Electron Microscopy and Staining Techniques
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Electron Microscopy and Staining Techniques

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Questions and Answers

It is used to stain structures a purplish ______

blue

The nucleus, and parts of the cytoplasm that contain ______ stain up in one colour (purple)

RNA

The study of the form and shape of structures is called ______

morphology

Cells are the building blocks of all animals and ______

<p>plants</p> Signup and view all the answers

There are over ______ different cell types in the human body

<p>200</p> Signup and view all the answers

Sex cells or ______ are cells that fuse during sexual reproduction

<p>gametes</p> Signup and view all the answers

In mammals, somatic cells make up all the internal organs, skin, bones, blood, and ______ tissue

<p>connective</p> Signup and view all the answers

The smallest units that perform all vital physiological ______ are cells

<p>functions</p> Signup and view all the answers

The cell membrane separates the cell contents (cytoplasm) from the extracellular fluid known as ______.

<p>interstitial fluid</p> Signup and view all the answers

The structure of the cell membrane is formed by a ______ bilayer.

<p>lipid</p> Signup and view all the answers

Phospholipids are the main component of cell membranes, making up about ______% of membrane lipids.

<p>50</p> Signup and view all the answers

Cholesterol is important for stabilizing the ______.

<p>membrane</p> Signup and view all the answers

Membrane proteins can act as receptors for ______ signaling between cells.

<p>chemical</p> Signup and view all the answers

Integral membrane proteins (IMPs) are permanently attached to the biological ______.

<p>membrane</p> Signup and view all the answers

Peripheral membrane proteins adhere only ______ to the biological membrane.

<p>temporarily</p> Signup and view all the answers

Glycolipids are involved in ______ communication between cells.

<p>intercellular</p> Signup and view all the answers

An electron microscope uses a beam of accelerated ______ as a source of illumination.

<p>electrons</p> Signup and view all the answers

The most commonly used staining system in microscopy is called ______.

<p>H&amp;E</p> Signup and view all the answers

Eosin is an ______ dye that stains structures red or pink.

<p>acidic</p> Signup and view all the answers

Haematoxylin can be considered as a ______ dye.

<p>basic</p> Signup and view all the answers

Periodic Acid-Schiff (PAS) stains are specifically used for identifying ______.

<p>carbohydrates</p> Signup and view all the answers

Regulatory protein subunits of many ion channels and transmembrane receptors may be defined as ______ membrane proteins.

<p>peripheral</p> Signup and view all the answers

Membrane carbohydrates are mainly found on the ______ surface, forming a coating called the glycocalyx.

<p>extracellular</p> Signup and view all the answers

Endocytosis is a cellular process that brings substances into the cell by forming a ______ containing the ingested material.

<p>vesicle</p> Signup and view all the answers

Pinocytosis is also known as fluid endocytosis or ______ phase pinocytosis.

<p>bulk</p> Signup and view all the answers

Phagocytosis is a process where the cell uses its plasma membrane to ______ a large particle.

<p>engulf</p> Signup and view all the answers

Exocytosis is a form of active transport in which a cell secretes molecules through an energy-dependent ______.

<p>process</p> Signup and view all the answers

The nucleus is bounded by a nuclear ______ which communicates with the cytoplasm through nuclear pores.

<p>envelope</p> Signup and view all the answers

Chromatin is composed of DNA and ______, forming a structure that packages DNA into more compact forms.

<p>protein</p> Signup and view all the answers

Multiple histones wrap into a 30-nanometer fibre consisting of nucleosome arrays in their most compact form called ______.

<p>heterochromatin</p> Signup and view all the answers

The ______ appears as a double nuclear membrane perforated by nuclear pores.

<p>nuclear envelope</p> Signup and view all the answers

The technique used to make internal structures of cells visible is called ______ fracture.

<p>freeze</p> Signup and view all the answers

Rough ER is characterized by its surface being studded with ______.

<p>ribosomes</p> Signup and view all the answers

The ______ apparatus is involved in sorting, packaging, and transporting cell products.

<p>Golgi</p> Signup and view all the answers

In the Golgi apparatus, the sacs or folds are called ______.

<p>cisternae</p> Signup and view all the answers

The nuclear pore complex is formed by concentric rings of ______.

<p>subunits</p> Signup and view all the answers

Smooth ER functions include lipid synthesis, membrane synthesis and ______.

<p>repair</p> Signup and view all the answers

Study Notes

Electron Microscopy

  • An electron micrograph uses an electron microscope to produce an image
  • Electron microscopes use accelerated electrons as a source of illumination

Staining

  • Specific structures or molecules can be identified in cells or tissues with stains
  • Different stains target specific structures
    • Haematoxylin stains nuclei and nucleic acids purple/blue
    • Eosin stains cytoplasm, elastic and reticular fibers red/pink
    • Toluidine blue stains nuclei and cytoplasm blue
    • Silver stains nerve and reticular fibers black/brown
    • Periodic acid-Schiff (PAS) stains carbohydrates purple/blue
    • Alcian blue stains acidic epithelial mucins and extracellular matrix blue
    • Cyanin stains myelin purple

