1.) In Paragraph 2, the authors state that the slush layers host a productive assemblage of autotrophic and heterotrophic organisms. (5 pts)

a.) Could you use the media below to demonstrate that an organism was autotrophic ? b.) Why(not) - i.e. what would you have to do to demonstrate autotrophy?

(NH₄)SO₄ 1.0 g

K₂HPO₄ 1.0 g

KH₂PO₄ 0.5 g

CaCl₂ 0.01 g

FeSO₄ 0.005 g

MgSO₄ 0.2 g

MnCl₂ 0.1 g

glucose 5 g

3.)All of the organisms isolated so far from icey environments have been of the Domain Bacteria, therefore, you would expect bacteria living in the ice to have which two of the following molecules in their membranes. Circle both. (4 pts)

ether-linked lipid, phospholipid, teichoic acid, tertiary structure of protein, glycan tetrapeptide

4.) Based on the discussion of productivity (at the bottom of paragraph 2), circle the graph below that best illustrates the effects of temperature on growth of these Alps bacteria as one grows from the winter cover to the pelagic zone. (5 pts)

5.) The bacteria highlighted in this article could be described as

a. hyperthermophiles

b. mesophiles

c. thermophiles

d. psychrophiles

e. psychophiles

6.) Briefly explain why bacteria that live at cold temperature need to maintain flexibility in their membranes and proteins. (4 pts)

7.) Ways in which membrane flexibility is maintained under low temps is by....

a. decreasing the amount of unsaturated bonds in the fatty acids

b. increasing the amount of unsaturated bonds in the fatty acids.

c. increasing the chain length of the fatty acids

d. increasing the hydrophobic amino acids in the membrane proteins

e. b, c, and d are correct

f. b and c are correct.

a. a-helix-rich proteins are more rigid in structure

b. b-pleated sheet -rich proteins are more rigid in structure

c. a-helix-rich proteins have H-bonds that break at low temperature

d. b-pleated sheet -rich have H-bonds that break at low temperature

e. none of the above seems likely

9.) Suppose in your infinite brilliance (and laboratory aptitude), you isolate the first (heterotrophic) Archaea from some ice samples. You then decide to compare the growth of your Archaeal isolate with that of a previously isolated heterotroph of the domain Bacteria. To measure growth, you decide to use the plate (viable) count method because

a. Archaea are too small to see with the light microscope

b. this is a quick and dirty method so you can have your answer in a few hours

c. only living cells are counted with this method

d. this method does not require that cells are culturable

e. this is the only way to measure growth of Archaea

10.) To do your plate counts of the Archaeal isolate, you take 1 ml of a liquid culture and add it to 99 ml of sterile saline, you repeat this, and then take 0.3 ml and add it to 2.7 ml sterile saline. When you plate 0.1 ml of this diluted sample onto suitable media, you obtain 52 colonies. What was the cell concentration in the original undiluted sample? Show all work to get credit. (5 pts)

11.) When you did your growth curves, you obtained the

growth curves shown on the right. (6 pts)

a. What is the lag time of culture 1?

1 hr.

b. What is the doubling time of culture 2?

25 - 30 minutes

c. Which culture has the fastest growth rate?

2

12.) Unfortunately, you labeled your flasks with a water-soluble marker (not a Sharpie‰ ), and the writing was no longer visible on your flasks. The next day, you decided to see if you could figure out which culture was which by inoculating new flasks of sterile media, and adding lysozyme at the time indicated. You got the results below.

a. Which curve belongs to the Bacteria, and which belongs to the Archaea? (3 pts)

b. Briefly (but accurately) explain how you know this. (4 pts)

13.) Bacteria face lots of stresses (other than cold temps), by living in these icey environments (see table in article)- what other modification(s) might you expect in these organism?

a. presence of carotenoids

b. ability to deal with low water availability

c. ability to maintain viability without reproducing

d. none of the above are likely adaptations.

e. a, b, and c are likely adaptations.

Protection from: desiccation, predation, sometimes chemicals, UV, O2 barrier if don't want O2.

16.) Yeast are in the Domain Eukarya - thus you would NOT expect to see which of the following in its cell envelopes. Circle all that apply! ( 6 points)

ether-linked phospholipid, secondary structure of protein - alpha helix, teichoic acid, ester linked phospholipid, glycan tetrapeptide

Endospore formers are all members of the Gram positive lineage of the Bacteria. Some endospore formers are facultative aerobes, others are obligate aerobes, and some are aerotolerant anaerobes.

