MB 251 Exam 1, Alice Lee

Several ways microbes affect our lives

Agents of disease, environmental damage, soil microbes decompose organic waste, producers in ecosystems, some produce ethanol and acetone. Microbes also produce vinegar, cheese, and bread. They also produce insulin and are in medicines. Bad microbes make up a biofilm

Viruses

Not cellular, very simple, core surrounded by protein coat, core made of nucleic acid

Bacteria

can be coccus(round), baccillus(rod), or spiral, has special peptidoglycan walls, some make their own food, some use organic compounds, some get nutrients from inorganic stubstances

Archaea

Similar to bacteria, no peptidoglycan in cell walls, often in extreme environments(hot, cold, extreme pH, very salty, etc)

Fungi

Can be multicellular(mushrooms) or unicellular(yeasts). Molds are most typical fungi, forms visible masses called mycelia

Protozoa

Unicellular, moves by pseudopods, flagella or cilia

Algae

are photosynthetic, wide range of size, abundant in any water, also in soil or in association with plants

Domains of Life

Bacteria, Archaea, Eukarya

Domain Bacteria includes

All pathogenetic prokaryotes, many non-pathogenetic prokaryotes found in soil and water. Includes photoautotrophic prokaryotes

Domain Archaea includes

no peptidoglycan in cell walls, carrys out unusual metabolic processes,, lives in extreme environments

-includes methanogens, extreme halophiles and hyperthermophiles

Domain Eukarya includes

plants, animals, protozoans, protists, and fungi

Scientific names are:

Genus is capitalized, species is lowercase

Ancient Microbiology Examples

-Early Egyptians knew how to make beer, wine, and bread

-Had mosaic law: avoid pork and seafood because of trichinosis risk

-Black Death

-Varro: believed diseases were caused by animals he couldnt see

Robert Hooke

Built Microscopes

-observed fleas, cork tree, mites and molds

-observed and made term "cells"

-led to cell theory later in history

didnt actually see cells, microscope was not powerful enough

Anton Van Leeuwenhoek

First to observe live microbes

termed them "animalcules"

first to actually see cells

Edward Jenner

in 1796, he inoculated a person with cowpox virus who was then protected from smallpox

-founded vaccination

Spontaneous generation

creatures like maggots, flies, toads, snakes, and microbes are formed directly from decaying matter

-thought to be from asexual reproduction, sexual reproduction, or from non living matter

Biogenesis

Living things arise from other living things

Louis Pasteur

-Disproved theory of Spontaneous Generation

-developed vaccines for cholera, anthrax and rabies

-inoculated chickens with old cholera microbes and they did not die. Took fresh cholera microbes and inoculated new chickens and the others from his experiment. New chickens died, the others did not

-Made rabies vaccine from fluid from old spinal cords

How Pasteurs work influenced Lister and Koch

Lister was a surgeon. He connected Pasteurs work connecting microbes and animal diseases to surgical wounds and diseases. He stated disinfecting wounds with phenol solution and it greatly decreased infections and death. Pasteur gave Koch the idea that microbes caused disease, but Koch proved that Anthrax was killing cattle in Europe and that it came from rod shaped bacteria.

Summarize the Germ Theory of Disease

Founded by , microorganisms might cause diseases. Linked activity of microorganisms to physical and chemical changes in organic materials from realization yeasts play crucial role in fermentation.

Kochs Postulates

1: Suspected pathogen must be present in all cases of diseased animals, but none in healthy ones

2:Suspected pathogen must be grown in pure culture

3: cells from pure culture cause disease in healthy animals

4: The suspected pathogen must be reisolated and be shown as the same as the original

Francesco Redi research

Disproved spontaneous generation. Took two jars, both with decaying meat. one had a lid and the other he left open. Maggots appeared on the one he left open. It was then said you need air for spontaneous generation, so Redi took the same two jars and covered one with gauze and left the other open. No maggots appeared in the one with gauze.

John Needham

Made a case for spontaneous generation. Found after he heated nutrient broth before pouring it into covered flasks, microbes grew inside of them.

Lazzaro Spallanzani

Disproved Needhams claims by saying microorganisms entered the flasks from the air. He showed that fluids being heated after being sealed did not develop growth.

Exceptions to Kochs Postulates

-not always possible to culture a microbe in pure culture, such as viruses or pathogens.(biofilms)

-Ethical concerns if humans are sole host(HIV)

-Animals not always available

-Some microbes can be cultured from healthy and sick people

Difference between Simple and Compound Microscopes

Single lens is used in a simple microscope, two are used in compound microscope.

