Microscopy Techniques and Cell Fractionation
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Questions and Answers

Which symptom is NOT commonly associated with AIDS?

  • Weight loss
  • Cancers
  • Flu-like symptoms (correct)
  • Diarrhoea

What role does stomach acid play in the immune system?

  • It kills bacteria. (correct)
  • It serves as a physical barrier.
  • It activates white blood cells.
  • It produces antibodies.

What process allows white blood cells to engulf and destroy pathogens?

  • Antigen presentation
  • Immunization
  • Phagocytosis (correct)
  • Apoptosis

Which component of the immune system is responsible for the humoral response?

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

What does the release of histamines during inflammation lead to?

<p>Increased blood vessel permeability (B)</p> Signup and view all the answers

Memory cells in the immune system are characterized by:

<p>Replicating themselves when faced with a familiar pathogen (D)</p> Signup and view all the answers

What is the function of lysozymes in the immune response?

<p>To kill bacterial cells by damaging their cell walls (C)</p> Signup and view all the answers

Specific immune responses are characterized by their reliance on which cells?

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

What is the primary function of mitochondria in a cell?

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

What structure is primarily involved in producing spindle fibers for cell division?

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

Which component of a prokaryotic cell is responsible for its rigid outer structure?

<p>Peptidoglycan cell wall (A)</p> Signup and view all the answers

What is the main outcome of the mitosis process?

<p>Formation of genetically identical daughter cells (A)</p> Signup and view all the answers

Which stage of the cell cycle involves the replication of chromosomes?

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

What type of enzymes do lysosomes contain?

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

What best describes virulence factors in viruses?

<p>Protective protein coat and lipid envelope (D)</p> Signup and view all the answers

What defines the arrangement of cells in multicellular organisms?

<p>Cells form tissues, which form organs, and then systems. (C)</p> Signup and view all the answers

What is the main role of cholesterol in the cell membrane?

<p>To make the membrane more rigid and prevent leakage (D)</p> Signup and view all the answers

Which process requires energy in the form of ATP?

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

What type of molecules can achieve movement through the phospholipid bilayer via diffusion?

<p>Non-polar, lipid soluble molecules (B)</p> Signup and view all the answers

In facilitated diffusion, what is required for transportation across the membrane?

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

Osmosis is defined as the diffusion of which molecules?

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

What process uses vesicles to transport particles into the cell?

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

Which statement correctly describes co-transport in epithelial cells of the ileum?

<p>It uses active transport to move sodium and glucose into the cell together (D)</p> Signup and view all the answers

What is the primary function of glycoproteins in the cell membrane?

<p>To act as receptors and attach cells to each other (A)</p> Signup and view all the answers

What role do T helper cells play in the immune response?

<p>They stimulate B cells and T killer cells to divide. (C)</p> Signup and view all the answers

What is the primary function of antibodies?

<p>Form antigen-antibody complexes. (B)</p> Signup and view all the answers

Which type of immunity results from the introduction of antibodies from another person or animal?

<p>Passive artificial immunity (B)</p> Signup and view all the answers

Which scenario best describes natural active immunity?

<p>Contracting a disease and recovering. (D)</p> Signup and view all the answers

What happens during the agglutination process involving antibodies?

<p>Antibodies clump pathogens together, making them easier for phagocytes to find. (D)</p> Signup and view all the answers

What is the primary limiting factor for the resolution of light microscopes?

<p>The wavelength of light (B)</p> Signup and view all the answers

What is a primary factor determining the success of a vaccination program?

<p>The severity of the side effects of the vaccine. (B)</p> Signup and view all the answers

Which of the following statements accurately describes transmission electron microscopes (TEM)?

<p>Electrons pass through thin specimens to form an image (A)</p> Signup and view all the answers

What characteristic of antibodies allows them to mark cells for destruction by phagocytes?

<p>Their Y-shaped structure. (D)</p> Signup and view all the answers

What is the maximum resolving power of light microscopes compared to electron microscopes?

<p>0.2 μm (D)</p> Signup and view all the answers

What is the outcome of a vaccination in terms of immunity?

