Exam 1 Q's

Question 1

1. A bacterial species is defined as a group of bacteria with: a. the ability to exchange genetic material b. Greater than 50% similarity by trait comparison c. Greater than 70% similarity by DNA/DNA hybridization d. Greater than 95% similarity by 16S rRNA sequencing

Answer 1

c. Greater than 70% similarity by DNA/DNA hybridization

Question 2

3. Which of the following types of microscopy allow you to visualize bacteria without killing them? a. phase-contrast microscopy b. scanning electron microscopy c. transmission electron microscopy d. bright field light microscopy with Gram staining

Answer 2

a. phase-contrast microscopy

Question 3

4. The resolution of light microscopy is ultimately limited by: a. focal length b. lens strength c. numerical aperture d. the wavelength of visible light

Answer 3

d. the wavelength of visible light

Question 4

5. 16S rRNA is found in the: a. nucleoid b. ribosome c. periplasm d. membrane

Answer 4

b. ribosome

Question 5

6. In bacteria, there are ___________ different monomers that make up proteins. a. 4 b. 16 c. 20 d. 64

Answer 5

c 29

Question 6

7. In bacteria, there are ___________ different monomers that make up RNA. a. 4 b. 16 c. 20 d. 64

Answer 6

a. 4

Question 7

8. Which part of lipopolysaccharide contains highly negatively charged sugars? a. core b. lipid A c. O-antigen d. teichoic acid

Answer 7

a. core

Question 8

9. Which is NOT true concerning extracellular polysaccharides: a. they reduce diffusion of molecules to the plasma membrane. b. they protect bacteria from a host’s immune system. c. they help bacteria stick to surfaces. d. they are required for growth.

Answer 8

d. they are required for growth

Question 9

10. The folding of a protein into a complex and specific three dimensional shape is called the ___________ structure. a. primary b. secondary c. tertiary d. quaternary e. none of the above

Answer 9

C and D

Question 10

11. Peptidoglycan is an especially stable cell wall polymer for all of the following reasons except: a. It contains β1-4 glycoside bonds. b. It contains unusual amino acids. c. It contains peptide bonds. d. It is hydrophobic.

Answer 10

d. It is hydrophobic.

Question 11

12. An extracellular crystalline shell of protein synthesized by some bacteria is called a(n): a. teichoic acid b. slime layer c. S-layer d. capsule

Answer 11

c. S-layer

Question 12

13. Molecular chronometers must have all of the following properties for the phylogenetic analysis of organisms except: a. it has regions of low sequence similarity between some organisms b. it has regions of high sequence similarity between some organisms c. it has different functions in different organisms d. it is present in all organisms being compared

Answer 12

c. it has different functions in different organisms

Question 13

a. Porin b. SMC c. MreB d. CreS e. Braun’s Lipoprotein 14. This protein connects the outer membrane to the peptidoglycan.

Answer 13

e. Braun’s Lipoprotein

Question 14

a. Porin b. SMC c. MreB d. CreS e. Braun’s Lipoprotein 15. This protein makes a rod cell, rod-shaped.

Answer 14

c. MreB

Question 15

a. Porin b. SMC c. MreB d. CreS e. Braun’s Lipoprotein 16. This protein makes the nucleoid, nucleoid-shaped.

Answer 15

b. SMC

Question 16

a. Porin b. SMC c. MreB d. CreS e. Braun’s Lipoprotein 17. This protein increases membrane permeability.

Answer 16

a. Porin

Question 17

a. Porin b. SMC c. MreB d. CreS e. Braun’s Lipoprotein 18. This protein directs peptidoglycan synthesis.

Answer 17

c, MreB

Question 18

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class 19. _______________ is defined by α and β linkages.

Answer 18

a. polysaccharide

Question 19

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class 20. _______________ is defined by the N and C termini.

Answer 19

c. protein

Question 20

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class 21. The largest macromolecule inside the cell is made of _____

Answer 20

nucleic acid

Question 21

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class 22. Peptidoglycan is made of _______________.

Answer 21

e. structure has properties of more than one macromolecular class

Question 22

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class 23. A bacterial capsule is made of _______________.

Answer 22

d. lipid

Question 23

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class

Answer 23

d. lipid

Question 24

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class

Answer 24

b. nucleic acid

Question 25

a. polysaccharide b. nucleic acid c. protein d. lipid e. structure has properties of more than one macromolecular class

Answer 25

c. protein

Question 26

T/F ## Footnote 27. Disulfide bridges are a common way to stabilize protein folding in the cytoplasm.

Answer 26

False

Question 27

True or False ## Footnote 28. Serotyping is a way of classifying bacteria based on antibody reactivity.