Leeuwenhoek used light microscopy with a simple microscope

Resolution

Limiting factor to see small objects

-ability of lens to distinguish between two adjacent objects as separate and distinct

-shorter wavelengths = better resolution

Refraction

Bending of light as it travels through substances with different densities

-typical glass has refractive index of 1.5

Magnification

process of making a smaller object larger in order to make out details

Bright Field Microscopy

Dark objects are visible against a bright background. Light reflected off the specimen does not enter the objective lens, and therefore shows contrast to the eye. Can see colored structures, best for fixed stained specimens

phase contrast microscopy

permits detailed examination of internal structures in living microorganisms

Darkfield Microscopy

Used to examine live microorganisms that are invisible to ordinary light microscope, cannot be stained by standard methods or are so distorted by staining that their characteristics cannot be identified.

Fluorescence microscopy

Takes advantage of the ability for substances to absorb short wave lengths of light. Pigment sticks to antibodies, and antibodies stick to bacterium. This causes the bacterium to be seen. Used to detect bacteria or other pathogenic microorganisms within cells, tissues, or other specimens.

Confocal Microscopy

Technique used to reconstruct three-dimensional images. Stained specimens with fluorochrome, then the microorganism is scanned to produce an image

Reasons for staining

Because most microbes are colorless, we have to stain them for observation

Simple Staining

A single basic dye. to highlight the entire microorganism so that the cellular shapes and basic structures are visible

Differential Stains

React differently with different kinds of bacteria and can be used to distinguish them

Gram Stain

differential stain, distinguishes bacteria into two groups, gram positive or gram negative.

-Purple/blue is gram positive

-Pink/Red is gram negative

Acid fast Stain

binds only to bacteria that have a waxy material in their cell walls. Used to identify all bacteria in genus Mycobacterium and the pathogenic strains of Nocardia genus

-differential stain

Special Stains

used to color or isolate specific parts of microorganisms, such as flagella or endospores, and to reveal capsule presence

Endospore Staining

Endospore is a resistent, dormant structure formed within a cell that protects bacterium in adverse conditions. Normal dyes cannot penetrate endospore, so special Scheffer-Fulton Endospore Stain.

-special stain

Flagella Staining

Flagella are too small to be seen with light microscope without staining, stain is used to build up flagella diameter until it can be visible under light microscope

-Special Stain

Light Microscope vs Electron Microscope

Electron Microscope has higher magnification capabilities, sees with electron beam, wavelength of .005nm, travels through high vacuum, electromagnetic lens, has higher resolution at .2nm

Light microscope max mag is 1000-1500x, .2um resolution, sees with visible light, 530nm wavelength, travels through air and sees with glass lense

TEM

gives 2D image of internal cell structures, samples have to have electron transparency. Need thin slices

SEM

gives 3D image of cell surface

Prokaryotic Cell Structure

Has cell walls, one circular unmembrane bound chromosome, no histones, no organelles, peptidoglycan cell walls in bacteria, pseudomurein cell walls in archaea

Both Prokaryotes and Eukaryotes...

have ribosomes, similar life processes, have DNA, made of same things, has cell membrane, acquire energy, similar metabolism, highly regulated

Eukaryotic Cell Structure

paired chromosomes in nuclear membrane, histones, organelles, polysaccaride cell walls(only in fungi, algae, plants), divides by mitosis

Bacillus

rod shaped, usually .5-1 um wide and 1-4 um long

Coccus

sphere shape, can be single, tetrad, staphylococcus(cluster), or streptococcus(chain)

Spiral

can be vibrio(comma shaped), spirillum(wave like), or spirochete(lots of loops)

Glycocalyx

Two types: Capsule and Slime Layer

-outside cell wall, usually sticky

Capsule

type of glycocalyx, it is neatly organized, hard to remove and firmly attached to cell wall. Immune system cannot recognize cell with capsule so it cannot destroy it

Slime Layer

unorganized and loose, easy to remove. Protects against phagocytosis and desiccation, aids in biofilm formation and has a role in pathogenesis. extra cellular polysaccharide allows cell to attach to others

Peptidoglycan

is a disaccharide (made of 2 Polymers: NAG and NAM), is in bacteria cell walls, cross linking and degree of cross linkage determines rigidity

Gram Positive Peptidoglycan

Mainly all of gram positive cell walls are peptidoglycan. Lysosomes can protect against gram positive pathogens because of lack of LPS

Gram Negative Peptidoglycan

Less peptidoglycan, peptidoglycan is surrounded by outer and inner membrane of cell. LPS is on outside of cell

LPS

Composed of 3 sections, can block hydrophobic compounds

-Lipid A: Anchor to membrane, is an endotoxin

-Core Polysaccharide: conserved and attached to Lipid A. Only structural and provides stability

-O Specific Polysaccharide: Functions as antigen, end of LPS and made of sugar molecules

Gram Negative Outer Membrane

Forms periplasm between outer and inner membrane, protects from phagocytes and antibodies, protective permeability layer, helps with binding to surfaces which helps pathogenesis, has porins for channels through cell membrane

Gram Positive Cell Wall

overall cell does better in dry environments b/c cell wall stops excess water loss, thick peptidoglycan, abundant teichoic acids, low lipid content, limited LPS, resistant to mechanical stress, penicillin sensitive, susceptibility to lysosome

Gram Negative Cell Wall

Thin peptidoglycan, no teichoic acids, has periplasm, has outer membrane, abundant LPS, high lipid content, susceptible to mechanical stress, excels in host environments, low susceptibility to lysosome or penicillin

Acid Fast Cell Wall

Waxy lipid(mycolic acid) bound to peptidoglycan

-mycobacterium, nocardia

Mycoplasms

no cell walls, but has sterols

Archaea walls...

absent or walls of pseudomurein

Microorganisms move in response to...

