Cytology: Membranous Organelles
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Questions and Answers

What is the main focus of cytology?

  • Study of cell membranes
  • Study of the nucleus
  • Study of lipids in cells
  • Study of cell organelles (correct)

Which stain is commonly used to visualize the cell membrane?

  • Methylene blue
  • Silver stain (correct)
  • Iodine stain
  • Hematoxylin and eosin

In mammals, the two major compartments of a cell are cytoplasm and __________.

  • Cell inclusions
  • Nucleus (correct)
  • Endoplasmic reticulum
  • Golgi apparatus

What distinguishes membranous organelles from non-membranous organelles in cells?

<p>Presence of membranes (D)</p> Signup and view all the answers

Which component is essential to all types of cells and is present in membranous organelles?

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

What is the main structural component of biological membranes?

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

What is the function of the polar hydrophilic head in a phospholipid molecule?

<p>Facilitates passage of specific ions and water-soluble substances (A)</p> Signup and view all the answers

How do integral proteins contribute to the cell membrane's function?

<p>Facilitate passage of specific ions and water-soluble substances (C)</p> Signup and view all the answers

What is the role of carbohydrates in the lipid bilayer?

<p>Protect the cell from physical and chemical injury (A)</p> Signup and view all the answers

How does osmium contribute to the trilaminar appearance seen by EM?

<p>Deposits on hydrophilic heads (B)</p> Signup and view all the answers

What is the main function of peripheral proteins in the cell membrane?

<p>Help in cell-cell recognition and adhesion (D)</p> Signup and view all the answers

Which function is NOT attributed to lipids in the cell membrane?

<p>Forming ion channels (B)</p> Signup and view all the answers

What is the function of rough endoplasmic reticulum?

<p>Protein synthesis for export (D)</p> Signup and view all the answers

Which organelle is directly related to the activity of the cells based on the number of mitochondria and their cristae?

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

What is the process where a cytoplasmic vesicle discharges its contents to the extracellular space?

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

Which stain is needed to visualize mitochondria as small granules or rod-like structures?

<p>Janus green or iron hematoxylin (A)</p> Signup and view all the answers

What is the primary function of smooth endoplasmic reticulum (SER) in a cell?

<p>Lipid synthesis and detoxification (B)</p> Signup and view all the answers

How do mitochondria reproduce themselves?

<p>By binary fission (A)</p> Signup and view all the answers

What is the main function of Smooth Endoplasmic Reticulum (SER) based on the provided text?

<p>Synthesis of lipid and steroid hormones (C)</p> Signup and view all the answers

Which of the following statements about the Golgi Apparatus is accurate according to the text?

<p>Variable in size based on cell location and activity (D)</p> Signup and view all the answers

How do secretory vesicles discharge their contents according to the text?

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

What distinguishes the immature face (cis face) from the mature face (trans face) in the Golgi Apparatus?

<p>Located near the Rough Endoplasmic Reticulum (RER) (A)</p> Signup and view all the answers

Which organelle originates lysosomes according to the text?

<p>Mature face of Golgi apparatus (C)</p> Signup and view all the answers

What type of enzymes do lysosomes contain as indicated in the text?

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

Study Notes

Cytology: Study of Cells

  • Cytology involves the study of cells, which consist of two main compartments: cytoplasm and nucleus.

Cytoplasmic Components

  • Cytoplasm contains:
    • Cell organelles
    • Cell inclusions
    • Cytosol (matrix)

Cytoplasmic Organelles

  • Organelles are essential to cell life and are present in all types of cells.
  • Classified into:
    • Membranous organelles
    • Non-membranous organelles

Membranous Organelles

  • Include:
    • Cell membrane
    • Mitochondria
    • Microtubules
    • RER (Rough Endoplasmic Reticulum)
    • SER (Smooth Endoplasmic Reticulum)
    • Golgi apparatus
    • Secretory vesicles
    • Lysosomes

Cell Membrane (Plasma Membrane, Plasmalemma)

  • Outer boundary of all cells
  • Appears as a thin, brown line with special stain (silver)
  • Composed of:
    • Lipids (phospholipid bilayer)
    • Proteins
    • Carbohydrates
  • Functions:
    • Provides entrance for fat-soluble components and drugs
    • Forms ion channels and carrier proteins
    • Gives definite shape to the cell
    • Protects internal contents
    • Selective barrier
    • Facilitates vesicular transport

Lipids

  • Provide an entrance for fat-soluble components and drugs
  • Bimolecular layer (two layers) of mixed phospholipid and some cholesterol
  • Each phospholipid molecule has:
    • A polar hydrophilic head
    • Two long, non-polar hydrophobic tails

Proteins

  • Includes:
    • Integral or intrinsic proteins (transmembrane)
    • Peripheral or extrinsic proteins (on cytoplasmic aspect of cell membrane)
  • Functions:
    • Forms ion channels and carrier proteins
    • Facilitates passage of specific ions and water-soluble substances

Carbohydrates

  • Project from the outer aspect of the lipid bilayer to form a surface coat or Glycocalyx
  • Functions:
    • Protects the cell from physical and chemical injury
    • Controls passage of substances
    • Helps cell-cell recognition and adhesion

Mitochondria

  • Functions:
    • Synthesizes ATP
    • Regulates Ca+2 homeostasis and protects cell from Ca+2 toxicity
  • Has its own DNA and can divide by simple binary fission
  • Composed of:
    • Outer and inner membranes
    • Intermembrane space
    • Matrix space
    • Matrix granules

Endoplasmic Reticulum (ER)

  • The largest membranous system of the cell
  • Composed of:
    • RER (Rough Endoplasmic Reticulum)
    • SER (Smooth Endoplasmic Reticulum)

RER (Rough Endoplasmic Reticulum)

  • Functions:
    • Protein synthesis for export and lysosomal enzymes
    • Synthesizes proteins for export and lysosomal enzymes
  • Present in large amounts in protein-forming cells
  • Composed of:
    • Flattened tubules (cisternae)
    • Covered with ribosomes

SER (Smooth Endoplasmic Reticulum)

  • Functions:
    • Synthesizes lipid and steroid hormones
    • Detoxification of drugs
    • Storage of Ca+2 (in muscle cells)
    • Synthesizes phospholipid of cell membrane
  • Composed of:
    • Branched tubules
    • No ribosomes on its membrane

Golgi Apparatus

  • Functions:
    • Chemical modification of protein
    • Condensation and sorting of protein
    • Formation of secretory vesicles and lysosomes
  • Composed of:
    • Flattened cisternae
    • Slightly curved
    • Dilated at the periphery
    • Present in stacks
    • Each stack has:
      • Convex (immature) = cis face, near RER
      • Concave (mature) = trans face, where secretory vesicles and lysosomes bud off

Secretory Vesicles

  • Originate from the mature face of Golgi apparatus
  • Discharge contents by exocytosis
  • Composed of:
    • Small, rounded, electron-dense, membrane-bound structures

Lysosomes

  • Membrane-bound vesicle containing hydrolytic enzymes
  • Originate from the mature face of Golgi apparatus
  • Composed of:
    • Two types:
      • Primary lysosomes
      • Secondary lysosomes

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Explore the study of cell membranes, cytoplasm components, and the nucleus in mammalian cells. Understand the structure and function of cell organelles, inclusions, cytosol, and the nucleus. Test your knowledge on cytoplasmic components and histology with this quiz!

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