Biology Chapter 16: Prokaryotic and Composite Organisms

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What was used to create the experimental environment for E. coli in the Meselson and Stahl experiment?

Regular hydrogen

Heavy nitrogen (correct)

Light oxygen

Standard carbon

What is the primary purpose of ultracentrifugation in the Meselson and Stahl experiment?

To observe the DNA structure

To separate the DNA based on density (correct)

To enhance DNA replication

To measure the temperature of DNA

What is the role of Toll-like receptors in relation to LPS?

They enhance the affinity of LPS to pathogens.

They modify the structure of Lipid A.

They inhibit the action of cationic antimicrobial peptides.

They serve to detect LPS in the system. (correct)

What happens to the DNA of E. coli when it is grown in normal nitrogen after being in heavy nitrogen?

The DNA becomes lighter Signup and view all the answers

What effect does the glycosylation of Lipid A have on pathogens?

It promotes their proliferation by making them undetectable. Signup and view all the answers

Which of the following statements about ribosomes is true?

Ribosomes are targeted by several antibiotics Signup and view all the answers

What does a sense codon do in the context of gene expression?

It signals the start of protein translation Signup and view all the answers

What is the function of the enzyme FlmK?

It adds a glucose molecule to Lipid A to alter its affinity. Signup and view all the answers

What is the primary action of cationic antimicrobial peptides (CAMP)?

They disrupt the prokaryotic cell membrane. Signup and view all the answers

Which role does ribosomal RNA (rRNA) play in ribosomes?

It forms the structural component of ribosomes Signup and view all the answers

What is true about gene expression in terms of its processes?

It involves transcription, translation, and regulation Signup and view all the answers

Which enzyme is involved in the dephosphorylation of Lipid A?

LpxE Signup and view all the answers

How can Gram-negative bacteria develop resistance to cationic antimicrobial peptides?

By modifying the cell membrane structure. Signup and view all the answers

What did the Meselson and Stahl experiment demonstrate about DNA replication?

DNA replication is semi-conservative Signup and view all the answers

What happens to the expression of a gene after horizontal gene transfer in bacteria?

The gene is expressed from the plasmid despite locus disruption. Signup and view all the answers

What role does the enzyme AlmG play in relation to Lipid A?

It adds a glycine to Lipid A enhancing its immune evasion. Signup and view all the answers

What components make up the large subunit of a prokaryotic ribosome?

31 proteins, 55 rRNA, and 23S RNA Signup and view all the answers

What role do flavonoids play in nodule development for mutualistic relationships?

They signal Rhizobia to activate Nod factor production. Signup and view all the answers

Which statement correctly describes the small subunit of a prokaryotic ribosome?

It contains 21 proteins and 165 rRNA of 1540 nucleotides. Signup and view all the answers

In the context of RNA base pairing within a ribosome, which statement is accurate?

16S rRNA has regions of stems and loops. Signup and view all the answers

Which feature distinguishes heterocysts in cyanobacteria?

They have thick walls to keep oxygen out. Signup and view all the answers

What is required as an essential ingredient for PCR?

Primers, polymerase, nucleotides, and Mg-containing buffer Signup and view all the answers

How does nitrogenase function in a mutualistic relationship between plants and bacteria?

It helps in the fixation of nitrogen, which is energy-intensive. Signup and view all the answers

What was a key factor in reclassifying cyanobacteria from algae to bacteria?

Their cellular structure, showing prokaryotic characteristics. Signup and view all the answers

Which of the following describes the crossing of P2 +/- female and P2 +/- male mice?

The expected results are approximately 1 +/+; 2 +/-; 1 -/- pups. Signup and view all the answers

What role does the peptidoglycan layer play in Gram positive bacteria?

It provides mechanical strength to withstand osmotic pressure. Signup and view all the answers

What is the main purpose of the Nod factors released from Rhizobia?

To bind to receptors to initiate plant nodule formation. Signup and view all the answers

What is a characteristic of intermolecular base pairing in DNA?

It involves complementary bases linking in opposite directions. Signup and view all the answers

What is the defining step that distinguishes Gram positive from Gram negative bacteria?

The decolorization step in the staining process. Signup and view all the answers

Which of the following is true about cyanobacteria?

