Cell Biology Basics

Study Notes

Cells are the basic units of life, and all living organisms are made up of cells.
A cell is the smallest unit of life that has a definite structure and performs a specific function.

The number of cells varies from organism to organism.
Organisms can be unicellular (made up of one cell) or multicellular (made up of multiple cells).
The shape of cells varies, and cells can be spherical, oval, or irregular in shape.
The size of cells also varies, and cells can be microscopic or macroscopic.

Animal cells are eukaryotic cells that lack a cell wall and have a true nucleus.
Plant cells are eukaryotic cells that have a cell wall and a true nucleus.
Unicellular organisms, such as bacteria, Amoeba, and Paramecium, are made up of a single cell.
Multicellular organisms, such as humans and plants, are made up of multiple cells.

The cell membrane, also known as the plasma membrane, surrounds the cell and regulates the entry and exit of substances.
The cytoplasm is the jelly-like substance that fills the cell and is the site of many of the cell's important biochemical reactions.
The nucleus is a large, round structure that contains genetic material and is the control center of the cell.
The cell wall provides structural support to plant cells and prevents them from bursting due to the entry of water.

Cell organelles are structures within the cytoplasm that perform specific functions.
Examples of cell organelles include mitochondria, endoplasmic reticulum, ribosomes, Golgi bodies, lysosomes, and centrioles.

Mitochondria are tiny, rod-shaped or spherical organelles that provide energy for the cell through the process of respiration.
They are found in large numbers in the cytoplasm of all cells.

The endoplasmic reticulum is an irregular network of tubular structures that is connected to the nucleus and the cell membrane.
It is involved in protein synthesis and transport.

Ribosomes are small structures scattered throughout the cytoplasm that are involved in protein synthesis.
They do not have a membrane and are found in large numbers in the cytoplasm.

Golgi bodies are a system of membrane-bound sacs that are involved in the packaging and processing of proteins.
They are found in eukaryotic cells.

Lysosomes are small, spherical structures that are involved in cellular digestion and recycling.
They contain digestive enzymes and are found in the cytoplasm of eukaryotic cells.

Centrioles are small, hollow structures found near the nucleus of an animal cell.
They are involved in cell division and are found in large numbers in the cytoplasm.

Plastids are organelles found in plant cells that contain pigments and are involved in photosynthesis.
Examples of plastids include chloroplasts, chromoplasts, and leucoplasts.

Vacuoles are spaces in the cytoplasm of a cell that are enclosed by a membrane and usually contain substances dissolved in water.
They are found in plant cells and are involved in storage and support.

Plant cells have a cell wall, chloroplasts, and a large central vacuole, whereas animal cells do not.
Plant cells are mostly stationary, while animal cells are mostly motile.
Plant cells store food in the form of starch, while animal cells store food in the form of glycogen.