Microorganisms Lecture 1: Cells Overview
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Questions and Answers

Which of the following is NOT a branch of microbiology?

  • Bacteriology
  • Virology
  • Mycology
  • Botany (correct)
  • Edward Jenner is known as the father of bacteriology.

    False (B)

    What is the primary advantage of small cell size in prokaryotic cells?

    Higher surface to volume ratio allows for faster nutrient and waste exchange.

    The study of fungi is known as __________.

    <p>Mycology</p> Signup and view all the answers

    Which microorganism is known to have a beneficial effect on human nutrition?

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

    Match the following morphological shapes with their descriptions:

    <p>Coccus = Spherical shape Bacillus = Rod shape Spirochete = Long, thin, wavy body Spirillum = Curved or spiral shape</p> Signup and view all the answers

    Eukaryotic cells generally have a faster growth rate compared to prokaryotic cells due to their larger size.

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

    List one function of the cytoplasmic membrane.

    <p>Selective barrier, protein anchor, or energy conservation.</p> Signup and view all the answers

    Which of the following are types of microbial cells?

    <p>Both A and B (C)</p> Signup and view all the answers

    All microorganisms are multicellular organisms.

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

    What are the two fundamental types of cells found in microorganisms?

    <p>Prokaryotic and Eukaryotic</p> Signup and view all the answers

    Cyanobacteria can carry out __________, a process that produces oxygen.

    <p>photosynthesis</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Prokaryotic cells = Single-celled organisms without a true nucleus Eukaryotic cells = Multicellular organisms with membrane-bound organelles Cyanobacteria = Bacteria that can carry out photosynthesis Anoxic Earth = Earth's early atmosphere without oxygen</p> Signup and view all the answers

    Which of the following is NOT a characteristic shared by prokaryotic and eukaryotic cells?

    <p>Presence of a nucleus (A)</p> Signup and view all the answers

    Microorganisms can live in complex communities.

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

    What was the state of the Earth's atmosphere when microorganisms first appeared?

    <p>Anoxic (no oxygen)</p> Signup and view all the answers

    What is the primary function of endospores?

    <p>Survival in unfavorable conditions (A)</p> Signup and view all the answers

    Endospores can only remain dormant for a few days before they must germinate.

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

    What three steps are involved in endospore activation and germination?

    <p>Activation, germination, and outgrowth</p> Signup and view all the answers

    The structure connecting the filament to the flagellum motor is called the ______.

    <p>hook</p> Signup and view all the answers

    Match the parts of a bacterial flagellum with their functions:

    <p>Filament = Main part composed of flagellin Hook = Connects filament to motor Flagellum motor = Generates torque for rotation Stator = Surrounds the rotor</p> Signup and view all the answers

    What drives the rotation of archaeal flagella?

    <p>Hydrolysis of ATP (A)</p> Signup and view all the answers

    The core of an endospore includes ribosomes and a nucleoid.

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

    What is the fastest known organism on Earth?

    <p>Methanocaldococcus</p> Signup and view all the answers

    What component makes up the tail of archaeal cell membranes?

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

    All bacteria have peptidoglycan in their cell walls.

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

    What type of cell wall structure is primarily found in Gram positive bacteria?

    <p>Multiple layers of peptidoglycan</p> Signup and view all the answers

    The toxic component of the Gram negative cell wall is called ______.

    <p>lipid A</p> Signup and view all the answers

    Match the following cell wall structures with their characteristics:

    <p>Gram positive = Thick peptidoglycan layer with teichoic acids Gram negative = Thin peptidoglycan layer with outer membrane Archaea = Variety of cell wall types including polysaccharides and proteins Peptidoglycan = Glycan tetrapeptide structure providing rigidity</p> Signup and view all the answers

    Which of the following describes the function of porins in Gram negative bacteria?

    <p>Act as channels for solute transport (C)</p> Signup and view all the answers

    The cell walls of archaea are typically composed solely of peptidoglycan.

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

    What is the basic unit of peptidoglycan?

    <p>Glycan tetrapeptide</p> Signup and view all the answers

    What is the primary function of the mitochondria in eukaryotic cells?