They possess unique organelles that separate oxygen and nitrogen-fixing processes. Signup and view all the answers

How does active transport differ from passive transport across membranes?

Active transport moves substances against their concentration gradient; passive transport moves them down. Signup and view all the answers

Why might RNA have both intramolecular and trans molecular base pairing?

To allow for configuration and regulation of RNA's structure. Signup and view all the answers

What role does magnesium play in PCR?

It is an essential metal cofactor required for the reaction. Signup and view all the answers

What happens to E. coli in high osmotic environments if penicillin is present?

The peptidoglycan layer is hindered, leading to the bursting of the cell. Signup and view all the answers

In mutualistic interactions, what signal does NodD respond to?

The presence of flavonoids released by the plant. Signup and view all the answers

Which form of transport moves substances downhill along their concentration gradient?

Facilitated diffusion. Signup and view all the answers

What does the presence of nitrogen-fixing organelles in marine algae indicate?

A unique evolutionary adaptation for nutrient acquisition. Signup and view all the answers

What is a characteristic of prokaryotic cells regarding their cell wall?

They can regulate the synthesis and degradation of their peptidoglycan layer. Signup and view all the answers

What can animal cells and eukaryotic microbes do that prokaryotic cells cannot?

Engage in phagocytosis due to their membrane structures. Signup and view all the answers

Which energy source is most commonly used in active transport mechanisms?

ATP. Signup and view all the answers

What structural feature allows Gram positive bacteria to stain differently compared to Gram negative bacteria?

Thick peptidoglycan layer. Signup and view all the answers

What occurs if a bacterial cell's peptidoglycan layer is compromised?

It may experience internal osmotic pressure leading to cell lysis. Signup and view all the answers

Which phylogenetic group is prominent in newborns?

Actinobacteria Signup and view all the answers

What does CFU stand for in microbial analysis?

Colony forming unit Signup and view all the answers

Which method focuses on analyzing the genes present in a microbial sample without culturing?

Culture independent sample Signup and view all the answers

In microbial analysis, what does it indicate if 62% of identified species are unknown?

This indicates a lack of data on the samples. Signup and view all the answers

What is a major characteristic of obligate anaerobes found in the gut?

They are harmed by oxygen and do not utilize it. Signup and view all the answers

What factor is most significant in determining the predominance of symbionts in the gut?

Respiratory electron acceptors Signup and view all the answers

What is a major limitation of culture-dependent methods for microbial analysis?

They fail to identify non-culturable microbes. Signup and view all the answers

What percentage of the microbial species identified in studies was unknown as of 2005?

62% Signup and view all the answers

Which of the following statements about facultative anaerobes is correct?

They can utilize oxygen or nitrate depending on availability. Signup and view all the answers

What is the significance of using massively parallel sequencing techniques in microbial studies?

It enables the sequencing of all available genomes in a sample. Signup and view all the answers

What phenomenon indicates that the bacterial cytoplasm can behave differently depending on the metabolic activity of the cell?

Fluorescence movement varies in growing populations Signup and view all the answers

Which of the following best describes the differences observed in fluorescence behavior in relation to bacterial growth conditions?

Non-growing bacteria maintain unchanged fluorescence signal across time. Signup and view all the answers

What was one method used to study fluorescence movement in bacteria?

Growing E. coli transformed with a plasmid. Signup and view all the answers

What characteristic of long RNA molecules contributes to the viscosity of the cytosol?

They exhibit intramolecular base pairing. Signup and view all the answers

In the study of bacterial cytoplasm, what was a significant observable difference between growing and disrupted bacterial populations?

Growing cells showed a dynamic fluorescence pattern. Signup and view all the answers

What does the movement of fluorescence in growing E. coli suggest about bacterial cytoplasm?

It has varied physical properties based on metabolic state. Signup and view all the answers

Which of the following statements about the properties of bacterial cytoplasm is correct?

Cytoplasmic properties can differ significantly between different bacterial strains. Signup and view all the answers

What role does metabolic activity play in the behavior of bacterial cytoplasm?

It enhances the fluidity and movement within the cytoplasm. Signup and view all the answers

What role does the sensor kinase play in the signaling pathway?

