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Micro > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

What is the benefit of being small?

A

Better chemical exchange wit the environment thus allowing faster growth

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2
Q

What is LUCA?

A

The last universal common ancestor.
-DNA as genetic material.
-RNA and protein to catalyze reaction
-lipid cell membrane
-two major branches—> bacteria
—> archaea and eukarya

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3
Q

What is the human microbiome?

A

Microbes that live in and on a human

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4
Q

Why can’t Kochs postulates describe the relationship between all microbes and disease?

A

Because most microbes cannot be cultured in a lab

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5
Q

What is bioremediation?

A

The use of microbes to clean up polluted environments

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6
Q

Why are microbes used for bioremediation?

A

They are able to degrade pollutants because of their metabolism via the biochemical pathways

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7
Q

What is the traditional way of distinguishing prokaryotes and why is it not ideal?

A

Through the similarities of genome sequence and phenotypes.
-Not all microbes can be cultured in a lab which makes it hard to categorize based on phenotype.

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8
Q

How are prokaryotes classified using OTU?

A

Classify proteins solely based on DNA sequence information

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9
Q

What is the 16s-rRNA?

A

encodes the ribosomal RNA
-located in the small subunit of prokaryotes

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10
Q

Cyanobacteria Characteristics

A

-Oxygenic photosynthesis
-original producer of atmospheric O2
-Produce half of the atmospheric O2
-unicellular and filamentous
-ancestor of chloroplast

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11
Q

Proteobacteria(gram negative)

A

Alpha- bacteria that live with plants
Beta- include pathogens
Gamma- include enterobacteria, vibrios, and psuedomonads
Epsilon- include helicobacter and pylori

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12
Q

Firmicutes

A

-Low GC content in genomes
-gram positive phylum but include mycoplasmas
- include endospore forming bacteria, include bacilli and clostridium classes
-include yogurt and cheese bacteria (lactobacillus)

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13
Q

Bacteroidetes

A

-may be oblige aerobes, facultative anaerobes, or obligate anaerobes
-include the genus bacteroides, which play a major component in the human gut microbiota

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14
Q

Actinobacteria (gram positive)

A

-high GC content in genomes
-include Streptomycin genus
-soil bacteria
-filamentous
-many species of streptomycin produce antibiotics

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15
Q

Example of Archaea Phyla

Crenarchaeota

A

-include thermoacidophiles that live in hot springs and prefer pH as low as 2.0
- Many metabolize sulfur
- Many live in the ocean in non extreme conditions

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16
Q

Example of Archaea Phyla

Euryarchaeota

A

-include methanogens(methane producers) and extreme halophiles( grow in high salt conditions)

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17
Q

In what phylum is streptomycin found in?

A

Actinobacteria

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18
Q

Define the 4 levels of protein structure

A

-Primary structure: the linear amino acid sequence
-Secondary structure: a repeating structure due to hydrogen bonds between amino acid side chains; a helix or b sheet
-Tertiary structure: the 3-dimensional structure or “fold”of the protein; depends on hydrogen bonds, electrical charges, and hydrophobic interactions between amino acid side chains; critical for protein function
-Quaternary structure: 2 or more independently-folded polypeptides together in a complex; often held together with disulfide bonds

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19
Q

What is transcription?

A

The synthesis of RNA from a DNA template by RNA Polymerase

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20
Q

Who are the main players in transcription? Of the players you mentioned,
indicate which ones are enzymes and which ones are regions on DNA or RNA.

A

RNA polymerase binds to the promoter also known as the transcription site (+1)
-In bacteria the promoter is the -35 and -10 region.

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21
Q

What is translation? Who are the players and how is it initiated?

A

-Process of mRNA—–> proteins
-Ribosomes, tRNA, amino acids, mRNA
-Ribosome binds to the shine delgarno sequence(ribosome binding site)

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22
Q

What is replication? Where does it begin? who catalyzes the reaction?

A

-Process of duplicating a DNA molecule
-origin of replication
-DNA polymerase catalyzes the reaction

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23
Q

What is recombination?

A

Genetic exchange between two different DNA molecules or different regions of the DNA molecule.

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24
Q

When does replication need to occur?

A

Cells must replicate their DNA before dividing. The new daughter cells must receive a copy of the genome

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25
Q

What are the two main electron microscopy?

A

TEM: make thin slices of the specimen so electrons can pass through

SEM: produces a 3D image

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26
Q

What does polymyxin disrupt?

A

Disrupts the structure of the cell membrane

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27
Q

What is passive transport?

A

Relies on diffusion, does not use energy

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28
Q

What is active transport?

A

-Requires energy
-mediates the entry of all nutrients

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29
Q

Bacterial vs Archaeal Cell Membrane

A

Bacterial cells are phospholipid (glycerol esters). In contrast, archael cell membranes;
-May or may not have phosphate(may not be phospholipid)
-are glycerol ethers
-may be lipid monolayers with diglycerol tetraethers

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30
Q

What is the role of the bacterial cell wall?

A

-Determines shape of bacteria and protects from osmotic stress

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31
Q

What is the bacterial cell wall made of?

A

-made of murein (peptidoglycan)

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32
Q

What enzyme can digest murein?

A

Lysozyme

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33
Q

what antibiotics can inhibit the synthesis of murein?

A

Penecillin and cephalosporins

34
Q

What is an isotonic environment?

A

Salt concentration outside and inside cell are the same

35
Q

What is a hypotonic environment?

A

Salt concentration outside the cell is less than inside the cell.
-water flows in causing cell to swell and burst

36
Q

What is a hypertonic condition?

A

Salt concentration outside the cell is more than inside the cell.
-water flows out of cell causing the cell to shrink

37
Q

What happens to a bacterial cell treated with lysozyme placed in a hypotonic condition?

