Biology Chapter on Prokaryotes vs Eukaryotes
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Questions and Answers

Which cellular structure is absent in bacteria, distinguishing them from eukaryotes?

  • Cytoplasm
  • Nucleus (correct)
  • Plasma membrane
  • Ribosomes

    • Which of the following is a fundamental distinction between bacteria and archaea?

  • Cellular size
  • Differences in chemistry and physiology (correct)
  • Mode of reproduction
  • Presence of DNA

    • Which of the following cellular components is common to both prokaryotic and eukaryotic cells?

  • Membrane-bound organelles
  • Cytoplasm (correct)
  • Nucleus
  • Lysosomes

    • Which of the following is exclusively composed of unicellular organisms?

    <p>Bacteria (C)</p> Signup and view all the answers

    Which of the following is a characteristic feature of eukaryotes, but not of prokaryotes?

    <p>Housing genetic material in a nucleus (C)</p> Signup and view all the answers

    Which of the following cellular components would be found in both a bacterium and a plant cell?

    <p>Ribosomes (B)</p> Signup and view all the answers

    To which domain of life do fungi belong?

    <p>Eukarya (B)</p> Signup and view all the answers

    Considering evolutionary relationships, what is directly indicated by the classification of bacteria and archaea as distinct domains?

    <p>Separate evolutionary lineages (A)</p> Signup and view all the answers

    Which of the following is the primary function of bacterial inclusions?

    <p>Storing excess nutrients for use in less favorable environments (A)</p> Signup and view all the answers

    What is the key characteristic of plasmids that distinguishes them from the bacterial chromosome?

    <p>Plasmids typically carry genes that confer advantageous traits, while bacterial chromosomes carry genes for basic cellular functions (D)</p> Signup and view all the answers

    Under which environmental condition would bacteria most likely form endospores?

    <p>In an environment with limited nutrients and harsh conditions (A)</p> Signup and view all the answers

    Which of the following structures is directly involved in the synthesis of proteins?

    <p>Ribosomes (A)</p> Signup and view all the answers

    Which of these cellular structures is NOT involved in bacterial survival but rather in conferring advantages?

    <p>Plasmids (B)</p> Signup and view all the answers

    Which characteristic is LEAST likely to be employed when initially describing a bacterial sample?

    <p>Smell (A)</p> Signup and view all the answers

    In what year was the bacterial cell wall staining method developed by Hans Christian Gram?

    <p>1884 (A)</p> Signup and view all the answers

    What is the primary structural characteristic of the bacterial nucleoid region?

    <p>Non-membrane bound region (C)</p> Signup and view all the answers

    Which enzyme class is directly involved in the supercoiling of bacterial DNA within the nucleoid?

    <p>Topoisomerases (D)</p> Signup and view all the answers

    Plasmids are best described as:

    <p>Extrachromosomal DNA molecules (D)</p> Signup and view all the answers

    What cellular process directly leads to an increase in Colony Forming Units (CFU) during bacterial growth?

    <p>Binary fission (A)</p> Signup and view all the answers

    Optical Density at 600nm (OD600) primarily measures:

    <p>The turbidity of a bacterial culture (A)</p> Signup and view all the answers

    Motile bacteria, in terms of oxygen requirements, are typically classified under which broad category?

    <p>The provided information does not directly link motility to oxygen requirements (B)</p> Signup and view all the answers

    Bacterial growth is fundamentally characterized by:

    <p>Population increase through binary fission (A)</p> Signup and view all the answers

    Which characteristic is LEAST likely to be associated with members of a regulon?

    <p>Close proximity to each other on the chromosome. (D)</p> Signup and view all the answers

    What primarily governs gene expression in gene-regulation pathways?

    <p>The action of molecular regulators that turn genes on and off. (A)</p> Signup and view all the answers

    What is the primary function of signal transduction pathways?

    <p>To move a signal from a cell's exterior to its interior leading to a specific reaction. (A)</p> Signup and view all the answers

    If a bacterium's signal transduction pathway is disrupted, what immediate consequence would most likely occur?

    <p>The bacterium would improperly respond to external environmental cues. (D)</p> Signup and view all the answers

    Which of the below is responsible for carrying out cellular biological processes?

    <p>Groups of interacting proteins. (B)</p> Signup and view all the answers

    What characteristic is not shared between gene regulation and biological pathways?

    <p>They are contained within the same chromosome region. (A)</p> Signup and view all the answers

    A bacterium encounters a sudden depletion of a key nutrient in its environment. Which type of pathway is most likely to be immediately activated to help the bacterium adapt?