It phosphorylates a histamine in response to external signals. Signup and view all the answers

How does magnesium affect the signaling pathway in bacterial cells?

Magnesium acts as a repressor, keeping the receptor kinase inactive. Signup and view all the answers

What is the primary function of the response regulator in the signaling pathway?

It serves as a substrate for kinase and directly activates genes. Signup and view all the answers

In Gram-negative bacteria, what can cause the sensor kinase to expose its hydrophobic interior?

Misfolded proteins in the environment. Signup and view all the answers

What happens to the pathway when magnesium levels drop in bacterial cells?

The pathway gets activated due to derepression. Signup and view all the answers

Which of the following best describes the nature of the signaling pathway discussed?

It is reversible and can adapt to changing conditions. Signup and view all the answers

What is the target gene associated with the signaling pathway in Gram-negative bacteria?

An enzyme for lysine modification on LPS. Signup and view all the answers

What does the activation of a response regulator usually involve?

Directly regulating transcription of target genes. Signup and view all the answers

What is the composition of the large subunit of a prokaryotic ribosome?

31 proteins + 55 rRNA + 23S RNA Signup and view all the answers

Which ribosomal RNA in prokaryotic ribosomes does not engage in base pairing due to loops?

16S rRNA Signup and view all the answers

Which component is not essential for the PCR process?

Ethidium bromide Signup and view all the answers

In a P2 +/- female crossed with a P2 +/- male mouse, what is the expected phenotypic ratio of offspring?

1:2:1 Signup and view all the answers

What is the primary role of magnesium in PCR?

Serves as a cofactor for polymerase Signup and view all the answers

What characteristic distinguishes intramolecular base pairing in RNA?

Base pairing occurs within the same molecule Signup and view all the answers

What type of genetic analysis is performed using PCR on tail snips of mice?

Genotyping Signup and view all the answers

How does intermolecular base pairing in DNA differ from intramolecular pairing in RNA?

Involves complementary strands binding in opposite directions Signup and view all the answers

What is the first step in the PCR process?

Heating to 95 degrees Celsius for 25 seconds Signup and view all the answers

During PCR, what happens during the annealing step?

Primers hybridize to the DNA template Signup and view all the answers

What temperature is used to polymerize DNA during PCR?

72 degrees Celsius Signup and view all the answers

In electrophoresis, which statement correctly describes the behavior of DNA fragments?

Smaller fragments migrate faster towards the positive end Signup and view all the answers

What is the primary purpose of using primers in PCR?

To hybridize at specific DNA sequences Signup and view all the answers

What does the characteristic fingerprint obtained from 16S rRNA analysis indicate?

The genetic similarity between organisms Signup and view all the answers

What is the purpose of digesting 16S rRNA with ribonuclease T1?

To separate the resulting digestion products Signup and view all the answers

Why are primers designed to point towards each other in PCR?

To flank the target sequence effectively Signup and view all the answers

What significant event allowed molecular oxygen to begin accumulating in the atmosphere?

The splitting of water Signup and view all the answers

Which photosystem is primarily responsible for the splitting of water?

Photosystem 2 Signup and view all the answers

What was the consequence of rising oxygen levels for life forms at that time?

The extinction of many anaerobic organisms Signup and view all the answers

In the context of water oxidation, what is meant by 'grabbing the low energy electron'?

Removing electrons from water molecules Signup and view all the answers

What role do chloroplasts play in oxygenic phototrophy?

They split water to release energy. Signup and view all the answers

What process occurs at the end of the mitochondrial respiratory chain?

Formation of water Signup and view all the answers

What is generated as reducing power during photosynthesis?

NADPH Signup and view all the answers

What reflects the growth of oxygen levels over time in Earth's history?

Evolution of aerobic respiration Signup and view all the answers

What distinguishes meiosis in eukaryotes from the reproductive processes in prokaryotes?

Only eukaryotes undergo meiosis, while prokaryotes do not. Signup and view all the answers

Why is cytoplasmic inheritance considered non-mendelian?

Cytoplasmic genetic material can result in a phenotype not following a simple ratio. Signup and view all the answers

What was the main hypothesis proposed by Constantin Merezhkowsky regarding chloroplasts?

