Microbiology Lecture Notes 3&4 – Flashcards

• Anton van Leeuwenhoek was a Dutch biologist who greatly improved microscopes and became the first person to see bacteria and protozoans. 
• Leeuwenhoek cast doubt on the theory of spontaneous generation by showing that grain weevils did not generate from decaying wheat, as was supposed, but from eggs deposited on the wheat. 
• Although we did not review this incident, Prof. McCleary noted Leewenhoek as providing the first chink in the theory of spontaneous generation.
• Note: Leewenhoek was also the first individual reviewed. 
• Think:Van Leewenhoek = chink  

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No. He improved magnification by stacking lenses.

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Robert Hooke

Here is a drawing he made of the cells in a piece of cork.

Note: One can remember this by thinking of the pirate Captain Hook, from Peter Pan, locked in a prison CELL

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He was an Englishman

His samples of cork came from the sacramental wine bottles of the church.

• Robert Hooke saw only the cell walls apparent in the dried out eukaryotic cells of the cork tree. 
• They look like this. 
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• Semmelweis established that some disease could be prevented with antiseptic agents
• He demonstrated this by introducing such an agent, chlorine based soap, to effectively reduce the incidence of puerperal fever during and after childbirth.
• Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction.
• Think: It is WEIS TO WASH (weis means wise in German)[image]

• Hooke coined the term "cell".
• His identification marked the beginning of cell theory, which stated that the cell is the basic structural, functional and biological unit of all living organisms.  

• Van Leewenhoek was the first to observe and describe microorganisms such as bacteria and protozoa via the magnifiying lenses of his many homemade microscopes. 

• Prior to Semmelweis's introduction of chlorine based handwash, the childbirth survival rate in the clinic was 30%
• Outside of the clinic it was 50%

Puerperal Fever

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• They both argued that puerperal fever resulted from contact between the physician and the patient. 
• They made this argument at roughly the same time
• Holmes advocated burning of the clothes and not assisting in delivery for an extended period.
• Ignaz Semmelweis introduced prophylaxis (handwashing in chlorine solution before assisting at delivery) which would considerably lower the puerperal mortality rate.

Physicians in training would visit the morgue to work between deliveries. 

Semmelweis required handwashing with a cholrine based product before and after examination of patients.

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• Semmelweis gave us handwashing and aspetic practice as a way of interrupting the spread of disease from person to person.
• He also showed us that Puerperal Fever was an Iatrogenic disease, the first identified as such. 

An iatrogenic disease. 

Note: Iatro is from the Greek word for doctor,

Iatrogenic= doctor-generated or doctor caused disease.

Nosocomial Disease 

fr. New Latin - nosocomi- hospital

• The IATROGENIC disease is a disease caused by medical personel and is often the result of a mistake that could have been avoided. 
• For example, this man has an injury obtained from receiving too much radiation treatment
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• A nasocomial disease, a disease acquired in a healthcare facility that is not the fault of medical personel. 

In the nasal sinuses.

BY BREATHING or sneezing, as well as other ways, though these were the ones noted in class. 

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• Insurance companies consider it nosocomial, an inherent risk of being in a health care facility. 

In most cases a UTI from an indwelling catheter is considered a nosocomial infection, an inherent risk of having such a catheter, unless some malfeasance or wrong doing can be proven.

• Iatrogenic Diseases those caused by medical personel, and for which they are liable or legally responsible require liablity insurance.

• Semmelweis's observations conflicted with the established scientific and medical opinions of the time and his ideas were rejected by the medical community. 
• Some doctors were offended at the suggestion that they should wash their hands and Semmelweis could offer no acceptable scientific explanation for his findings. 
• In 1865, Semmelweis was committed to an asylum, where he died at age 47 after being beaten by the guards, only 14 days after he was committed.
• This is wiki sourced, just saying. 

No. Pasteurization is not designed to create a sterile product. 

• Unlike sterilization, pasteurization is not intended to kill all micro-organisms in the food. 
• It aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and is consumed before its expiration date). 
• Commercial-scale sterilization of food is not common because it adversely affects the taste and quality of the product.

• Pasteur's experiments with the wine industry showed him that microorganisms could change the wine to vinegar
• This may have led to the insight that microorganisms could possibly effect people negatively as well. 
• This connection was implied by Prof. McCleary

• Louis Pasteur conducted experiment with chickens who had chicken cholera.
• He extracted some material (pus perhaps) from chickens with the disease.
• He injected this into some healthy chickens
• The healthy chickens got sick confirming the idea that illness spreads when "something" in a sick individual is spread to a healthy individual. 

