BIMM 120 Midterm 1

Microbiology

study of microorganisms and microbes

Pathogen

disease-causing microorganism

Decomposition

breaking down of organic matter from dead organisms into forms which decomposers (e.g. saprophytic fungi) are able to process them

endosymbiont

 in symbiotic relationship, lives within the body or cell of another organism

commensalism

• relationship between organisms in which one organism derives benefit and the other is unaffected

Differences between prokaryotes and eukaryotes

• Denseness of eukaryotic DNA is higher than eukaryotes

• Eukaryotic nuclear envelope keeps DNA organized, prokaryotic DNA floats in nucleoid

• Membrane bound organelles in Euk, not in Prok

• Eukaryotic chromosomes are typically linear, prokaryotic circular

• No introns prokaryotes, present in eukaryotes

• Transcription and translation coupled in prokaryotes, separate steps in eukaryotes

What is the relationship between the prokaryote/eukaryote distinction and the taxonomic category “domain?”

Prokaryote and eukaryote have a relationship with the taxonomic category “domain” in the sense that they are themselves domains. Life can be divided into three primary domains, archaea, prokarya, and eukarya.

Archaea are similar to bacteria since they are…

• single celled

• mostly have cell walls

• non nuclear

• extremely small (0.5-1 micron)

• reproduce quickly ~20min

• producers or consumers

• possibly living in extreme conditions

Archaea are different from bacteria since they are…

• highly genetically dissimilar

• dissimilar in molecular makeup

• different in cell wall, membrance, metabolic pathway structures

Are Archaea more closely related to bacteria or eukaryotes? How would you determine this?

• Archaea are more closely related to eukaryotes than they are to bacteria. You may be able to determine this through sequencing of RNA/DNA genomes and looking for similarities, or you could look at details of the organisms and find similarities there. Eukaryotes and archaea have much more similar metabolic pathways than eukaryotes.

Bacteria

• a member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organized nucleus, including some that can cause disease.

Archaea

• microorganisms that are similar to bacteria in size and simplicity of structure but radically different in molecular organization. Higher proportion of archaea are extremophiles, plasma membrane structure is very different from bacteria.

Protist

•  any eukaryote which is not a fungus, plant, or animal, which includes single celled or multicellular organisms (i.e. seaweed)

algae

single celled photosynthetic protist

protozoa

nonphotosynthetic single celled protist

fungus

eukaryote which secretes enzyme into the environment around it to digest food, absorbing nutrients

yeast

single celled fungus

virus

an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.

Example of Bacteria, Archaea, Protist, Algae, Protozoa, Fungus, Yeast, Viruses

E. Coli, Thermoproteota, Paramecium, Diatoms Paramecium, Ringworm, Bakers Yeast, Influenza

Are bacteria, archaea, protists, algae protozoa, fungi, yeast, viruses, single or multicellular?

Are bacteria, archaea, protists, algae protozoa, fungi, yeast, viruses, consumers or producers?

• bacteria : both

• archaea : no

• protisits : both

• algae : producer

• protozoa : consumer

• fungus : consumer

• yeast : consumer

• viruses : consumer

Earliest documented records of infectious disease

Earliest documented infections ~3800 bce, plague

1st Visualization of Microbes

Antony van Leeuwenhoek, 1676, first microscopes

First modern vaccination

• Edward Jenner 1796, cowpox ulcer pus scratched into child’s arm for smallpox immunity

First recognition of disease spread by dirty hands

Ignaz Semmelweis 1846, maternity ward

Founders of Modern microbiogy

Koch and Pasteur

Pasteur, disproval of spontaneous generation - boiled broth in curved neck flask which let trapped air escape, allowing for dust and bacteria to collect away from broth. Broth was heated and cooled slowly to sterilize, remained sterile until put into contact with bacteria and dust

Koch, postulates -

1. in all cases of disease, microbe must be found

2. microbe must be able to be isolated from host

3. microbe must be able to reinfect a different host, show same characteristics of disease

4. microbe must then be re-isolated again from reinfected host

First discovery of antibiotic

alexander fleming, 1928, penicillin

First eradication of disease

1977, smallpox

Virus, Bacteria, Eukaryotic Cell sizes

Resolution definition

ability of a microscope to distinguish details of a specimen or sample

resolution requirements

• adequate contrast between light and dark

• wavelength of light is smaller than object

• adequate magnification

Limit of resolution

smallest distance over which two points can be distinguished as separate

light interactions with matter

absorb, refract, reflect, scatter

reason for immersion oil

so light isn’t lost at the glass oil interface

brightfield

• utilizing simple stains like crystal violet, methylene blue, carbol fuchsin

  • Negative staining looks like darkfield, all of background is stained but sample is not!

phase contrast

slows the speed of the incident light, retarding the phase in a way that causes destructive interference between wavelength of speciment and wavelength of light. Results in being able to see live transparent organisms that have been darkened

DIC

phase contrast but with polarized light

Darkfield

utilizes only scattered light to visualize organisms. specimen is obliquely lit, and may allow view of much smaller objects

transmitted electron microscopy

transmitted electrons emitted and detected by fluorescent screen

scanning electron microscopy

scattered electrons are detected, 3D image

what is needed for proper resolution?

adequate contrast, magnification, and wavelength of light smaller than object

what do eukaryotes and prokaryotes have in common?

• eukaryotes and prokaryotes…

• have DNA

• have ribosomes

• have plasma membrane

• have cytoplasm

• have motor elements like flagella

coccus

coccobacillus

vibrio

bacillus

spirillium

spirochete

Prokaryotic Plasma membrane is a…

fluid mosaic. proteins are half the weight of the plasma membrane. receptors for environmental conditions, nutrient transport, secretion pores, ETC and ATP synthase, and pathogenic virulence factors are all in the plasma membrane

Plasma membrane

unsat = loose, sat = tighter, hopanoids can form even tighter membranes at high temperatures. Archaea have even more methods to conserve membrane integrity at high temperatures like making tetraether lipds to make a monolayer, or cyclizing isoprene to increase membrane stiffness

cell walls

help maintain shape, resist osmotic pressure, resist harsh conditions