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

    Mitosis is unique only to prokaryotic cells.

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

    What is the primary role of histones in eukaryotic cells?

    <p>To tightly pack DNA into chromosomes</p> Signup and view all the answers

    The process of converting a diploid cell into haploid cells is called ______.

    <p>meiosis</p> Signup and view all the answers

    Match the following cellular structures with their functions:

    <p>Chloroplasts = Photosynthesis Hydrogenosomes = Fermentative metabolism Nucleus = Contains chromosomes Mitochondria = Aerobic respiration</p> Signup and view all the answers

    Which component of taxonomy refers to the process of characterizing organisms?

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

    Binomial nomenclature consists of three names for classifying organisms.

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

    Who is credited with founding the science of taxonomy?

    <p>Carolus Linnaeus</p> Signup and view all the answers

    Which of the following statements correctly describes Chargaff’s Rule?

    <p>A pairs with T and G pairs with C (A)</p> Signup and view all the answers

    In prokaryotes, DNA replication is unidirectional.

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

    What enzyme is primarily responsible for replicating chromosomal DNA in prokaryotes?

    <p>DNA polymerase III</p> Signup and view all the answers

    In RNA transcription, the chain grows in the ______ direction.

    <p>5' to 3'</p> Signup and view all the answers

    Match the following DNA replication terms with their definitions:

    <p>Leading Strand = Synthesis occurs continuously toward the replication fork Lagging Strand = Synthesis occurs discontinuously away from the replication fork Topoisomerase = Enzyme that prevents over-winding of the DNA Proofreading = Mechanism to detect and correct mismatches in DNA</p> Signup and view all the answers

    What is the function of primase in DNA replication?

    <p>To provide a primer for DNA polymerase (D)</p> Signup and view all the answers

    Intrinsic terminators require additional factors for transcription termination.

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

    The nucleic acid backbone consists of alternating ______ and ______ molecules.

    <p>sugar, phosphate</p> Signup and view all the answers

    Flashcards

    Prokaryotic Cell

    A single-celled organism, lacking membrane-bound organelles, including bacteria and archaea.

    Eukaryotic Cell

    A complex cell (often multicellular), with membrane-bound organelles, including everything other than bacteria and archaea (like plants, animals, fungi, and protists).

    Microbial Cell

    Small living units that interact with environment and other cells, often part of communities.

    Cell Membrane

    The membrane that separates the cell's internal environment from the outside.

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    Cytoplasm

    The jelly-like substance inside a cell, holding organelles & important materials.

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    Microbial Diversity

    The variety of forms and functions of microorganisms, beyond just bacteria.

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    Cyanobacteria

    Ancient bacteria capable of photosynthesis, playing a key role early in Earth's history.

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    Anoxygenic Phototrophic Bacteria

    Bacteria performing photosynthesis without oxygen production.

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    Prokaryotic Cell Size & Growth

    Small size of prokaryotic cells leads to a high surface-to-volume ratio, enabling faster nutrient uptake, waste removal, and overall growth, compared to larger cells.

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    Bacterial Cell Morphology

    Bacteria come in various shapes, including spherical (coccus), rod-shaped (bacillus), spiral (spirillum), and comma-shaped (vibrio).

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    Cytoplasmic Membrane Function

    The cytoplasmic membrane acts as a selective barrier, controls what enters and leaves the cell, anchors essential proteins, and plays a role in energy production for the cell.

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    Surface-to-Volume Ratio in Cells

    Small cells have a higher surface area to volume ratio, enabling faster nutrient intake and waste removal compared to larger cells.

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    Branches of Microbiology

    Microbiology is categorized into different studies, focusing on specific groups of microorganisms like bacteria, protozoa, fungi, viruses, and photosynthetic eukaryotes.

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    Microorganism Impact on Humans

    Microorganisms are significant in various ways, including causing illness, acting as helpers in agriculture and nutrition, contributing to food production, and being useful in industrial processes.

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    Cell Membrane Structure

    A phospholipid bilayer forms the cell membrane, with a hydrophobic core that repels water. This structure is crucial for protecting the cell and controls what enters and exits the cell.

