Cell Structure and Prokaryotic Cells
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Questions and Answers

What is the primary method of reproduction in prokaryotic cells?

  • Meiosis
  • Binary fission (correct)
  • Budding
  • Mitosis

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

  • Shape of the cell
  • Presence of a flagellum
  • Type of nucleus
  • Cell wall composition (correct)

Which of the following is NOT a characteristic of prokaryotic cells?

  • Use of flagella for movement
  • Lack of membrane-bound organelles
  • High metabolic rate
  • Presence of a nucleus (correct)

Which of these accurately describes eukaryotic cells?

<p>Have membrane-bound organelles (D)</p> Signup and view all the answers

What role do capsules serve in some prokaryotic cells?

<p>Provide additional protection (D)</p> Signup and view all the answers

Which type of organism is categorized as a eukaryotic cell?

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

What is the typical generation time for binary fission in prokaryotic cells?

<p>20 minutes (C)</p> Signup and view all the answers

What is the main function of the cell wall in eukaryotic cells that possess it?

<p>Provide structural support (B)</p> Signup and view all the answers

What structure maintains cell shape and protects against mechanical stress in eukaryotic cells?

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

Which component of the plasma membrane is primarily responsible for selective permeability?

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

What role do microtubules play in eukaryotic cells?

<p>Maintain cell shape and aid in chromosome separation (A)</p> Signup and view all the answers

Which of the following is NOT a function of the cytoskeleton?

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

Which structure in eukaryotic cells contains DNA and controls cellular activities?

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

What type of cells are categorized as agranulocytes?

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

Which statement correctly describes the maturity process of B-lymphocytes?

<p>They are produced in the bone marrow and mature in the bone marrow. (A)</p> Signup and view all the answers

What is the primary function of monocytes in the immune response?

<p>To act as phagocytes and process antigens (D)</p> Signup and view all the answers

In what form do B-lymphocytes function after they transform?

<p>As plasma cells producing antibodies (C)</p> Signup and view all the answers

Which organ is primarily involved in the maturation of T-lymphocytes?

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

Which of the following statements about lymphocytes is false?

<p>They actively ingest foreign particles. (B)</p> Signup and view all the answers

What best describes the morphology of monocytes?

<p>Highly variable morphology and size (C)</p> Signup and view all the answers

Which location is NOT associated with the production of lymphocytes?

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

What results from the maturation of B-lymphocytes?

<p>Production of antibodies (C)</p> Signup and view all the answers

Which characteristic is specific to prokaryotic cells?

<p>Are typically unicellular organisms (A)</p> Signup and view all the answers

What is a primary function of the cell wall in prokaryotic cells?

<p>To maintain cell shape and protection (C)</p> Signup and view all the answers

Which component is NOT typically found in eukaryotic cells?

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

What is the role of the additional membrane layer found in some Gram-negative bacteria?

<p>To protect against antibiotics (D)</p> Signup and view all the answers

How does the small size of cells contribute to their functionality?

<p>Increases surface area to volume ratio for diffusion (C)</p> Signup and view all the answers

During which method of reproduction do prokaryotic cells typically divide?

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

What determines the various types and shapes of cells?

<p>Their functions and positions within organisms (C)</p> Signup and view all the answers

Which of the following statements best describes the hereditary material in cells?

<p>It is DNA passed from cell to cell during division (D)</p> Signup and view all the answers

What is a key difference between plant and animal cells?

<p>Plant cells contain chloroplasts for photosynthesis (B)</p> Signup and view all the answers

In which type of cell would you find a more complex endoplasmic reticulum network?

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

Which of the following organelles is responsible for synthesizing ribosomal RNA subunits?

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

Which structure is primarily involved in modifying, sorting, and distributing proteins?

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

What is the primary function of the Smooth Endoplasmic Reticulum?

<p>Lipid synthesis and hormone production (D)</p> Signup and view all the answers

Which of the following correctly describes mitochondria?

