exam 1 - microbial world, bacteria, eukaryal microorganisms, archaea, and viruses

Question 1

Bacteria use a variety of means to attach to solid substrates including

Answer 1

b and c - look at screenshot and fix

Question 2

The complete function of the S-layer remains unclear. The fact that the S-layer is found in cultures isolated from natural sources, but is typically lost by cells in laboratory cultures, suggests:

Answer 2

The S-layer may play a role in protecting cells from viruses and predatory bacteria found in nature but not in laboratory cultures; production of an S-layer is very energetically costly to the bacterium - therefore, they are unlikely to produce the S-layer unless necessary

Question 3

The correct sequence from latest (most inclusive) to the smallest (least inclusive) taxonomic group is

Answer 3

class - order - family - genus - species

Question 4

TonB receptors mediate high-affinity transport across ________

Answer 4

the outer membrane

Question 5

a bacterial type strain is:

Answer 5

a reference specimen that is deposited in a central depository

Question 6

T/F: it is believed that there are very few species of bacteria yet to be discovered and described

Answer 6

F: it is estimated that ~98% of bacterial species still remain to be discovered

Question 7

bacterial cell walls are composed of

Answer 7

chitin

Question 8

eukaryal cell walls are composed of ___

Answer 8

peptidoglycan

Question 9

fungal cell walls are usually composed of ____

Answer 9

cellulose

Question 10

why are mitochondria and chloroplasts semi-autonomous organelles?

Answer 10

while mitochondria and chloroplasts are membrane-bound, contain their own DNA, and replicate independent of the cell, they require proteins to be translated in the cytoplasm of the cell; their essential proteins are made in the cell cytoplasm

Question 11

which group of eukaryal microorganisms plays a key role in the fermentation of alcoholic beverages

Answer 11

fungi

Question 12

a major difference between mitosis and meiosis is:

Answer 12

the goal of mitosis is for the cell to generate two identical daughter cells, while the goal of meiosis is for the cell to generate four identical daughter cells; metabolism, growth, and reproduction are the three primary characteristics that distinguish living organisms from non-living

Question 13

what cellular organelle might be the result of an endosymbiotic event?

Answer 13

nucleus; membrane-bound organelles in eukaryal are theorized to have arisen from endosymbiotic events

Question 14

T/F: one line of evidence suggesting eukaryal cells arose via endosymbiosis, is the fact that mitochondria and chloroplasts are surrounded by peptidoglycan-like layers

Answer 14

F: mitochondria and chloroplasts are surrounded by a plasma membrane and not peptidoglycan

Question 15

a characteristic that is unique to the domain Archaea is:

Answer 15

a cell membrane constructed from unique lipids; lipids that comprise the archaea plasma membrane are distinct from those found I bacteria and eukarya

Question 16

halophiles rely on a high intracellular concentration of which ion to maintain osmotic balance?

Answer 16

K+

Question 17

T/F: Archaeal flagella are composed of more than one type of flagellin

Answer 17

T

Question 18

This early microbiology pioneer developed a set of criteria for linking a specific microorganism to a specific disease

Answer 18

Robert Koch - Koch’s four postulates set criteria for linking a specific disease

Question 19

What are the three domains of life?

Answer 19

Bacteria, Archaea, and Eukarya; development of polymerase chain reaction (PCR) led to classification of organisms into the three domains of life

Question 20

Why is the term “microbes” more general than the term “microorganisms”?

Answer 20

the term “microbe” includes viruses, which are not considered to be living, and as such are not considered to be mircoorganisms

Question 21

T/F: polypeptides are the most abundant macromolecule in the cell on a dry weight basis

Answer 21

T: polypeptides aka proteins make up ~50% of the dry weight of cells

Question 22

Which molecular tool MOST assisted in providing a more reliable way to verify the assertions made my Woese et al. in their 1990 paper on phylogeny?

Answer 22

Polymerase Chain Reaction (PCR): the sequencing of rRNA developed by Woese et al. was tedious and time consuming; development of PCR by Dr. Kary Mullis provided a more reliable way of classifying organisms into the three domains of life proposed

Question 23

which best describes the chemical structure of the plasma membrane in bacteria?

Answer 23

a bilayer of phospholipids; the plasma membrane of both gram-positive and gram-negative bacteria is made up of a phospholipid bilayer

Question 24

within a population of E. coli cells, you frequently observed rod-shaped cells that are significantly larger than the rest. this species is not known to be pleomorphic. which is most likely the explanation for tour observation?