    <p>A metabolic pathway to find or synthesize the nutrient. (D)</p> Signup and view all the answers

    How are cellular processes organized in bacteria?

    <p>Spatially and temporally. (B)</p> Signup and view all the answers

    Which of the following bacterial species is associated with causing tetanus?

    <p>Clostridium tetani (C)</p> Signup and view all the answers

    What is the process by which certain bacteria transform into highly resistant, dormant structures?

    <p>Sporulation (C)</p> Signup and view all the answers

    Which of the following characteristics is NOT typically associated with bacterial endospores?

    <p>Enhanced metabolic activity (A)</p> Signup and view all the answers

    What is the primary function of pili in bacteria beyond adhesion?

    <p>Transfer of DNA (A)</p> Signup and view all the answers

    What determines the directional movement of bacteria using flagella?

    <p>Tumbling and running (C)</p> Signup and view all the answers

    What environmental cue is associated with magnetotaxis in bacteria?

    <p>Magnetic fields (D)</p> Signup and view all the answers

    What feature is associated with pathogens that occupy limited ecological niches?

    <p>Smaller genomes (C)</p> Signup and view all the answers

    What is the primary role of plasmids in bacterial survival?

    <p>Conferring beneficial genes for specific conditions (C)</p> Signup and view all the answers

    What is the implication of bacteria exchanging plasmids?

    <p>Horizontal gene transfer (A)</p> Signup and view all the answers

    Which structure enables bacteria to move in aqueous environments?

    <p>Flagella (A)</p> Signup and view all the answers

    What gradients do flagella help bacteria respond to?

    <p>Chemical, light and magnetic fields (A)</p> Signup and view all the answers

    Which bacterial disease is linked to Clostridium perfringens?

    <p>Gangrene (D)</p> Signup and view all the answers

    What is the effect of plasmids encoding for antibiotic resistance genes in bacteria?

    <p>Increased ability to resist antibiotics (A)</p> Signup and view all the answers

    Which feature distinguishes pili from Fimbriae?

    <p>Pili are longer and less numerous (D)</p> Signup and view all the answers

    What bacterial condition is associated with Clostridium difficile?

    <p>Pseudomembranous colitis (A)</p> Signup and view all the answers

    Which of the following is the most direct effect of a mutation in a structural gene?

    <p>Change in the amino acid sequence of a protein. (D)</p> Signup and view all the answers

    A bacterium is exposed to UV radiation, resulting in an increased mutation rate. What cellular process is most directly affected by this mutagen?

    <p>DNA replication and repair. (C)</p> Signup and view all the answers

    If a repressor protein is mutated such that it can no longer bind to its operator sequence, what is the most likely outcome?

    <p>Transcription of the associated gene will occur constitutively. (D)</p> Signup and view all the answers

    What is the primary difference between an operon and a regulon in bacterial gene regulation?

    <p>An operon is transcribed as a single mRNA molecule, while a regulon consists of multiple operons or genes. (A)</p> Signup and view all the answers

    Which of the following best describes the function of sigma ($\sigma$) factors in prokaryotic transcription?

    <p>They guide RNA polymerase to specific promoter sequences. (D)</p> Signup and view all the answers

    A particular gene in E. coli is always expressed regardless of environmental conditions. This gene would best be described as:

    <p>Constitutive. (C)</p> Signup and view all the answers

    Which of the following mutations would likely have the LEAST impact on the phenotype of an organism?

    <p>A point mutation in the noncoding region of DNA. (D)</p> Signup and view all the answers

    If a chemical agent caused a 1000-fold increase in the mutation rate of a bacterium, what would be the most significant immediate consequence?

    <p>Drastic change in the bacterial phenotype due to accumulated genetic errors. (B)</p> Signup and view all the answers

    A researcher discovers a new small RNA (sRNA) molecule in bacteria. Based on the information provided, what is the most likely function of this sRNA?

    <p>Regulating gene expression. (D)</p> Signup and view all the answers

    Which of the following characteristics is LEAST likely to be associated with 'housekeeping genes'?

    <p>Involved in specialized metabolic pathways. (C)</p> Signup and view all the answers

    Flashcards

    Bacteria

    Single-celled organisms that lack a nucleus and membrane-bound organelles.

    Eukarya

    One of the three domains of life, consisting of organisms with eukaryotic cells that have a nucleus.

    Prokaryotes

    Organisms, like bacteria and archaea, that are single-celled and do not have a nucleus.