<p>Has an inner membrane folded into cristae (C)</p> Signup and view all the answers

What type of cells primarily consist of ribosomes for protein synthesis?

<p>Both prokaryotic and eukaryotic cells (C)</p> Signup and view all the answers

Lysosomes are involved in which of the following processes?

<p>Digestion of macromolecules (C)</p> Signup and view all the answers

Which component of the eukaryotic cell is continuous with the nuclear envelope?

<p>Rough Endoplasmic Reticulum (B)</p> Signup and view all the answers

How do protein synthesis and metabolism regulation primarily occur in a eukaryotic cell?

<p>Using nucleus and rough endoplasmic reticulum (C)</p> Signup and view all the answers

Which organelle's structure includes flattened membranous sacs known as cisternae?

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

What is not a function of lysosomes?

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

Flashcards

Prokaryotic cell

A simple cell lacking membrane-bound organelles and a nucleus. It usually has a cell wall.

Eukaryotic cell

A complex cell with membrane-bound organelles and a nucleus. Includes plants, animals, fungi, etc.

Cell wall (bacteria)

A rigid outer layer found in some cells, particularly bacteria. Its structure helps determine Gram stain results.

Gram-positive bacteria

Bacteria that appear purple after staining with the Gram stain. They have a thick cell wall.

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Gram-negative bacteria

Bacteria that appear pink after staining with the Gram stain. They have a thinner cell wall and an outer membrane.

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Binary fission

A type of asexual reproduction in prokaryotic cells (like bacteria), producing genetically identical offspring.

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Generation time

The time it takes for a population of cells to double.

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Membrane-bound organelles

Cellular structures (like mitochondria, endoplasmic reticulum) surrounded by membranes.

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Nucleus

The control center of the cell, containing genetic material (DNA), directing protein synthesis, and regulating cell metabolism.

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Nucleolus

A structure within the nucleus that synthesizes ribosomal RNA subunits, essential for protein synthesis.

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Endoplasmic Reticulum (ER)

A network of membranous tubules and sacs involved in protein synthesis and transport (rough ER) and diverse metabolic activities (smooth ER).

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Rough ER (RER)

The portion of the ER studded with ribosomes, responsible for synthesizing and transporting proteins.

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Smooth ER (SER)

The portion of the ER lacking ribosomes, involved in diverse metabolic activities such as hormone production and lipid synthesis.

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Golgi Body

A stack of flattened membranous sacs that modifies, sorts, and distributes proteins from the rough ER to various destinations.

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Ribosomes

Small granules found in all cells, responsible for synthesizing proteins based on mRNA genetic information using amino acids from the cytoplasm.

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Lysosomes

Organelles containing hydrolytic enzymes to digest macromolecules, recycle old organelles, and digest dead cell remains.

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Mitochondria

Organelles with two membranes, responsible for cellular respiration and energy production (ATP).

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What is the major function of the nucleus?

The nucleus directs protein synthesis, stores genetic material, and regulates cell metabolism.

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Cell Wall Function

The cell wall maintains cell shape, supports growth, provides mechanical strength, and prevents bursting. It also protects against pathogens and mechanical stress and acts as a carbohydrate reserve.

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Plasma Membrane

The plasma membrane encloses the cytoplasm, providing shape and protection. It's semi-permeable, allowing selective material passage. It's composed of a phospholipid bilayer with embedded proteins.

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Fluid Mosaic Model

A model describing the plasma membrane structure. It highlights the phospholipid bilayer with embedded proteins that can move laterally, giving it a fluid-like nature.

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Cytoskeleton: What does it do?

The cytoskeleton is made of filamentous protein networks, providing mechanical support and maintaining cell shape. It fixes organelle locations and aids substance movement within the cell.

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Types of Cytoskeleton Filaments

There are three types of cytoskeleton filaments: microfilaments support muscle contraction; microtubules maintain cell shape and assist in chromosome separation; intermediate filaments prevent excessive stretching and fix organelle positions.

