CMMB 343 midterm 1

Question 1

what are some problems for cells at low temp?

Answer 1

proteins, membrane, DNA, RNA all too rigid

Question 2

what are some solutions to low temp problems for cells?

Answer 2

increase membrane fluidity, decrease RNA stability (less GC), increase flexibility of enzymes

Question 3

Almost all cultured ?? are sulfur or hydrogen-oxidizing.

Answer 3

hyperthermophiles

Question 4

what is different between Archaea membranes and Eukarya/Bacteria membranes?

Answer 4

Archaea have isoprene chains and are bound to ether linkages while E/B have fatty acid tails bound with ester linkages

Question 5

what are the major functions of cell membrane?

Answer 5

1. Cell’s permeability barrier
2. Anchors key proteins
3. Major role in energy conservation and consumption

Question 6

how many bacteria cells are there in 1 g of soil? what % of biomass do they account for on Earth?

Answer 6

1,000,000,000

20-50%

Question 7

Conan the bacterium

Answer 7

• Deinococcus radiodurans
• most radiation resistant organism (>1000 times dose that will kill humans)
• multiple copies of its genome, switches which one is in use while others repair

Question 8

Louis Pastuer

Answer 8

• Discovered that alcoholic fermentation was a biologically mediated process
  – Disproved theory of spontaneous generation
  – Led to the development of aseptic technique
  – Developed early vaccines (rabies)

Question 9

Robert Koch

Answer 9

– Demonstrated the link between
microbes and infectious diseases (CAUSATIVE AGENTS of anthrax and tuberculosis)
– Koch’s postulates
– Developed techniques (solid media) for obtaining pure cultures of microbes, some still used today (1st to use agar plates)
– Awarded Nobel Prize for Physiology and Medicine in 1905

Question 10

Sergei Winogradsky

Answer 10

• father of microbio
• W column
• proposed chemolithotrophy (oxidation of inorganic compounds to get energy, autotrophy - carbon from CO2)
• linked specific bacteria to specific biogeochemical transformations (N and S cycles)

Question 10

Koch’s postulates

Answer 10

a set of criteria for proving that a given microorganism causes a disease

Question 11

W. column: what gradients exist?

Answer 11

bottom-up = sulfide concentration (highest at bottom)

top-down = oxyfgen concentration (highest at top, more areboic bacteria - cyanobacteria at very top layer)

Question 12

father of bacterial taxonomy? what did the OG taxonomy include?

Answer 12

Ferdinand Cohn

4 groups based on shape: cocci, rod, sphere, filamentous

Question 13

chemolithotroph

Answer 13

energy source = inorganic chemicals (H2, H2S, NH4+, etc)

Question 14

chemoorganotroph

Answer 14

energy source = organic chemicals (sugars, proteins, etc)

Question 15

heterotroph

Answer 15

carbon source = organic chemicals

Question 16

autotroph

Answer 16

c source = CO2

Question 17

early tree of life made by? based on?

Answer 17

Haeckel, based on belief that evolution strives towards higher complexity

Question 18

Universal tree of life: newest version

Answer 18

by Carl Woese who used DNA not just morphology, used ribosomal RNA since every living thing has ribosomes

Question 19

why is important to include sucrose in cell suspensions?

Answer 19

sucrose lowers the water activity of the cell suspension, preventing too much water from leaving the cells causing lysis

Question 20

if the water activity is higher inside the cell than in the solution, what will happen?

Answer 20

water moves out of cell

Question 21

what is the salt-in strategy?

Answer 21

• cells will accumulate KCl
• cheaper method energetically
• salts damage enzymes tho
• mostly Archaea

Question 22

what is the compatible solutes strategy?

Answer 22

• accumulate organic solutes (the cells make them)
• more expensive
• Bacteria and Eukarya
• no damage to enzymes

Question 23

plasmolysis

Answer 23

cell shrivels from negative pressure from water leaving the cell, cell wall is ripped off

Question 24

water moves from areas of ? water activity to ? water acitivity

Answer 24

high to low water activity (aw)

Question 25

high solute content = ? aw

Answer 25

low water activity

Question 26

aerobes

Answer 26

need O2 for respiration

Question 27

microaerophiles

Answer 27

need O2, but at low levels (less than atmospheric levels), have some enzymes that are damaged by O2

Question 28

facultative anaerobes

Answer 28

can respire O2, but don't require it

Question 29

aerotolerant anaerobes

Answer 29

don't respire O2, but are NOT damaged by it (has no effect on them)

Question 30

obligate anaerobes

Answer 30

don't respire O2 and ARE damaged by it (highly sensitive)

Question 31

what is something that can be used to determine which of the 5 oxygen related species and organism is?

Answer 31

thioglycolate broth a complex medium that separates microbes based on O2 requirements

Question 32

why is oxygen toxic?