    Eukaryotes

    Organisms whose cells have a nucleus, can be unicellular or multicellular.

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    Life Domains

    The three main categories of life: Bacteria, Archaea, and Eukarya.

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    Membrane-bound organelles

    Structures found in eukaryotic cells but absent in prokaryotes, like the nucleus and mitochondria.

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    DNA

    The genetic material present in all living organisms, found in both prokaryotic and eukaryotic cells.

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    Ribosomes

    Molecular machines that produce proteins, found in all cell types.

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    Cell Shape

    The structural form of bacterial cells, such as cocci, bacilli, or spirilla.

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    Colony Shape

    The overall appearance or form of a bacterial colony, which can be circular, irregular, or filamentous.

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    Optical Density (OD600)

    A measurement of the concentration of bacteria in a culture, assessed at 600 nm wavelength.

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    Colony Forming Units (CFU)

    A unit used to estimate the number of viable bacteria in a sample, derived from colony counts.

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    Gram-Positive Bacteria

    Bacteria that retain the violet stain used in Gram staining, characterized by a thick peptidoglycan layer.

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    Binary Fission

    The process by which bacteria reproduce asexually, splitting into two identical cells.

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    Nucleoid

    The irregularly shaped area in a bacterial cell that contains the genetic material (DNA).

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    Colony Colour

    The pigmentation of a bacterial colony, which can indicate specific species or conditions.

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    Bacterial Growth Curve

    A graphical representation of the growth of a bacterial population over time, showing phases like lag, log, stationary, and death.

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    Growth Requirements

    Environmental factors like oxygen, temperature, and pH that influence bacterial growth.

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    Regulon

    A group of genes regulated by the same regulatory protein, with separate promoters.

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    fliA Regulon

    A regulon responsible for flagellar biosynthesis, involves sigma factor fliA.

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    Gene Regulation

    The control of gene expression through various regulatory mechanisms and pathways.

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    Metabolic Pathways

    Sets of interconnected biochemical reactions that convert substrates into products within a cell.

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    Molecular Regulators

    Proteins that turn genes on and off, influencing gene expression.

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    Signal Transduction Pathways

    Processes that transmit signals from a cell's exterior to its interior, triggering internal responses.

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    Receptors

    Specialized structures on cell surfaces that detect external signals and initiate signal transduction.

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    Protein Interactions

    Interactions between proteins that lead to biological processes essential for survival.

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    Plasmids

    Small, double-stranded DNA molecules that often carry advantageous genes.

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    Inclusions

    Cytoplasmic structures that store excess nutrients for later use.

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    Endospores

    Dormant structures that protect bacterial DNA in harsh conditions.

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    Antibiotic resistance

    The ability of bacteria to survive and grow despite antibiotic treatment.

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    Genetic Diversity

    The variation of genes within a species, impacting evolution and adaptability.

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    Mutations

    Changes in DNA sequences that can occur during DNA replication or due to external factors.

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    Mutagens

    Agents that increase the rate of mutations, including chemicals and radiation.

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    Genome

    The complete set of genetic material, including chromosomes and plasmids.

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    Genotype

    The full collection of genes contained within an organism’s genome.

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    Phenotype

    Observable characteristics of an organism defined by gene expression.

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    Promoter

    DNA sequence where transcription machinery binds to initiate gene transcription.

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    Repressors

    Proteins that suppress transcription, keeping genes turned off.

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    Activators

    Proteins that enhance transcription, turning genes on.

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    Operon

    A sequence of DNA with structural genes transcribed together under a single promoter.

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    Sporulation

    The transformation process of certain bacteria into endospores for survival.

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    Bacillus anthracis

    Bacteria that cause anthrax and can form endospores.

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    Clostridium tetani

    Bacteria that cause tetanus and can form endospores.

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    Fimbria

    Thin, hair-like structures on bacteria that help them attach to surfaces.

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    Pili

    Longer and fewer than fimbriae; assist in adhesion and DNA transfer.

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    Conjugation

    The process through which bacteria transfer DNA using pili.

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    Flagella

    Whip-like structures bacteria use for movement in water.

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    Chemotaxis

    Movement of bacteria in response to chemical signals.

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    Tumbling and Running

    Directional movements of bacteria controlled by their flagella.

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    Horizontal Gene Transfer

    The process by which bacteria exchange genetic material.

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    Genome Size Variation

    The size of a bacterium's genome varies based on dependency on its host.

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    Pathogens Genome

    Pathogens with specific niches have smaller genomes compared to environmental bacteria.