<p>Production of memory B cells for future rapid responses. (C)</p> Signup and view all the answers

Which characteristic is true for both transmission electron microscopes (TEM) and scanning electron microscopes (SEM)?

<p>They require a vacuum for operation (C)</p> Signup and view all the answers

Which is a disadvantage of using scanning electron microscopes (SEM)?

<p>They have a lower resolution than TEM (A)</p> Signup and view all the answers

What is the formula used to calculate magnification in microscopy?

<p>Size of image / size of real object (B)</p> Signup and view all the answers

What factor leads to the requirement for specimens to be very thin in transmission electron microscopy?

<p>The ability for electrons to penetrate the specimen (D)</p> Signup and view all the answers

Which of the following describes a benefit of using electron microscopes over light microscopes?

<p>They provide higher resolution images (B)</p> Signup and view all the answers

Why are unvaccinated individuals often protected in a vaccinated population?

<p>Vaccinated individuals create herd immunity. (A)</p> Signup and view all the answers

What characteristic of the Influenza virus complicates long-term immunity?

<p>It undergoes antigenic drift. (D)</p> Signup and view all the answers

Which ethical concern is associated with vaccine production?

<p>Animal testing can occur during the production and testing of vaccines. (B)</p> Signup and view all the answers

What is one application of monoclonal antibodies in cancer treatment?

<p>They target antigens on cancerous cells to destroy them. (C)</p> Signup and view all the answers

How do monoclonal antibodies assist in HIV diagnosis?

<p>By targeting specific antigens for detection. (D)</p> Signup and view all the answers

What role does reverse transcriptase play in HIV replication?

<p>It converts RNA into DNA for integration into the host genome. (C)</p> Signup and view all the answers

Which of the following is NOT a reason why vaccines may fail to prevent disease outbreaks?

<p>High costs of production. (C)</p> Signup and view all the answers

What can happen to monoclonal antibodies when used in indirect therapy?

<p>They can enhance the effectiveness of the drug they're attached to. (D)</p> Signup and view all the answers

Flashcards

Resolution

The ability of a microscope to distinguish between two objects that are close together.

Resolving Power

The minimum distance apart that two objects can be distinguished as separate objects in an image.

Electron Microscope

A type of microscope that uses a beam of electrons to illuminate a specimen.

Transmission Electron Microscope (TEM)

A type of electron microscope that transmits a beam of electrons through a thin specimen.

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Scanning Electron Microscope (SEM)

A type of electron microscope that scans a beam of electrons across the surface of a specimen.

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Magnification

The size of an image as seen through a microscope divided by the size of the real object.

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Light Microscope

A type of microscope that uses visible light to illuminate a specimen.

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Resolution Limit of Light Microscopes

The wavelength of light limits the resolution of a light microscope to 0.2um.

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Mitochondria

A cell organelle with a double membrane, folded inner membrane forming cristae, containing enzymes for respiration.

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Centrioles

Hollow cylinders composed of microtubules, involved in producing spindle fibers during cell division.

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Ribosomes

Small organelles responsible for protein synthesis.

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Lysosomes

Vesicles containing digestive enzymes, bound by a single membrane, involved in breaking down waste materials.

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Mitosis

A type of cell division that produces two identical daughter cells, used for growth and asexual reproduction.

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Interphase

The stage in the cell cycle where the cell grows, prepares to divide, replicates chromosomes and organelles.

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Cytokinesis

The final stage of cell division where the cytoplasm divides and two daughter cells are formed.

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Cell division-mitosis

A type of cell division resulting in new cells with identical genetic material, used for growth and asexual reproduction.

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Humoral Response

A type of immune response that involves antibodies produced by B cells to target specific pathogens.

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Cell-mediated Response

A type of immune response that involves T cells attacking infected cells directly.

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Antibodies

Proteins produced by B cells that bind to specific antigens on pathogens, marking them for destruction.

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Agglutination

The process of clumping together multiple pathogens with antibodies, making them easier for phagocytes to engulf.

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Active Immunity

Immunity that develops after exposure to a pathogen, either naturally or through vaccination.

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Passive Immunity

Immunity gained from receiving antibodies directly, either through the placenta or injection.

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Vaccine

A weakened or inactive version of a pathogen that stimulates the immune system to produce antibodies and memory cells.

