Module 1: Section 2

Question 1

Taxamony

Answer 1

Life
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 2

Bacterial taxa

Answer 2

Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 3

Viral taxa

Answer 3

Order
Family
Sub-family
Genus
Species

Question 4

Selective pressure

Answer 4

Any environmental factor that affects an organism’s fitness, driving evolution through competition and adaptation

Question 5

Microbial Adaptation

Answer 5

Microbes adjust to nearly any environment, even toxic ones, by evolving traits that improve survival

Question 6

Human Microbiome - 4 Dominant Phyla

Answer 6

1. Actinobacteria
2. Bacteroidetes
3. Firmicutes
4. Proteobacteria

Question 7

Actinobacteria

Answer 7

• gram-positive bacteria
• aerobic
• Mostly found in soil

Question 8

Bacteroidetes

Answer 8

• gram-negative bacteria
• colonized almost all habitats on Earth

Question 9

Firmicutes

Answer 9

• gram-positive
• often form endospores

Question 10

Proteobacteria

Answer 10

• major gram-negative phylum
• includes diverse array of bacteria

Question 11

Bacteriodes

Answer 11

• Phylum Bacteroidetes
• most predominant genus in the gut

Question 12

Streptococcus

Answer 12

• Phylum Firmicutes
• Most predominant genus in the mouth

Question 13

Pathogenic bacteria

Answer 13

• Bacteria that have the ability to cause infection
• Some of these bacteria are opportunistic pathogens

Question 14

opportunistic pathogens

Answer 14

• Microbes that take advantage of an opportunity that is not usually available to infect another organism
• ex. A weakened immune system

Question 15

Commensal bacteria

Answer 15

• Non-pathogenic and have a symbiotic relationship with the host
• Mainly composes human microbe

Question 16

What does commensal mean?

Answer 16

Biological relationship where one species benefits and the other is neither benefited or harmed

Question 17

How Bacteria Gain Genetic Diversity?

Answer 17

• Bacteria acquire genetic diversity through changes in their genome
• Can occur by 2 processes: mutations or gene transfer and recombination

Question 18

Mutations

Answer 18

• Changes in DNA that occur spontaneously or from external mutagens
• Spontaneous mutations occur through errors in DNA replication or repair
• Chemical mutagens in the environment can cause mutation in DNA sequence

Question 19

Gene transfer and genetic recombination

Answer 19

• Bacteria gain diversity via horizontal gene transfer (between unrelated organisms)
• Examples: Transformation, transduction, conjugation, or plasmid transfer

Question 20

Transformation

Answer 20

Uptake of naked genetic material from the surrounding environment

Question 21

Conjugation

Answer 21

Direct transfer of genetic material from one bacterial cell to another (bacterial mating)

Question 22

Transduction

Answer 22

Process in which bacterial DNA is moved from one bacterium to another by a virus, often a bacteriophage

Question 23

Transposition

Answer 23

• Occurs when there is a “jumping” of genes from one chromosomal location to another within an organism

Question 24

Effect of transposition

Answer 24

• Can increase or decrease gene expression
• insertion into a gene usually stops protein production
• If the transposon is inserted into the promoter region it could increase or decrease expression of a gene

Question 25

Compensatory mutations

Answer 25

Mutations that correct for a loss of fitness due to earlier mutations

Question 26

4 main mechanisms by which bacteria become resistant to antibiotics

Answer 26

1. Target protection 2. Target modification 3. Prevention of intracellular antibiotic accumulation 4. Antibiotic detoxification

Question 27

Target protection

Answer 27

Production of a protein that disrupts the interaction between an antibiotic and its target

Question 28

Target modification

Answer 28

Alteration of amino acid sequences in target sites in bacteria

Question 29

Prevention of intracellular antibiotic accumulation

Answer 29

- Increased expression of bacterial efflux mechanisms - Results in increased ability of bacteria to remove antibiotics from cell

Question 30

Antibiotic detoxification

Answer 30

- Increased ability of bacteria to alter or degrade antibiotic - This reduces antibiotic effects

Question 31

Human impact on microbial diversity, 2 main examples:

Answer 31

1. Climate change 2. Use of antibiotics

Question 32

Climate change

Answer 32

- Soil warming increases microbial activity, speeding up decomposition and respiration - This therefore increases the release of CO2, altering the carbon cycle

Question 33

Use of antibiotics

Answer 33

- Antibiotics reduce GI microbial diversity immediately - Some recover within a week, others can take months - Low-abundance species may never return

Question 34

Herd immunity

Answer 34

When enough people in a population are immune to a disease (through vaccination or prior infection), its spread is slowed or stopped

Question 35

Carbon cycle

Answer 35

Microbes carry out about half of Earth’s photosynthesis, removing CO₂ from the atmosphere and turning it into organic matter

Question 36

Nitrogen cycle

Answer 36

- Microbes convert nitrogen between forms (N₂, NH₃, NO₂⁻, NO₃⁻) to support ecosystems - Fertilizers and livestock increase nitrogen emissions, raising nitrous oxide (N₂O) release into the atmosphere