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What is a Granulocyte?

A type of white blood cell that has granules in its cytoplasm. These granules help the cell fight off infections.

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What is an Agranulocyte?

A type of white blood cell that lacks granules in its cytoplasm.

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What are Lymphocytes?

A type of Agranulocyte that plays a crucial role in the immune system. Lymphocytes have little cytoplasm and are produced in lymph nodes, spleen, bone marrow, and intestinal mucosa.

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What are the two types of lymphocytes?

T-lymphocytes (mature in the thymus) and B-lymphocytes (mature in the bone marrow).

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What do B-lymphocytes do?

B-lymphocytes transform into plasma cells, which produce antibodies to protect against various infections.

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What are Monocytes?

A type of agranulocyte that has highly variable morphology and size. They migrate to tissues like the liver, lymph nodes, and lungs, where they can stay for days or years.

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What do Monocytes do?

Monocytes are actively phagocytic, which means they engulf and digest foreign particles.

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How do Monocytes help with the immune response?

Monocytes process antigens (foreign substances) and present them to B- and T-lymphocytes, which helps activate the immune system.

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What is a plasma cell?

A specialized type of B-lymphocyte that produces antibodies in large quantities.

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What is the function of antibodies?

Antibodies are proteins that bind to specific antigens on invading pathogens, helping to neutralize or destroy them.

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What's the function of the cell wall in prokaryotes?

The cell wall provides structural support, maintains cell shape, and protects the cell from osmotic stress.

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What is peptidoglycan?

A complex sugar molecule found in the cell walls of most bacteria, providing structural integrity and strength.

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What's the significance of the additional membrane layer in Gram-negative bacteria?

The outer membrane, containing lipopolysaccharide, acts as a barrier against antibiotics and other harmful substances.

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Why does surface-to-volume ratio matter for cells?

A large surface area-to-volume ratio allows for efficient diffusion of nutrients and waste products across the cell membrane.

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What is the role of DNA in cells?

DNA carries genetic information, determining the cell's characteristics and passing them on to daughter cells during division.

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Why do cells have different shapes and sizes?

Cells have various shapes and sizes depending on their specific roles and functions within the organism.

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Study Notes

Cell Structure, Function, and Properties

  • Cells are the fundamental units of life, either unicellular or multicellular.
  • Cell theory was developed by Robert Hooke in 1665.
  • Biochemistry and energy flow occur within cells. This includes processes like energy production and transfer.
  • Cells contain hereditary information (DNA) passed from cell to cell during division.
  • Cells exhibit varied types, shapes, and positions, influenced by purpose and placement.
  • Small cell size results in a high surface-to-volume ratio, which enhances diffusion rates.

Prokaryotic Cells

  • Prokaryotes are unicellular organisms, including bacteria and archaebacteria.
  • Prokaryotic cells lack membrane-bound organelles and a nucleus.
  • Their DNA is not contained within a membrane-bound nucleus.
  • Cell walls are made of peptidoglycan and maintain cell structure.
  • Prokaryotes reproduce asexually, by binary fission. This occurs approximately every 20 minutes under suitable conditions, rapidly increasing population numbers.
  • Some bacteria have an extra layer called a lipopolysaccharide.
  • This layer differentiates between Gram-positive and Gram-negative bacteria.

Eukaryotic Cells

  • Eukaryotes include plants, animals, fungi, slime molds, protozoa, and algae.
  • They are larger than prokaryotes and have a defined nucleus.
  • Possess membrane-bound organelles.
  • Contain a distinct nucleus enclosed by a nuclear envelope.
  • Undergo meiosis and mitosis for growth and reproduction.
  • These processes lead to replication and cell division for development and maintenance.