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Herd Immunity

The idea that if a high percentage of the population is immune, then a pathogen cannot spread easily.

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Skin as a barrier

A tough outer layer of skin made of keratin, acting as a physical barrier against infection.

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Lysozyme

A natural chemical found in secretions like tears and mucus, it breaks down bacteria's cell walls, destroying them.

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Phagocytosis

The process where white blood cells (like macrophages) engulf and destroy pathogens.

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Histamines

Chemicals released by damaged tissues, causing blood vessels to dilate, increasing blood flow and immune cell access to the infected area.

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Antigens

A group of proteins that are unique to each cell, identifying it as 'self' or 'non-self.'

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Non-Specific Immune Response

The body's general, non-specific response to infection, including inflammation, lysozyme action, interferon, and phagocytosis.

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Memory Cells

Immune cells that remember specific pathogens and rapidly respond if they encounter them again, providing long-term immunity.

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Specific Immune Response

A type of immune response that specifically targets and destroys pathogens. It involves B cells and T cells.

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Passive Diffusion

The movement of molecules from a region of high concentration to low concentration across a semi-permeable membrane, without requiring energy.

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Bulk Transport (Endocytosis & Exocytosis)

The movement of large particles into or out of a cell using vesicles. In endocytosis, vesicles bring particles in and in exocytosis, they release particles out.

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Active Transport

A type of membrane transport that requires specific carrier proteins to move molecules across the membrane. It requires energy input, often in the form of ATP.

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Osmosis

A type of passive transport where water moves from a region of high water potential to low water potential across a semi-permeable membrane.

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Facilitated Diffusion

The movement of molecules across a membrane with the help of transport proteins. This is a type of passive transport that does not require energy.

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Co-transport

A type of active transport that uses the movement of one molecule (often an ion) to drive the movement of another molecule across the membrane.

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Membrane Proteins

Types of proteins embedded in the cell membrane that act as receptors, signal transmitters, and contribute to cell structure and movement.

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Cholesterol

Lipid molecule that helps regulate membrane fluidity. It makes the membrane more rigid and prevents leakage.

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Antigenic Variation

A phenomenon where a pathogen's surface antigen changes, rendering existing immunity ineffective. This occurs because the immune system can no longer recognize and attack the modified pathogen.

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Monoclonal Antibodies

Monoclonal antibodies are specific to a single type of antigen. These antibodies can be created in large quantities to target and destroy specific cells, such as cancer cells, by attaching to their antigens.

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Indirect Therapy Using Monoclonal Antibodies

Drugs can be attached to monoclonal antibodies, allowing them to deliver these drugs directly to cells displaying specific antigens. This targeted delivery reduces side effects compared to traditional chemotherapy.

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HIV Replication

HIV, the virus responsible for AIDS, replicates by binding to the CD4 protein on T-helper cells, a critical component of the immune system's defense. This allows the virus to enter the cell and replicate using the cell's machinery.

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Reverse Transcriptase

HIV uses the enzyme reverse transcriptase to convert its RNA genetic material into DNA, which then integrates into the host cell's genome. This is a key step in the virus's replication cycle.

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HIV Attachment Proteins

These proteins embedded in the lipid envelope of the HIV virus are crucial for binding to and entering host cells like T-helper cells.

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Pregnancy Testing and Monoclonal Antibodies

Antibodies are used in pregnancy tests to detect the presence of a specific hormone, HCG, which is produced during pregnancy. The detection reaction results in a visible signal indicating pregnancy.

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Study Notes

Microscopy Techniques

  • Light microscopes use light to resolve images 0.2 µm apart. Resolution is limited by the wavelength of light.
  • Magnification = size of image/size of real object.
  • Resolution is the minimum distance between two objects that can be distinguished. Higher resolution means a clearer image.
  • Electron microscopes use a beam of electrons, allowing resolution of objects closer than 0.2 µm.
  • Transmission electron microscopes (TEM) examine thin sections of specimens to see internal structures.
  • Scanning electron microscopes (SEM) examine the surface of a specimen to produce 3D images.
  • Limitations of electron microscopes include the need for a vacuum environment and complex staining processes, which can introduce artefacts.