Answer 27

True

Question 28

True or False ## Footnote 29. Mitochondria were once bacteria.

Answer 28

True

Question 29

True or False 30. Eukaryotes and Bacteria have been on Earth for the same amount of time.

Answer 29

False

Question 30

True or False ## Footnote 31. In fluorescence microscopy, the light source and detector are on the same side of the sample.

Answer 30

True

Question 31

True or False ## Footnote 32. In transmission electron microscopy, the electron emitter and detector are on opposite sides of the sample

Answer 31

True

Question 32

True or False ## Footnote 33. Detergents kill cells by disrupting the membrane.

Answer 32

True

Question 33

Epulopiscium fishelsoni Escherichia coli Magnetospirillum magnetotactum Mycobacterium tuberculosis Mycoplasma pneumoniae Vibrio fischeri 34. Which organism of the week is unusual with respect to thearchitecture of its cell envelope (plasma membrane and external structures)? (1 pt). How is theenvelope unusual? (2 pts)

Answer 33

Mycoplasma pneumoniae – no peptidoglycan, membranes contain cholesterol Mycobacterium tuberculosis – two capsules with a waxy mycolic acid layer

Question 34

Epulopiscium fishelsoni Escherichia coli Magnetospirillum magnetotactum Mycobacterium tuberculosis Mycoplasma pneumoniae Vibrio fischeri 35. Which organism of the week challenges either our definition of a bacterium or the definitionof a bacterial species (1 pt)? Why does this organism challenge the definition (2 pts)?

Answer 34

Escherichia coli – two members of the same species have same 16S rRNA sequence but genome differs by 25% (2) Epulopiscium fishelsoni – cells are not small, visible to naked eye (2). Division is not binary but division mechanism isn’t part of the bacterial definition (0). Mycoplasma pneumoniae – all bacteria have peptidoglycan, except Mycoplasma and close relatives

Question 35

Epulopiscium fishelsoni Escherichia coli Magnetospirillum magnetotactum Mycobacterium tuberculosis Mycoplasma pneumoniae Vibrio fischeri 36. Which organism of the week was thought to have organelles? (1pt) What did the internal structures turn out to be instead? (2 pts)

Answer 35

Epulopiscium (1), internal daughter cells (2) Magnetospirillum (1), membrane invaginations containing magnetite (2), storage granules (1), magnetosomes (1), while both of the latter are correct, they were also the cause of the confusion and I’m looking for something about membrane invaginations to distinguish them from organelles. Mycoplasma (1), attachment organelle (1), proteinaceous endoskeletal element (2).

Question 36

37.Cell interior. a) What is an organelle? (2 pts)

Answer 36

Membrane enclosed intracellular compartment (2)

Question 37

b) Why do bacteria not need organelles? (2 pts)

Answer 37

Small with a high surface area to volume ratio (2)

Question 38

c) What is a nucleoid? (2 pts)

Answer 38

Region of the bacterial cell containing the compacted chromosome, not enclosed by an additional nuclear membrane (2)

Question 39

d) What is one advantage to having a nucleoid rather than a nucleus? (2 pts)

Answer 39

Rapid signal transduction (2) Coupled transcription/translation (2)

Question 40

Nomenclature/Taxonomy. a) Why are bacteria unable to be organized by the traditional species definition as set by Linnaeus? (2 pts)

Answer 40

They do not reproduce sexually (2)

Question 41

b) What is numerical taxonomy? (2 pts)

Answer 41

Organizing by trait similarity (2)

Question 42

c) What is phylogenetics? (2 pts)

Answer 42

Organizing by similarity of a shared polymer sequence molecular chronometer (gene/protein) (2)

Question 43

d) Describe two ways in which analysis of 16s rRNA sequences changed the way biologists think about the organization of life on earth? (2 pts)

Answer 43

5 Kingdom tree \> 3 Kingdom tree Archaea discovered Molecular ecology invented/microbiome Discovery that photosynthesis is a broadly distributed trait Proof of endosymbiotic theory of organelles

Question 44

39. Membranes. a) Explain the Fluid-Mosaic Model of biological membranes (2 points).

Answer 44

Fluid – molecules laterally diffuse rapidly in a phospholipid bilayer (1) Mosaic – proteins embedded throughout the bilayer (1)

Question 45

b) Give three types of damage that threaten the stability of biological membranes. For each type of damage, describe one specific way that bacteria defend against this damage (6 points).

Answer 45

Thermal - Adjust fatty acid content in phospholipids Osmotic - Build peptidoglycan sacculus beyond membrane to contain membrane expansion Chemical - Make outer surface highly negatively charged/charge barrier to discourage diffuse of hydrophobic molecules to membrane