• Pasteur had extracted the disease carrying medium too early. Out of a host for too long, the organism, a bacteria, died. 

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Vaccination!

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• Not very.
• Rabies is "universally" fatal, with only three known exception in history.
• (According to class lecture it is only one person but that's a bit outdated. The others were also treated with the Milwaukee protocol developed in the noted Wisconsin case. )

• Pasteur gave the boy a series of 12 (10 according to lecture) intra-abdominal shots every (other according to lecture) day for 10 days. These were from rabbits and were of increasing virulence. 

• Robert Koch is remembered for Koch's postulates which are steps to equate a specific organism with a specific disease.

Koch's Postulates

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1. Obtain organism from diseased individual.
2. Grow the organism in pure culture in the laboratory.
3. (a)Introduce the organism into an unexposed or naive individual (b)and produce the same disease symptoms.
4. Retrieve the same kind of organism from the newly diseased individual.

• Koch's postulates tell us the __________ of a disease
• a. symptoms
• b. cause, specifically the organism that causes the disease.
• c. course
• d.  treatment

Joseph Lister         Think Lister = Listerine 

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Joseph Lister gave us aseptic surgery

• NOTE: Antiseptics kills or inhibits the growth of microorganisms on the external surfaces of the body.  
• Aseptic technique aims to minimize exposure to germs in medical or surgical setting.

• Joseph Lister. The spray seen in the previous image and below is phenol or carbolic acid, used to create aseptic condictions during the treatment and as the child healed.   

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Joseph Lister who gave us aseptic surgery via carbolic acid or phenol. 

(after whom listerine is named)

• Paul Ehrlich is often called the father of chemotherapy.
• Think EhrliCH CHEMOTHERAPY
• He gave us the first drug that targetted a specific pathogen. 
• The drug was called Salvarsan. It was used for the treatment of syphilis.

• An antibiotic
• produced by a living organism 
• either kills or retards the growth of another living organism
• e.g. pencillin
• A drug
• a synthetic compilation. 
• amoxicillan

The treatment of disease with chemicals.

Paul Ehrlich 

Alexander Flemming discovered Penicillin 

Think: Flem = Phlegm = Disgusting 

• Fleming was noted for his untidy if productive laboratory, which perhaps contributed to the production of the mold that produced penicillen

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• Flemming was classfying microorganism.
•  He noted that one of his plates was contaminated with an organism that seemed to repell the bacteria growing on the plate.
• This organisms was a type of mold, a fungus that produces what would be called penicillin

• The antibiotic substance protects the organism's territory by keeping competing bacterial neighbors at bay. 

Zones of Inhibition

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• The discovering of transposons, of jumping genes. 
• Genetic segments that have the ability to relocate from one part of the gene to another. 

• Transposons are segements of DNA that are capable of independent replication and insertion within new positions within the same or another chromosome or plasmid. 
• Barbara McClintock discovered them. 

• Because bacteria have PLASMIDS. 
• Bacteria can take the gene off the main chromosome, put it on the plasmid, then retreive it from the plasmid and put it back in the main chromosome, almost at will.
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Stanley Prusiner discovered prions as a disease causing agent. 

Think: PRUSINER= PRIONS

• Fungi
• approaching mulicellular
• Protozoa & Algae
• Fungi, protozoa and algae have all the "bells and whistles"
• Bacteria 
• Streamlined
• Viruses 
• More stripped down than bacteria
• Prions - proteins
• Not even cellular

• Prions replicate by a process called recruitment 
• when the prion encounters its normal counterpart, it causes that protein to unfold and refold, rendering it unfunctional.
• The body stores these unusable proteins in the brain leading to encephalopathy, disorder or disease of the brain

A prion disease. 

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• Bacterial ribsomes (70S or 70 Svedburg units) are somewhat smaller and less dense than eukaryotic ribsomes (80S).
• Although we did not review it in class, the book notes that eurkaryotes have both 70S (in organelles) and 80S ribosomes.  
• Ribosomes function as the site of protein synthesis.