A

-it will lose its shape and then will burst

38
Q

What happens to a bacterial cell treated with lysozyme placed in isotonic solution?

A

-it will lose its shape but nothing would occur to it

39
Q

What are some characteristics of a gram negative bacteria?

A

-thin cell wall
-outer membrane
-periplasm
-LPS
-Porins

40
Q

What is LPS?

A

The outer leaflet of the outer membrane of gram negative bacteria
-has 3 components: Lipid A, core polysaccharide, O antigen

41
Q

What are porins?

A

Special channels in the outer membrane of gram negative bacteria
-Diffusion of hydrophilic nutrients

42
Q

What are acid fast bacteria and what makes them different?

A

-bacteria in the mycobacteria genus
-have a thick waxy layer of mycolic acid that protects them from disinfectants and acid
- grow slowly due to the lipid layers that slow the entry of nutrients in the cell and require a lot of energy to synthesize

43
Q

What are mycoplasmas?

A

Bacteria that lack a cell wall

44
Q

What is a capsule?

A

Layer of slime usually made of polysaccharides
-retains water which keeps cell from drying
-helps cells adhere to surfaces

45
Q

What type of motility do pili do?

A

Twitching

46
Q

What is the purpose of pili?

A
  • conjugation( transfer of DNA material)
    -fimbriae
    —>attachment
    —->twitching motility
47
Q

What are nucleoids and its characteristics?

A

Nucleoids are where prokaryotes have their nucleus instead of a nucleus.
-its highly supercoiled, condensed, and compacted
-DNA gyrase adds negative supercoils

48
Q

What antibiotic inhibits DNA gyrase?

A

Quinolone

49
Q

What antibiotic inhibits RNA polymerase?

A

Rifampin

50
Q

Which antibiotics target ribosome synthesis?

A

aminoglycosides, tetracyclines, chloramphenicols, erythromycin

51
Q

Distinguish between soluble and membrane proteins

A

cell lysis and high speed centrifugation

52
Q

Test whether protein is located in the cytoplasm

A

GFP fusion

53
Q

Test whether protein is in the periplasm

A

spheroplast formation and centrifugation

54
Q

Blue PhoA

A

protein in the periplasm

55
Q

White PhoA

A

protein in the cytoplasm

56
Q

You are studying protein Y in E. coli. You perform spheroplasting and centrifugation and obtain that its in the pellet. If you fused PhoA to the C-terminus of Protein Y, can you predict the color of E.coli expressing this fusion?

A

You wouldn’t be able to determine the color because the c-terminus in the membrane can be facing the cytoplasm or periplasm.

57
Q

How are non culturable microbes studied?

A

using FISH(fluorescent in situ hybridization) which uses fluorescently-labeled DNA probes which hybridize to specific DNA sequences in cells. Also by using fluorescent antibody probe that uses antibodies to identify proteins that are specific to a bacteria.

58
Q

Minimal medium

A

A defined medium that has only specific chemical compounds needed for growth

59
Q

Rich/complex

A

Abundance of nutrients
-precise chemical composition is unknown

60
Q

What is the lag phase?

A

cells are metabolically active but are not growing at full speed during adjustment to new medium

61
Q

What affects the lag phase?

A

-number of cells inoculated
-age/growth of cells in inoculation
-anything else that affects metabolism such as type of media or bacteria

62
Q

What is occurs in the log phase?

A

-cells are growing at a maximal constant rate
- cells double in one generation time

63
Q

What affects the log phase?

A

-anything that affects metabolic rate

64
Q

What is the stationary phase?

A

Growth rate is slowed down due to limited nutrients, amount of space, and buildup of waste

65
Q

How many endospores can be produced by one bacteria?

A

One

66
Q

Which bacteria can form endospores?

A

Firmicutes
—-> Bacillus and Clostridium

67
Q

Why do bacteria form endospores?

A

For survival but once there is favorable conditions they are able to germinate again

68
Q

What is quorum sensing?

A

Bacteria communicating with one another via secreted molecules called autoinducers.

69
Q

How does quorum sensing work?

A

-when a sufficiently high concentration of autoinducer is present, the
autoinducer binds to the LuxR protein, activating LuxR
-active LuxR turns on expression of the lux operon, which encodes the
gene for luciferase (the enzyme that produces light).

70
Q

What is biofilm?

A

a community of bacterial cells attached to a
surface by means of exopolymeric substances

71
Q

Are biofilm bacterial cells planktonic or sessile?

A

Sessile

72
Q

Why are biofilms important?

A

-They trap nutrients for cell growth
-increase antibiotic resistance of bacteria

73
Q

How are biofilms formed?

A

-loose attachment to surface
-a stable attachment to the surface via formation of micro colonies
-secretion of exopolymeric matrix that encases the bacteria

74
Q

Where are biofilms found?

A

-teeth cavities
-hospital tubes

75
Q

How do bacteria choose whether to form biofilms?

A

High levels of cyclic-di-GMP in cells favor biofilm formation

76
Q

Two ways bacteria become antibiotic resistant

A

-Mutation in DNA gyrase
-Receiving indole from charitable neighbor

77
Q

Barophiles

A

Grow faster at higher atmospheric pressure

78
Q

Psychrophile

A

Grow at low temperatures ——-> 5 degrees Celsius

79
Q

Mesophiles

A

Live in normal conditions—-> 37 degrees Celsius

80
Q

Connection between biofilms and increase of heart attacks

A

Stress—->norepinephrine——>increase in iron in blood——>dispersal of biofilm in plaque——>rupture of plaque from artery wall—->blood clots——>heart attack ot stroke

Micro (10 decks)

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