Classification and Characteristics of Cells

Classification of Cells

• Living cells, the smallest units of independent existence, are divided into eukaryotes and prokaryotes
• Eukaryotes possess a nucleus, while prokaryotes lack one
• All bacteria lack a nuclear membrane, and their nuclear content is suspended in the cytoplasm

Pathogenic Organisms

• Pathogens are microorganisms capable of causing disease in animals or humans
• Specifically, prokaryotic cells are pathogenic.

Characteristics of Bacteria

• Bacteria have a rigid cell wall containing a layer of peptidoglycan, which provides them with a defined shape
• Bacteria reproduce through binary fission
• Bacteria exhibit considerable morphological diversity, aiding in their identification, and their size is small compared to eukaryotic cells

Bacterial Sizes and Morphology

• Red blood cells are easily observed using conventional light microscopy, with a size of 7 µm.
• Bacillus bacteria are rod-shaped, generally stained by the Gram method.
• A clear field microscope and 1,000x magnification are needed to observe them
• Coccus bacteria are spherical and form chains or cluster, with a size of 1 μm
• Spirochaeta bacteria are thin and helical, requiring dark-field microscopy or special staining methods to demonstrate them, at a 10 μm size.

Morphological Differences in Bacteria

• Bacteria come in cocci (spheres), bacilli (rods), and spirilla (spirals) shapes.

Cocci Arrangements

• Cocci can be arranged in groups, chains (streptococci), pairs, or tetrads

Bacilli and Spirilla Features

• Bacilli: elongated rods that resemble sticks
• Spirilla: shorter and more coiled than spirochetes

Capsule Structure

• The bacterial capsule is a well-defined structure firmly attached to the cell wall

Capsule Composition and Function

• Capsules are mostly composed of polysaccharides (sugars), although some bacteria produce polypeptide capsules
• Capsules functions include resistance to phagocytosis, desiccation, and toxic substances, as well as aiding in surface fixation

Bacterial Surface Coverings

• Bacteria may have capsules, glycocalyx (mucous layer), or biofilm coatings on their surface

Capsule Staining

• Capsules require special stains to be visible, such as those used to stain the capsules of cocci white

Cell Wall Function

• The cell wall protects bacteria from mechanical damage and osmotic lysis and allow for the staining of the bacteria
• It provides flexibility and selective permeability, allowing substances to enter or exit

Gram-Positive Cell Walls

• Gram-positive bacteria have a relatively thick and uniform cell wall, composed of peptidoglycan and teichoic acids
• Gram-positive bacteria stain purple or blue

Gram-Negative Cell Walls

• Gram-negative bacteria have a thinner cell wall and an outer membrane containing peptidoglycan that contains molecules of LPS (Lipopolysaccharide)
• Gram-negative bacteria stain pink

Gram Staining

• Acid teichoic is not relevant to Gram staining

Gram Staining Procedure

• Gram staining: bacteria are fixed, stained with crystal violet, treated with iodine, decolorized with alcohol, and counterstained with safranin
• Crystal violet stains all cells blue or purple.
• Iodine acts as a mordant, enhancing the stain's adherence
• Gram-positive cells retain the crystal violet stain due to their thick peptidoglycan layer.
• Alcohol decolorizes Gram-negative cells because of external layer breaking down
• Safranin then stains the decolorized Gram-negative cells pink

Nucleoid Differences

• Eukaryotes have two or more chromosomes within a membrane-bound organelle (nucleus), procaryotes have no nucleus
• Nucleoid structures are present in almost all bacteria for genetic material

Genes in the Chromosome

• Bacterial genes encode life functions, inside a circular, single chromosome of double-stranded DNA
• Chromosome size is related to its environment and the complexity/adaptation of the bacteria

Plasmids

• Plasmids are small, autonomous DNA fragments separated from the genome
• Plasmids can transfer genes between cells, code for antibiotic resistance, and produce exotoxins
• Plasmids are are not always needed and can be transferred leading to antibiotic resistance across other bacteria