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Structure and shape of the E.coli 70S ribosome. The large 50S ribosomal subunit (red) and small 30S ribosomal subunit (blue) are shown with a 200 Angstrom (20 nm) scale bar. For the 50S subunit, the 23S (dark red) and 5S (orange red) rRNAs and the ribosomal proteins (pink) are shown. For the 30S subunit, the 16S rRNA (dark blue) and the ribosomal proteins (light blue) are shown.

Proteins are put together or synthesized in the ribosomes. 

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• Ribosomal RNA (rRNA) and protein subunits. 
• It's not one of each. Both subunits contain both. The larger subunit contains two molecules of ribosomal RNA, the smaller contains one. 

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• Translation: The DNA is unzipped, copied by RNA polymerase into mRNA and rezipped.
• This occurs in the cytoplasam in prokaryotes

• After the DNA is unzipped and copied by RNA polymerase into mRNA (transcription) it goes to the ribosome, (rRNA ; protein subunits), where translation occurs. 
• TRANSLATION
•  mRNA's code is read three units (1 codon) at a time at the ribosome.
• tRNA brings the complementary piece of code (anticodon) which is attached to an amino acid, to the ribosome. 
• As the code (mRNA) is fed through the ribosome, these amino acids link and form a polypeptide chain. 
• these are the proteins that DNA codes for and those that make all organisms function.  

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• The cell wall is an invariant structure in bactera. That is, all bacteria have them.
• It is a variant structure in prokaryotes because some archae do not have them. 

• Peptidoglycan
• Proteins and carbohydrates
• Peptide- Protein/ Glycan - carbohydrates 

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NOWHERE!

The only place peptidoglycan is found is in bacterial cell walls. 

• Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria, forming the cell wall.
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The CELL WALL

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Peptidoglycan is thicker in gram positive cell walls than it is in gram negative cell walls. 

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• Gram positive cell walls are characterized by the presence of teichoic acids. 

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• Teichoic acids are negatively charged. They therefore attract cations, notably minerals (e.g. iron, zinc, copper, sodium) needed by the bacteria, to the cell walls of gram positive bacteria. 
• Teichoic acids allow the insertion of cell wall subunits which act let gussets, in letting the cell wall increase in size without lysis.  
• They do this with the aid of autolysins
• Teichoic acids play a role analogous to O antigens in gram negative cells. They function as an identification mechanism and are the target for which the host develop antibodies (See host recognition below)

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Lipotechoic Acids extend into plasma membrane and Wall Techoic Acids hook into cell wall

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Peptidoglycan. 

• Gram negative cell walls are more mechanically fragile because they have a thinner layer of peptidoglycan.

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• The peptidoglycan of the cell wall of gram negative bacterial cells is relatively thin.
• The peptidoglycan of the cell walls of the gram positive bacterial cells is relatively thick.

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• The outer membrane is superficial to the peptidoglycan layer of the cell wall in gram negative bacteria. 
• It contains Lipopolysarccharide (LPS) complexes containing
• Lipid A ( an endotoxin)
• Core polysaccharide (provides stability)
• O polysaccaharide (functions as antigen)
• It also contains lipoproteins, and phospholipids (in yellow) though we did not review these components.

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Porins. 

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Lipopolysaccharides or LPS are found in the outer membrane of the cell wall of gram negative bacteria. 

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O antigens or O polysaccharides

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The "O" [Oh] in E. coli O157 indicates the specific O antigen in the outer membrane of the bacterial cell wall. It is this O antigen or O polysaccharide that allows for identification of the particular strain. 

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Lipid A, an endotoxin! -

Note: Endotoxins are released at the END of the bacterias life, that is, when it dies. 

Lipid A, an endotoxin. 

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• Because it is the result of bacterial cell death. If one treats the bacterial infection too rapidly, the endotoxic shock kills the patient. If one treats it too slowly, the bacteria themselves can kill the patient. 

• Gram positive bacteria are more effectively treated with penicillin. 
• Penicillin targets the peptidoglycan in the cell wall of gram positive cells. The LPS provides a barrier through which penicillin cannot reach the peptidoglycan.

• If a molecule would like to enter a gram negative cell, it must pass through the porin, an integral protein channel in the outer membrane of gram negative cell walls. 
• Nutrients such as B12, iron, amino acids, disaccharides, etc do this on a regular basis. 

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• NO, They are not.
• They can only preclude entrance based on size. 
• Selective permeability means that the cell membrane has some control over what can cross it, so that only certain molecules either enter or leave the cell. 
• The cell walls of bacteria will let anything that can fit in get in. 

