Exam 3 study guide lecture

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Questions and Answers

What characteristic distinguishes archaea from bacteria in terms of their cell wall composition?

Archaea have peptidoglycan in their cell walls.

Archaea have a cellulose-based cell wall.

Archaea lack peptidoglycan and may contain pseudopeptidoglycan. (correct)

Archaea have a cell wall made of chitin.

Why are many archaeal species difficult to discover and characterize?

They thrive in extreme environments that are hard to replicate in labs. (correct)

They exist in easily replicable laboratory environments.

They are less abundant than bacterial species.

They lack genetic diversity.

Which of the following is a notable characteristic of Streptomyces griseus?

It produces antibiotics including streptomycin. (correct)

It lacks branching filaments.

It is a unicellular organism.

It is a type of extremophile.

What is one of the unique adaptations that allow some archaea to thrive in extreme environments?

Linked lipids in their cell membranes. Signup and view all the answers

What role do Streptomyces species play in soil health?

They decompose organic matter and inhibit other microorganisms. Signup and view all the answers

Which statement about the genetic and biochemical differences of archaea is accurate?

Archaeal genetic processes are more akin to those of eukaryotes. Signup and view all the answers

What can be said about the structural composition of bacterial cell walls?

They typically contain peptidoglycan, providing rigidity. Signup and view all the answers

What environment might you expect to find many archaeal organisms thriving in?

Deep-sea hydrothermal vents. Signup and view all the answers

What is the main function of RNA polymerase during transcription?

To unwind the DNA and synthesize a mRNA strand Signup and view all the answers

In which cellular location does translation occur?

Cytoplasm Signup and view all the answers

What is the correct order of steps in transcription?

Initiation, Elongation, Termination Signup and view all the answers

Which component of translation binds to the mRNA and facilitates the addition of amino acids?

tRNA Signup and view all the answers

What happens during the elongation phase of transcription?

RNA polymerase synthesizes mRNA by adding RNA nucleotides Signup and view all the answers

What is a positive role of certain strains of E. coli in the human body?

They aid in digestion and vitamin production. Signup and view all the answers

How is the polypeptide chain formed during translation?

By the ribosome linking amino acids brought by tRNA Signup and view all the answers

What initiates the transcription process?

RNA polymerase binding to the promoter region Signup and view all the answers

Which of the following diseases is NOT caused by pathogenic strains of Enterobacteriaceae?

Influenza from viruses. Signup and view all the answers

What is the role of the termination signal in transcription?

To signal RNA polymerase to stop and release the mRNA Signup and view all the answers

What do fecal coliforms indicate when found in water sources?

The presence of pathogens from fecal matter. Signup and view all the answers

Why are rapid tests for Enterobacteriaceae important?

They serve as indicators of potential fecal contamination and food safety. Signup and view all the answers

Which of the following is a characteristic of Enterobacteriaceae?

They are facultatively anaerobic bacteria. Signup and view all the answers

Which one of the following is a well-known fecal coliform?

E. coli Signup and view all the answers

What is a negative effect of some species in the Enterobacteriaceae family?

They can cause severe foodborne illness. Signup and view all the answers

How are fecal coliforms related to infectious diseases?

Their presence suggests the risk of contamination by fecal pathogens. Signup and view all the answers

What is a key difference between the cell wall compositions of bacteria and archaea?

Bacteria have peptidoglycan while archaea lack it. Signup and view all the answers

Which type of lipids is primarily found in archaeal membranes?

Ether-linked lipids Signup and view all the answers

Which of the following statements is true regarding the environments where archaea typically thrive?

They thrive in extreme conditions like high temperatures and salinity. Signup and view all the answers

Which bacterial group is identified as the earliest known to evolve?

Cyanobacteria Signup and view all the answers

What distinguishes proteobacteria from non-proteobacteria?

Proteobacteria are a large diverse phylum with many known species. Signup and view all the answers

How do the metabolic types differ between non-proteobacteria and proteobacteria?

Non-proteobacteria exhibit a wider range of metabolic types. Signup and view all the answers

What role do Bacteroides play in the intestines of animals?

They aid in digesting complex molecules and contribute to gut health. Signup and view all the answers

Which group of bacteria is known for nitrogen fixation among diverse lifestyles?

