Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbio 3220 > Exam 2 - Lecture 12 > Flashcards

Exam 2 - Lecture 12 Flashcards

1
Q

many _____________ _____________ are used as starting substrates for amino acids

A

precursor metabolites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what atom is a major component of protein, nucleic acids, coenzymes, and more?

A

nitrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are potential sources of nitrogen used by cells?

A
  • ammonia (NH3)*
  • nitrate (NO3-)*
  • nitrogen gas (N2)
  • *most cells use these
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why is ammonia easily incorporated into organic material?

A

it is more reduced than other forms of inorganic nitrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

ammonia is added to ______-_____________ under high ammonia conditions to form ______________

A

alpha-ketoglutarate; glutamate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what enzyme transfers amino groups to carbon skeletons?

A

transaminases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what enzyme reduces nitrate to nitrite?

A

nitrate reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what enzyme reduces nitrite to ammonia?

A

nitrite reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what enzyme catalyzes the reduction of atmospheric nitrogen (N2) to ammonia?

A

nitrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what organisms have nitrogenase?

A

only bacteria and archaea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how many ATP and electrons does it cost the cells to reduce N2 to NH3? what % of cellular ATP can this process consume?

A
  • 16 ATP and 8 electrons
  • up to 20% cellular ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

which two amino acids have sulfur groups?

A

cysteine and methionine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is an example of a coenzyme that contains sulfur?

A

coenzyme A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

where is sulfur commonly obtained from?

A
  • external sources
  • intracellular amino acid reserves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

sulfate (SO4,2-) has to be ________ in order to be incorporated into organic molecules

A

reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is assimilatory sulfate reduction?

A

sulfate is reduced into hydrogen sulfide (H2S) and then is used to synthesize cysteine. cysteine is then used to make sulfur contained organic compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the first step in assimilatory sulfate reduction? how many ATP does it use?

A
  • sulfate activation through the formation of PAPS (phosphoadenosine 5’-phosphosulfate)
  • uses 2 ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what takes place after sulfate reduction in assimilatory sulfate reduction? how many NADPH are used?

A
  • sulfate in PAPS is sequentially reduced to sulfite (SO3-) and H2S
  • 2 NADPH used
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the final step of assimilatory sulfate reduction?

A

H2S is used to create cysteine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how do fungi make cysteine? how about bacteria?

A
  • fungi: H2S + serine
  • bacteria: H2S+ O-acetylserine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is transamination? what serves as the source of the amino group?

A
  • the direct addition of amino groups to precursor metabolites to make some amino acids
  • glutamate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

glutamate + pyruvate = ?

A

alanine

23
Q

glutamate + oxaloacetate = ?

A

aspartate

24
Q

what is an amino acid biosynthetic pathway?

A

when the carbon skeleton is first modified in a precursor metabolite and that single precursor gives rise to several amino acids

25
Q

what four amino acids can be made biosynthetically from oxaloacetate?

A

threonine, methionine, lysine, and isoleucine

26
Q

what is a nucleoside?

A

nitrogenous base + 5 carbon sugar

27
Q

what is a nucleotide?

A

nucleoside + phosphate

(base + sugar + phosphate)

28
Q

which end of DNA has the phosphate? how about the hydroxyl?

A
  • 5’-phosphate
  • 3’-OH
29
Q

what are the purines? are they made of one or two rings?

A
  • adenine and guanine
  • 2 joined, cyclic rings
30
Q

what are the pyrimidines? are they made of one or two rings?

A
  • cytosine, uracil, and thymine
  • single ring
31
Q

how many steps is the purine biosynthesis pathway?

A

11 complex steps

32
Q

what is the base of all purine molecules?

A

ribose-5-phosphate

33
Q

what is the first purine product formed? all initial products are _______________

A
  • inosinic acid
  • ribonucleotides
34
Q

how are purine deoxyribonucleotides made from ribonucleotides?

A

by the reduction of the 2’-OH to a 2’-H

35
Q

what are the first two pyrimidines made?

A

(deoxy)uridine and (deoxy)cytidine

36
Q

what are the starting molecules for pyrimidine biosynthesis?

A
  • aspartic acid
  • high energy carbamoyl phosphate
  • (and bicarbonate and glutamate)
37
Q

what is the important difference between purine and pyrimidine biosynthesis?

A
  • purine rings are synthesized while attached to ribose
  • ribose is added AFTER synthesis of the pyrimidine ring
38
Q

what % of Earth’s surface is water? what % of that water is freshwater and salt water?

A
  • 70% of the surface
  • 97.5% salt, 2.5% fresh
39
Q

what are important physical factors for microbes in aquatic environments?

A
  • dissolved O2 (most important)
  • dissolved CO2
  • temperature
  • pH
  • light penetration
40
Q

in the very deep ocean, oxygen concentration __________ with depth

A

increases

41
Q

in warm environments, oxygen may become _________ a few meters below the surface

A

limited

42
Q

the constant exchange of CO2 at the water’s surface is called the:

A

carbonate equilibrium system

43
Q

what is high levels of atmospheric CO2 causing in the carbonate equilibrium system? what does this do to the water?

A
  • higher CO2 dissolution into seawater
  • it decreases the pH
44
Q

what is an estuary?

A

a semi-closed coastal region where a river meets the sea

45
Q

what is the characteristic salinity profile of an estuary called?

A

a salt wedge

46
Q

microbes in estuaries must be able to withstand large changes in salt concentration. what is their salt requirement?

A

halotolerant

47
Q

are estuaries nutrient rich or poor?

A

rich

48
Q

what is eutrophication? can this lead to algal blooms?

A
  • enrichment of an ecosystem with chemical nutrients, typically compounds containing phosphorus and nitrogen, which can be caused by pollution
  • yes
49
Q

what are harmful algal blooms?

A

HABs are blooms that occur when a single microbial species (algae or cyanobacteria) grows at the expense of other members of the community

50
Q

what toxins are released by cyanobacteria into the environment from the algal blooms in Lake Erie?

A

microcystins

51
Q

drinking or swimming in algal blooms can cause _________

A

illness

52
Q

what are two ways algal blooms harm other members in the community?

A
  • strips all the oxygen from the water
  • photosynthesizing microorganisms and plants can’t get light
53
Q

what is the euphotic zone?

A

the range of water depth where light penetrates with enough intensity so that the rate of photosynthesis by microscopic autotrophs exceeds the collective rate of respiration
- basically there’s enough light for photosynthesis here

54
Q

what microbe is the most numerous in marine ecosystems?

A

virioplankton

Microbio 3220 (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions