Exam 3 Review

Question 1

Which is not true regarding the cardinal range of bacteria?
A. the optimal temperature is closer to the minimum
B. the minimum temperature is the lowest temperature that allows proper membrane function
C. the maximum temperature is the highest temperature allowable before key enzymes begin to denature
D. all of the above are true
E. None of the above are true

Answer 1

A

Question 2

Bacteria living in psychrophilic conditions would exhibit which of the following characteristics?
A. the presence of long fatty acid chains within the membrane
B. a dominance of polar bonds within proteins
C. significant beta sheet structures within the secondary structure of proteins
D. the presence of di-inositol phosphate
E. all of the above would be exhibited in a psychrophile
F. none of the above would be exhibited in a psychrophile

Answer 2

B

Question 3

Which is not true of plasmids?
A. they are usually circular
B. they can replicate independently of the chromosome
C. they can be present in different copy numbers
D. their typical size is about 1/5 the size of an average bacterial chromosome
E. all of the above are true
D. none of the above are true

Answer 3

D

Question 4

Which of the following is not true of bacterial replication?
A. replication is bi-directional from the replication fork
B. to maintain short generation times, multiple origins of replication are present
C. the next round of replication can occur before the previous round has been completed
D. there is both a lagging and leading strand
E. all of the above are true
F. none of the above are true

Answer 4

B

Question 5

Which of the following is not a similarity between replicative DNA polymerase and the RNA polymerase used in transcription?
A. both require nucleoside triphosphates
B. both polymerize in the 5’ to 3’ direction
C. both require templates
D. both require primers to initiate new strand synthesis
E. all of above are traits of both enzymes
F. none of the above are shared traits

Answer 5

D

Question 6

T/F: bacteria can regulate their internal temperature in an effort to stabilize themselves in different environments

Answer 6

False

Question 7

T/F: thermophilic microorganisms tend to have unsaturated fatty acid dominating within their membranes

Answer 7

False

Question 8

T/F: Exopolysaccharide coatings are common amongst thermophilic and hyperthermophile organisms

Answer 8

False

Question 9

T?F: most acidophiles are categorized within the archaeal domain rather than the bacterial domain

Answer 9

True

Question 10

T/F: Bacteria within the staphylococcus genus grow best in very low salt concentrations, but can also survive in the absence of salt

Answer 10

False

Question 11

T/F: Microaerophilic bacteria are named because they generate smaller colonies when cultured in an oxygen concentration

Answer 11

False

Question 12

T/F: Aerotolerant anaerobes tend to express the same set of enzymes to deal with toxic oxygen by-products as aerobic environments

Answer 12

False

Question 13

T/F: Topioisomerases are involved in both the initiation of bacterial replication and the termination of replication

Answer 13

True

Question 14

T/F: In bacteria there tends to be one main sigma factor used for transcription but alternative factors are usually required for special circumstances

Answer 14

True

Question 15

T/F: All 64 codons of the genetic code encode amino acids

Answer 15

False

Question 16

T/F: 5S rRNA is found in the large ribosomal subunit of both prokaryotes and eukaryotes

Answer 16

True

Question 17

T/F: polysomes are observed in all three domains to improve efficiency of translation

Answer 17

true

Question 18

The majority of pathogenic microorganisms are going to be classified as ___________ based on their optimum temperature

Answer 18

mesophiles

Question 19

The upper threshold in regard to temperature for eukaryotic organisms is going to be _____ degrees Celsius and so far, for bacteria, we have not identified any organisms above _______ degrees Celsius

Answer 19

60 degrees
95 degrees

Question 20

What is the difference between a psychrophile and psychotolerant microorganism?

Answer 20

Psychrophiles live in constant cold, psychrotolerants tolerate cold

Question 21

The role of cryoprotectants such as glycerol and various sugars is to:

Answer 21

prevent the formation of ice crystals

Question 22

Why would sodium bicarbonate or potassium be added to culturing media?