Cytoplasmic Membrane

• The cytoplasmic membrane transports nutrients, eliminates waste, and allows the passage of certain substances based on size and need
• It's a selective barrier for nutrients, wastes, mechanical support, metabolic processes, and signal detection

Ribosomes

• Ribosomes are structures found in eukaryotic and prokaryotic cells, distributed in the cytoplasm, and made of proteins
• Responsible for protein synthesis for cell processes

Cytoplasm

• Cytoplasm: aqueous liquid containing nuclear material, ribosomes, nutrients, enzymes, and other molecules for cell maintenance and metabolism

Flagella and Pili

• Flagella aids in bacterial movement through a filament, hook and a basal body structure
• Pili are fine, straight, hair-like appendages on bacterial cell walls of gram-negative bacteria for adhesion
• Pili can transfer DNA between bacteria

Endospores

• Endospores are highly resistant, vegetative spores formed by bacteria to ensure survival in adverse environments
• Bacillus and Clostridium form spores, which are broken down through autoclaving.
• Spores can be in dry environments

Immune System in Bacterial Diseases

• Host animals respond to pathogens with immune cells and molecules, triggered by invading pathogens
• An immune response is a series of related events
• The route of the response depends on of the agent and the type of disease

Pattern Recognition

• The innate immune system recognizes molecular patterns on pathogens (PAMPs) through sentinel cells

PAMPs

• PAMPs are molecules emitted by the pathogen, recognized by sentinel cells
• They are molecular structures recognized as danger signals

Sentinel Cells

• Sentinel cells are innate immune system cells that detect PAMPs and activate immune responses
• Sentinel cells are mast cells, dendritic cells, Langerhans cells, and macrophages.

Cytokines

• Cytokines help sentinel cells identify pathogens

Cytokine Production

• Infection induces production of cytokines (IL-1, TNFα, IL-6) that are related to the “behaviour of the disease."

Fever

• The body increases cytokine to activate necrosis factor, to have the immune system control the pathogen
• Fever indicates the inflammatory response. While it can contribute towards healing, it needs moderation

TLRs

• TLRs recognize sentinel cell signals
• TLR signaling pathways detect pathogens

Innate Immunity

• Anatomical barriers such as skin and mucous prevent pathogen penetration
• Physiological processes trigger defense from pathogens
• Gut's healthy flora prevents pathogen colonization

Antimicrobial Peptides

• The body uses peptides to attack the membranes of pathogenic molecules
• Body creates these with: defensins and catelicidins

Células efectoras del sistema inmune innato

• Células efectoras del sistema inmune innato:
• Neutrófilos: combaten infecciones bacterianas mediante fagocitosis y liberación de productos tóxicos
• Macrófagos: fagocitan patógenos y presentan antígenos
• Células NK: destruyen células infectadas o tumorales mediante perforinas y granzimas
• Células T yo: Juegan un rol en la defensa contra infecciones bacterianas y virales mediante la liberación de citoquinas y actividad citotóxica.

Adaptive Immunity

• Adaptive immunity occurs after sentinel cells that detect alerts the host by presenting to T helper

Adaptive Cell Instructions

• Adaptive cells are instructed through cellular and body detection

Adaptive Immunity Phases

• Responses occur by antibodies/cells for antigen detection

Humoral Response

• adaptive
• Mediated by antibodies and B cells

Cellular Response

• Adaptive response mediated by T cells
• T CD8+ (cytotoxic) and T CD4+ (helper) cells activate macaophages
• Helper cells activate bacterial infections in MHC-1 by releasing cytokines.

Immune Answer

• Lymphocytes and T CD4 trigger infections, with CD8 producing cytokines.

Responses to Bacterial Infections

• Gram-positive vs gram-negative infections: structure, detection, response, and resistance

Gram Reaction with Inmune

• Structure has thick cellular levels with peptidoclycan, acid • Immune responds with peptidoglycan in walls, to detect as such, in the walls. • Immune detects denritic, causing activation/ response with neutrophils. • Bateria activates by removing parts and not being destroyed.