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    Environmental Bacteria

    Bacteria found in diverse environments tend to have larger genomes.

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    Study Notes

    Introduction to Bacteria

    • Bacteria, Archaea, and Eukarya are life domains
    • Eukaryotes have nuclei enclosing DNA separate from the rest of the cell
    • Animals, plants, fungi, and single-celled protists are examples of Eukaryotes
    • Bacteria and Archaea are prokaryotes, single-celled organisms
    • Prokaryotes do not have membrane-bound organelles
    • Common features in both Eukaryotes and Prokaryotes include DNA, plasma membrane, cytoplasm, and ribosomes
    • Prokaryotes generally tend to be smaller than Eukaryotes

    Describing Bacteria

    • Cell shape/arrangement: Coccus, coccobacillus, vibrio, bacillus, cocci, diplococci, streptococci, staphylococci, sarcina, bacilli, diplobacilli, streptobacilli, spirilla, spirochetes, etc.
    • Cell size: Average sizes vary, but E. coli is 1.1-1.5 µm, and B. anthracis is 1.0-1.2 µm, and B. subtilis is 0.25-0.5 µm.
    • Colony shape: Round, irregular, filamentous, rhizoid
    • Colony size: Small, moderate, large
    • Colony colour: Various colours depending on the species
    • Smell: Odor varies depending on the species

    Bacterial Growth

    • Binary fission: Asexual reproduction where a cell divides into two identical daughter cells
    • The Growth Curve: Stages of bacterial growth include Lag phase, logarithmic (log) phase, stationary phase, and death phase
    • Bacteria reproduce via exponential growth during the log phase
    • Some bacteria exhibit anaerobic or aerobic behaviour
    • Environmental factors affect growth rates

    Bacterial Structures

    • Nucleoid: Single, circular chromosome, not membrane-bound, supercoiled
    • Plasmids: Small, circular DNA molecules, not part of the chromosome, replicate independently
    • Ribosomes: Sites for protein synthesis
    • Inclusions: Store excess nutrients: glycogen, starch, etc.
    • Endospores: Dormant structures protecting bacterial genomes under unfavourable conditions
    • Fimbriae and Pili: Structures allowing bacteria to adhere and move & interact with their environment: Fimbriae are shorter, while pili are longer and allow for DNA transfer(conjugation).
    • Flagella: Structures used for motility in aqueous environments, and respond to various external signals, including chemicals, light, and magnetic fields

    Bacterial Taxonomy

    • Taxonomy classifies organisms into naturally related groups, with common levels of classification: Domain, Phylum, Class, Order, Family, Genus, and Species
    • Taxonomy uses similarities and relationships in organism classifications
    • Nomenclature uses international standards for naming organisms

    Genetic Diversity

    • Mutations: During DNA replication, mutations can occur, and repair mechanisms minimize errors. Exposure to external mutagens can cause a higher rate of mutation
    • Genetic diversity: Bacteria exhibit varying genome sizes, some with small genomes that tend to be host dependent and others with large genomes, that respond to their external environment and can exchange genes between each other.
    • Horizontal gene transfer: The process whereby DNA is exchanged between bacteria through methods including conjugation, transduction, and transformation.

    Bacterial Cell Wall

    • Gram-positive: Thick peptidoglycan layer, distinctive purple colour after Gram staining, lack of outer lipid membrane, Teichoic and lipoteichoic acids present
    • Gram-negative: Thin peptidoglycan layer, pale reddish colour after Gram staining, presence of outer lipid membrane, lack of Teichoic and lipoteichoic acids

    Growth Requirements

    • Energy source: Chemical (chemo) or light (photo)
    • Carbon source: Organic compounds (hetero) or carbon dioxide (auto)
    • Final electron acceptor: Oxygen (aerobic), or other inorganic compounds (anaerobic metabolism)
    • Temperature: Psychrophilic, mesophilic, thermophilic, and hyperthermophilic bacteria exist.
    • pH: Acidophilic, neutral, and alkaline bacteria exist that grow in different pH levels.
    • Oxygen: Aerobic, anaerobic, facultative anaerobic, microaerophilic, or aerotolerant behaviour

    General

    • Gene regulation: A variety of methods exist, including Operons, regulons. Signal pathways and biological pathways.

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    Test your knowledge on the fundamental differences between prokaryotic and eukaryotic cells with this quiz. From cellular structures to evolutionary classifications, assess your understanding of these distinct domains. Perfect for students studying cellular biology and microbiology.

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