BIO201 – Topic 2: The Human Cell and Its Components
Course Code: BIO 201
Course Name: Human Biology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism-Free | 2025 Edition | A4 Format)
2.1 Introduction
The human cell is the fundamental unit of life. All body structures and functions originate from
cells, which form tissues, organs, and organ systems. Understanding cell structure and
function is essential to human biology and medicine.
2.2 Definition of a Cell
A cell is the smallest structural, functional, and biological unit of life capable of performing all
vital processes. In humans, cells vary in shape, size, and function but share common features
such as membranes, cytoplasm, and organelles.
2.3 Types of Human Cells
Human cells are eukaryotic, meaning they contain a nucleus and membrane-bound organelles.
Major categories include:
1. Somatic cells – Make up the body tissues and organs.
2. Gametes (sex cells) – Sperm and ova, responsible for reproduction.
2.4 Structure of the Human Cell
Main components include:
• Cell membrane – Regulates movement of substances.
• Cytoplasm – Holds organelles and supports metabolism.
• Nucleus – Contains DNA and controls activities.
• Mitochondria – Produce energy (ATP).
• Endoplasmic Reticulum – Transports materials.
• Golgi apparatus – Modifies and packages proteins.
• Lysosomes – Break down waste.
• Ribosomes – Site of protein synthesis.
• Centrioles – Aid in cell division.
• Cytoskeleton – Maintains cell shape.
2.5 Specialized Human Cells
Examples include:
• Nerve cells (neurons) – Transmit impulses.
• Red blood cells – Carry oxygen.
• Muscle cells – Contract to produce movement.
• Epithelial cells – Line and protect body surfaces.
2.6 Cell Division
Cells divide for growth, repair, or reproduction. Two main types:
1. Mitosis – Produces identical body cells.
Course Code: BIO 201
Course Name: Human Biology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism-Free | 2025 Edition | A4 Format)
2.1 Introduction
The human cell is the fundamental unit of life. All body structures and functions originate from
cells, which form tissues, organs, and organ systems. Understanding cell structure and
function is essential to human biology and medicine.
2.2 Definition of a Cell
A cell is the smallest structural, functional, and biological unit of life capable of performing all
vital processes. In humans, cells vary in shape, size, and function but share common features
such as membranes, cytoplasm, and organelles.
2.3 Types of Human Cells
Human cells are eukaryotic, meaning they contain a nucleus and membrane-bound organelles.
Major categories include:
1. Somatic cells – Make up the body tissues and organs.
2. Gametes (sex cells) – Sperm and ova, responsible for reproduction.
2.4 Structure of the Human Cell
Main components include:
• Cell membrane – Regulates movement of substances.
• Cytoplasm – Holds organelles and supports metabolism.
• Nucleus – Contains DNA and controls activities.
• Mitochondria – Produce energy (ATP).
• Endoplasmic Reticulum – Transports materials.
• Golgi apparatus – Modifies and packages proteins.
• Lysosomes – Break down waste.
• Ribosomes – Site of protein synthesis.
• Centrioles – Aid in cell division.
• Cytoskeleton – Maintains cell shape.
2.5 Specialized Human Cells
Examples include:
• Nerve cells (neurons) – Transmit impulses.
• Red blood cells – Carry oxygen.
• Muscle cells – Contract to produce movement.
• Epithelial cells – Line and protect body surfaces.
2.6 Cell Division
Cells divide for growth, repair, or reproduction. Two main types:
1. Mitosis – Produces identical body cells.
