Chapter 5: The Fundamental Unit of Life | Summary

Cells typically consist of three main parts: the plasma membrane, nucleus, and cytoplasm.

Each of these components plays vital roles in cell functioning and maintaining cellular life.

Different cells contain different shapes and organelles depending on their functions, such as nerve cells, muscle cells, and blood cells.

The plasma membrane is a selectively permeable membrane that controls the movement of substances in and out of the cell.

It allows passive transport (diffusion and osmosis) and is composed of lipids and proteins.

Osmosis is the movement of water through a selectively permeable membrane from a region of low solute concentration to high solute concentration.

Endocytosis, such as in Amoeba, allows cells to engulf food and materials.

Present only in plant cells, the cell wall is a rigid outer covering made of cellulose.

It provides structural support and protects cells from bursting in hypotonic environments.

Plasmolysis is the shrinkage of cytoplasm due to water loss through osmosis.

The nucleus controls cell activities and contains genetic material in the form of DNA and chromosomes.

It is enclosed by a double membrane with pores that allow exchange with cytoplasm.

It plays a role in inheritance, gene expression, and cell reproduction.

In prokaryotic cells, the nucleus is not membrane-bound and is called a nucleoid.

Cytoplasm is the fluid-filled region inside the cell membrane but outside the nucleus.

It houses various membrane-bound organelles in eukaryotic cells like mitochondria, ER, Golgi apparatus, lysosomes, and plastids.

In prokaryotic cells, such organelles are absent, and functions are carried out by the cytoplasm.

Cell division occurs for growth, repair, and reproduction.

Mitosis produces two identical daughter cells, used for growth and repair.

Meiosis results in four daughter cells with half the chromosome number, used in gamete formation.

Both types of division are essential for continuity of life.

Cell – Basic structural and functional unit of life.

Plasma Membrane – Selectively permeable outer boundary of the cell.

Nucleus – Control center of the cell, contains DNA.

Cytoplasm – Fluid content containing organelles.

Organelle – Specialized structures performing specific functions.

Osmosis – Movement of water across a membrane.

Endocytosis – Process of engulfing materials into a cell.

Plastids – Organelles in plant cells involved in photosynthesis and storage.

Mitosis – Cell division for growth/repair.

Meiosis – Cell division for gamete formation.