Microbes Exam 1

What is included in microorganisms?

bacteria, viruses, helminths, fungi, protozoa, prions

infections

causes an active problem in the system

symbioses

mutually beneficial

When was Antoni van Leeuwenhoek

late 1600s

What did Antoni van Leeuwenhoek discover and what did he do with it?

simple microscope, first visualization of microorganisms

What did van Leeuwenhoek call the eukaryotes he saw in his microscope?

Animalcules

When did Louis Pasteur make his discovery?

late 1800s

What experiment did Pasteur do and what did it disprove

Swan Neck Flask Experiment which disproved Spontaneous Generation

What is spontaneous generation

notion that nonliving matter could give rise to living organisms

Pasteur’s Experiment

Boiled broth within the swan necked flask to kill any organisms

What is special about the bent necks in Pasteur’s experiments?

Allowed for gas exchange but prevent the introduction of dust adn microbes into the broth

If necks were broken in some of the necks of Pasteur’s experiment what occured?

contamination from air within 24 hours

what happened in Pasteur’s Experiment when he tilted the flasks

dust in neck contaminated the broth within 24 hours

Why do you boil the broth in Pasteur’s experiment?

It sterilizes the solution

When did Robert Koch conduct his experiment?

late 1800s

What did Robert Koch discover?

Anthrax - rod shaped bacteria

What did the discovery of anthrax do?

it established the Germ Theory of Disease

Germ Theory of disease

Pasteur’s Swan Neck Flask - Anthrax Experiment

Koch’s Postulates

Criteria used to demonstrate a certain microorganism causes a certain disease

What pathogens do Koch’s Postulates no work for?

Tuberculosis and Leprosy

Koch’s Postulates (#1)

Organism should be present in animals suffering from disease but absent in healthy individuals

Koch’s Postulates (#2)

Organisms cultivated in pure (alone) culture away from the animals body - disease does NOT originate in the individual

Koch’s Postulates (#3)

Culture, when transferred to a susceptible animal should initiate characteristic disease symptons

Koch’s Postulates (#4)

Organism reisolated from the animals, cultures in the lab and determined to be the same as the original

Problem with Koch’s Postulate (#1)

Carriers - harbor/transmit without disease

Problem with Koch’s Postulate (#2)

Some diseases are normal flora

Problem with Koch’s Postulate (#3)

Some organisms cannot be grown in culture

Problem with Koch’s Postulate (#4)

If immune to pathogen - disease will not be caused in susceptible animal

Redi

Late 1600s, decaying meat experiments, similar to Pasteur

Needham

1700s, similar to Pasteur, did not effectively boil to kill all organisms

Spallanzi

1700s, contradicted Needham, similar to Pasteur, sealed flasks and found no contamination

Buchner

1800s, discovrered amino acods

Gram

1800s, Gram stain technique

Gram Stain Technique

how to understand what we look at in the microscope

Semmelweis

1800s, handwashinng, decreased mortality in labor and delivery

Nightingale

1800s, nursing, hygiene standards

Snow

1800s, epidemiology

Jenner

1700/1800s, Vaccines, brings in small pox inoculation

Ehrlich

1800s, “Magic Bullets” —> pills

Prions

protein that is misfolded (and cause more), infection & spontaneously

Eukaryotes

Cells that contain membrane bound organelles

Why can eukaryotes be harder to treat

Because human cell types are the same type of cell

Prokaryotes

cells that lack a membrane bound nucleus and other organelles

Viruses

are neither eukaryotic or prokaryotic and are dependent on cells for all life cycle functions

Eukaryotic DNA

Linear, double stranded, housed within the nucleus, packaged with histone, diploid, mitosis and meiosis

Prokaryotic DNA

Circular, haploid, double stranded, located in the nucleoid region (NOT protected), plasmids

What are plasmids?

separate from chromosomal DNA which holds DNA genes that can increase cell viability or pathogenicity

Pathogenicity

incrase in ability to infect you or the severity of its infection

Gram Positive

very thick cell wall structure, good at surviving outside of a host

Gram Negative

Thin cell wall, outer membrane, and cell membrane; not great at surviving outside of a host

Cell Wall

complex semi-rigid structure, provides shape, external to the plasma membrane, provides protection, made up of peptidoglycan

Peptidoglycan Structure

disaccharide structure that alternates between NAG and NAM with a tetrapeptide chain attached to each NAM

Tetrapeptide chain attached to NAM

amino acids alternate stereoisomers of each other, parallel tetrapeptide chains are generally linked by peptide cross bridges

carbohydrate backbone of peptidoglycan

10-65 sugars

Peptide cross bridge

is what causes the most variation and connects aa4 (L) to aa3 (D)

What does the outer membrane of the cell wall of a G- cell contain

LPS, which is toxic to humans

G⁺ cell wall

Up to 25 layers, which can cause type and strain variation, peptide cross bridges will vary

G^- Cell Wall

no characteristic peptide cross bridge, usually a peptide bond exists between DAP (#3) and Ala (#4) on different tetrapeptide side chains

Periplasmic Space

Only in G^- bacteria, space between the outer surface of plasma membrane and the inner surface of outer membrane, gel like consistency due to proteins

Periplasmic Proteins

Hydrolytic Enzymes, Binding Proteins, Chemoreceptors

Plasma Membrane

Thin structure inside the cell wall, encloses the cytoplasm, phospholipids and proteins, two regions, selective barrier

Why is it relevant that the plasma membrane does not contain cholesterol

it makes cells more susceptible to temperature change