Final Short Answers Flashcards
What impact does biofilm formation have on the efficacy of antibiotics in clinical settings, and what strategies can be used to overcome this challenge?
Challenges:
- reduced antibiotic penetration: biofilms provide a protective matrix that limits the penetration of antibiotics into the bacterial community, making it difficult for drugs to reach and kill all the bacteria
- antibiotic tolerance: bacteria within biofilms can enter a dormant or slow-growing state, rendering them less susceptible to antiobiotics that target actively diving cells.
- formation of persistent cells: within biofilms, bacteria can develop cells with enhanced antibiotic tolerance
Strategies:
- combination therapy: using multiple antibiotics with different mechanisms of action can enhance the effectiveness of treatment against biofilm-associated infections. This approach targets bacteria at different stages of growth and disrupts biofilm formation more effectively
- biofilm-disructing agents: incorporating biofilm-disrupting agents such as enzyms or antibiofilm compounds (e.g. quorum sensing inhibitors can help destabilize biofilms and enhance antibiotic penetration.
What is the role of gut microbiome in ruminant digestion?
The gut microbiome in ruminants help to facilitate the breakdown of complex plant materials that the animal is unable to do on its own.
- microbes assist in the digestion of fiber and proteins. Bacteria in the rumen breakdown cellulose into simpler sugars that the animal can digest and absorb
- microbes in the rumen ferment carbohydrates, producing volatile fatty acids which serve as important energy sources for the ruminant host
- microbes synthesize essential nutrients which contribute to the overall nutritional status of the ruminant
- the gut microbiome of ruminants produces methane as a byproduct of microbial fermemnation.
How does the gut microbiome affect bovine health?
A healthy gut microbiome is essential for maintaining bovine health. The gut microbiome aids in the digestion of dietary components, such as fiber and proteins, and enhances the absorption of nutrients, including volatile fatty acids, vitamins, and minerals. The gut microbiome interacts closely with the host immune system. A balanced gut microbiome helps maintain immune homeostasis, reducing the risk of gastrointestinal disorders and metabolic diseases in cattle.
How does selective pressure contribute to antibiotic resistance in bacteria?
Selective pressure drives the evolution of antibiotic resistance in bacterial populations by favoring the survival and proliferation of resitant strains. When bacteria is exposed to antibiotics, susceptible strains are killed, while resitant strains survive and proliferate. This creates a selective advantage for resistant bacteria, leading to their dominance within microbial populations. Selective pressure for antibiotic resistance is promoted by the overuse and misuse of antibiotics. Prolonged or inappropriate antibiotic use increases the exposure of bacteria to selective pressure, accelerating the emergence and spread of resistant strains.
Describe the biological carbon pump and its role in carbon cycling in marine ecosystems.
The biological carbon pump is a set of processes in which inorganic carbon is fixed via photosynthesis. The organic matter is sequestered away from the atmosphere into the deep ocean. Marine phototrophs in the photic zone of the ocean fixes carbon dioxide into biomass. A portion of this biomass is converted back to CO2 via aerobic respiration, while the other biomass sinks to the bottom of the ocean (e.g when the photoplankton die)
Discuss the impact of rising sea temperatures on the biological carbon pump and the potential consequences for global carbon cycling.
rising sea temperatures can affect the composition and activity of microbial communities that are involved in the biological carbon pump. surface layer warming increases the stratification of the water column and reduces the nutrient supply. A decrease i nutries leads to less organic matter produced at the surface and reducing the amount of carbon transported to the deep. This can have a feedback effect on the climate system. reduced carbon sequestration may contribute to higher atmospheric CO2, further warming the climate.
Describe the stages of biofilm development
stage 1: free floating bacteria adhere to surface
stage 2: cells aggregrate, form micro colonies and excrete extracellular polymeric substances (ie. slime). At this stage the attachment become irreversible
stage 3: biofilm is formed. It matures and form multi-layered clusters
stage 4: further maturation of the biofilm, providing protection against host defense mechanisms and antibiotics
stage 5: the biofilm reaches a critical mass and disperses free floating bacteria, ready to form biofilms on other surfaces
quorum sensing plays a key role in biofilm formation by allowing microbes to communicate and coordinate their activities at diffeerent stages of the process.
Compare and contrast the structures of RNA and DNA
DNA:
- double helix
- Adenine pairs with thymine
- contains deoxyribose sugar
RNA:
- single strand
- adenine pairs with uracil
- contains ribose sugar
- often folds back on itself to form complex hirpins and other secondary structures
Why is the 16S rRNA used as a molecular fingerprint for bacterial identification and what is the role of hypervariable regions?
the 16S rRNA is present in all bacteria as it is an essential gene. It has a distinctive structure with conserved regions and variable (hypervariable) regions. These regions exhibit sequence differences that are unique to different bacterial taxa. By sequencing and analyzing these regions, researchers can create “molecular fingerprints” or unique genetic profiles for different bacterial species. These profiles can then be compared to databases of known 16S rRna sequences to identify and classify unknown bacteria.
Describe the role of microbes in composting process (in the context of microbial metabolism)
Microbes decompose complex organic material into simpler compounds through metabolic processes.
- organic material can be decomposed via aerobic respiration, which involves the breakdown of organic material in the presence of oxygen. This process generates energy for microbial growth and produces CO2 and water
- in the absence of oxygen, microbes can utilize fermentation pathways. This anaerobic process breaks down organic material, producing alcohols and carbon dioxide
Briefly describe the lytic and lysogenic cycles of bacteriophage
Lyric:
-Bacteriophage injects the genetic material (DNA or RNA) into the bacterial host
- the phage hijacks the bacterial machinery to replicate its genetic material and produce viral components
- the newly sythesized components form phages and eventually the host bacteria bursts open, destroying the cell (lysis) and releasing the phages to infect other hosts.
lysogenic:
- bacteriophage injects genetic material into the bacterial hosts
- instead of immediately replicating, the phage integrates its DNA into the genome of the host
- as host cell multiplies, its DNA is replicated along with the integrante phage DNA.
- the phage can persist within the host population for an extended period of time without causing cell death
- environmental cues can eventually cause the phage to enter the lytic cycle
How does CRISPR-Cas immunity protect bacteria from viral infections?
When bacteria encounters viral infections it can capture snippets of the viral DNA or RNA and incorporate them into its own genome as short, repetitive sequences known as spacers. These spacers are intergrated into the CRISPR locus of the bacterial genome, forming a CRISPR array. Essentially each spacer in the array corresponds to a specific sequence from a viral genome, serving as a memory of past viral infections. If the bacterium survives the infection, later reinfection of the same phage causes transcription of the spacers into CRISPR RNA (crRNA). The crRNA then joins the Cas complex to cleave the phage DNA. This CRISPR-Cas system provide microbes with an addaptive immune response against viral infections.
Why is microbial diversity important for ecosystem functioning? Describe two examples.
microbial diversity is crucial for ecosystem functioning due to the various roles tht different microbial species play in biogeochemical cycles.
nutrient cycling:
- different microbial species specialize in the breakdown of specific organic compounds such as cellulose, ligning, proteins into simpler forms tht can be used by other organisms. for example in forest ecosystems, microbial communities in the soild decompose leaf litter and dead plant material, releasing nutrients like carbon and nitrogen back into the soil. this enriches the soil and supports the growth of plans which in turn provide habitat and food for other organisms
symbiotic/syntropic relationships
- two or more organisms carry out a metabolic function that none of them can do alone.
