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Questions and Answers
What is the first step in the process of cell fractionation?
What is the first step in the process of cell fractionation?
Which organelle is sedimented first during differential centrifugation?
Which organelle is sedimented first during differential centrifugation?
What prevents organelles from bursting during the cell fractionation process?
What prevents organelles from bursting during the cell fractionation process?
Which part of the nucleus contains nuclear pores?
Which part of the nucleus contains nuclear pores?
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What is the primary function of the rough endoplasmic reticulum (RER)?
What is the primary function of the rough endoplasmic reticulum (RER)?
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Which structure is responsible for packaging and processing proteins and lipids?
Which structure is responsible for packaging and processing proteins and lipids?
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What is the role of the nucleolus within the nucleus?
What is the role of the nucleolus within the nucleus?
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The smooth endoplasmic reticulum primarily produces what type of molecule?
The smooth endoplasmic reticulum primarily produces what type of molecule?
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What is the primary function of mitochondria in a cell?
What is the primary function of mitochondria in a cell?
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What structure is primarily responsible for cell division and the formation of spindle fibers?
What structure is primarily responsible for cell division and the formation of spindle fibers?
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Why is mitosis important for living organisms?
Why is mitosis important for living organisms?
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What are ribosomes primarily involved in?
What are ribosomes primarily involved in?
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What is the function of pili in prokaryotic cells?
What is the function of pili in prokaryotic cells?
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During which stage of the cell cycle does the cell prepare for division?
During which stage of the cell cycle does the cell prepare for division?
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What do mesosomes do in prokaryotic cells?
What do mesosomes do in prokaryotic cells?
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What distinguishes viruses from living cells?
What distinguishes viruses from living cells?
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What process do single-celled organisms like yeast use to reproduce?
What process do single-celled organisms like yeast use to reproduce?
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In binary fission, where do the replicated DNA molecules attach within the prokaryotic cell?
In binary fission, where do the replicated DNA molecules attach within the prokaryotic cell?
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Which component of the cell membrane allows lipid-soluble molecules to pass through?
Which component of the cell membrane allows lipid-soluble molecules to pass through?
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What is the primary role of proteins integrated throughout the cell membrane?
What is the primary role of proteins integrated throughout the cell membrane?
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What is the fluid mosaic model's main characteristic?
What is the fluid mosaic model's main characteristic?
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What type of replication occurs in viruses after they inject their nucleic acids into a host cell?
What type of replication occurs in viruses after they inject their nucleic acids into a host cell?
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What type of proteins are located on the surface of the cell membrane?
What type of proteins are located on the surface of the cell membrane?
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Which type of molecule in the membrane acts as receptors for certain molecules?
Which type of molecule in the membrane acts as receptors for certain molecules?
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What role does cholesterol play in the cell membrane?
What role does cholesterol play in the cell membrane?
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Which type of movement requires energy in the form of ATP?
Which type of movement requires energy in the form of ATP?
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What describes facilitated diffusion?
What describes facilitated diffusion?
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What is the primary function of glycoproteins in the cell membrane?
What is the primary function of glycoproteins in the cell membrane?
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During osmosis, water moves from
During osmosis, water moves from
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What does co-transport primarily utilize for moving substances?
What does co-transport primarily utilize for moving substances?
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Which statement is true about active transport?
Which statement is true about active transport?
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What happens during endocytosis?
What happens during endocytosis?
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What is a characteristic that distinguishes bacteria from viruses?
What is a characteristic that distinguishes bacteria from viruses?
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How do glucose and amino acids enter the epithelial cells mentioned in the content?
How do glucose and amino acids enter the epithelial cells mentioned in the content?
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What is one factor that can increase the rate of gas exchange by diffusion?
What is one factor that can increase the rate of gas exchange by diffusion?
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What is the primary reason bacteria can survive independently while viruses cannot?
What is the primary reason bacteria can survive independently while viruses cannot?
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What is the first symptom of HIV infection?
What is the first symptom of HIV infection?
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What structure do viruses lack compared to bacteria?
What structure do viruses lack compared to bacteria?
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Tuberculosis (TB) is caused by which of the following?
Tuberculosis (TB) is caused by which of the following?
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Which statement correctly describes the progression of HIV infection?
Which statement correctly describes the progression of HIV infection?
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Which of the following symptoms is NOT associated with AIDS?
Which of the following symptoms is NOT associated with AIDS?
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What role do lysozymes play in the immune system?
What role do lysozymes play in the immune system?
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Which of the following statements accurately describes an aspect of the specific immune response?
Which of the following statements accurately describes an aspect of the specific immune response?
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What triggers inflammation during a non-specific immune response?
What triggers inflammation during a non-specific immune response?
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What characterizes phagocytosis in the immune response?
What characterizes phagocytosis in the immune response?
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Which cells are primarily responsible for the humoral immune response?
Which cells are primarily responsible for the humoral immune response?
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What is the primary function of interferons in the immune response?
What is the primary function of interferons in the immune response?