Answer 32

exposure to O2 yeilds toxic byproducts: - superoxide (O2-) - hydrogen peroxide (H2O2) - hydroxyl radical (OH.) which is the WORST

Question 33

what do these do? 1. catalase 2. peroxidase 3. superoxide dismutase 4. superoxide dismutase/catalse combo 5. superoxide reductase

Answer 33

1. 2H2O2 --> 2H20 + O2 (gets rid of hyd peroxide) 2. H2O2 + NADH --> 2H20 (rid of hyd peroxide) 3. 2 O2- --> H2O2 (rid of superoxide, but makes hydrogen peroxide, now need 1 or 2) 4. 4O2- --> 2H2O + 3O2 5. reduces O2- to H2O2, oxidizes rubredoxin in process

Question 34

gram positive cell

Answer 34

- thick peptidoglycan cell wall - one (innner) membrane - purple on gram stain

Question 35

gram-negative cell

Answer 35

- outer membrane - periplasm (contains thin peptidoglycan cell wall) - cytoplasmic (inner) membrane - pink/red on gram stain

Question 36

True or false: Membranes do not allow the passage of ions, sugars or amino acids (large or strongly polar molecules). These must be transported.

Answer 36

true

Question 37

are saturated or unsaturated fatty acid tails preferred for psychrophiles?

Answer 37

unsaturated, the double bonds in the tails don't pack as tightly, make the membrane more flexible which is needed in colder temps

Question 38

thermophiles prefer (saturated/unsaturated) fatty acid tails in their membranes?

Answer 38

saturated

Question 39

?? lipids lack fatty acids, but have isoprenes instead

Answer 39

Archaeal

Question 40

? can exist as lipid monolayers, bilayers, or mix of both

Answer 40

archaeal membranes

Question 41

why are monolayers beneficial to certain Archaea?

Answer 41

less membrane fluidity, can survive in hotter temps (thermophiles)

Question 42

are ether or ester linkages more stable?

Answer 42

ether (Archaea)

Question 43

explain the 3 transport protein mechanisms

Answer 43

1. simple transport: transmembrane transport protein 2. group translocation: series of proteins 3. ABC system: 3 components, bing protein, ATP-hydrolyzing protein, transmembrane prot

Question 44

most ? are Gram neg

Answer 44

bacteria (not Bacteria)

Question 45

gram neg or pos are often pathogens?

Answer 45

GRAM POS

Question 46

are g - or + better halophiles? why?

Answer 46

gram pos cells are better halophiles, have and increased internal pressure,

Question 47

do gram neg or pos cells have crosslinks btw DAP and D-alanine carboxyls on adjacent glycan strands

Answer 47

gram-negative

Question 48

teichoic acids only found in? what do they do?

Answer 48

the peptide wall of gram-positive cells they are antigenic (kill bacteria), maintain cell shape and porosity of wall, capture cations (Ca2+, Mg2+), phosphate reservoir, regulate cell wall turnover (autolysins)

Question 49

periplasm

Answer 49

space btw cytoplasmic and outer membranes in gram neg

Question 50

what 3 keys structures make up Lipopolysaccharides?

Answer 50

- O-specific polysaccharide - core polysaccharide - Lipid A (endotoxin)

Question 51

the cell wall and membrane together make up?

Answer 51

cell envelope

Question 52

What is transglycosylase role in peptidoglycan synthesis?

Answer 52

Peptidoglycan synthesis requires two activities: transglycosylase (TG) to polymerize the glycan chains and transpeptidase (TP) to catalyze peptide cross-linking between two adjacent glycan chains.

Question 53

how come penicillin can be used in humans to target bacteria?

Answer 53

eukaryotes don't have peptidoglycan, but bacteria do and autolysin activity continues causing autolysis of bacteria cell

Question 54

what does penicillin do?

Answer 54

inhibits transpeptidase activity - leads to cell death

Question 55

beta-lactamase

Answer 55

provides bacterial cells with antibiotic resistance (ex it becomes resistant to penicillin)

Question 56

what can freely pass through the cytoplasmic membrane?

Answer 56

dissolved O2 and simple alcohols

Question 57

LPS (Lipopolysaccharides are unique to?

Answer 57

outer membrane of gram neg bacteria

Question 58

bacterial cells that move can only sense a gradient by identifying ? changes and NOT ? differences `

Answer 58

they sense temporal changes NOT spatial changes cuz they r small

Question 59

in general prokaryotes or eukaryotes grow in higher temps?

Answer 59

prokaryotes

Question 60

are phototrophic or non phototrophic organisms able to grow at higher temps?

Answer 60

NON-PHOTOTROPHIC

Question 61

peptide INTERBRIDGE is present in?

Answer 61

gram pos Bacteria

Question 62

the presence of diglycerol tetraethers in some archaea indicate what kind of cell membrane?

Answer 62

monolayer

Question 63

The person who described the "wee animalcules" was

Answer 63

Antoni van Leuuwenhook

Question 64

_______ are charged molecules that are partially responsible for the ________ charge of the Gram-positive bacterial cell surface.

Answer 64

teichoic acids negative

Question 65

Which of the following is an example of a cultured marine chemoorganotrophic bacterium that contains proteorhodopsin and is a member of the SAR11 clade?

Answer 65

pelagibacter

Question 66

what is ANI and what is it most commonly used for?

Answer 66

average nucleotide identity, used for genome sequencing

Question 67

what inhibits the FtsZ ring?

Answer 67

MinCD

Question 68

endospores are only in gram ?

Answer 68

positive