Example: Escherichia coli Human Classification Eukarya Animalia Chordata (spinal cord) Mammalia (mammary glands) Primates (Grasping hands) Hominidae (bipedalism) Homo (human) sapiens (intelligent) Classification Example: Baker’s Yeast Bacteria Microbes are classified mostly based on…. Eubacteria Proteobacteria (Pseudomonodata)Morphological characteristics, Gammoproteobacteria Differential staining, Enterobacteriales Biochemical testing, Enterobacteriaceae DNA based methods. Escherichia Coli Naming Bacteria Bacteria are named using Linnaeus’s binomial classification system (having two Latinized names) ○ Genus name, capitalized (Escherichia) ○ Species name, not capitalized (coli) ○ Both names are italicized: Escherichia coli Bacteria names are frequently instructive Escherichia: Theodore Escherich Coli: From the colon  What is the binomial nomenclature for humans? – Homo sapien (Genus species) What is the binomial nomenclature for yeast? – Saccharomyces cerevisia (Genus species)  “Genus species” are used to name organisms (binomial nomenclature) The first letter in Genus is always capitalized The species is all small letters The Genus species should always be italicized or underlined – Staphylococcus aureus Homo sapien Or Or – Staphylococcus aureus Homo sapien Anatomy of a Bacterial Cell Envelope External to the cytoplasm Plasma membrane - selectively permeable Cell wall ○ Composition determines Gram positive vs. Gram negative ○ Prevents osmotic rupture of cell membrane Outer membrane (in Gram negatives only) Capsule (not present in all cells)  Gram Positive Bacteria 1. Thick peptidoglycan (PG) layer 2. Stain purple with Gram stain 3. Contain teichoic acids but not lipopolysaccharide (LPS) 4. No outer membrane 5. Sensitive to penicillin (mostly)  Gram Negative Bacteria 1. Thin PG layer 2. Stain pink/red with Gram stain 3. Contain LPS but not teichoic acids 4. Contain two membranes 5. Not sensitive to penicillin Examples of G+ and G- Bacteria Gram-Stain Learning Objectives Detail the process of the Gram-staining procedure and note its importance in distinguishing between Gram+ and Gram- cells Interpret the results of a Gram stain in order to identify Gram+ vs. Gram- cells  The Gram Stain The Gram stain is an important first step in the identification of bacteria pathogens. ○ Choice of antibiotics is influenced by the Gram stain reaction Broad spectrum antibiotics work against Gram+ and Gram – Narrow spectrum antibiotics work against Gram+ or Gram – 2/6/25 Components of a Bacterial Cell And Cell Division by Binary Fission Learning Objectives Describe the structure, function, and location of the components of a bacterial cell Outline the process of binary fission Compare and contrast plasmids vs. chromosomal DNA Distinguish between the different flagellar arrangements Bacterial chromosome and plasmids Cytoplasm and Nucleoid Cytoplasm = all of cell’s contents enclosed within the plasma membrane Nucleoid = region of cytoplasm containing chromosomal DNA ○ Double stranded DNA (dsDNA) ○ One or more circular and/or linear chromosomes Bacteria divide and reproduce their DNA by process of Binary Fission  Plasmids Small, circular, independently replicating pieces of dsDNA ○ Encode limited number of genes ○ Expand genetic capability of host cell Transferable from donor to recipient Endospores Extremely hardy structures that are highly resistant to heat, drying, radiation, and a variety of chemical compounds Make cells viable for long periods of time (centuries or longer) Important pathogens ○ Bacillus anthracis → anthrax, potential bioweapon ○ Clostridium spp. → tetanus, botulism, gas gangrene Process of endospore formation: A bacterial cell under unfavorable conditions…. 1. The mother cell DNA replicates 2. Membrane forms around DNA to form forespore 3. Protective cortex and outer membrane forms around the spore 4. Protein coat forms around the cortex 5. Mother cell lyses and spore is released Flagella Used for motility ○ Long, hollow, filament made of subunits called flagellin ○ Rotates like a propeller Aids in chemotaxis ○ Movement towards attractant or away from repellant Can have many arrangements ○ Single ○ Polar ○ Bipolar ○ Dispersed  Pili: Fimbriae and Sex Pilus Singular = pilus Shorter, straighter, and thinner than flagella Made of filaments composed of pilin protein Function ○ Adhesion - anchor for colonization of host cells and other surfaces ○ Transmission of DNA (via sex pilus) - form a bridge between donor and recipient bacterial cells