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    Importance of Bacteria Shape

    Bacteria's shape directly affects its ability to function. Different shapes promote different attributes which further affects the role of the bacteria in their environment.

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    Hydrophilic Region

    The water-attracting portion of a phospholipid molecule, typically found on the outer layer of the cell membrane.

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    Ester Linkage

    The chemical bond that connects glycerol to fatty acids in a phospholipid molecule.

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    Ether Linkage

    The chemical bond that connects glycerol to fatty acids in a phospholipid molecule, specifically in archaeal membranes.

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    Isoprene

    A repeating unit that makes up the tail of archaeal phospholipids.

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    Osmotic Lysis

    The bursting of a cell due to the influx of water caused by differences in osmotic pressure.

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    Peptidoglycan

    A rigid polysaccharide found in the cell walls of most bacteria, providing structural strength.

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    Teichoic Acid

    An acidic molecule found in the cell walls of gram-positive bacteria, attached to peptidoglycan.

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    Lipoteichoic Acid

    An acidic molecule found in the cell walls of gram-positive bacteria, attached to the lipids.

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    Endospore

    A highly resistant, dormant form of a bacterial cell, capable of surviving harsh conditions.

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    Sporulation

    The process by which a vegetative bacterial cell converts into an endospore.

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    Germination

    The process by which an endospore reverts back to a vegetative bacterial cell.

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    Flagella

    Long, thin appendages that rotate, propelling bacteria through liquid environments.

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    Archaella

    Similar to flagella, but found in archaea, rotating for movement.

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    Filament (flagellum)

    The main part of a flagellum, made of multiple flagellin protein molecules.

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    Hook (flagellum)

    Connects the filament to the flagellum motor, allowing for rotation.

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    Flagellum Motor

    The complex machinery that powers the rotation of the flagellum.

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    Gliding Bacteria

    Certain bacteria that move across surfaces without using flagella, requiring direct contact with a solid surface.

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    Eukaryotic Cell Division

    The process of cell replication in eukaryotic organisms, involving mitosis and meiosis.

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    Nucleus

    The central control center of eukaryotic cells, housing the chromosomes and nucleolus.

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    Nucleolus

    A structure within the nucleus where ribosomal RNA (rRNA) is synthesized.

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    Mitochondria

    Organelles in eukaryotic cells responsible for cellular respiration, providing energy for the cell.

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    Hydrogenosomes

    Organelles found in anaerobic eukaryotic microbes, producing energy through fermentation.

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    Taxonomy

    The science of classifying organisms, organizing them into groups based on shared characteristics.

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    Binomial Nomenclature

    A two-part naming system for organisms, using genus and species names, established by Carolus Linnaeus.

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    What are the base pairs in DNA?

    Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C).

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    What is Chargaff's Rule?

    The amount of Adenine (A) in DNA always equals the amount of Thymine (T) or Uracil (U) in RNA, and the amount of Guanine (G) always equals the amount of Cytosine (C).

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    What is semiconservative replication?

    When DNA replicates, each new double helix contains one original strand from the parent molecule and one newly synthesized strand.

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    What is the purpose of the primer in DNA replication?

    The primer is a short RNA sequence that provides a starting point for DNA polymerase III to attach and begin DNA synthesis.

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    What is the difference between the leading and lagging strand?

    The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in Okazaki fragments.

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    What is the role of topoisomerase in DNA replication?

    Topoisomerase prevents supercoiling of the DNA strand by cutting and rejoining the DNA molecule.

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    What is proofreading in DNA replication?

    DNA polymerase can detect mismatches in base pairing and correct them, ensuring high accuracy in DNA replication.

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    What are the key steps of transcription?

    Transcription involves the process of copying DNA into RNA using RNA polymerase. The process includes initiation, elongation, and termination.