Cell Fractionation

  • Cell fractionation is a technique to separate cellular components for detailed study.
  • Differential centrifugation is a common method.
  • Homogenization is the initial process of blending cells to form a homogenate.
  • Centrifugation spins the homogenate at increasing speeds to separate organelles by density.
  • Heavier organelles settle first, then lighter ones.
  • Organelles are collected in pellets.

Cell Structure

  • Eukaryotic cells have a nucleus and membrane-bound organelles.
  • Nucleus contains chromatin and nucleolus (ribosome production).
  • Rough endoplasmic reticulum (RER) has ribosomes attached and processes proteins.
  • Smooth endoplasmic reticulum (SER) processes lipids.
  • Golgi apparatus processes and packages proteins & lipids.
  • Lysosomes contain digestive enzymes.
  • Mitochondria have a double membrane with cristae, where respiration occurs.

Prokaryotic Cells

  • Prokaryotic cells (e.g., bacteria) lack a nucleus and membrane-bound organelles.
  • Cell wall, capsule, plasmid, flagellum, pili, and ribosomes are important prokaryotic components.
  • Mesosomes are infoldings of the cell membrane that contain enzymes for respiration.

Cell Division - Mitosis

  • Mitosis is cell division that produces genetically identical daughter cells for growth and repair.
  • Mitosis occurs in four stages: prophase, metaphase, anaphase, and telophase.
  • Interphase describes the cell cycle phases before mitosis, where DNA replicates.
  • Cytokinesis is the division of the cytoplasm.
  • Binary fission is the process of prokaryotic cell division.

Biological Membranes

  • Membranes are composed of a phospholipid bilayer with embedded proteins.
  • Functions include controlling movement of substances, receptor functions, and cell adhesion.
  • Components of membranes include phospholipids, cholesterol, glycolipids, and glycoproteins.

Cell Transport

  • Passive transport includes diffusion (small, nonpolar molecules), facilitated diffusion (polar molecules with transport proteins), and osmosis (water).
  • Active transport moves substances against their concentration gradient using energy.
  • Exocytosis & endocytosis transport large molecules.
  • Co-transport couples the movement of one substance with another across a membrane.

Bacteria and Viruses

  • Bacteria are prokaryotic cells with a cell wall and DNA.
  • Viruses are non-living particles with genetic material (DNA or RNA) enclosed in a protein coat.
  • Viruses depend on host cells to replicate.

Immunity

  • Physical barriers prevent infection (skin, stomach acid).
  • Non-specific immunity (inflammation, lysozyme, phagocytosis) responds to pathogens generally.
  • Specific immunity responds to antigens with B and T lymphocytes.
  • B cells produce antibodies (humoral response)
  • T cells attack infected cells (cell-mediated response).
  • Memory cells allow faster response to repeated infections.

Vaccines

  • Vaccines introduce antigens to stimulate an immune response without causing disease.
  • Active immunity (vaccines/natural infection) involves the body producing antibodies.
  • Passive immunity (antibody injection/mother's milk) involves receiving antibodies.
  • Factors affecting vaccine success include cost, side effects, and ease of administration.

Ethical Considerations

  • Ethical concerns regarding vaccine production, testing on animals/humans, and compulsory measures should be addressed.
  • Herd immunity occurs when a significant portion of the population is immune, limiting spread of disease.

Monoclonal Antibodies

  • Monoclonal antibodies are identical antibodies produced against a specific antigen.
  • Applications include cancer therapy, diagnosis, and pregnancy tests.

HIV

  • HIV is a retrovirus causing AIDS.
  • HIV has a lipid envelope, capsid, and RNA genetic material with reverse transcriptase enzyme.

Antibiotics and Viruses

  • Antiretroviral drugs target HIV's replication process, but antibiotics are ineffective against viruses (as they lack cell walls).
  • ELISA methods can detect specific HIV antigens.

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Description

Explore the fascinating world of microscopy techniques and cell fractionation. Learn about light and electron microscopes, their resolution capabilities, and the processes involved in cell fractionation, including differential centrifugation. This quiz will help you understand key concepts and applications in biological microscopy.

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