Bacteria, fungi, viruses
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Questions and Answers

What is the primary structural component of the cell wall in fungi?

  • Cellulose
  • Chitin (correct)
  • Lignin
  • Peptidoglycan

Which of the following characteristics is true for filamentous fungi?

  • They are considered multicellular organisms.
  • They possess branching networks called hyphae. (correct)
  • Each cell contains multiple nuclei.
  • They reproduce only sexually.

During which process do yeasts reproduce asexually?

  • Fragmentation
  • Binary fission
  • Spore formation
  • Budding (correct)

What distinguishes a dimorphic fungus from a monomorphic fungus?

<p>Dimorphic fungi can exist in both yeast and mold forms. (A)</p> Signup and view all the answers

In which form does a dimorphic fungus typically exist inside a host?

<p>As a yeast (C)</p> Signup and view all the answers

What role do molds frequently play in relation to health in humans?

<p>They are opportunistic pathogens. (D)</p> Signup and view all the answers

Which statement accurately describes how molds are dispersed in the environment?

<p>By production of spores that are often transported by wind or water. (A)</p> Signup and view all the answers

What distinguishes Gram Positive bacteria from Gram Negative bacteria in terms of cell wall structure?

<p>Gram Positive has a thick peptidoglycan layer. (D)</p> Signup and view all the answers

What role do plasmids play in bacterial cells?

<p>They carry genes that may confer advantages like resistance. (B)</p> Signup and view all the answers

Which of the following correctly describes the Gram staining process?

<p>Crystal violet is the initial dye used in the process. (C)</p> Signup and view all the answers

How do ribosomes in bacterial cells function?

<p>They are sites of protein synthesis. (B)</p> Signup and view all the answers

Which statement accurately describes the structure of flagella in bacteria?

<p>They are composed of a single protein polymer in a helical form. (B)</p> Signup and view all the answers

What is the main role of pili in bacterial cells?

<p>Enabling cell adhesion. (A)</p> Signup and view all the answers

In the context of Gram staining, what is the final color of Gram Negative bacteria after the staining process?

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

What characteristic of the nucleoid distinguishes it from the cell's plasmids?

<p>Holds the chromosomal DNA essential for basic functions. (D)</p> Signup and view all the answers

What is a primary role of fungi in ecosystems?

<p>Breaking down organic matter and recycling nutrients (D)</p> Signup and view all the answers

Which component is NOT typically found in the cell wall structure of fungi?

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

What distinguishes dimorphic fungi from monomorphic fungi?

<p>They can exist as both mold and yeast depending on environmental conditions. (D)</p> Signup and view all the answers

Which method do yeasts primarily use for reproduction?

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

Penicillin, a well-known antibiotic, is derived from which type of organism?

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

What characteristic defines multicellular filamentous fungi, also known as molds?

<p>They form hyphae that create a network. (B)</p> Signup and view all the answers

What is a common feature of pathogenic dermatophytes?

<p>They cause infections in humans and animals. (C)</p> Signup and view all the answers

What is one of the primary differences between mold and yeast?

<p>Mold predominantly forms multicellular structures. (C)</p> Signup and view all the answers

What type of reproduction do molds primarily utilize?

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

Which of the following is NOT a general type of fungi mentioned?

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

What is the composition of the cell wall in Gram-positive bacteria?

<p>Single, thick layer of peptidoglycan (A)</p> Signup and view all the answers

Which of the following is NOT a shape classification of bacteria?

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

What is the function of the capsule in certain bacteria?

<p>Provide protection against phagocytosis (A)</p> Signup and view all the answers

How does the plasma membrane function in bacteria?

<p>It regulates substance transport and plays a role in respiration (A)</p> Signup and view all the answers

What distinguishes Gram-negative bacteria from Gram-positive bacteria?

<p>A thinner peptidoglycan layer (A)</p> Signup and view all the answers

Which statement accurately describes the cytoplasm of bacterial cells?

<p>It is a gel-like substance containing various organic molecules and cell components (A)</p> Signup and view all the answers

Which type of bacteria would likely be resistant to certain antibiotics due to their cell wall structure?

<p>Gram-negative bacteria with thin peptidoglycan layers (A)</p> Signup and view all the answers

Which role does the cell wall NOT play in bacterial cells?

