Biological Terms and Definitions

Cell:

• The smallest unit that is able to perform the basic functions of life.
• Represents the basic building block of all living organisms.

Unicellular:

• An organism that is made up of a single cell.
• Examples: Bacteria, Amoeba.

Multicellular:

• An organism that is made up of many cells.
• Includes organisms like humans, plants, and animals.

Microscope:

• An instrument that uses glass lenses to magnify objects.
• Essential tool for viewing cells and microorganisms.

Bacteria:

• A large group of unicellular organisms that sometimes cause disease.
• Examples: Escherichia coli, Streptococcus.

Cell Membrane:

• The outer boundary of the cytoplasm; controls what enters and leaves the cell.
• Function: Protects the cell and helps maintain homeostasis.

Cytoplasm:

• A thick gelatin-like material contained within the cell membrane.
• Contains organelles and is the site for many metabolic reactions.

Nucleus:

• Structure in a eukaryotic cell that contains the genetic material that a cell needs to reproduce.
• Acts as the control center of the cell.

Eukaryotic Cell:

• Has a nucleus which contains genetic material.
• Example organisms: plants, animals, fungi.

Prokaryotic Cell:

• A cell that lacks a nucleus and other organelles, with DNA that is not organized into chromosomes.
• Examples: Bacteria and Archaea.

Organelle:

• Structure in a plant or animal that is enclosed by a membrane and performs a specific function.
• Examples include mitochondria, endoplasmic reticulum, etc.

Cell Wall:

• Protective outer covering that lies just outside the cell membrane of plant cells.
• Provides structure and support to the cell.

Chloroplast:

• An organelle in a plant cell that contains chlorophyll.
• Function: Site of photosynthesis.

Mitochondria:

• Organelles that release energy by using oxygen to break down sugars.
• Known as the powerhouse of the cell.

Specialization:

• Specific organization of a cell and its structure that allows it to perform a specific function.
• Allows for division of labor among cells.

Tissue:

• A group of similar cells that are organized to do a specific job.
• Types include muscle tissue, connective tissue, etc.

Organ:

• Structure in a plant or animal that is made up of different tissues working together.
• Examples include the heart, lungs, and leaves.

Organ System:

• Different organs and tissues working together.
• Examples include the digestive system, respiratory system.