Plant Cells

  • Plant cells have rigid cell walls.
  • The cell wall is made of various layers, including primary and secondary cell walls.
  • Plant cells contain chloroplasts for photosynthesis and large central vacuoles.
  • Chloroplasts contain chlorophyll, which enables plants to create their own food.
  • The large vacuoles in mature plant cells maintain internal pressure, essential for cell rigidity (turgidity).
  • Cytoplasm is separated from the external environment by the plasma membrane, allowing selective material passage through controlled processes.
  • Adjacent plant cells are connected by plasmodesmata and the middle lamella and the process of substance exchange.

Animal Cells

  • Animal cells have no cell walls.
  • They are enclosed by plasma membranes.
  • Movement is assisted by flagella.
  • Animal cells contain organelles like mitochondria, responsible for metabolism and energy production (ATP).
  • Animal cells contain no chloroplasts
  • Animal cells have centrioles.
  • Glycogen is the storage form of food reserves in animal cells.
  • Cell shape is typically irregular and varies considerably depending on the type of cell and its purpose.

Tissues

  • Tissues are groups of cells of similar structure and function working together.

  • Epithelial, connective, muscle, and nerve tissues are fundamental tissue types.

  • Epithelial tissues cover body surfaces and line cavities. Four main types exist: squamous, cuboidal, columnar, and stratified.

  • Squamous tissue forms thin, smooth, and strong sheets of cells.

  • Found in areas that require rapid diffusion, like blood vessels and linings of the lungs and internal organs.

  • Cuboidal and columnar cells form linings with specialized functions.

  • Cuboidal cells are cube-shaped and are responsible for secretions.

  • They are involved in absorption and secretion of materials. Examples include glands.

  • Columnar cells are pillar-like shaped, primarily specialized for nutrient absorption and secretion. For example, columnar tissues line the intestine, involved in both digestion and nutrient uptake.

  • Stratified cells form multiple protective layers. Examples of these protective layers include the epidermis (skin) and lining of the esophagus, which are exposed to mechanical stress.

  • Connective tissue supports and connects other tissue types.

  • Muscle tissue enables movement. It is either smooth (involuntary) or striated (voluntary).

  • Cardiac muscle is a special type of striated muscle, found only in the heart.

  • Nerve tissue transmits electrical signals.

  • Nerve cells (neurons) are involved in communication and signal transduction via the nervous system.

Blood cells

  • Blood is a fluid connective tissue, crucial for transport and defense.
  • Blood is categorized into formed elements and plasma.
  • Red blood cells are made in the bone marrow, non-nucleated and flexible.
  • They contain hemoglobin and are essential for oxygen transport.
  • White blood cells have diverse functions, classified as granulocytes and agranulocytes.
  • They are part of the body's immune system, fighting infections. Granulocytes (neutrophils, eosinophils, and basophils) have granules in their cytoplasm while agranulocytes (lymphocytes and monocytes) do not.
  • Each type of cell plays a significant role in immune protection or oxygen transport.

Cartilage

  • Cartilage is a specialized connective tissue, supporting and cushioning various parts of the body.
  • It has a firm yet flexible texture, facilitating functions such as support and shock absorption.
  • Three main types exist: hyaline, elastic, and fibrous.
  • Hyaline cartilage is the most common type, found on bone surfaces and in respiratory passages.
  • Elastic cartilage is flexible and is found in the ear and throat.
  • Fibrous cartilage is strong and is present in intervertebral discs.

Bones

  • Bones provide support, protect organs, and are strong levers.
  • Bones are made from calcium-phosphate mineral deposits.
  • Two types exist: spongy and compact bone.
  • Compact bones have a tough, hard exterior while spongy bones are porous.
  • Osteocytes (bone cells) are essential for bone maintenance and growth.

Other Tissues

  • Other types of tissue include nervous and muscle, which are crucial for body functions and communication.

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Explore the fundamental concepts of cell structure, function, and properties in this quiz. Learn about the differences between prokaryotic and eukaryotic cells, including their unique characteristics and reproductive methods. Test your knowledge on cell theory, DNA, and the role of cells in life.

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