ANS 150 Animal Health and Disease--Midterm 1

Light Microscope

found in most schools, use compound lenses and light to magnify objects. The lenses bend or refract the light, which makes the object beneath them appear closer (1,000-2,000 times)

Stereoscope

this microscope allows for binocular (two eyes) viewing of larger specimens

Scanning Electron Microscope

allow scientist to view a universe too small to be seen with a light microscope. SEMs do not use light waves; they use electrons (negatively charged particles) to magnify objects up to 2 million times

Transmission Electron Microscope

also uses electrons, but instead of scanning the surface (as with SEMs) electrons are passed through very thin specimens. Specimens may be stained with heavy metal salts. Up to 10,000 times

3 magnifications of a light microscope

Scanning, low and high

each objective will have the written magnification. In addition to this the ocular (eye) lens has a magnification

How to calculate total magnification

total magnification=magnification of eyepiece (ocular) x magnification of objective lens

types of light microscopes

Compound light microscopy

dark field microscopy

phase-contrast microscopy

differential interference contrast microscopy

fluorescence microscopy

confocal microscopy

Unit of measurement for cells and microscopic organisms

micrometer (micron)

1 micron= 1x10^-6 meters/ 1x10^-3 mm

1 mm= 1x10^6 nanometers/ 1x10^3 microns

How small is a micrometer?

1. a human hair is about 100 microns wide

2. a red blood cell is about 8 microns wide

3. typical animal cell is about 10-100 microns wide

Components of a naked virus

capsid

nucleic acid

Components of an enveloped virus

Envelope

spike

capsid

nucleic acid

Why are viruses not classified in any kingdom yet?

Because they are not really alive.

they only show signs of life after they infect the host cell

Does not carry out any metabolic functions on its own and cannot reproduce on its own--until it invades the host cell

only replicate when living in a host cell

Components of a virus

DNA/RNA core

Core is surrounded by protein coat

coat may be enclosed in a lipid envelope

naked or enveloped virus connected to a rod and sheath with tails on the bottom

viroids

nucleic acid without protein coating

prions

infectious proteinaceous particles

Types of Eukaryotes

Protozoa

Algae

Fungi

multicellular animal parasites

helminths

flatworms and round worms

Fungi

Chitin cell walls

Use organic chemicals for energy

Molds and mushrooms are multicellular, consists of mycelia (composed of filaments called hyphae)

yeasts are unicellular

Protozoa

unicellular eukaryote

Absorb or invest organic chemicals

May move using pseudopods, cilia, or flagella

e.g. Amoeba

Algae

unicellular/multicellular

eukaryotes

has cellulose walls

gain energy through photosynthesis

produce molecular organic compounds

Bacteria

Prokaryotes

has peptidoglycan cell walls

binary fission

utilize organic/inorganic chemicals or photosynthesis to obtain energy

Archaea

Prokaryotes

lack peptidoglycan

usually live in extreme environments and could be found in soils, gut, etc.

Binary fission, fragmentation, budding

utilize organic compounds such as sugars, to ammonia, metal ions, or hydrogen gas such as

-methanogens

-extreme halophiles

-extreme thermophiles

Linnaeus

system for scientific nomenclature

Each organism has two names:

1) Genus (capitalized)

2) Specific epithet (lowercase)

Could be named as an honor to the scientist

Has a latin origin

Horizontal Gene Transfer

Gene expansion for microns to adapt to their environment horizontally to relatives that are only distantly related eg. other species and other genera

-through mechanisms such as transformation, transduction, and conjunction, genetic elements such as plasmids, transposons, interns, and even chromosomal DNA can readily be spread from one microorganism to another

How microbes adapt to their environment

Microbes are known to live in remarkably diverse environments, many of which are extremely harsh

this adaptability is a result of their ability to quickly modify their repertoire of protein functions by modifying, gaining, or losing their genes

horizontal gene transfer

5 types of microorganisms

bacteria

protozoa

fungi

algae

virus

Characteristics of Bacteria

Cell Type: Prokaryotic

Membrane: Unbranched fatty acid chain

Cell Wall: Peptidoglycan

rRNA sequence: unique

Characteristics of Archaea

Cell Type: Prokaryotic

Membrane: branched hydrocarbon chains

Cell Wall: No peptidoglycan

rRNA sequence: unique

Characteristics of Eukarya

Cell Type: Eukaryotic

Membrane: unbranched fatty acid chain

Cell Wall: No peptidoglycan

rRNA sequence: unique

the Tree of Life

is based largely on rRNA genes (encode for proteins) which have evolved slowly, allowing for detection of homologies between distinctly related organisms

eukaryotes and archaea are more closely related to each other than bacteria

3 domain system

Bacteria

Archaea

Eukarya

supported by data from many sequenced genomes

highlights the importance of single celled organisms in the history of life

Bacteria and Archaea are single celled

Domain Eukarya

Plants

animals

fungi

red and green algae

amoebas

ciliates

diatoms

forums

euglenozoans

Domain Archaea

Nanoarchaeotes

Methanogens

Thermophiles

Domain Bacteria

Proteobacteria

Mitochondria

Clamydias

Spironchetes

Gram-positive bacteria

Cyanobacteria

Chloroplasts

Early classifications

either plants or animals

later five kingdoms were recognized: Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia

more recently the 3 domain system

Classification in order

Species

Genus

Family

Order

Class

Phylum

Kingdom

Domain

Microbes in our lives

some are pathogenic (disease-causing)

decompose organic waste

produces through photosynthesis

play role in industry

produce fermented food

produce products used in manufacturing (cellulose) and treatment (insulin)

