Microbio exam

cells that lack membrane-bound organelles are called

prokaryotes

which is FALSE?

• archaea and bacteria do not have a nucleus

• eukaryotes are more closely related to archaea

• archaea are not known to cause human diseases

• bacteria and archaea have cell walls of peptidoglycan

bacteria and archaea have cell walls of peptidoglycan (ONLY BACTERIA DO)

the current universal phylogenetic tree that compares the three domains of life uses what type of comparison?

the RNA sequence of each organism

image of e.coli taken at HIGH magnification

SEM(Scanning Electron Microscope)

What is the correct order of Gram-stain reagents

CV, iodine, ethanol, safranin

MSA is ___ for mannitol fermentation and ___ for halophilic Gram-positive bacteria

differential, selective

grappling hook structures in archaea that aid in attachment

hami

the bacteria Zymomonas is very efficient at producing ___ due to Entner-Doudroff metabolic theory

ATP

Mycobacteria leperae is a bacterium that contains mycolic acids in the cell wall. Which stain would you use to visualize the bacterium?

Acid-Fast stain

you have found a compound that disrupts a cells ability to make its own ATP which microbe would it NOT affect

virus

bacteria that are killed in the presence of oxygen are known as

obligate anaerobes

what functions are mediated by bacterial fimbriae/pili

transfer of DNA and attachment to host cells (I,II)

which of the following characteristics is NOT unique to eukaryotes

contain ribosomes

a microbe that grows optimally in the presence of NaCl or other salts

Halophile

which of the following is unique to archaea

specialized membranes that can withstand high temps and extreme environments

what phase of growth: maximum growth at this stage; population increasing at const. rate; cells growing at fast rates and population uniform

log (exponential) phase

the process of transcription directly produces __ from DNA

mRNA

know promoter region draw it!!!!!!

know promoter region draw it!!!!!!

what is NOT correct regarding a nucleus vs nucleoid?

a nucleoid is surrounded by a membrane, while a nucleus is not surrounded by a membrane

you isolate an unknown bacterium from an environmental sample and want to perform a series of tests to help identify the bacterium. which of the following is most useful?

dichotomous key

in a microbial growth curve, why are cells in the population dying at an exponential rate

lack of nutrients and accumulation of waste

what is NOT a mechanism by which bacteria uptake DNA

Tat system

in redox rxns, the transfer of energy occurs via the transfer of electrons, usually in the form of a hydrogen atom. in our example in class NAD+ is the ___ form, and NADH is the ___ form

oxidized, reduced

oil immersion is helpful when using the ___ magnification because it ____

100X, increases the amount of light passing through the specimen

anerobic and aerobic respiration differ

in the electron acceptor at the end of the ETC

ethanol or lactic acid can be produced using which bacterial metabolism pathway

fermentation

which of the following processes is the most energy efficient for creating the most ATP

aerobic respiration

a bacterium is using a metabolic pathway that includes glycolysis, the TCA cycle, and ETC with O2 as the final acceptor. What is the best environment for this bacterium to grow using this type of metabolism?

an aerobic environment with high concentration of carbohydrates such as packaged food

which of the following statements correctly describes flagella

flagella aid in microbial motion toward or away from a stimulus

when a microbe synthesizes large protein molecules from small AA building blocks with the input of energy, the process is called

anabolism

in fermentation, the final electron acceptor is __ which allows the amount of NAD+ to increase in the cell

pyruvic acid

the regulation of the lactose utilization genes is complex because it involves sensing two external factors. when lactose is present and glucose is low, the lacI repressor is ___ and the CAP activator is ___ leading to ______

not repressing transcription, activating transcription, transcription of the lactose utilization

The ultimate goal of metabolism is to reproduce the cell (TRUE OR FALSE)

true

the ETC is found in the mitochondrial membrane in bacteria and the plasma membrane in eukaryotes (TRUE OR FALSE)

false

transmission electron microscopy views a cross-section inside of cells (TRUE OR FALSE)

true

microbes in a biofilm are usually more susceptible to drugs and immune response compared to individual microbes (TRUE OR FALSE)

false

DNA replication of circular chromosomes in bacteria is bidirectional, allowing for fast replication times compared to linear chromosomes (TRUE OR FALSE)

true

fungi are eukaryotes and therefore lack membrane-bound nucleus (TRUE OR FALSE)

false

you are a researcher tasked with designing a drug called Disruptase which disrupts transcription of imaginary UWP1 gene in bacteria. Since you are in charge of the project you decide the mechanism of how Disruptase interferes with the process of transcription. Draw a diagram of process of transcription and indicate in diagram where Disruptase acts to disrupt transcription. In addition, write an explanation of how Disruptase disrupts transcription.

Disruptase could prevent the binding of RNA polymerase which prevents the unzipping of the DNA preventing transcription right away from the beginning.

Bacteria A has catalase and superoxide dismutase, and Bacteria B has catalase only. Based on this data, which potentially toxic molecule can these bacteria withstand and why? If you are working in normal conditions in our microbio lab room and add a drug which disrupts the function of catalase, which of the two bacteria would still be able to survive in the normal lab conditions?

The potentially toxic molecule it could withstand would be oxygen. This is because oxygen can exist in potentially toxic forms called radicals. Enzymes can help break down radicals into its non-toxic forms.

Bacteria A would still be able to survive in the normal lab conditions if a drug was added that disrupts catalase as it still contains dismutase while bacteria B only had catalase.

summarize the notion of the Endosymbiotic Theory, being sure to describe how mitochondria developed. Include two other pieces of evidence that support the notion of the Endosymbiotic Theory

The endosymbiotic theory is the theory that claims that eukaryotes developed from a large anaerobic prokaryote and a small aerobic prokaryote. The small and large prokaryotes unified because the large prokaryote depended on the small for ATP production via aerobic cellular respiration. The small prokaryote became the mitochondria of the eukaryotic cell.

Evidence to support the endosymbiotic theory is that the mitochondria have similar ribosomal structures (70S ribosomes) to the prokaryotes and chloroplasts and mitochondria have circular genomic DNA

Louis Pasteur used a swan neck flask to disprove this theory : ________

Please describe the results of his experiment (why was the swan neck important) and why it disproves the theory

Spontaneous generation (SG)

Previously, some people believed that spontaneous generation could not occur if airflow was cut off because air was thought to be necessary for life to develop. However, Pasteur’s experiment showed that air could enter the flask while microorganisms in dust were trapped in the bend of the swan neck by gravity. The broth remained free of microbial growth because the microorganisms could not reach it. When the flask was exposed to the trapped microorganisms, growth occurred. This disproved spontaneous generation and supported the idea that microorganisms come from other microorganisms rather than arising spontaneously.

Deep Sea Diver has returned to the lab after collecting samples. After some analysis, she realizes one ocean sample contains a high amount of tryptophan. She adds bacteria to the sample and realizes the bacteria can actively grow and replicate. For the bacteria growing on this sample, would you expect the trp operon to be active or inactive and explain why? Is the trp operon an inducible or a repressible operon? Why is it advantageous for a bacterium to regulate gene expression through inducible or repressible options?

The trp operon is repressible. The trp. in the environment causes the repressor to inactivate the operon as the microbe will use the trp in the environment instead. This is advantageous because it saves energy by not expressing the gene all the time unless it is needed.

extra credit: name the process by which bacteria turn atmospheric N2 into other forms of nitrogen that are usable by other organisms. Where can these bacteria be found found?

Nitrogen fixation; found in soil