Histology and Cell Culture Quiz

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Questions and Answers

What is the primary function of eukaryotic cells?

Structural support and protection

Photosynthesis and energy storage

Absorption, digestion, and excretion (correct)

Cell division and immunity

Which is a characteristic feature of cells that affects their shape?

The number of organelles present

The size of the cell wall

The type of tissue they comprise (correct)

The amount of genetic material they contain

What aspect of the cell membrane is visible under an electron microscope?

It consists of multiple color layers

It appears as a single dense layer

It appears as two electron dense bands separated by an electron lucent layer (correct)

It is transparent and shows no significant features

How are electron-lucent areas characterized in a specimen?

They are areas through which electrons passed Signup and view all the answers

What is the typical thickness of the unit membrane observed in cells?

8-10 nm Signup and view all the answers

What distinguishes histology from cytology?

Histology focuses on tissues, while cytology focuses on cells. Signup and view all the answers

Which method is primarily used for observing live cells in a controlled environment?

Cell culture Signup and view all the answers

What is the role of the cytoskeleton in a cell?

It helps maintain cell shape and facilitates movement. Signup and view all the answers

Which of the following is NOT a method of studying cells?

Magnetic resonance imaging (MRI) Signup and view all the answers

What is the relationship between the cell membrane and organelles?

The structure of the cell membrane supports organelle function. Signup and view all the answers

What is the predominant component of the cell membrane by percentage?

Proteins (60%) Signup and view all the answers

Which type of transport requires energy to move substances across the cell membrane?

Active transport Signup and view all the answers

Which of the following is NOT a function of trans-membranous proteins?

Transporting energy Signup and view all the answers

What role do integral membrane proteins primarily serve in a cell membrane?

Serving as ion channels and receptors Signup and view all the answers

What structural feature of the fluid mosaic model describes the mobility of lipids and proteins within the membrane?

Fluid dynamic Signup and view all the answers

What does histochemical and cytochemical methods primarily focus on?

Identifying and localizing specific substances in cells or tissues Signup and view all the answers

Which type of staining method stains only one structure or substance, such as orcein for elastic fibers?

Specific histological methods Signup and view all the answers

Which statement correctly describes prokaryotic cells?

They lack a nuclei and are generally smaller than eukaryotic cells. Signup and view all the answers

What is the purpose of using physical methods in histochemical and cytochemical procedures?

To identify substances by their physical properties, like fluorescence Signup and view all the answers

What does haematoxylin stain primarily target in cells?

The nucleus and other structures in the cytoplasm Signup and view all the answers

In which staining method do substances enter cells via phagocytosis?

Vital staining methods Signup and view all the answers

What distinguishes eukaryotic cells from prokaryotic cells?

Larger size and presence of membrane-limited organelles Signup and view all the answers

What kind of affinity is used in certain physical methods for staining?

Affinity for fluorescent substances Signup and view all the answers

Study Notes

Histology

The study of microscopic structures and functions of the human organism, including the organization of tissues and organs.
Cytology is the study of cell structure and functions.

Cell and Tissue Culture

Definition: The maintenance and study of live cells and tissues outside the body (in vitro).
Uses:
- Direct observation of living cells
- Performing experiments not possible in vivo (within the body)
- Research on cell structure and function
- Genetic or chromosomal analyses
- Studying molecular changes in cancer

Staining methods

General Histological Methods:
- Staining the nucleus and other structures in the cytoplasm (e.g., hematoxylin stains the nucleus, eosin stains basic cell components like mitochondria)
Specific (special) Histological Methods:
- One dye stains only one structure or substance (e.g., orcein stains elastic fibers)
Vital Staining:
- Dyes enter cells without harming them, either by diffusion or phagocytosis (e.g., staining cellular components)
Histochemical and Cytochemical Methods:
- Identify and localize specific substances like fat or enzymes in cells or tissues using physical or chemical procedures on histological sections
  - Chemical methods: e.g., identifying glycogen using periodic acid Schiff (PAS)
  - Physical methods: Based on staining affinity due to physical properties, e.g., fluorescent substances (vitamin A)