Gram Different Reactions with Inmune

• Structure has thin cellular levels with lipopolysaccharides (LPS) • Immune responds with peptidoglycan in walls(TLR 4) • The surface is recognized activates a response that is strong/cytokines with macrophils, that self affect. • LPS can induce a great response and massive ctytokines shock, causing sepsis.

Vaccination Strategy

• Vacnnies are surface proteins induce immune/protective response.
• To the streptrococco Pneumoniae.

Vaccination, negative Strategy

• Vacine based outside membrane/coat/layers of LPS, ex. neisseria and escherichia.

Vacinnation Process

• Intracelulares are distinct, due to living inside cells.

Characteristics of Bacterias

• Responds and reacts, making sure there are the parts if there is a cell that has entered.

Gram Reaction - Vaccination

• If the bacteria is not a meal or cant stop if its too big, itll have extra shield for the inmmune.

Characteristics of Bacterias: vaccination

• Has a different response for those cells/ bacterias, they create an extra shield, so their is a lack of being affected.

AntiBodies Response

• ExtraCellular bacterias.
• Main, TH2 anitobodies, phogocytosis, for neutralizing
• Low chance unless there is a cellular activation

Intracelluar Response is distinct

• Cells enter and are activated, its limited to those that can make more cells, due to limitations.

BioSafety principles include:

• Containment of dangerous biological agents and toxins
• Combination of primary and secondary barriers
• Safe equipment and practices

Risk groups:

• Group 1 - Not associated with disease in healthy adults
• Group 2 - Rarely serious human diseases; preventative or therapeutic interventions often available
• Group 3 - Serious or lethal human diseases; preventative or therapeutic interventions may be available
• Group 4 - Likely cause serious or lethal human diseases for interventions which are available on a broad spectrum.

Lab Sample Analysis

• The investigation of laboratory of bacterial deceases is needed to identified etiological agent to determine its susceptibly to atibiotics To make clinic diagnosis, you have ensure to know patient and animal history

Sample Collection

• Sample collect on specific areas. before clinical signs.

To collect samples: its important to:

• Be specific when removing part
• Microbial will be in that area

Prevent Contanments

• Prevent pathogens by any means due to being important.

Things labs need to hear

• Ensure the lab receives and knows more info.

Samples of Fluids

• 2 cm3 aprox of liquid.

Blood Sampls

• Serum of fluids or part in the body

How to prevent cros contaiments?

• When samples have an amplification and is specific on pcr for zoomotic.

Steps for Tíssues

• To collect samples: its important to: Be specific when removing part - Tissue has to be 1cm2

• To have it clear to where you got it, be accurate Avoid putting liquid or contamination.

Sample collection

• Avoid putting liquid and getting blood/tissues samples.

Swab Samples

• Swabbing sample of liquid with bigger surface area for the best source/case

Special Cultures: Diagnosis Lab of Specific Pathogens

• Lab provide equipment so that it is stable.

Wound Samples

• To collect open wounds without causing danger or contamination of the body by being accurate of how much/small the wound is

Tinna Samples

• Tonna samples will only be relevant and specific on area to draw blood for how specific it has to be.

Why we cant frezze

• It makes blood lysate.

Feces sample?

• Get it to lab immediatley so you can check sample. and get transport.

Urine Samples

• For culture

For Abessos

• Recoltate as much puss as they cans. and take off side.

Eyeball samples

• When cutting away to take off tissue

Milk from cow

• Wont use cow/milk treated with medicine

Labelling

• Name and info will be important, send it with samples in case they ask for more or if the job gets mixed, so important its specific with sample to prevent mix up.

Ear Sample

• Puss/or infection from ears to be removed by ear cleaners.
• Conjupitual sample requires steriile and precise movements, after, fix and clear.

Animal Sample

• Use a sample depending on animal but if there are things such pressure or lack of area may affect process.

Clean Samples

• Disposing items away form other animals that are getting stressed.

Cloaca Process for Taking Samples

• Make sure its closed well to avoid anything falling, use label

Samples of swabs

• Can eliminate material for a liquid.