A Spheroplast

Protoplasts: Have their cell wall entirely removed and are gram +

Spheroplasts: Have their cell wall only partially removed and are gram -

These cell may retain metabolic functions

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Protoplast

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• Confers and consistent/ constant shape
• Maintains a rigid structure for mechanical protection 
• Provides anchor point for flagella
• MOST IMPORTANTLY: Prevents bacterial cell walls from rupturing in a hypotonic solution. (Water moves into the cell but it can not expand beyond the confines of the cell wall) 

• The cell wall prevents bacterial cells from bursting in a hypotonic solution, when water moves into the cell.
• The cell wall does not prevent the bacterial cell from drying up in a hypertonic solution.   
• Think: hypertonic= hypertension > salt, drying out cell

• Because a hypertonic solution is inhospitable to bacterial cells.
• Their cell walls offer no protection against the dehydration that occurs in a hypertonic solution. 
• Plasmolysis is the process in which plant cells lose water in a hypertonic solution. 
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The plasma membrane (or cell membrane) encloses the cytoplasm of the bacterial cell.

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Phospholipid bilayer

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• Cholesterol is absent from the plasma membranes of prokaroytic cells but present in eukaryotic cell's plasma membranes.
• This makes the cell membranes of prokaryotes less stable. 
• The book also notes carbohydrates.

• Proteins
• Integral proteins
• Peripheral proteins. 

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• The phospholipid bilayer is composed of hydrophlic phosphate heads and two hydrophobic lipid tails. 
• It is the main molecules of the plasma membrane in both prokaryotic and eukaryotic cells.

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• The proteins that span the width of the plasma membrane are integral proteins. 
•  Integral proteins are involved in transport. 

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• Osmosis, diffusion and facilitated diffusion are all types of passive transport that can occur at the integral proteins in the plasma membrane of bacterial cells. 

SIMPLE DIFFUSION is characterized by movment of molecules from an area of high concentration to an area of low concentration until equilibrium occurs.

SIMPLE DIFFUSION occurs in the phospholipid bilayer. 

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• Facilitated Diffusion is the movement of ions or small molecules from an area of high concentration to an area of low concentration requiring the use of a protein carrier but not the use of energy.

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OSMOSIS

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Ionic Transport.

• Ionic transport involves the movement of charged particles

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• Group translocation, in which substances are chemically altered during transportation across the membrane, and thereby locked into the cell. 

• Ionic transport/Active transport
• It was called this in lecture, though the textbook simply calls it active transport and notes that not only ionic molecules move into the cell in this way.

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• Passive transport requiring protein carriers:
• Osmosis
• Passive Transport.
• Facilitated diffusion
• Active transport requiring protein carriers
• ionic/active transport 
• group translocation

• Group translocation, a type of active transport, preserves the concentration gradient by chemically altering a substance as it moves via the protein carrier through the plasma membrane.
• The plasma membrane is not selectively permeable to the new substance so that once in, it cannot leave the cell. 
• The concentration of the original substance remains higher outside of the cell than in the cell because of the alteration. 

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• Group translocation or TRANSLOCATION

• Peripheral proteins:
• May function as enzymes that catalyze chemical reactions
• Acts as scaffold for support.
• Mediate change is membrane shape during movement.
• We didn't talk much about these. Prof. McCleary noted that they were markers, and that sites for reactions. These functions are from the book. p.90
• They are distinguished from integral proteins in that they don't span the entire cell membrane and are easily removed from the membrane 
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Cholesterol  (as well as carbohydrates, though we did not discuss these) p.100

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• The electron transport system for bacteria, as well as photosynthesis for bacteria converting light energy into chemical energy is located in the cell or plasma membrane.

• The cell membrane contains enzymes capable of catalzying chemical reactions that breakdown nutrients and produce ATP

• The cell membrane, specifically enzymes in the cell membrane that catalyze chemical reactions that break down nutrients and form ATP, this is part of the eletron transport system/chain. 
• In addition there are bacteria who use pigments and enzymes involved in photosynthesis. 

1. DNA ATTACH: Binary fission begins with the single DNA molecule replicating and both copies attaching to the cell membrane.
2. GROW BETWEEN: Next, the cell membrane begins to grow between the two DNA molecules. 
3. PINCH INWARD: Once the bacterium just about doubles its original size, the cell membrane begins to pinch inward.
4. A cell wall then forms between the two DNA molecules dividing the original cell into two identical daughter cells.