Microbiology semester 1 Flashcards
Arthopods need a microscope to be seen. Are they microbes?
No.
What is the size range of a microbe?
mm to 0.2um.
How much smaller are viruses then microbes?
10 times smaller.
Why can microbes divide quickly?
They have few internal membranes.
What can microbes, such as mushrooms and kelps form?
Multicelluar assembleges.
What do multicellular assembleges contain?
Differentiated cells with a particular function.
What did Carl Woese do?
Proposed the three domains.
The earliest form of life comes form bacterial communities called ________.
Stromatalities.
How old are stromatalites?
3.4 billion years old.
What can the outermost organisms on stromatalites do?
Photosynthesise.
What do the inner most organisms in a stromatalite do?
They support sulphur reducing bacteria.
Would rubisco rather fix C12 or C13?
C12.
Rocks depleted of C13 show evidence for what?
Early life.
How far can isotopic ratios date back life to?
3.8 million years.
What are the 8 elements required for early life?
C, H, N, O, Mg, Fe, K, Ca.
What was the temperature thought to be on early Earth?
Between the freezing and boiling point of water. It could have varied due to pressure.
What two things could have provided an energy source on early Earth?
Sunlight and reduced minerals.
What could early cyanobacteria do?
Split water into oxygen.
Evidence of oxygen in the atmosphere comes from the oxidation of what?
Iron.
What iron form is soluble.
Fe2+.
What can Fe3+ form?
Precipitates.
What oxidised Fe2+ to Fe3+ on early Earth?
Chemolithrophs.
Chemolithotrophs could oxidise Fe2+ using the oxygen produced from what organism?
Cyanobacteria.
Where could have BIFS directly arose from?
Anaerobic photosynthesis with FE2+ acting as the electron donor.
What could have occurred in cycles until all the marine oxygen was used up?
Photoferrotrophy.
What is the most convincing evidence of early life?
Microfossils.
What do convincing microfossils need to show?
A regular 3D pattern.
Why are archean microfossils less regular?
Because most of the rock was metamorphic allowing it to be greatly modified by temperature and pressure.
What is a biosigniture?
A chemical indicator for life.
Although some biosignitures date earlier than fossils why is it difficult to say this is proof for earlier life?
As it is hard to rule out nonbiogenic explanations for the production of biosignatures.
What is a hopanoid an example of and why?
A biosignature as it is only produced by bacteria.
What hopanoid derivative was found in sedimentary rock in western Australia?
2 methlyopane.
What does the presence of hopanoids and its 2 methylopane derivative allow you to conclude?
That some bacteria were present at the end on the archean eon.
What is the ‘Metabolists Model’?
Metabolism forming simple organic compounds then more complex compounds with nucleic acids evolving later.
The metabolism of what compound is the bases of the ‘Metabolists Model’ theory?
CO2.
How does the ‘Metabolists Model’ propose how CO2 metabolism originated?
Through self sustaining reactions.
What is it possible to spontaneously form from water and carbon dioxide?
Acetate (C2).
What could early pathways forming simple organic molecules be promoted by?
Minerals and porous surfaces acting as catalysts.
What could catalyse carbon fixation in the ‘Metabolists Model’?
FeS. This is a self sustaining reaction. These iron centres are still found in the electron transport chain.
What can CO2 be abiotically polymerised into?
TCA cycle intermediates.
Where does the ‘Metabolists Model’ propose amino acids came from?
Intermediates of the TCA cycle.
The ‘Metabolists Model’ proposes that each amino acid originally came from a TCA cycle intermediate. What does it propose then happens to the amino acids?
The amino acid would be complexed into a dinucleotide forming the first two amino acids of a codon. This explains why most amino acids with specified by a codon starting with the same 2 nucleotides are synthesised from the same TCA cycle intermediate.
Do all models of early life depend upon the formation of an enclosed space?
Yes.
Why can fatty acids spontaneously form micelles?
They are ampiphillic.
What can micelles form under certain conditions?
Hollow vesicles of membrane that can take up molecules such as RNA.
What is ‘RNA world’?
The theory that nucleotides arose spontaneously and formed RNA. This catalyses the chemical reactions needed to form genetic material.
Is DNA or RNA proposed as the first information molecule?
RNA.
Does it require less energy to form and degrade RNA than DNA?
Yes.
Is uracil or thymine easier to form?
Uracil. This is proven by the fact that it is formed earlier in the biochemical pathway.
What is a ribozymes?
RNA with enzymatic processes which can also cleave itself and synthesise complementary RNA strands.
One of the key steps in protein synthesis is peptide bond formation, which is catalysed by peptidyl transferase activity found where?
The ribosomal RNA. This is another reason in which RNA world is currently the number one theory about the origin of life.
Why is it thought that DNA took over from RNA as the genetic material?
It is more stable.
Why is it unknown if RNA world would work?
Because the temperature on early earth was unknown.
Do we know the role of methane on early Earth and the source of the first cell?
No.
What is the difference between panspermia and neopanspermia?
Panspermia is the theory of origin of life form space and neopanspermia is the theory that life continuously comes to Earth from space.
How big where the balloons used by Hoyle and Wickramasingme in 2000?
30km.
How much did each balloon launch cost?
£500,000.
How high up was life found by Hoyle and Wickramasingme in 2000?
41km up.
What did Chris Rose and Alex Baker use instead of balloons in 2014?
Highly sterile sampling drawers.
How much did the sampling drawers cost?
£3000.
What did Chris Rose and Alex Baker find?
New stratospheric particles of 30um 27km up.