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    Study Notes

    Lecture 1: Microorganisms

    • Microorganisms, also called microbes or germs, are too small to be seen with the naked eye, requiring a microscope. They exhibit diverse forms and functions, including single-celled organisms like bacteria and protozoans and multicellular eukaryotes.
    • Microbial cells interact dynamically with their environment and other cells. Two fundamental types are prokaryotic and eukaryotic cells.
    • Prokaryotic cells, including bacteria and archaea, are simpler than eukaryotic cells, which possess membrane-bound organelles.
    • Prokaryotic cells lack a true nucleus, with genetic material located in a nucleoid region. Eukaryotic cells have a true nucleus.
    • Both prokaryotic and eukaryotic cells share common structures such as cell membranes, cytoplasm, ribosomes, and genetic material (DNA).

    Microbial Cells: Prokaryotic vs Eukaryotic

    • Prokaryotic: Single-celled organisms (bacteria, archaea). Simpler structure; lack membrane-bound organelles like a nucleus.
    • Eukaryotic: Multicellular or single-celled organisms. More complex structure; possess membrane-bound organelles.

    Differences between Prokaryotic and Eukaryotic Cells

    • Prokaryotes are simpler, lacking membrane-bound organelles.
    • Eukaryotic cells have true nuclei and membrane-bound organelles.
    • Shape and structure differ: prokaryotes have simpler forms, while eukaryotes can be diverse.

    Microbial Origins and Microscopy

    • Life on Earth first appeared between 3.8 and 4.8 billion years ago.
    • Early life lacked oxygen.
    • Later evolution of photosynthesizing organisms resulted in the Great Oxygenation Event.
    • Robert Hooke was an early observer and described "cells."
    • Antoni van Leeuwenhoek observed and documented bacteria.
    • Microscopy now uses light or electrons, improving resolution and magnification.

    Lecture 2: Cells of Bacteria and Archaea

    • Cell Structure: Prokaryotic (bacteria and archaea) cells contain a cell membrane, often a rigid cell wall, and cytoplasm. External structures like capsules, fimbriae, and pili can also be present.
    • Surface-to-Volume Ratio: Small cells have a higher surface-to-volume ratio, allowing for quicker nutrient uptake and waste removal.
    • Cell Membrane Function: The Cytoplasmic membrane separates the inside of the cell from the environment.
    • It acts as a selective barrier regulating what enters and exits the cell
    • Anchors proteins for various functions, including energy production
    • Microbial Cell Morphology: The cell's shape differs between bacterial and archical cells
    • Bacteria is spherical, rods, spiral or curved.

    Bacterial Cell Walls

    • Peptidoglycan: A rigid polymer, component of bacterial cell walls, providing structural support and resistance to osmotic lysis.
    • Differences in Gram-positive and Gram-negative bacteria: The structure of the cell wall, including the presence/absence of an outer membrane and peptidoglycan layers, determines how the cell interacts with dyes (distinguish gram reaction).
    • Gram-positive: Thicker peptidoglycan layer, retaining crystal violet stain in a gram stain.
    • Gram-negative: Thinner peptidoglycan layer, losing the stain and taking up counterstain. The presence of an outer membrane further contributes to their differences in cell wall structure.

    Lecture 3: Microbial Taxonomy

    • Taxonomy is the science of classifying organisms.
    • Methods and criteria, including morphology (shape and arrangement), staining, growth characteristics, nutritional requirements, and physiological properties, are used to classify organisms.
    • Binomial nomenclature is the formal system of naming species (genus species).

    Lecture 4: Flow of Genetic Information

    • DNA Replication: DNA replicates in a semiconservative manner, producing two identical copies of the original DNA molecule.
    • Transcription: DNA is transcribed to mRNA, a process that results in a molecule complementary to a specific DNA sequence.
    • Translation: mRNA is translated into proteins through the process of assembling amino acids.

    Lecture 11: RNA Transcription

    • DNA synthesis involves leading and lagging strands with replication forks in both directions.
    • RNA polymerase plays a key role in transcription, using DNA as a template to synthesize RNA.
    • Transcription termination regions are critical sequences that signal the end of transcription, a crucial step for preventing indefinite RNA chains.

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    This quiz covers the fundamental concepts of microorganisms, focusing on the differences between prokaryotic and eukaryotic cells. It explores their structures, functions, and interactions with their environment. Perfect for beginners looking to understand basic microbiology principles.

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