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Cell Structure And Function

Unravel the intricate world of cell structure and function to uncover the secrets behind the building blocks of life.

USMLE Guide: Cell Structure And Function


The USMLE (United States Medical Licensing Examination) is a series of exams that assess a physician's ability to apply knowledge, concepts, and principles to practice medicine. This guide aims to provide a comprehensive overview of cell structure and function, which is an essential topic for the USMLE exams.

I. Cell Structure

A. Plasma Membrane

  • Description: The plasma membrane is a selectively permeable barrier surrounding the cell.
  • Key components: Phospholipid bilayer, integral and peripheral proteins, cholesterol.
  • Functions: Regulates the movement of substances in and out of the cell.

B. Nucleus

  • Description: The nucleus is the control center of the cell.
  • Key components: Nuclear envelope, nucleolus, chromatin.
  • Functions: Stores genetic material (DNA) and controls cellular activities.

C. Cytoplasm

  • Description: The cytoplasm is the fluid-filled region between the plasma membrane and nucleus.
  • Key components: Cytosol, organelles, cytoskeleton.
  • Functions: Supports organelles and cellular processes.

D. Endoplasmic Reticulum (ER)

  • Description: The ER is a network of membranes involved in protein synthesis and lipid metabolism.
  • Key components: Rough ER (with ribosomes) and smooth ER (without ribosomes).
  • Functions: Rough ER synthesizes and modifies proteins, while smooth ER synthesizes lipids and detoxifies drugs.

E. Golgi Apparatus

  • Description: The Golgi apparatus is a stack of flattened membranes involved in protein processing and packaging.
  • Key components: Cisternae, vesicles.
  • Functions: Modifies, packages, and sorts proteins for transport within and outside the cell.

F. Mitochondria

  • Description: Mitochondria are double-membraned organelles involved in energy production.
  • Key components: Outer and inner mitochondrial membrane, cristae.
  • Functions: Produces ATP through cellular respiration.

G. Lysosomes

  • Description: Lysosomes are membrane-bound vesicles containing digestive enzymes.
  • Key components: Acid hydrolases.
  • Functions: Breaks down cellular waste and foreign substances.

H. Peroxisomes

  • Description: Peroxisomes are membrane-bound organelles involved in lipid metabolism.
  • Key components: Oxidases, catalases.
  • Functions: Detoxifies harmful substances and breaks down fatty acids.

II. Cell Function

A. Cell Division

  • Description: Cell division is the process by which cells reproduce and create new cells.
  • Key processes: Mitosis (somatic cells) and meiosis (germ cells).
  • Functions: Growth, repair, and reproduction.

B. Protein Synthesis

  • Description: Protein synthesis is the process of creating proteins from DNA instructions.
  • Key processes: Transcription (DNA to RNA) and translation (RNA to protein).
  • Functions: Building blocks for cell structure and performing cellular functions.

C. Cell Signaling

  • Description: Cell signaling is the communication between cells to coordinate cellular activities.
  • Key components: Receptors, ligands, signal transduction pathways.
  • Functions: Regulates growth, development, and response to the environment.

D. Cellular Respiration

  • Description: Cellular respiration is the process of converting nutrients into ATP.
  • Key processes: Glycolysis, Krebs cycle (Citric Acid Cycle), Electron Transport Chain.
  • Functions: Provides energy for cellular activities.

E. Cell Cycle Control

  • Description: Cell cycle control ensures proper timing and progression of cell division.
  • Key components: Cyclins, cyclin-dependent kinases (CDKs).
  • Functions: Prevents uncontrolled cell growth and maintains genomic integrity.


Understanding cell structure and function is crucial for medical professionals. This USMLE guide has provided an informative overview of the key components, functions, and processes related to cell structure and function. Remember to integrate this knowledge with clinical scenarios to excel in the USMLE exams.

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