H&E Staining

  • Haemotoxylin & Eosin (H&E) is the most commonly used staining system
  • Eosin is an acidic dye that stains structures red or pink
  • Haematoxylin is a basic dye that stains structures purplish blue

Definitions

  • Morphology studies the form and shape of structures
  • Morphometry measures the shape of structures
  • Stereology uses 2D images to study 3D structures

The Cell

  • Cells are the building blocks of all animals and plants
  • Cells originate from the division of pre-existing cells
  • Cells are the smallest units that perform all vital physiological functions
  • Each cell maintains homeostasis at the cellular level
  • Cytology studies cellular structure and function

Cell Types

  • There are over 200 different types of cells in the human body
  • Each cell type specializes to carry out a specific function
  • Different tissues combine to form organs
  • Every cell type is equally important due to its contribution to the organ's functionality

Cell Membrane

  • Separates the cell contents (cytoplasm) from the extracellular fluid
  • Functions:
    • Physical isolation
    • Regulation of exchange with the environment
    • Sensitivity to the environment
    • Structural support

Cell Membrane Structure

  • Composed of a lipid bilayer with specialized proteins and carbohydrates
  • Each lipid molecule is amphipathic:
    • Hydrophilic end (phosphate)
    • Hydrophobic end (lipid)
  • Forms a bilayer in water

Membrane Lipids

  • Three main types:
    • Phosphoglycerides (phospholipids):
      • Around 50% of membrane lipid
      • Surround and anchor proteins (examples include phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine)
    • Cholesterol:
      • Stabilizes the membrane
    • Glycolipids:
      • Involved in intercellular communication
      • Examples include sphingolipids, gangliosides

Membrane Proteins

  • Functions:
    • Attach cytoskeletal filaments to the cell membrane
    • Attach cells to the extracellular matrix
    • Transport molecules into and out of cells
    • Act as receptors for chemical signalling between cells
    • Possess specific enzymatic activity

Membrane Proteins

  • Integral membrane proteins (IMPs): Permanently attached to the biological membrane & comprise a significant fraction of proteins encoded in an organism's genome
  • Peripheral membrane proteins: Adhere temporarily to the biological membrane & attach to integral membrane proteins, or penetrate the peripheral regions of the lipid bilayer

Membrane Carbohydrates

  • Mainly found on the extracellular surface as a coating called the glycocalyx
  • Functions:
    • Lubrication and protection
    • Anchoring and locomotion
    • Specificity in binding
    • Recognition

Transport Across Cell Membranes

  • Diffusion: Gases, lipophilic, or small molecules
  • Active Transport: Na2+ ions
  • Bulk Transport:
    • Endocytosis:
      • Pinocytosis
      • Phagocytosis
    • Exocytosis

Endocytosis

  • Cellular process in which substances are brought into the cell
  • The material to be internalized is surrounded by an area of the cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material

Pinocytosis

  • Also known as fluid endocytosis and bulk-phase pinocytosis
  • Small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane, resulting in a suspension of the particles within a small vesicle inside the cell
  • Pinocytotic vesicles subsequently fuse with endosomes to hydrolyze the particles

Phagocytosis

  • Process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome
  • It is one type of endocytosis
  • In multicellular organisms, phagocytosis is a major mechanism used to remove pathogens and cell debris

Exocytosis

  • Form of active transport and bulk transport in which a cell transports molecules out of the cell by secreting them through an energy-dependent process

The Nucleus

  • Bounded by the nuclear envelope
  • Communicates with the cytoplasm through nuclear pores
  • Contains:
    • Cellular DNA
    • Nucleoli (rRNA, mRNA, tRNA)
    • Nucleoproteins

Chromatin

  • Complex of DNA and protein found in eukaryotic cells
  • Primary function: Packaging long DNA molecules into compact, dense structures:
    • DNA wraps around histone proteins, forming nucleosomes and the "beads on a string" structure (euchromatin)
    • Multiple histones wrap into a 30-nanometer fiber consisting of nucleosome arrays in their most compact form (heterochromatin)

Important Nuclear Structures

  • Nuclear envelope: Double nuclear membrane (NM) is perforated by nuclear pores (P)
  • Nuclear pores: Formed by concentric rings of subunits that form the nuclear pore complex

Endoplasmic Reticulum

  • Network of membranous tubules, vesicles, and cisternae
  • Two types:
    • Rough ER (surface is studded with ribosomes): Function - protein synthesis
    • Smooth ER: Functions - lipid synthesis, membrane synthesis and repair

Golgi Apparatus

  • Membrane system involved in sorting, packaging, and transporting cell products
  • Functions:
    • Modification of macromolecules by adding sugars
    • Proteolysis of peptides into active forms
    • Sorting of macromolecules into membrane-bound vesicles
    • Transport of lipids around the cell
    • Creation of lysosomes
  • Sacs or folds of the Golgi apparatus are called cisternae

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Description

Explore the fascinating world of electron microscopy and various staining techniques in histology. This quiz covers how electron microscopes work, the specifics of staining different cellular structures, and the common H&E staining method. Test your knowledge on how these techniques are used to visualize and identify cell components.

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