Microorganisms can cause infections in:

respiratory system

CNS

GI tract

Urinary tract

genital system

skin, soft tissues and wounds

joint and bones

Characteristics of a Microorganism

too small

germ-rapidly growing cell

has habitat

lives in a population

communities are either swimming freely or attached to a surface (biofilm)

Interact between communities--may either be

-harmful (because of waste products) or

-beneficial (cooperative feeding efforts-waste-->nutrient)

Size Range of Microbiology

20 nanometers to 5 micrometers

Two themes involved in Microbiology

Basic: cellular processes

Applied: concerning agriculture, industry and health

Microbiology

study of microorganisms

foundation of modern biotechnology

many specialized fields

Koch's Postulates (1884)

the critical test for the involvement f a microorganism in a disease

1. the agent must be present in every case of the disease

2. the agent must be isolated and cultured in vitro

3. the disease must be reproduced when a pure culture of the agent is inoculated into a susceptible host

4. the agent must be recoverable from the experimentally infected host

This eventually led to

DEVELOPMENT OF PURE CULTURE TECHNIQUES STAINS, AGAR, CULTURE MEDIA, PETRI DISHES

1546 Hieronymus Fracastorius

wrote "on contagion" the first known discussion of the phenomenon of CONTAGIOUS INFECTION

1835 Agostino Bassi de Lodi

Showed that a disease affecting silkworms was caused by a fungus--the first MICROORGANISM to be recognized as a CONTAGIOUS AGENT OF ANIMAL DISEASE

1847 Ignaz Semmelweiss

decided that doctors in Vienna hospitals were spreading childbed fever while delivering babies. He starting forcing doctors under his supervision to WASH THEIR HANDS BEFORE TOUCHING PATIENTS

1857 Louis Pasteur

proposed the "germ theory of disease" fought to convince surgeons that germs existed and carried diseases, and dirty instruments and hands spread germs and therefore disease. PASTEUR'S PASTEURIZATION PROCESS KILLED GERMS AND PREVENTED THE SPREAD OF DISEASE

1867 Joseph Lister

INTRODUCED ANTISEPTICS IN SURGERY By spraying carboxylic acid on surgical instruments, wounds and dressings, he reduced surgical mortality due to bacterial infection considerably

1876 Robert Koch

was the first to CULTIVATE ANTHRAX BACTERIA outside the body using blood serum at body temperature

DEMONSTRATED THE FIRST DIRECT ROLE OF A BACTERIUM IN A DISEASE

Immunology

The study of the physiological mechanisms that hosts use to defend their bodies from invasion by all sorts of other organisms

Immunity

The ability to resist against infection

Antigen

Any foreign material that is specifically bound by specific antibody or specific lymphocytes

Antibody

Serum proteins formed in response to immunization and interact with antigens

Immune response

all of the phenomena that result from specific interactions of cells of the immune system with antigen. Immune response is the result of clonal expansion of T and B cells

Grandfathers of Immunology

Robert Koch:

-cellular immunity to tuberculosis

Emil Von Behring

-Serum antitoxins

Fathers of Immunology

Ilya llicc Mechnikov:

-Phagocytosis

Paul Ehrlich

-Antitoxin

Nobel Prizes for immunology research since 2002

2008 two french guys for their discovery of human immunodeficiency virus

2011 3 dudes their discoveries concerning the activation of innate immunity

Early concepts in Immunity

Phagocytosis (cellular immunity)

Side chain theory

Three functions of Immunity

Immune defense

Immune homeostasis

Immune surveillance

Normal manifestation of immune defense

Anti-infection

Abnormal manifestation of immune defense

hypersensitivity

immunodeficiency

normal manifestation of immune homeostasis

eliminate injured and senile cells

tolerate self components

Abnormal manifestations of immune homeostasis

immune dismodulation

autoimmune disease

normal manifestations of immune surveillance

destroy transformed cells (anti-tumor)

prevent persistent infection

Abnormal manifestations of immune surveillance

Tumor (cancer) or persistent virus infection

two types of immunity

Innate Immunity

Adaptive Immunity

Innate Immunity

Fast

mediated by cells, barriers, chemicals, proteins

no memory

native immunity (born with it)

pattern recognition but non-specific

responds to all antigens

Adaptive Immunity

Slow

mediated by lymphocytes

acquired Immunity

specific

responds to specific antigens by developing antibodies so it can recognize it if it encounters it again (has a memory for it)

enchanted by the second stimulation of the same antigen

transferable

self limitation

Components of non-specific immunity

temperature

pH

Barriers (skin, feathers)

Microflora

Cilia

Cells (neutrophils, macrophages)

