Cytology

Faculty of Sciences - Cytology

  • Instructor: Ibrahim Al Halabi

  • Course: Cytology

  • Academic Year: 2020-2021

Chapter 1: Cell Biology

1.1 Cell Doctrine

  • Defines the fundamental principles of cellular biology:

    • Cells are the basic units of structure and function in all life forms.

    • Cells originate from preexisting cells through division.

    • Organisms are composed of cells and their secretions.

    • Cells maintain life's continuity through processes like mitosis, meiosis, and fertilization.

    • Each cell possesses dual roles: individual life and contribution within multicellular organisms.

Chapter 2: Molecular Components of Cells

2.1 Introduction

  • Main atoms in cells:

    • Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) constitute ~95% of cell mass.

    • Other essential elements include Phosphorus (P), Calcium (Ca), Sulfur (S), Chlorine (Cl), Sodium (Na), Potassium (K), and Magnesium (Mg) (~4%).

    • Trace elements (e.g., Zinc (Zn), Copper (Cu), Iodine (I)) are necessary in minimal amounts.

  • Cells consist of organic and inorganic compounds:

    • Inorganic: Water (H2O) and mineral salts.

    • Organic: Proteins, carbohydrates, lipids, nucleic acids, vitamins.

  • Water is the most prevalent molecule in living organisms.

2.2 Inorganic Compounds

2.2.1 Water

  • Water (H2O) is neutral and highly polar, enabling hydrogen bonding.

  • Hydrogen bonds allow interactions with other molecules and ionic bonding with salts.

2.2.2 Mineral Salts

  • Salts (e.g., NaCl, KCl) dissolve in water and ionize, impacting physiological functions (ion concentration, pH, osmotic pressure).

  • Concentration differences between cellular and interstitial fluids regulate ion transport.

  • Essential metal ions (e.g., iron for hemoglobin, calcium for signaling) play vital roles in cellular activity.

2.3 Organic Compounds

2.3.1 Proteins

  • Second most abundant molecules after water; most diverse macromolecules.

  • Functions: Structure, signaling, transport, metabolism, immunity, and catalysis (e.g., enzymes).

  • Proteins consist of unbranched amino acid polymers influenced by genes.

Function of Proteins

  • Determine cell identity (e.g., HLA systems, blood groups).

  • Interact with each other or other biomolecules for diverse functions.

  • Not primary energy sources compared to lipids or carbohydrates.

Diverse Chemical Composition

  • Proteins are linear polymers of amino acids with specific sequences determining their functions.

  • Amino acids are soluble in water; proteins may be soluble (e.g., albumin) or insoluble (e.g., collagen).

2.3.2 Carbohydrates

  • Sugars play roles in energy storage, structure (e.g., cellulose), and cell recognition.

  • Monosaccharides (e.g., glucose) are the simplest form.

  • Polysaccharides contribute to structure and carbohydrate storage.

2.3.3 Lipids

  • Lipids function as energy sources and structural components of membranes (e.g., phospholipids).

  • Comprise fatty acids, triglycerides, phospholipids, glycolipids, and steroids.

2.3.4 Nucleic Acids

  • Store and express genetic information (DNA, RNA).

  • Composed of nucleotides (sugar, base, phosphate).

  • Variations between DNA and RNA include structure, base composition, and location.

Chapter 3: Cell Types

3.1 Differences Between Eukaryotes and Prokaryotes

  • Eukaryotes have membrane-bound organelles including a nucleus.

  • Prokaryotes lack a nucleus and membrane-bound organelles.

3.2 Eukaryotic Cell Structures

  • Main organelles: plasma membrane, nucleus, cytoskeleton, endoplasmic reticulum, Golgi apparatus, ribosomes, mitochondria, lysosomes.

3.3 Plant Cell Properties

  • Unique structures: cell wall (made of cellulose), plastids (e.g., chloroplasts), and central vacuoles.

3.4 Prokaryotes

  • Prokaryotes categorize into eubacteria and archaebacteria, lacking complexity of eukaryotic cells.

Chapter 4: Plasma Membranes

4.1 Introduction

  • Plasma membranes are critical for maintaining cellular integrity and metabolic reactions.

  • Selectively permeable to solutes.

4.2 The Lipid Bilayer

  • Comprised of phospholipids with hydrophobic tails and hydrophilic heads.

4.3 Fluid Mosaic Model

  • Represents the dynamic nature and structure of cellular membranes.

4.4 Polarization and Functional Domains

  • Cells have distinct functions based on membrane composition and protein distribution.

Chapter 5: Ribosomes

5.1 Introduction

  • Ribosomes translate mRNA into proteins, composed of rRNA and ribosomal proteins.

5.2 Ribosome Structure

  • Consist of two subunits for protein synthesis.

Chapter 6: Endoplasmic Reticulum

  • Divided into rough (RER) and smooth (SER), each serving distinct roles in protein and lipid synthesis.

Chapter 7: Golgi Complex

  • Responsible for the maturation, sorting, and secretion of proteins and other macromolecules.

Chapter 8: Lysosomes

  • Dissolve intracellular debris and participate in cellular digestion and recycling processes.

Chapter 9: Peroxisomes

  • Involved in oxidation reactions and detoxification processes.

Chapter 10: Mitochondria

  • Create ATP through aerobic respiration and are vital for metabolism in eukaryotic cells.

Chapter 11: Plastids

  • Include chloroplasts, responsible for photosynthesis in plants.

Chapter 12: Cytoskeleton

  • Provides structural support, motility, and intracellular transport in eukaryotic cells.

Chapter 13: Organization of the Nucleus

  • Contains genetic information and controls gene expression in the cell.

Chapter 14: Cell Cycle

  • Includes interphase and M phase, responsible for cell growth and division.