Alpha proteobacteria Signup and view all the answers

What is a notable characteristic of Archaea compared to bacteria regarding pathogenicity?

No archaeal species has been identified as pathogenic. Signup and view all the answers

Which of the following statements about the cell wall composition of bacteria and Archaea is true?

Archaea lack peptidoglycan entirely in their cell walls. Signup and view all the answers

How do membrane lipids differ between Archaea and bacteria?

Archaea have ether-linked lipids, making their membranes more resilient. Signup and view all the answers

What defines resident bacteria compared to transient bacteria?

Resident bacteria live stably on or within the body. Signup and view all the answers

Which of the following is true about pathogenic bacteria?

Pathogenic bacteria invade host tissues or produce toxins. Signup and view all the answers

What is a unique feature of the genetic machinery of Archaea compared to bacteria?

Archaea's processes are more similar to eukaryotes. Signup and view all the answers

How do Archaea differ from bacteria in terms of their ecological roles?

Archaea and bacteria play distinct ecological roles. Signup and view all the answers

Which of the following is FALSE regarding transient bacteria?

Transient bacteria permanently colonize the body. Signup and view all the answers

Study Notes

Transcription & Translation

Transcription converts DNA into mRNA.
Transcription occurs in the nucleus.
Transcription involves RNA polymerase.
Translation converts mRNA into a protein.
Translation occurs in the ribosome.
Translation involves rRNA, mRNA, and tRNA.

Transcription Steps

Initiation: RNA polymerase binds to the promoter region of DNA.
Elongation: RNA polymerase unwinds the DNA, reads one strand, and synthesizes complementary mRNA by adding RNA nucleotides (A, U, C, G).
Termination: RNA polymerase reaches a termination signal in the DNA sequence, releases the mRNA strand, and stops. The DNA rewinds.

RNA Polymerase

Binds to DNA.
Unwinds the double helix.
Reads the DNA template strand.
Synthesizes a complementary mRNA strand.

Translation Steps

Initiation: The ribosome assembles around the mRNA strand. A tRNA with an anticodon complementary to the mRNA’s start codon (usually AUG) binds, bringing the first amino acid.
Elongation: As the ribosome moves along the mRNA, each codon pairs with a tRNA anticodon. Each tRNA brings a specific amino acid, which the ribosome links into a growing polypeptide chain.
Termination: The ribosome reaches a stop codon on the mRNA, signaling the end of translation. The polypeptide chain is released, and the ribosome disassembles.

Bacteria vs. Archaea

Cell wall composition: Bacteria have peptidoglycan in their cell walls, while Archaea lack peptidoglycan and have unique cell wall structures.
Membrane lipids: Bacteria have ester-linked lipids, while Archaea have ether-linked lipids in their cell membranes.
Genetic machinery: Archaeal genetic processes (like transcription and translation) are more similar to eukaryotes than to bacteria despite being prokaryotic.
Environment: Archaea are often extremophiles living in harsh conditions, while bacteria are found in a wider range of environments.

First & Latest Evolving Bacteria

First bacterial group to evolve: Cyanobacteria, which played a major role in oxygenating Earth's atmosphere through photosynthesis.
Latest bacterial group to evolve: Proteobacteria, which display a high level of diversity and include many modern bacterial species.

Proteobacteria

A large and diverse phylum of gram-negative bacteria.
Includes many known bacteria, such as E. coli and Salmonella.
Primarily chemoheterotrophs.
Includes groups like alpha, beta, gamma, delta, and epsilon proteobacteria with varied lifestyles.

Non-Proteobacteria

A broad category of gram-negative bacteria that do not belong to the proteobacteria phylum.
Exhibit a wide range of metabolic types, including phototrophs, anaerobes, and extremophiles.
Examples include cyanobacteria, Bacteroides, and Spirochetes.

Bacteroides

Anaerobic bacteria commonly found in the intestines of animals.
Essential for digesting complex molecules and contributing to gut health.

Cyanobacteria

Often found in aquatic environments.
Can sometimes form harmful algal blooms.
Fix atmospheric nitrogen, converting it into a usable form for plants and other organisms.

