Cytology Summary

Cytology Overview

  • Cytology is the study of cells, vital for understanding cellular structure and function.
  • Cells are the fundamental unit of life, enclosed by a cell membrane and containing protoplasm.

Cell Theory

  • All living organisms are composed of cells.
  • Cells arise from preexisting cells via division.

Major Cell Structures

  • Cell Membrane: Semi-permeable barrier.
  • Cytoplasm: Contains cytosol and organelles.
  • Nucleus: Houses genetic material.

Organelles in Cytoplasm

Membranous Organelles:

  • Mitochondria
  • Endoplasmic Reticulum (ER)
  • Golgi Apparatus
  • Lysosomes
  • Peroxisomes
  • Vacuoles

Non-Membranous Organelles:

  • Ribosomes
  • Cytoskeleton
  • Centrosome and Centrioles

Cell Membrane Structure

  • Composed of phospholipids, embedded proteins, and carbohydrates.
  • Fluid mosaic model explains membrane structure.
  • Proteins have specific roles including transport and cell recognition.
  • Carbohydrates on the extracellular side aid in cell recognition.

Transport Mechanisms

  • Passive Transport: No energy needed (e.g., simple diffusion, facilitated diffusion).
  • Active Transport: Requires ATP to move substances against their concentration gradient.

Endocytosis and Exocytosis

  • Endocytosis: Process of taking materials into the cell; includes phagocytosis and pinocytosis.
  • Exocytosis: Expels materials from the cell via vesicles.

Mitochondria

  • Known as the powerhouses of the cell; produce ATP through cellular respiration.
  • Feature their own DNA and RNA.

Endoplasmic Reticulum (ER)

  • Rough ER: Studded with ribosomes, synthesizes proteins.
  • Smooth ER: Lacks ribosomes, involved in lipid synthesis and detoxification.

Ribosomes and Protein Production

  • Ribosomes are where protein synthesis takes place, can be free in cytoplasm or bound to the rough ER.

Golgi Apparatus

  • Modifies, sorts, and packages proteins for secretion.

Lysosomes

  • Contain hydrolytic enzymes for digestion.
  • Formed from the Golgi apparatus, involved in breaking down waste materials.

Cytoskeleton

  • Network of protein filaments that provide structural support, facilitate movement, and organize cell components.
  • Composed of microfilaments, intermediate filaments, and microtubules.

Nucleus

  • Contains nucleoplasm, chromatin, and nucleolus.
  • Responsible for housing genetic information and regulating cell activities.