Answer 24

cells are at different stages of growth before binary fission; during replication by binary fission, cells will elongate significantly, therefore, if there are no conditions of stress, as you frequently observe these larger cells, the most likely explanation is that you are observing cells prior to cell division

Question 25

T/F: the bacterial flagellum is structurally and functionally related to the eukaryal flagellum

Answer 25

F: bacterial and eukaryal flagella are not related in any way

Question 26

which of these describes the peritrichous arrangement of flagella?

Answer 26

flagella all around the cell

Question 27

polar flagella

Answer 27

only at the end(s) of the cell

Question 28

monotrichious bacteria

Answer 28

single, polar flagellum

Question 29

lophotrichous bacteria

Answer 29

> 1 flagellum at one or both ends

Question 30

amphitrichous bacteria

Answer 30

flagella at both ends

Question 31

peritrichous bacteria

Answer 31

multiple flagella all over cell surface

Question 32

what feature unites the members of the phylum Proteobacteria?

Answer 32

gram-negative; the phylum Proteobacteria is made up of gram-negative bacterial species, as is the phylum Bacteroides; the phylum Firmicutes and Actinobacteria are composed of gram-positive bacterial species

Question 33

what is the main function of the FtsZ protein in the bacterial cell?

Answer 33

cell division; FtsZ polymerizes into filaments that bundle together to form the Z-ring on the inner side of the plasma membrane to generate the division plane and facilitate proper cell division

Question 34

what is a plasmid?

Answer 34

plasmids are extra-chromosomal circular pieces of DNA that can be transferred from bacterium to bacterium

Question 35

the bacterial chromosome is a highly condensed structure that is tightly wound around itself to fit into the bacterial cell. what is the main enzyme responsible for condensing the DNA?

Answer 35

DNA topoisomerase is responsible for condensing the bacterial chromosome

Question 36

if mutations occur in genes encoding proteins of the general secretory pathway, then which bacterial regions may be deprived of key proteins?

Answer 36

plasma membrane, gram-negative outer membrane, and periplasmic space; if there is a mutation in the sec pathway, the plasma membrane and periplasmic space of both gram-negative and gram-positive bacteria, as well as the outer membrane of gram-negative bacteria would be deprived of proteins that are secreted through this pathway

Question 37

short hair-like protrusions on the surface of some bacterial cells, used primarily for attachment but occasionally for motility, are called ___

Answer 37

pili

Question 38

yesterday, you inoculated two separate overnight cultures of Escherichia coli and Staphylococcus aureus, respectively. Today in the morning, you realize that you forgot to label the two cultures. Your lab instructor suggests to compare the two cultures under the microscope and to identify the cultures by carrying out the Gram-stain procedure. Which of the following statements is NOT true?

Answer 38

both species display spherical morphology and form cluster. After the Gram staining procedure, Staphylococcus aureus will appear pink while Escherichia coli remains purple; the alcohol is used during the Gram-staining procedure to stabilize the crystal violet in Gram-negative bacteria – THIS IS BECAUSE - E. coli are rods, and not spherical; iodine is the stabilizing step in the gram staining process, alcohol is for the extraction of the crystal violet die

Question 39

peptidoglycan is cross-linked between what constituents in gram-negative bacteria?

Answer 39

DAP and D-alanine amino acids; peptidoglycan is cross-linked from the lysine-derivative DAP tot he D-alanine of another subunit

Question 40

T/F: flagella-mediated motility in bacteria does not require energy

Answer 40

F: rotation of the flagella occurs at the expense of the proton motive force (PMF)

Question 41

what is the reaction/function of bacterial B-lactamase enzymes?

Answer 41

inactivate penicillin; B-lactamase cleaves the B-lactam ring of B-lactam antibiotics and would therefore directly inactivate the function of penicillin and other B-lactam antibiotics, which themselves target and inhibit the function of the bacterial transpeptidase enzyme to inhibit cell wall synthesis

Question 42

they type III secretion system is evolutionarily related to proteins involved in making what structure?

Answer 42

flagella; the type III secretion system (T3SS) is evolutionarily related to the bacterial flagella, which utilizes a T3SS-like process to build the functional flagellum on the extra-cellular surface of the bacterium

Question 43

eukaryal proteins that are secreted outside of the cell undergo modification before secretion. which organelles are involved in this secretion pathway?

Answer 43

the endoplasmic reticulum (rough) and Golgi apparatus are involved in the protein secretion and trafficking pathway; proteins are translated from mRNA and processed at rER, and are the folded/modified at the Golgi apparatus prior to secretion

Question 44

the appearance of mitochondria within eukaryal cells is defined as an evolutionary Big Bang; which landmark ability might have preceded it?

