Skip to main content
Back

Cellular Anatomy: Structure and Function of the Cell

NotesPracticeVideo lessons

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Cellular Anatomy

Introduction to Cells

Cells are the fundamental units of life in all plants and animals. They serve as the structural building blocks and perform all vital functions necessary for the survival and operation of the body.

  • Trillions of cells exist in the human body, each specialized for particular functions.

  • Cells form all body structures and are responsible for all essential physiological processes.

Basic Components of the Cell

Each cell is composed of distinct regions and structures that contribute to its function.

  • Cytoplasm: The internal fluid of the cell, containing cytosol and organelles.

  • Cytosol: The liquid portion of the cytoplasm where many metabolic reactions occur.

  • Organelles: Specialized structures within the cell that perform specific tasks.

  • Plasmalemma (Cell Membrane): The outer boundary of the cell, also known as the phospholipid bilayer.

Overview of Cell Structure

The cell can be divided into the plasmalemma and the cytoplasm, which itself contains cytosol and organelles. Organelles are further classified as nonmembranous or membranous.

Component

Subdivisions

Examples

Plasmalemma

Cell membrane

Phospholipid bilayer

Cytoplasm

Cytosol, Organelles

Fluid, structures

Organelles

Nonmembranous, Membranous

See below

Organelles of the Cell

Classification of Organelles

Organelles are specialized structures within the cell, classified based on the presence or absence of a surrounding membrane.

  • Nonmembranous organelles: Lack a surrounding membrane.

  • Membranous organelles: Enclosed by a membrane.

Nonmembranous Organelles

These organelles are not surrounded by membranes and are essential for structural support, movement, and protein synthesis.

  • Cytoskeleton: Provides structural support and shape to the cell; involved in intracellular transport.

  • Microvilli: Fingerlike projections that increase the surface area for absorption.

  • Cilia: Hair-like structures that move substances across the cell surface.

  • Flagella: Long, whip-like structures used for cell movement (e.g., sperm cells).

  • Ribosomes: Sites of protein synthesis; can be free in the cytosol or attached to the endoplasmic reticulum.

Membranous Organelles

These organelles are surrounded by membranes and perform specialized functions within the cell.

  • Mitochondria: The "powerhouse" of the cell, responsible for producing ATP through cellular respiration.

  • Nucleus: Contains genetic material (DNA) and controls cellular activities.

  • Endoplasmic Reticulum (ER): Network of membranes involved in protein and lipid synthesis. Subdivided into rough ER (with ribosomes, synthesizes proteins) and smooth ER (without ribosomes, synthesizes lipids and carbohydrates).

  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

  • Lysosomes: Contain digestive enzymes to break down waste materials and cellular debris.

  • Peroxisomes: Contain enzymes (such as catalase) to break down hydrogen peroxide and detoxify harmful substances.

Summary Table: Organelles of the Cell

Type

Organelles

Main Function

Nonmembranous

Cytoskeleton, Microvilli, Centrioles, Cilia, Flagella, Ribosomes

Structure, movement, protein synthesis

Membranous

Mitochondria, Nucleus, Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Peroxisomes

Energy production, genetic control, synthesis, packaging, digestion, detoxification

Key Terms and Definitions

  • ATP (Adenosine Triphosphate): The primary energy carrier in cells, produced mainly by mitochondria.

  • Phospholipid Bilayer: The fundamental structure of the cell membrane, composed of two layers of phospholipids.

  • Protein Synthesis: The process by which cells build proteins, primarily at ribosomes.

Example: Protein Synthesis in the Cell

Protein synthesis begins at the ribosomes, where messenger RNA (mRNA) is translated into a polypeptide chain. Ribosomes attached to the rough endoplasmic reticulum produce proteins for export or for use in membranes, while free ribosomes synthesize proteins for use within the cytosol.

Additional info:

  • Centrioles, though not listed in all slides, are also nonmembranous organelles involved in cell division.

  • Cellular respiration in mitochondria can be summarized by the equation:

Pearson Logo

Study Prep