Taxis. Response behavior is directed cell movements.

-catching prey, looking for nutrients, avoiding predators

Phototaxis

photon intensity

Chemo Taxis

chemical compound concentration

aerotaxis

oxygen concentration

Peritrichous

Flagella distributed all over cell surface

monotricous

a single flagellum at one pole

Lophotrichous

"tuft" of flagella at one pole

Amphitrichous

Flagella on both poles of cell

3 parts of flagellum

1: Filament is long outer region of flagellin proteins

2: Filament attached to slightly wider "hook"

3: Hook attaches to basal body, which anchors hook and flagellum to cell. Basal body has rod inserted into set of rings

Flagellum basal body

goes L ring, P ring, MS ring, C ring

L ring embedded in outer membrane

P ring in peptidoglycan layer

MS and C ring embedded in cytoplasmic membrane

Mot proteins are flagellum motor and encase MS and C ring. Fli proteins are motor switch, inside the mot protiens and between MS and C ring

Fimbriae

Occurs at poles or whole cell surface, adheres to eachother and surfaces, involved in biofilms, helps adhere to parts of body which helps bacteria colonize and infect

Pili

Longer and fewer than Fimbriae, only 1-2 per cell, only with DNA transfer between 2 cells, can sometimes be involved in twitch motility.

Prokaryotic Plasma Membrane Function

Acts as a selective barrier. has phospholipid bilayer and lack carbohydrates, sterols.

Exoenzymes

Made in the cell and released by the cell to start extracellular digestion

Amylases

exoenzyme that hydrolyzes starch into mono- and dissacharide subunits

Proteases

exoenzyme that hydrolyzes protiens into polypeptides and amino acid sub units

Caseinase

exoenzyme that hydrolyzes the milk protein casein

Lipases

enzymes that break down lipids

Prokaryotic Ribosomes

Called 70S

-Made of subunit 30S and 50S

50S involved in peptide bond formation

30S provides A,P,E binding sites in decoding mRNA and monitors base pairing

Eukaryotic Ribosomes

Called 80S

-made of 40S and 60S

40S monitors complementarity of tRNA anticodon and mRNA

60S catalyzes peptide bond formation

Prokaryotic Bacterial Genome

The nucleoid of a bacterial cell usually contains a single thread of double stranded (ds) DNA. The nucleoid can be spherical, elongated, or dumbbell shaped. The bacterial DNA is packaged in loops back and forth. The chromosome is attached to the cells membrane

Prokaryotic Bacterial Genome Replication

The central point is the origin of replication (oriC), At the opposite end is the terminus. At the origin, the DNA double helix is melted open by binding proteins, and then DNA polymerase synthesizes new strands in both directions. Called theta replication

Plasmids structure

Small, circular double stranded DNA molecules not attached to main chromosome. Replicate independently of the chromosome and they tend to have their own genes

Plasmid Function

they may carry genes for antibiotic resistance, tolerance to heavy toxic metals, the production of toxins, synthesis of specialized enzymes for degradation of unique compounds, and used in transferring genetic material between cells in a process called conjugation.

Inclusion Bodies

Used in metabolism, storage, and motility

Volutin

Inclusion body, storage forms of inorganic polyphosphates that can be broken down for amino acids

Sulfur Granules

Inclusion Body, inclusions of sulfur, energy reserve and plays part in carbon fixation

Gas Vesicles

Inclusion body, provides buoyancy, exclusively in prokaryotes in aquatic habitats

Magnetosomes

Inclusion Body, acts like magnets, organisms with these orient themselves with earths magnetic field lines

Endospores

a dormant and highly resistant cell to preserve the cell's genetic material in times of extreme stress. Often result from extreme nutrient deprivation. stability may come from spore specific chemicals such as dipicolinic acid and proteins that protect the DNA

Carbon

~50% of dry weight of cell, required for growth, all cells require carbon

Nitrogen

~13% of dry weight of cell,

Needed for protein synthesis. Used primarily to form the amino group of amino acids of proteins. Acquired from amino acids, NH4+, NO3-, N2 fixation

phosphorus

Needed for nucleic acid synthesis and phospholipids, ATP, and protiens

-almost all entirely gotten from PO42-(inorganic)

Sulfur

Sulfur is used in amino acids (cysteine and methionine), and vitamins (thiamine, biotin, and lipoic acid).

obtained from either S containing-amino acids (organic sources), sulfide or sulfate which are inorganic

Oxygen

Comes with carbon and hydrogen from organic energy sources.