Complement

Serum proteins

Components of specific immunity

B cells (derived from bursa of Fabricius or bone marrow)-->Antibody: IgM, IgG, IgE, IgA

T cells (thymus derived)

Killer and helper T cells

Abundance of leukocytes

Neutrophils 40-75%

Lymphocyte 20-50%

Monocyte 2-10%

Eosinophil 1-6%

Basophil <1%

3 Mechanisms of Innate immunity

Barriers

Humoral factors

Cells

Innate barriers

physical barrier: Skin and mucosa

Chemical barrier:antimicrobial substances in secretion of skin and mucosa

biotic barrier: normal flora existing on the surface of skin and mucosa

anatomic barriers: blood-brain barrier, blood-placental barrier, blood-thymus barrier

Innate humoral factors

Complement

lysozyme

interferons (IFN)

C-reactive protein

Cells participating in innate immunity

Phagocyte: endocytosis and phagocytosis mononuclear phagocytes

-monocytes

-neutrophils

-eosinophils

Natural Killer cells

Dendritic cells

Basophils

Mast cells

Neutrophil

activated function is phagocytosis and activation of bactericidal mechanisms

polymorphonuclear

phagocytosis (specialize in capture, engulfment, and killing)

Short life span (hours)

work in anaerobic conditions (damaged tissue)

Macrophage

Phagocytosis and the killing of microorganisms

-activation of T cells and initiation of immune response

Antigen presenting cells (APC)

long lived

first cell to respond to invading microorganism

secrete cytokines that recruit neutrophils and other leukocytes

Dendritic cell

Activated function: antigen uptake in peripheral sites and antigen presentation in lymphoid organs

In the blood and tissues--mature and migrate to the lymph nodes

distinctive star shape

act as cellular messengers that call up an adaptive immune response

activated by innate signals

Eosinophil

Activated function: killing of antibody-coated parasites

Basophil

Activated function: unknown

parasites?

Mast cell

Activated function: release of granules containing histamine and active agents

resident in all connective tissues

Natural Killer Cells

an innate lymphocyte

do not require prior immunization or activation

attach to target cells

cytotoxic granules are released onto surface of cell

effector proteins penetrate cell membrane and induce programmed cell death

Two functions:

-kill virus infected cells

-impede viral replication by secreting cytokines

How infection triggers inflammation

-Bacteria trigger macrophages to release cytokines and chemokines

-Vasodilation and increased vascular permeability cause redness, heat, and swelling

-Inflammatory cells migrate into tissue, releasing inflammatory mediators that cause pain

How Antigens are taken from tissue to T cells

-Immature dendritic cells reside in peripheral tissues

-Dendritic cells migrate via lymphatic vessels to regional lymph nodes

-Mature dendritic cells activate naive T cells in lymphoid organs such as lymph nodes

Pathogen Associated Molecular Patterns (PAMP)

allows the immune cell to recognize the pathogen as an infectious agent

Pattern Recognition Receptors (PRR)

Define the responsiveness of the host cells

Composition of adaptive immunity

T cells: cell mediated immunity

B cell" Humoral immunity or antibody mediated immunity

Education of B and T lymphocytes

-A single progenitor cell gives rise to a large number of lymphocytes each with a different specificity

-removal of potentially self reactive immature lymphocytes by clonal deletion

-pool of mature naive lymphocytes

-proliferation and differentiation of activated specific lymphocytes to form a clone of effector cells

Process of immune response

Antigen recognition

induction of response

regulation of response

Professional Antigen Presenting cells

Dendritic cell

Macrophage

B lymphocyte

Two Signal to activate a lymphocyte

1. Antigen-receptor binding and co-stimulation of T cell by dendritic cell (Proliferation and differentiation of T cell to acquire effector function

2. Antigen-receptor binding and activation of B cell by T cell (Proliferation and differentiation of B cell to acquire effector function)

Small resting lymphocyte

not encountered antigen

small amount of cytoplasm

absence of rough ER

condensed chromatin

Lymphoblast

Encountered antigen in lymph nodes

active cytoplasm

enlarged nucleus with diffuse chromatin

Effector B and T cells

Encountered antigen in lymph nodes

large amount of cytoplasm

prominent nucleoli

presence of ER

Cytotoxic T cell activation

-Virus infected cell

-cytotoxic T cell recognizes complex of viral peptide with MHC class I and kills infected cell

MHC

Major histocompatibility complex

MHC class I antigen processing pathway

virus infects cell

viral proteins synthesized in cytosol

peptide fragments of viral proteins bound by MHC class I in ER

bound peptides transporter by MHC class I to the cell surface

MHC class II antigen processing pathway

-bacterium infects macrophage and enters vesicle producing peptide fragments

-bacterial fragments bound by MHC class II in vesicles

-bound peptides transported by MHC class II to the cell surface

OR

-antigen bound by B cell surface receptor

-antigen internalized and degraded to peptide fragments

-fragments bind to MHC class II and are transported to the cell surface

T helper 1 and T helper 2 cells

T helper 1 cell recognizes complex of bacterial peptide with MHC class II and activates macrophage

T helper 2 cell recognizes complex of antigenic peptide with MHC class II and activates B cell