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

What feature do pleomorphic bacteria exhibit?

<p>Multiple forms and shapes (B)</p> Signup and view all the answers

Which of the following descriptions accurately reflects the nature of viruses?

<p>Viruses are acellular entities that lack characteristic features of life and require a host to replicate. (B)</p> Signup and view all the answers

In the lytic cycle, which of the following occurs after the virus injects its genetic material into the host cell?

<p>The virus genetic information instructs the host cell to produce viral components, leading to cell lysis. (C)</p> Signup and view all the answers

What is the main difference between the lytic cycle and the lysogenic cycle?

<p>In the lysogenic cycle, the viral material integrates into the host DNA and remains inactive during cell division. (B)</p> Signup and view all the answers

Which statement about viral components is false?

<p>All viruses have a lipid envelope surrounding their capsid. (B)</p> Signup and view all the answers

What triggers the lytic cycle from the lysogenic state in viral replication?

<p>Environmental stress or changes within the host cell. (A)</p> Signup and view all the answers

HIV primarily targets which type of cell in the immune system?

<p>T helper cells (C)</p> Signup and view all the answers

What role does the capsid play in a virus?

<p>It protects the viral RNA or DNA and aids in host cell recognition. (B)</p> Signup and view all the answers

Why are viruses not classified as prokaryotes or eukaryotes?

<p>Both B and C are correct statements. (B)</p> Signup and view all the answers

Which statement correctly explains why a virus cannot replicate without a host?

<p>Viruses have no cellular machinery to produce new viral particles. (C)</p> Signup and view all the answers

In viral biology, what does the term 'cell lysis' refer to?

<p>The destruction and disintegration of a host cell releasing new viruses. (D)</p> Signup and view all the answers

Flashcards

Nucleoid

The region in a bacterial cell containing the chromosome, which is the molecule that carries the genetic information for the cell.

Ribosomes

Tiny structures found in the cytoplasm of bacterial cells, responsible for protein synthesis.

Plasmids

Extrachromosomal DNA molecules found in some bacteria, carrying genes not essential for basic survival. They can provide advantages like antibiotic resistance.

Cell Wall

A rigid structure surrounding the bacterial cell, providing strength and protecting it from osmotic pressure.

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Gram Positive Cell Wall

A type of cell wall found in bacteria characterized by a thick layer of peptidoglycan. They stain purple with Gram staining.

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Gram Negative Cell Wall

A type of cell wall found in bacteria characterized by a thin layer of peptidoglycan sandwiched between two lipid bilayer membranes. They don't retain the purple dye and are stained pink.

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Pili

Hair-like structures on the surface of bacteria that help them adhere to surfaces.

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Flagella

Whip-like structures that enable bacteria to move.

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Cocci

Spherical-shaped bacteria.

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Bacilli

Rod-shaped bacteria.

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Spirilla

Spiral-shaped bacteria.

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Pleomorphic

Bacteria that can exhibit various shapes.

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Capsule

A protective outer layer surrounding some bacteria, preventing phagocytosis and promoting adhesion.

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Cytoplasm

The gel-like substance within a bacterial cell, containing enzymes and other essential components.

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Plasma membrane

The selectively permeable membrane surrounding a bacterial cell, regulating nutrient intake and waste removal.

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Prokaryotic cells

Simple cells lacking membrane-bound organelles, such as mitochondria, Golgi complexes, and endoplasmic reticulum.

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Decomposers

Fungi play a crucial role in ecosystems by breaking down dead plants and animals, releasing nutrients back into the environment.

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Nutrient Cycling

Fungi are responsible for the decomposition of organic matter, releasing essential nutrients like nitrogen and oxygen back into the environment.

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Budding

A type of fungal reproduction where a single-celled organism (yeast) splits into two identical daughter cells.

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Spore Formation

A type of fungal reproduction involving the production of tiny, airborne reproductive units called spores.

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Dimorphic Fungi

Fungi that can switch between two forms, a mold-like filamentous form and a yeast-like single-celled form.

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Monomorphic Fungi

Fungi that remain in a single form, either mold-like or yeast-like, throughout their life cycle.

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Fungal Cell Wall

A tough, rigid structure surrounding fungal cells, composed of chitin, beta-glucan and ergosterol.

