Non-membranous Organelles Quiz

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the structure of glycogen granules as observed under TEM?

Spherical electron dense granules surrounded by a membrane

Cylindrical granules with a limiting membrane

Flat, irregular shaped granules with variable density

Rosette shaped electron dense granules (correct)

What distinguishes secretory granules as per their structural properties?

Unique flat shape with no membrane

Array of colorful granules with diverse functions

Variable size and surrounded by a membrane (correct)

Homogeneous size and membrane presence

What does the term 'singlet ring appearance' refer to in tissue histology?

The arrangement of collagen fibers in connective tissue

The unique color staining method used for cells

The morphology of adipose connective tissue cells (correct)

The structural arrangement of blood vessels

What type of staining is used for visualizing fat cells in histology?

Sudan III Signup and view all the answers

What is the distinguishing feature of lipid droplets as seen under TEM?

Electron dense and rounded with no limiting membrane Signup and view all the answers

Which of the following is NOT a non-membranous organelle?

Nucleus Signup and view all the answers

What is the histological appearance of ribosomes when examined using light microscopy?

They show basophilia of the cytoplasm. Signup and view all the answers

Which cytoplasmic structure functions as part of the cytoskeleton in cells?

Microtubules Signup and view all the answers

What type of structure do centrioles consist of?

9 triplets of microtubules Signup and view all the answers

Which technique is used to visualize microtubules in cells?

Immunofluorescent staining Signup and view all the answers

In which cellular structures are microtubules found primarily?

Cilia and flagella Signup and view all the answers

What characterizes the structure of microtubules in transverse section (T.S)?

They appear as small circles formed of protofilaments. Signup and view all the answers

Which statement is true about the function of microtubules?

They play a role in cell division by forming the mitotic spindle. Signup and view all the answers

What is the structure that forms the central component of the shaft of a cilium?

Two single microtubules Signup and view all the answers

Which of the following is NOT a component of cilia?

Microfilament Signup and view all the answers

How many triplet microtubules form the wall of a centriole?

9 Signup and view all the answers

What is the diameter range of thin filaments in the cytoskeleton?

6-8 nm Signup and view all the answers

Cilia help in spreading a thin film of which substance across a surface?

Mucus Signup and view all the answers

Which component is NOT part of the structure of the cilium?

Calcium channels Signup and view all the answers

What type of substances can cell inclusions include?

Nutritive substances and pigments Signup and view all the answers

What is the main function of the microvilli?

To absorb nutrients Signup and view all the answers

Study Notes

Non-membranous Organelles

Non-membranous organelles don't have a membrane surrounding them.
They are comprised of:
- Ribosomes
- Microtubules
- Centrioles
- Cilia and flagella
- Cell Filaments

Ribosomes

Small, non-membranous, dynamic organelles found free or attached to the rough endoplasmic reticulum (rER).
Can be identified at the light microscope (LM) level by the basophilia of the cytoplasm.
- This basophilia can be:
  - Diffuse: Spread throughout the cytoplasm
  - Localized: Contained within specific areas
Can be identified at the electron microscope (EM) level by their electron-dense granules.
- These granules appear free in the cytoplasm or attached to rER.
- Polyribosomes: Ribosomes attached together by mRNA, forming whorl-like figures.

Microtubules

Non-membranous organelles present in all cells, particularly where stiffness, shape, or oriented motion is required.
Found in: blood platelets, cilia, flagella, mitotic spindle, etc.
Identified at the LM level as filaments after using immunofluorescent staining techniques.
Identified at the EM level as long, straight, cylindrical, non-branching structures (longitudinal section).
The wall of a microtubule is composed of 13 protofilaments (transverse section).
Microtubule diameter remains constant.
Functions:
- Cytoskeleton of the cell
- Formation of the mitotic spindle
- Formation of centrioles and the axoneme of cilia and flagella
- Movement of organelles and vesicles in the cytoplasm

Centrioles

Non-membranous organoids present near the nucleus and Golgi apparatus in all cells except red blood cells and nerve cells (which don't divide).
Identified at the EM level as a short cylinder with a wall composed of 9 triplets of microtubules.
- Each triplet is formed from 3 microtubules (a, b, and c).
  - Microtubule a is formed of 13 protofilaments, while b and c are formed of 10 protofilaments.

Cilia

Elongated, motile structures that extend from the free cell surface.
Present in ciliated epithelium.
Identified at the LM level as short, fine, hair-like processes arising from the free cell surface.
Identified at the EM level as outgrowths of the cells covered by a plasma membrane.
Each cilium is comprised of:
- Basal body: A centriole that has migrated to near the cell surface.
- Shaft (axoneme): Formed of two single microtubules in the center and nine paired (doublets) microtubulues arranged circularly around the periphery.
- Rootlets: Extend from the deep aspect of the basal body.
- Basal foot: Attached laterally to the basal body.
Functions:
- Spreading a thin film of fluid or mucus across a surface.
- Modified to receive stimuli (light stimuli in rods and cones of the retina).

Flagella

Resemble cilia but are longer and usually present as a single structure.

Cell Filaments

Classified based on diameter:
- Thick Filaments: 10-15 nm, such as myosin filaments.
- Intermediate filaments: 8-10 nm, such as neurofilaments.
- Thin filaments: 6-8 nm, such as actin filaments.

Cell Inclusions

Temporary constituents of the cell.
Can be:
- Nutritive substances: Proteins (secretory granules), carbohydrates (glycogen), and fats (lipid droplets).
- Pigments: Endogenous (melanin, hemoglobin, hemoglobin derivatives such as hemosiderin, lipofuscin) and exogenous (carbon, tattoo particles).
- Crystalloids: E.g., present in Sertoli cells.

Learning Objectives

Enumerate non-membranous organelles.
Identify the histological structure of ribosomes at the LM and EM levels.
Describe the histological structure of microtubules at the EM level.
Identify the histological structure of centrioles at the EM level.
Describe the histological structure of cilia at the LM and EM levels.
Identify the histological structure of microvilli at the LM and EM levels.
Identify different types of cell inclusions.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on non-membranous organelles, including ribosomes, microtubules, and their functions in cells. This quiz covers identification techniques and the role of these organelles in cellular structure and motion. Prepare to explore their significance in both light and electron microscopy.