The Cell

Eukaryotic Cells:
- e.g. human and animal cells
- Large
- Have a definite membrane-limited nucleus
- Cytoplasm contains membrane-limited organelles
Prokaryotic Cells:
- e.g. bacteria
- Small
- Have a cell wall outside the plasma membrane
- Lack nuclei
- Lack membrane-limited organelles
Shape of Cells:* Round, oval, flat, cubical, or columnar
Size of Cells:* Small (cerebellum), medium (liver), or large (ovum)
Functions of Cells:* Absorption, digestion, excretion, respiration, ion transport, secretion, sensation, conduction, and contraction.

Electron Microscopy

Transmission Electron Microscopy (TEM):
- Beams of electrons pass through tissue sections
- Electron-lucent: White (bright) areas where electrons passed through easily
- Electron-dense: Dark areas where electrons were absorbed or deflected
Scanning Electron Microscopy (SEM):
- Beams of electrons apply to the surfaces of cells, tissues, and organs
- The surface is spray-coated with a thin layer of heavy metal (e.g., gold)
- Reflects electrons in a beam scanning the specimen
- Reflected electrons are captured, creating a 3D black and white image

Structure of the Eukaryotic Cell

Cell Membrane
Nucleus
Cytoplasm

Cell Membrane

Light Microscope (LM):
- Not easily visible, but can be inferred by dye deposition
- Can be stained by PAS or Silver
Electron Microscope (EM):
- Appears as two electron-dense bands separated by an electron-lucent one (trilaminar membrane or unit membrane)
- 8-10 nm thickness

Cell Membrane Molecules

Carbohydrate (10%)
Lipid (30%)
Protein (60%)

Fluid Mosaic Model

Proposed by Singer & Nicolson
Lipid: Forms the bilayer
Phospholipid molecule:
- Head: Hydrophilic (water-loving)
- Tail: Hydrophobic (water-fearing)
Cholesterol: Interacts with lipid bilayer, influencing fluidity.

Membrane Proteins

Integral membrane proteins:
- Embedded within the lipid bilayer
- e.g., Ion channels, receptors, enzymes, transporters/carriers
Peripheral membrane proteins:
- Attached to the surface of the membrane
- Often interact with integral membrane proteins
Functions of Membrane Proteins:*
Ion Channels: Allow specific ions to pass through the membrane
Receptors: Bind to signaling molecules, initiating cellular responses
Enzymes: Catalyze reactions at the membrane surface
Transporters/Carriers: Move specific molecules across the membrane
Markers (glycoproteins): Identify cell type
Cell Adhesion: Facilitate cell-to-cell connections

Membrane Transport

Simple Diffusion: Movement of molecules across the membrane from high to low concentration, no energy required (e.g., gases, ions)
Osmosis: Diffusion of water across a semipermeable membrane
Facilitated Diffusion: Movement of molecules across the membrane with the help of transport proteins, no energy required (e.g., sugars, amino acids)
Active Transport: Movement of molecules against their concentration gradient, requires energy (e.g., protein channels)
Exocytosis: Release of cellular products from the cell, uses vesicles
Endocytosis: Uptake of extracellular material into the cell, uses vesicles
Selective Permeability: Controlled entry and exit of materials based on receptors in the cell coat

Modifications in Cell Membranes

Microvilli: Finger-like projections that increase surface area for absorption (e.g., small intestine)
Cilia: Hair-like projections that move particles (e.g., removal of dust from inspired air in the respiratory passages)
Flagella: Long, whip-like structures for movement (e.g., tails of sperm)

Function of Trans-Membranous Proteins

Osmoregulation: Maintain cell volume
Receptors: Detect and respond to signals
Ion Channels: Allow specific ions to pass through the membrane
Barrier: Regulate the exchange of materials between the cell and its environment

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Description

Test your knowledge on histology, cytology, and cell culture techniques. This quiz covers the microscopic structures of human tissues, methods of staining, and the significance of cell culture in scientific research. Challenge yourself to see how well you understand these essential biological concepts.