The difference between aerotolerant anaerobes and strict anaerobes is the lack of certain kinds of enzymes in the strict anaerobes.

18a.) Briefly - i.e. a sentence or so-, describe the function of the enzymes in the aerotolerant anaerobes (that are missing in the strict anaerobes). (3 pts)

18b.) Suppose you isolate an endospore former from some marine sediments. You find it displays the following growth behavior in thioglycollate tubes. Therefore, with respect to its oxygen requirements, you would say this organism is a(n) facultative aerobe . (3 pts)

19.) If you were trying to elicit spore formation, which medium would you probably grow your organism in and WHY? (Both recipes shown are per liter of dH₂O). (4 pts)

(NH₄)SO₄ 1.0 g Yeast extract 5.0 g

K₂HPO₄ 1.0 g Beef extract 3.0 g

KH₂PO₄ 0.5 g NaCl 2.0 g

CaCl₂ 0.01 g glucose 1.0 g

FeSO₄ 0.005 g

MgSO₄ 0.2 g

MnCl₂ 0.1 g

20.) Suppose you want to do some biochemical tests of your isolate. You inoculated a flask and agar plate of the same medium and incubated the cultures for them same amount of time .

a.) Compare the cells indicated by the arrow with cells growing in the liquid culture: (hint: are the cells (indicated by the arrow) most likely in lag, log, or stationary phase, and (how) does this differ from the cells grown in a liquid culture)? Explain ( 3 points)

b.) For your endospore stain, would you want to use the cells indicated by the arrow, or the cells from a liquid culture? Why? (3 pts)

21. Which of the following describe the endospore producing bacteria?

Mark "T" (true) or "F" (false) for each sentence. (1 point each)

T The position of an endospore (wiothin the cell) varies among genera, and it is genetically determined

F In a gram stain, vegetative cells of endospore forming bacteria appear pinkish-red.

F Endospores are resistant to heat because they have lots of saturated fats in their membranes

F Endospore formers have gene(s) that encode porins.

T Endospore formers lack the gene(s) to produce LPS

Beer production involves the fermentation of grain sugars into alcohol flavored by the addition of hops. When beer goes bad, the most common culprits are certain species of lactobacilli (members of the lactic acid bacteria) that grow in the brewing beer ruining its taste and appearance....eewwww yuck!

22. Most bacteria (except the lactobacilli) are unable to grow in beer because hops have antimicrobial properties. Thus beer is a(n)

a. antibiotic medium

b. defined medium

c. differential medium

d. selective medium

e. synthetic medium

23. Circle the graph below which shows that beer spoilage lactobacilli are better adapted than most other bacteria to withstand the alcohol content of beer (4-5%) (4 points)

circle top right graph

24.) Several steps occurred which lead to the origin of life on this planet. Based on the model presented in class, and your assigned reading - provide the most logical order for the following events. (1 happened first, 6 happened most recently) (6 pts)

6 RNA-directed translation increased in accuracy until the development of catalytic proteins (enzymes). Enzyme dependent metabolism progressively replaced protometabolism.

2 Polymeric building blocks (i.e. polynucleotides, polysaccharides, polypepetides formed from the monomeric building blocks by dehydration reactions on mineral surfaces.

5 There was a Darwinian selection of primitive cells - (cellular evolution) in which primitive cells containing mutations that produced more accurate replication, or more useful proteins competed more effectively for resources and grew faster.

1 Radiation in the form of UV and lightning struck the early anaerobic atmosphere which consisted of gases such as CH₄,H₂O, CO, N₂, NH₃, H₂S, HCN and trace amounts of CO and H₂. This resulted in monomeric building blocks (i.e. sugars, amino acids, purines, pyrimidines, nucleotides, thioesters, fatty acids being formed

3 There was a Darwinian selection for molecules (i.e. RNA and lipids) based on their stability in the environment, and a selection for RNA based on its ability to replicate titself and ultimately proteins- so called - molecular evolution.

4 stable self-replicating molecules (i.e. RNAs) were encapsulated into membranes (or membrane/protein complexes) to form primitive self-replicating entities (protogenote)

YEE - HAW!! YIPPY-I-O-I-A!!!!

GO HAVE YOURSELF A FINE REST OF THE DAY!