What did the new particle, discovered by Chris Rose and Alex Baker, have a structure off?
A diatom.
They also found a Proboscis and Sphincter and Sheild particles. They came in at speed as the sample tray was damaged. One sample also contained a surface covered in fillaments/ knitted mycelium and bifurcating filaments.
How long where the samples taken after volcanic eruptions?
2 years.
If no volcanic eruptions have taken place in the last two years, what is the biggest size particle able to float up into the stratosphere?
5um.
What was used to examine the particles?
A scanning electron microscope and EDX.
Do algae cause disease?
No. They cause toxic blooms.
are septicaemia and meningitis caused by bacterial or viral infections?
Bacterial.
Who came up with ‘miasma’?
Van Leeuwenhoek. He looked at bacteria on teeth and added water which he used as an extra lens.
What did Lady Montague Wortley find?
She went to Turkey and found that they were inoculating with small pox.
Who introduced vaccination?
Edward Jenner and Bejamin Jetsy. Used cowpox to inoculate with small pox.
What did Semmelweis do?
Made people wash their hands. He thought disease was caused by dead flesh.
What did Louis Pasteur disprove in the 1860s?
Spontaneous generation. He proved that microbes came from the air.
What is Kochs postulate?
- Disease is caused by a single organism.
- You can get this organism by isolating it from a person with the disease.
- If you take the organism and inject into an animal/human they will get the disease.
Who came up with Antiseptic surgery?
Lord Lister.
Is antiseptic surgery used today?
No - aseptic surgery is.
What did Paul Ehrilch discover?
Salversan 606.
What did Salversan 606 kill?
Siffalysis.
What did Hazen and Brown discover?
Nystain which can treat thrush.
What did Marshell and Warren prove in the 80’s?
That bacterium caused stomach ulsers.
What is heterotophy?
Energy is obtained by breaking down preformed carbon via respiration.
What is autotrophy?
Energy is gained by performing chemical reactions. Carbon is fixed from carbon dioxide in the air.
Plants take up nitrogen in which two forms?
Nitrate or ammonium.
What step in the nitrogen cycle involves converting organic nitrogen into ammonium in most aerobic and anernobic bacteria?
Ammonification.
What is nitrification an example of?
Chemoautotrophy.
In nitrification what do nitrosomonas oxidise ammonium to?
Nitrite.
In nitrification what do nitrobacter oxidise nitrite too?
Nitrate.
In denitrfication is nitrate oxidised or reduced into nitrogen gas?
Reduced.
What conditions does denitrificaiton happen in?
anaerobic.
What type of bacteria can carry out denitrification?
Heterotrophic.
What stage in the nitrogen cycle is utilized to covert urea into a safe waste gas?
Denitrification.
What stage of the nitrogen cycle can be abiotic or symbiotic?
Nitrogen fixation.
What bacteria is found in the root nodules of leguminous plants, forming a symbiotic relationship with the plant by fixating nitrogen?
Rhizobium.
Each plant produces an attractant specific to a certatin rhizobium, attracting that rhizobium and causing a mutualistic symbiotic relationship to form. What does the rhizobium gain form the plant?
Sugar.
When rhizobium infects the plant is there a specify infection process?
No.
Rhizobium infects the plant via a crack in the _____. They then multiple greatly forming a ______ which the plant then lays down a _______ around.
Root, bacteroid, nodule.
What type of bacteria are involved in abiotic nitrogen fixation?
Azotobacter. These live in soil and are also point in soil to increase its nitrogen content.
Who was involved in the production of the first sewer?
Sir John Bazelgette.
The first sewer was found in London. What shape was it?
Egg shaped.
The first sewage system resulted in solids forming on the bottom and liquid forming above this. Where are the anaerobes found?
In the solid. Aerobes are found in the liquid.
What are filter beds made from?
Stone or coke.
What is the structure of a filter/contact bed?
Round with a rotating arm in the middle.
Filter beds only contain aerobic microbes. True or False?
False. They contain aerobic and anaerobic microbes.
What is the most effective sewage process?
The activated sludge process.
What is the brush for in the activated sludge process?
To remove large objects.
What is the buffled tanked made out of in the activated sludge process?
Concrete.
The first tank in the activated sludge process is the aeration tank. What is the second block?
The anerobic digester, also known as the clarifier. Carbon dioxide, energy and methane are removed here. Methane is then purified and can be used to power the sewage or is sold.
What does a membrane coliform count involve?
Testing water for bacteria.
What does BOD stand for?
Biological oxygen demand. The oxygen content of water is checked over a few days to ensure the absence of microbes.
What type of organism causes wilt disease on plants?
Fungi. This fungi alters the xylem meaning water can not be correctly transported around the plant.
What percentage of crops are lost to disease?
1/4.
How do fungi spread?
Spores. It is the spores that are the infective agent. Fungi can spread through air and water.
What organism causes post harverst deterioration?
Fungi.
How are zoospores transmitted?
In water.
Fungi enter the plant through the _____ . They germinate to form an _________ . _____ _____ is produced first and forms a _______ _______ structure. The ________ pushes down under the leaf and produces a ________. The contents of the ________ is squeezed into the ______ causing the infection. The _______ increases the surface area for infection.
- Leaf
- Appressorium
- Germ tube
- Boxing glove
- Appressorium
- Stylet
- Appressorium
- Leaf
- Haustorium.
In what three ways can a plant fight back against an infection?
- Waxy surface/ surface hairs.
- Infection enclosed by a layer of cork.
- Phytoalexins produced.