Midterm 1.2

Question 1

Certain DNA sequences are better choices than others. Which ones?

Answer 1

Typically looking for highly conserved genes with a highly conserved function that slowly accumulates mutations over time

Question 2

The most common DNA sequence that gets used for determining phylogenetic relationship is ______

Answer 2

ribosomal RNA of the small subunit (SSU) of the ribosome

Question 3

What regions of rRNA are useful for identifying relationships?

Answer 3

Variable regions

Question 4

What regions of rRNA are useful for PCR?

Answer 4

Conserved regions

Question 5

What does mitochondria contain?

Answer 5

Contain own genomes, ribosomes

Question 6

Tell everything we should know about Staphylococcus auerus

Answer 6

Cocci: Spheres
Common component of human microbiota
Opportunistic pathogen (through wounds)
Can enter bloodstream and cause life-threatening infections

Question 7

Tell everything we should know about Neisseria gonorrhoeae

Answer 7

Cocci: spheres
Gram negative coccus
Etiological agent of the common STD gonorrhea

Question 8

Tell everything we should know about Streptococcus pyogenes

Answer 8

Cocci: spheres
Can cause a range of diseases, including “step throat”. Can also be carried by healthy individuals

Question 9

Tell everything we should know about Salmonella enterica

Answer 9

Bacilli: rods
Common cause of “food poisoning” worldwide. Also causes of Typhoid fever”

Question 10

Tell everything we should know about Vibrio cholerae

Answer 10

Vibrio: comma shaped or bent rod
Important human pathogen, especially in developing world, that causes profuse diarrhea and dehydration

Question 11

Tell everything we should know about Helicobacter pylori

Answer 11

Helical
Commonly found in human stomach, often innocuous
Cause of vast majority of stomach ulcers, stomach cancers

Question 12

Tell everything we should know about Borrelia burgdorferi

Answer 12

Spirochetes
Pathogen that causes Lyme disease, transmitted by ticks

Question 13

Tell everything we should know about Caulobacter crescentus

Answer 13

Appendaged/budding
Used as a model system to study bacterial cell cycle, assymetric cell division
Cell cycle can be synchronized, facilitating its characterization

Question 14

Tell everything we should know about Chloroflexus aurantiacus

Answer 14

Filamentous
Photosynthetic bacterium that does not produce O2
Studied to understand the evolutionary origins of photosynthesis

Question 15

What causes different morphologies/changes of morphology? (3)

Answer 15

1. Differentiation into different cell types or spore formation
2. Altered morphology in response to environmental cues
3. Altered morphology due to mutation

Question 16

What are the major structures of cell envelope? (4)

Answer 16

Cytoplasmic membrane,
Cell wall,
Outer membrane,
S-layers

Question 17

What are the functions of the cytoplasmic membrane?

Answer 17

1. Permeability barrier: prevents ;eakage and functions as a gateway for transport of nutrients into, and wastes out of, the cell
2. Protein anchor: site of proteins that participate in trasnport, bioenergetics, and chemotaxis
3. Energy conservation: site of generation and dissipation of the proton motive force

Question 18

What kind of backbone is conserved in bacteria?

Answer 18

Glycerol phosphate backbone

Question 19

What are the 2 faces of the cytoplasmic membrane?

Answer 19

Cytoplasmic face (faces the cytoplasm)
Periplasmic face (faces outwards)

Question 20

What is the primary function of cell wall?

Answer 20

Prevent cells from bursting due to osmotic pressure
Also provides cell shape, rigidity

Question 21

Explain what is the difference in cell wall between Gram + & gram - (!)

Answer 21

Gram + bacteria: Thick cell wall, no outer membrane
Gram - bacteria: Thin cell wall, have an outer membrane

Question 22

Peptidoglycan (!)

Answer 22

A lattice-like structure formed from chains of glycans linked together by peptide bridges
Peptido (short peptides) glycan (sugars)
- Sugar backbone and peptide crosslinks