Answer 22

To act as a buffer

Question 23

Provide one mechanism that allows an acidophile to survive in a low pH environment

Answer 23

highly impermeable membrane

Question 24

Is the following statement most likely true or false: an alkaliphile that grows in an environment of pH 10 accounts for the same increase in its internal cytoplasmic pH by expressing additional chaperone proteins. Please defend your answer

Answer 24

false, the internal cell pH must be 5-9 or the cell will die almost instantly

Question 25

a main way to handle a _______ environment is to increase the internal concentration of a compatible solute. a compatible solute is defined as _____________________

Answer 25

hypertonic, molecules that dont disrupt cells metabolism

Question 26

T/F the amount of compatible solute that can be maintained by a cell is genetically determined

Answer 26

True

Question 27

Is the following statement most likely true or false: a completely fermentative bacteria living in an oxygenic environment would not produce toxic oxygen by products. Please defend your answer

Answer 27

True, in complete fermentation the ETC is not used so there are no side reactions that produce toxic products

Question 28

In lecture, we talked about the use of _________________ broth to determine the oxygen requirements of a bacteria

Answer 28

thioglycollate

Question 29

Provide one way thioglycollate broth limits oxygen

Answer 29

use of agar

Question 30

Describe how a strict aerobe will grow in thioglycollate broth?

Answer 30

only will grow in pink, oxygen rich layer

Question 31

Thioglycollate broth does not work well for identifying microorganisms that fall into the _____________ category

Answer 31

microaerophiles

Question 32

Important to the DNA replication process is separating the two strands of the DNA chromosomes, please provide the 3 proteins within the replisome that are imperative in this

Answer 32

origin binding proteins, single stranded binding proteins, helicases

Question 33

In bacteria, how is DNA polymerase I different in enzymatic activity from DNA polymerase III

Answer 33

DNA polymerase I uses 5’ to 3’ exnuclease activity

Question 34

To complete the replication of a bacterial chromosome ___________ proteins bind to _________ sites that are found on the opposite side of the chromosome from the origin of replication. Ultimately, the chromosomes are separated and bind to _________ a component within the divisome

Answer 34

tus, ter, FtsK

Question 35

Why is it necessary that the chromosome is condensed in all 3 domains in life

Answer 35

Because it is very large, and does not need to be exposed at all times

Question 36

The ___________ region of a bacterial cell contains the chromosome that is usually condensed by __________, the most common topioisomerase in bacteria

Answer 36

nucleoid, DNA Gyrase

Question 37

Topioisomerases are categorized into class I or class II molecules based on:

Answer 37

whether they nick one strand or two strands

Question 38

Explain the difference in function/roles of a histone like protein in bacteria versus histones in eukaryotes

Answer 38

Histone-like proteins bind to DNA using their positive charge to stabilize the domains, DNA in eukaryotes will wrap around histones to condense

Question 39

Provide two differences between archaeal and eukaryotic histones

Answer 39

both have histone folds, but archaea don’t have the N and C terminals
Archaea uses 4 clusters, while eukarya use 8

Question 40

Is the following statement most likely true or false? positive supercoiling is common throughout the prokaryotic domain. Please defend your answer

Answer 40

False, use negative supercoiling, Hyperthermophiles are the exception using the reverse DNA gyrase

Question 41

You have two students who just started working in your lab and they have been working on their culturing techniques and obtaining a standard closed batch culture curve. When comparing their standard curves, you notice that ben always ends up with a curve that has a longer lag phase than Megan’s. They are both using the same bacteria and counting method - what could explain this difference????

Answer 41

ben is not keeping the bacteria happy. They are depleting their resources/nutrients so his lag time will be significantly longer since the cells have to accumulate and build what they need

Question 42

The direct count method requires a microscope and a ________________

Answer 42

hemocytometer

Question 43

Explain two advantages that direct count has compared to the viable count method

Answer 43

easier to count
can count alive and dead cells
higher count
faster

Question 44

Provide one limitation of the direct count method

Answer 44

dead cells can be counted skewing the counts