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What is the role of memory cells in the immune system?
What is the role of memory cells in the immune system?
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Study Notes
Methods of Studying Cells
- Light microscopes use convex glass lenses to resolve images 0.2µm apart. Resolution is limited by the wavelength of light.
- Magnification is calculated as image size divided by real object size.
- Resolution is the smallest distance between two objects that can be distinguished as separate.
- Electron microscopes have higher resolution (0.1nm) than light microscopes, enabling the study of smaller structures.
- Transmission electron microscopes (TEM) use a beam of electrons passing through a thin section of a specimen. Darker areas indicate areas that absorb electrons.
- Scanning electron microscopes (SEM) use a beam of electrons that scan the surface of a specimen, creating a 3D image based on the scattering pattern.
- Electron microscopes require a vacuum environment to prevent electron deflection.
Cell Fractionation and Ultracentrifugation
- Cell fractionation separates cellular components to study them in detail.
- Differential centrifugation is a common method.
- Homogenization is the initial blending of cells to form a homogenate.
- The homogenate is spun in a centrifuge at increasing speeds, separating organelles by density. Heavier organelles settle first.
- Each step results in a pellet (sedimented material) and a supernatant (liquid).
- Organelles are separated based on their density.
- The process is carried out in cold, buffered solutions to prevent damage.
Cell Structure
- Eukaryotic cells have a nucleus and membrane-bound organelles.
- The nucleus encloses DNA, with nuclear pores for molecule exchange. It has a nucleolus involved in ribosome production.
- The rough endoplasmic reticulum (RER) folds and modifies proteins with ribosomes attached.
- The smooth endoplasmic reticulum (SER) synthesises and processes lipids.
- The Golgi apparatus modifies, sorts, and packages proteins and lipids.
- Mitochondria are responsible for respiration, containing cristae for increased surface area.
- Lysosomes contain digestive enzymes.
- Centrioles are involved in cell division.
Prokaryotic Cells
- Prokaryotic cells (bacteria) lack organelles and have a single circular DNA.
- Cell wall, capsule, plasmids, flagellum, pili, are examples of prokaryotic cell structures.
- Mesosomes are infoldings of the cell membrane, involved in respiration (and other functions).
Cell Division - Mitosis
- Mitosis produces genetically identical daughter cells for growth and repair.
- Mitosis involves four stages: prophase, metaphase, anaphase, telophase.
- Interphase is the phase of cell growth and DNA replication before mitosis.
- Cytokinesis is the division of the cytoplasm to form two daughter cells.
- Binary fission is the cell division method in prokaryotes, differing from mitosis in the stages.
Biological Membranes
- Cell membranes are fluid mosaics.
- The membrane is comprised of a phospholipid bilayer.
- Hydrophilic heads face outward, hydrophobic tails inward, this structure controls permeability.
- Proteins, cholesterol, glycolipids are embedded in the membrane, performing various functions.
- Proteins include integral (transmembrane) and peripheral proteins.
- Cholesterol regulates membrane fluidity.
- Glycolipids and glycoproteins act as cell recognition markers.
Cell Transport
- Passive transport (diffusion, osmosis, facilitated diffusion) moves substances down a concentration gradient.
- Active transport moves substances against the concentration gradient, requiring energy (ATP).
- Exocytosis and endocytosis transport large substances.
- Co-transport couples movement of one substance with another.
Bacteria and Viruses
- Bacteria are prokaryotic; viruses are non-living.
- Cell wall structures and organelles are features of bacteria, absent in viruses.
- Genetic material (DNA/RNA) is a key component of both, but structurally different.
Immune Response
- Physical barriers include skin and stomach acid.
- Non-specific responses include inflammation, lysozyme action, and phagocytosis.
- Specific responses involve lymphocytes (B cells and T cells);
- B cells produce antibodies (humoral response),
- T cells have cell-mediated response.
- Memory cells speed up subsequent immune response.
- Vaccination uses antigens to stimulate immunity.
Antibodies
- Antibodies are proteins that bind to specific antigens (foreign substances).
- They form an antigen-antibody complex which can trigger various immune responses, like phagocytosis and clumping.
Ethical Considerations
- Ethical concerns exist around vaccine development, testing, and usage.
- Considerations include animal use, safety for humans, and compulsory vaccination.
Monoclonal Antibodies
- Monoclonal antibodies are identical antibodies produced in labs.
- They are used therapeutically (directly targeting cancerous cells), diagnostically (measuring specific components), and for pregnancy testing.
HIV
- HIV is a virus responsible for AIDS.
- Its structure includes a lipid envelope, capsid, RNA genetic material, and reverse transcriptase.
- ELISA is a diagnostic test for HIV.
Antibiotics
- Antibiotics are largely ineffective against viruses.
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Description
Explore the techniques of studying cells, including light and electron microscopy. Learn about the principles of resolution, magnification, and cell fractionation, which are essential for understanding cellular components. This quiz covers the essential methodologies used in modern cell biology.