Chloroplasts originated from bacterial ancestors. Signup and view all the answers

What discovery did Ivan Wallin contribute that was based on Merezhkowsky's findings?

Chloroplasts have two membranes, supporting endosymbiotic theory. Signup and view all the answers

What kind of evidence did Merezhkowsky rely on to support his hypothesis about chloroplasts?

Microscopy observations. Signup and view all the answers

Which of the following best describes the nature of cytoplasmic inheritance?

The phenotypes may show variability not explained by nuclear inheritance. Signup and view all the answers

What time period was Ivan Wallin associated with regarding his studies on chloroplasts?

Early 20th century. Signup and view all the answers

What role do chloroplasts play in plant cells based on their origin?

They are involved in photosynthesis. Signup and view all the answers

Study Notes

Introduction Chapter 16

Composite organisms are a combination of prokaryotic cells, such as mitochondria and chloroplasts, that are integral to the organism's survival.
Plants are considered more composite than other organisms due to their ability to survive independently of external factors.
Horizontal gene transfer is the process by which genetic material is exchanged between organisms.
Some bacteria are invisible to the naked eye, but can be seen with a microscope.
The idea that bacteria grows on potatoes was inaccurately attributed to Robert Hooke instead of the correct scientist.
Microbes have stable identities and maintain similarities in various environments, including plants and animals.

II. Lecture ~ Basic Structures and Processes in Prokaryotic Cells

Prokaryotic cells have regions of the cytoplasm not bounded by membranes, distinguishing them from eukaryotic cells.
The bacterial cytoplasm has properties that differ, often due to metabolic activity.
Examples of methods to study bacteria include growing and observing the expression of fluorescent proteins.
The bacterial cell envelope is crucial for its basic structural and functional properties.
The function of peptidoglycans in bacteria is to provide structural support by resisting osmotic pressure.
Gram-negative bacterial cell walls differ from Gram-positive cells due to the presence of an outer membrane.
The outer membrane is associated with the peptidoglycan layer, providing a barrier against various substances.
The Gram stain is a technique to differentiate Gram-negative and Gram-positive bacteria, owing to differences in peptidoglycan composition.

III. Lecture ~ August 26

Outside-in signaling: Prokaryotic cells have fewer complex signaling pathways compared to eukaryotic cells.
Sensor kinases detect external signals and phosphorylate response regulators.
Response regulators affect gene expression or other cellular processes, enabling the cell to adjust to its environment.
Signaling transduction across membranes is crucial for all life.
The cell membrane is vital in prokaryotic signaling.

IV. Lecture August 28 ~ Genomes

Genomes: A database of genes is maintained, and the standard sense codons are ‘TAA’ and ‘ATG’.
The 16S rRNA component of the ribosome is used to study phylogenetic relationships between organisms.

V. September 4

Woese developed a revolutionary experimental approach to study microbes by labeling RNA and DNA to track interactions and evolutionary connections.
Ribosomes are crucial components for microbial processes.
Enzymes such as endonucleases and exonucleases play specific roles in isolating and studying various RNA components.

VI. September 9

RNA is both an information molecule and a catalyst, but DNA is more stable and less reactive.
Mitochondria and ribosomes were hypothesized to have proteins and RNA originally, but now are considered mostly protein components instead.
Life likely evolved in an oxygen-poor environment and the development of oxygen was a significant event.

VII. Lecture - Sept 11

Meiosis is not typically present in prokaryotes.
Cytoplasmic inheritance is not Mendelian.
Chloroplasts likely originated from cyanobacteria through endosymbiosis.
The 19th and 20th centuries saw many key discoveries in cellular biology and microbiology that continue to shape our understanding of microbial communities today.

VIII. Lecture - Sep 16

Microbiota refers to the community of microorganisms.
Symbionts generally coexist. Pathogens cause harm.
Fermentation uses inorganic molecules as electron acceptors. Respiration uses organic molecules.
Homeostasis means the bacteria populations maintain consistent levels, with similar numbers of cells as humans present.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fascinating world of composite organisms and prokaryotic cells in this quiz. Learn about the significance of structures like mitochondria and chloroplasts, as well as concepts such as horizontal gene transfer. Test your knowledge on bacteria and their roles in different environments.