Enterobacteriaceae

A large family of gram-negative facultatively anaerobic bacteria that primarily inhabit the intestines of animals.
Includes species like E. coli, Salmonella, and Klebsiella.
Often found in the intestinal tract, as well as in soil, water, and plants.

Significance of Enterobacteriaceae

Positive: Certain strains of E. coli are beneficial for gut health, aiding in digestion and vitamin production.
Negative: Other members are pathogenic and can cause diseases such as:
- Food poisoning (Salmonella)
- Urinary tract infections (Proteus)
- Pneumonia (Klebsiella)

Fecal Coliforms

A subgroup of coliform bacteria that originate from the intestines of warm-blooded animals.
Used as indicators of fecal contamination in water sources.
Their presence suggests that pathogens from fecal matter might be present.

Relation to Enterobacteriaceae

Fecal coliforms are part of the Enterobacteriaceae family.
E. coli is a well-known fecal coliform and is commonly used as an indicator of water quality.

Relation to Infectious Disease

The presence of fecal coliforms in water sources indicates potential contamination by fecal pathogens.
This increases the risk of infectious diseases such as cholera, dysentery, and hepatitis.

Rapid Enterobacteriaceae Tests

Designed to quickly identify Enterobacteriaceae.
Used to ensure food and water safety.
Help to prevent disease outbreaks by detecting fecal coliforms like E. coli.

Bacillus

Used in research and industry due to their robustness and ability to produce enzymes and antibiotics.

Actinobacteria Example

Streptomyces griseus is a filamentous bacterium known for its soil dwelling, "earthy" odor and for producing antibiotics, including streptomycin.

Actinobacteria Characteristics

Have a high GC content.
Form branching filaments.
Play a critical role in soil health by decomposing organic matter and inhibiting the growth of other microorganisms through antibiotic production.

Archaeal Characteristics

Extreme environment adaptation: Many Archaea are extremophiles thriving in harsh environments.
Unique membrane lipids: Archaeal cell membranes contain ether-linked lipids, which are more stable and suited to extreme conditions.
Genetic and biochemical differences: Archaeal genetic machinery is more similar to that of eukaryotes than bacteria, even though they are prokaryotic.

Archaeal vs. Bacterial Cell Walls

Archaea: Lack peptidoglycan. Instead, they have a unique substance called pseudopeptidoglycan or other structural polymers in their cell walls, which help them maintain stability in extreme environments.
Bacteria: Typically have a cell wall made of peptidoglycan, which provides rigidity and protection.

Undiscovered Archaea

Many archaeal species have yet to be discovered and characterized because:
- Difficulty culturing: Archaea often live in extreme environments that are challenging to replicate in the laboratory.
- Unique environmental needs: Some Archaea require very specific conditions that are not easily maintained outside their natural habitat.
- Limited tools for study: Traditional microbial research techniques are often less effective for Archaea.

Archaea Pathogenicity

No archaeal species has been identified as pathogenic or associated with infectious disease.
Archaea are generally nonpathogenic, likely due to their differences in cell structure, lack of traditional virulence factors, and their distinct ecological roles.

Bacteria vs. Archaea Differences

Cell wall composition: Bacteria have peptidoglycan in their cell walls, while Archaea do not.
Membrane lipids: Bacteria have ester-linked lipids, while Archaea have ether-linked lipids.
Genetic machinery: Archaeal DNA replication, transcription, and translation processes are more similar to eukaryotes than bacteria.

Resident vs. Transient Bacteria

Resident bacteria: Stable, long-term microbes that live on or within our bodies, particularly in areas like the gut, skin, and respiratory tract. They play essential roles in maintaining health.
Transient bacteria: Temporary bacteria that do not permanently colonize the body. They may come from the environment or food, but they are not usually harmful.

Pathogenic Bacteria

Bacteria that can cause disease by invading host tissues, producing toxins, or evading the immune system.
Have specific virulence factors that allow them to infect and harm the host.
Not all bacteria are pathogenic, and resident bacteria can also be pathogenic under certain conditions.

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Description

This quiz covers the key processes of transcription and translation in biology. It includes details about the roles of RNA polymerase and ribosomes, along with the steps involved in synthesizing mRNA and proteins from DNA. Test your understanding of these essential biological mechanisms.