7 CHARACTERISTICS OF LIFE

Cellular Organization

All living things are built from cells, which are the fundamental structural units of life. An organism can be single-celled (unicellular, like amoebas) or made of trillions of cells working together in specialized teams (multicellular, like humans or trees).

Reproduction

Life must be able to create more life so the species doesn't go extinct. This happens either asexually (a single organism cloning itself, like bacteria dividing) or sexually (two parents combining genetic material to produce unique offspring).

Metabolism

Living things need energy to survive, grow, and repair themselves. Metabolism is the sum of all chemical reactions inside an organism that convert food or sunlight into usable energy.

Homeostasis

This is the process of maintaining a stable internal environment despite changes in the outside world. For example, your body sweats to cool down when it is hot or shivers to generate heat when it is cold, keeping your internal temperature right around 37°C (98.6°F).

Heredity

All living organisms possess a genetic code written in DNA (deoxyribonucleic acid). This molecular blueprint dictates an organism's traits and is passed down from parents to offspring during reproduction.

Response to Stimuli

Living things interact with their surroundings. When the environment changes, they respond to that stimulus. This can be immediate and behavioral (like a cat running away from a loud noise) or gradual and physical (like a plant bending toward a sunny window)

Growth and Development

All life changes over time. Growth means getting physically larger or increasing cell count, while development refers to the programmed changes an organism goes through as it matures (like a caterpillar transforming into a butterfly or a seed sprouting into a tree).

Autotrophs

uses photosynthesis to make their own food

Heterotrophs

must consume other organisms for energy

Phospholipid Bilayer

separate their internal, highly organized biochemical chaos from the randomness of the outside world.

Selective Permeability

the cell membrane controls exactly what enters and exits, allowing the cell to concentrate the specific enzymes, ions, and substrates needed to drive the chemical reactions of life.

Adenosine Triphosphate

ATP meaning

Anabolic

building up pathways

Catabolic

breaking down pathways

Electron Transport Chain

In cellular respiration, electrons are stripped from organic molecules (like glucose) and passed down an_

Stimulus

(like a hormone, a light photon, or a toxin) acts as a ligand and binds to a specific receptor protein on the cell surface.

Epigenetics

the study of how your behaviors and environment can cause changes that affect how your genes work. While your DNA sequence provides the instruction manual for your body, ___ acts as a set of chemical bookmarks that tell your cells which genes to turn "on" or "off".