Answer 44

evolution of phagocytosis; bacteria are typically taken up by eukaryal cells through phagocytosis; therefore, if mitochondria were derived from bacteria taken up by eukaryal cells to develop an endosymbiotic relationship, phagocytosis would have to have evolved first

Question 45

the result of meiosis is the production of:

Answer 45

four haploid cells; meiosis involved two rounds of cell division, with only one round of DNA replication/duplication that precedes the first cell division; after the first round of division there will be two diploid cells (2n), after the second round of division, there will be four haploid cells (1n) with half of the genetic material of the original cell that. began the meiosis process

Question 46

T/F: the slime mold Dictyostelium discoideum is classified as a fungus

Answer 46

F: slime molds represent their own class of eukaryal microbes and are not classified as fungi

Question 47

most cell walls of algae are composed of ____

Answer 47

cellulose

Question 48

an encysted protozoan cell is located in a temperate lake that is thawing as spring weather finally arrives. What plasma membrane modifications might be observed as it adapts to its changing environment?

Answer 48

increased concentrations of saturated fatty acids within its phospholipid bilayer; decreased sterol concentrations within the plasma membrane

Question 49

which of the following is a plasma membrane structural adaption for archaea life at high temperatures?

Answer 49

lipid monolayers instead of bilayers; ether linkages instead of ester linkages; isoprenoids instead of fatty acids

Question 50

there is wide variability in physiology and morphology both between and within the major groups of archaea. in light of this variability, on what basis are species assigned to each phylum within the domain?

Answer 50

species are assigned to phyla based on nucleic acid sequence similarity

Question 51

viral nomenclature is based on

Answer 51

the geographic location where the virus was first discovered; the disease the virus causes; the physical characteristics of the virus

Question 52

T/F: lytic viruses (bacteriophages) replicate within the bacteria and lyse the host cell while lysogenic viruses can remain in a non-lytic state for an extended period of time

Answer 52

T: lytic bacteriophages replicate within and lyse the bacterial cell to dissipate new visions; lysogenic bacteriophages incorporate their genome within the bacterial genome and can remain within the cell for an extended period

Question 53

the shape of viruses is determined by their

Answer 53

capsid; the viral RNA/DNA genome is enclosed by a protective protein shell, known as a capsid, which often exhibit helical or icosahedral shapes; the shape of the nuclei-capsid (capsid + genome) dictates the shape of the virus

Question 54

molecular chaperones are proteins involved in which eukaryal cell process?

Answer 54

protein folding; chaperones are proteins that assist other proteins in folding properly

Question 55

what are the three major structures that comprise the eukaryal cytoskeleton?

Answer 55

microtubules, microfilaments, and intermediate filaments; each component is made up of a different type of protein subunit

Question 56

microtubules are made up of

Answer 56

alpha- and beta-tubulin

Question 57

microfilaments are made of the protein ___

Answer 57

actin

Question 58

intermediate filaments are made of various proteins including ___, ____, and ____

Answer 58

keratin, laminate, and vimentin

Question 59

what is not a challenge for life at high temperatures for archaea?

Answer 59

generating sufficient activation energy to initiate enzyme catalyzed reactions

Question 60

what can high temperatures do in archaea?

Answer 60

impact plasma membrane integrity, denature DNA, and cause damage to or induce protein unfolding

Question 61

T/F: to date, all known archaea methanogens are obligate anaerobes

Answer 61

T: this means they require the absence of oxygen to survive

Question 62

unlike bacteria, the cytoplasmic membrane of archaea:

Answer 62

can exist as a monolayer; some archaea can have a plasma membrane made of a lipid monolayer, instead of a bilayer; in the case of a monolayer, a phosphoglycerol molecule is found on both ends of the lipid

Question 63

synthetic DNA fragments are incubated with either eukaryal histones or archaeal histones. Observation shows that 15 eukaryal histone complexes form along the length of the synthetic DNA. How many archaeal histone complexes would you predict to associate along this DNA?

Answer 63

40

Question 64

viral genomes may consist of which of these molecules?

Answer 64

single and double stranded DNA, single and double stranded RNA; viral genomes can encompass all of these possibilities, depending upon the virus type

Question 65

what is the viral capsid composed of?

Answer 65

one or more types of viral proteins

Question 66

T/F: enveloped viruses acquire their envelope from host cell membranes

Answer 66

T: enveloped viruses obtain their envelope from the host cell

Question 67

how does the structure of the influenza virus differ from that of the tobacco mosaic virus (TMV)?

Answer 67

TMV is a naked virus, while influenza is enveloped; TMV is not an enveloped virus; TMV does not have a viral RNA polymerase associated
with its chromosomal fragment, while each of the 8 RNA chromosomal fragments of Influenza is associated with its own viral RNA polymerase; All viruses have a linear chromosome, whether it is made from DNA or RNA.