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Molds

A type of multicellular fungi that grow in filamentous strands called hyphae.

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Yeast

Unicellular, oval-shaped fungi that reproduce by budding.

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Dermatophytes

A group of fungi that cause infections of the skin, hair, and nails.

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Are viruses alive?

Viruses are not considered living organisms because they lack key characteristics of life, such as the ability to reproduce independently.

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Size of viruses

Viruses are much smaller than cells, often being measured in nanometers.

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Virus classification

Viruses are classified as prokaryotes or eukaryotes. They are not classified as one or the other.

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Structure of viruses

Viruses contain genetic material (DNA or RNA) enclosed in a protein coat called a capsid.

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Additional features of viruses

Viruses can have additional features, such as enzymes and outer envelopes.

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Virus replication

Viruses cannot replicate independently. They require a host cell to reproduce.

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Lytic cycle

In the lytic cycle, a virus enters a host cell, replicates itself using the host's resources, and ultimately destroys the host cell, releasing new viruses.

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Lysogenic cycle

In the lysogenic cycle, a virus integrates its genetic material into the host cell's DNA. The virus remains dormant, replicating along with the host cell.

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HIV and T helper cells

HIV is a retrovirus that attacks T helper cells, weakening the immune system.

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Treatment of HIV

Medications can help slow the replication of HIV, but they cannot cure the infection.

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What are fungi?

Fungi are eukaryotic organisms that obtain nutrients by absorbing organic matter from their surroundings, often dead or decaying material.

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What is chitin?

The primary component of the fungal cell wall, providing structural support and rigidity. Think of it as the fungi's 'skeleton.'

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What are filamentous fungi? (molds)

Filamentous fungi, also known as molds, are multicellular organisms composed of branching, thread-like structures called hyphae. These hyphae form a network called mycelium.

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What are yeasts?

Yeast are single-celled fungi that reproduce asexually by budding, where a smaller daughter cell forms from the parent cell.

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What is the difference between monomorphic and dimorphic fungi?

Monomorphic fungi exist in a single form, while dimorphic fungi can switch between two forms: mold and yeast. The form they take depends on environmental factors such as temperature.

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Why do some fungi change form?

When fungi are in the environment outside a host, they often exist as molds. However, when they are inside a host, they often switch to a yeast form due to the higher temperature within the host.

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Why are some people allergic to mold?

Mold antigens are common allergens, causing allergic reactions in some individuals. This is because molds release tiny particles that trigger the immune system.

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Study Notes

Bacteria

  • Bacteria are prokaryotic cells
  • Lack membrane-bound organelles
  • Surrounded by layers forming the cell envelope
  • Cell wall - key role is protection, conserve of peptidoglycans, helps differentiate bacteria (negative or positive)

Gram Positive vs Gram Negative

  • Gram Positive

    • Thick cell wall (up to 30 layers of peptidoglycan)
    • The cell wall prevents bacteria from shrinking or swelling under differing osmotic pressure
    • Retains crystal violet dye during Gram staining

  • Gram Negative

    • Thinner peptidoglycan layer
    • Lipid bilayer membranes sandwiched between two layers
    • Loses crystal violet dye during Gram staining.
    • Will stain pink after counterstaining

  • Shape examples:

    • Cocci (spherical)
    • Bacilli (rod-shaped)
    • Spirilla (spiral-shaped)
    • Pleomorphic (having many forms)

  • Capsule

    • Some bacteria have a capsule
    • Helps to provide protection, aid in adhesion, considered as an important virulence factor.

  • Cytoplasm

    • Features scattered cell components, such as ribosomes

  • Ribosomes

    • Sites of protein synthesis

  • Nucleoid

    • Irregularly shaped region containing the chromosome, which is essential to provide instruction for protein synthesis

  • Plasmids

    • Extrachromosomal DNA, can be circular or linear. Not essential, but may offer an advantage, such as resistance.

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Description

Explore the fascinating world of bacteria, focusing on their unique prokaryotic structure and the important differences between Gram-positive and Gram-negative bacteria. Understand their cell walls, shapes, and the significance of Gram staining in microbiology. This quiz will enhance your knowledge about the essential traits of these microscopic organisms.

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