A group of tissues with a similar function

Organ

Georgetown University

- Atom
- Molecule
- Macromolecule
- Cell
- Tissue
- Organ
- Organ system
- Organism
- Population
- Community
- Ecosystem
- Biosphere / Ecosphere

Traditional Biological Organisation Scheme

The cell is the fundamental unit of life. While cells vary significantly in size, shape, structure, and function—categorized primarily into prokaryotic and eukaryotic cells—they all share a few fundamental components at their simplest level of construction. The internal structures of a cell are analogous to the organs inside a human body, with unique components suited to specific functions.

Cell

Solomon, Eldra P.; Berg, Linda R.; Martin, Diana W. (2002), Biology (6th ed.), Brooks/Cole, ISBN 0-534-39175-3, LCCN 2001095366

Biology by Solomon, Berg, and Martin

Molecule 

The smallest piece of a chemical element or ordinary matter

Atom

Tissue

A group of organs that work together to execute one or more functions.

Organ system

Any living thing that functions as a singular entity

Organism 

A group of organisms that are (1) the same species (2) in a shared geographical area, and (3) able to interbreed

Population (Biology)

Groups of populations of different species that interact with each other.

Community (Biology)

An ecosystem describes the interactions between groups of organisms from all biological domains and nonliving things in a shared geographical space.

Ecosystem

All life on Earth (the sum of all ecosystems on earth)

Biosphere / Ecosphere

There are many types of macromolecules such as: 

- carbohydrates
- lipids
- proteins
- nucleic acids

Types of Macromolecules

The molecular structures and processes of cellular life and their roles in the function, reproduction, and development of living organisms.

- The Central Dogma of Life
- Cell Organelles

Molecular and Cellular Biology

The (metabolic) center of a neuron. It is in charge of keeping the cell alive

Cell body

Cell-cell interactions describe the process in which one cell influences the differentiation of neighboring cells during the development of the nervous system. This process is a key reason why vertebrate brains are less hardwired and more susceptible to environmental cues and experience. In contrast, invertebrate development, such as in C. elegans, is more hardwired and relies less on cell-cell interactions, making their mitotic lineages strictly predictable and easier to trace.

Cell-Cell Interactions

Although cells share certain fundamental characteristics, they exhibit remarkable variety in their structure, function, and metabolic activity. The two primary categories of cells are prokaryotic cells, which lack a nucleus, and eukaryotic cells, which possess a well-organized, membrane-bound nucleus.

Types of Cells

Developed in the 17th century following early observations of microscopic life, the cell theory is a foundational scientific principle. It posits three main claims: the cell is the fundamental unit of life, all living organisms contain at least one cell, and new cells can only arise from pre-existing cells.

Cell Theory

Animal cell organelles are specialized sub-cellular structures that perform specific functions necessary for the cell's survival, growth, and homeostasis. These include membrane-bound organelles such as the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes, as well as non-membrane-bound structures like ribosomes.

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