Characteristics of Life

Characteristics of Life

All living things share characteristics such as being made of one or more cells, reproducing, moving, acquiring and using energy, growing and developing, having levels of organization, containing genetic information, responding to their environment, and adapting and evolving.

Cell Theory

States that living things are made up of one or more cells, all cells come from pre-existing cells, and the cell is the basic unit of life.

Unicellular

Made up of one cell.

Multicellular

Made up of more than one cell.

Eukaryotic Cells

Cells that contain a membrane-bound true nucleus and other membrane-bound organelles.

Prokaryotic Cells

Cells that have DNA which is NOT surrounded by a membrane and which have no membrane-bound organelles.

Reproduction

The main purpose is to produce offspring, which ensures genetic continuity from generation to generation.

Sexual Reproduction

The type involving sperm and egg.

Gametes

Sperm and egg.

Asexual Reproduction

The type NOT involving sperm and egg.

Locomotion

Movement exhibited by organisms that are free moving and can move on their own.

Tropic Growth Movements

Directional growth responses to stimuli.

Nastic Growth Movements

Non-directional growth responses to stimuli.

Growth Movements

Movements exhibited by organisms that are NOT free moving.

Autotrophs

Organisms that can MAKE their own glucose using a green pigment called chlorophyll in a process called photosynthesis.

Photosynthesis

A process in which organisms make their own glucose using chlorophyll, along with the energy found in sunlight.

Chlorophyll

A green pigment used to make glucose.

Sunlight

Energy used in photosynthesis.

Heterotrophs

Organisms that CANNOT make their own glucose. They must consume other organisms for energy.

Acquiring Energy

Can be done in two major ways: some organisms are autotrophs and some are heterotrophs.

Using Energy

Done through chemical reactions within the cells of an organism.

Metabolism

The sum of these chemical reactions.

Anabolism

The BUILDING UP of large and complex molecules from small and simple ones.

Catabolism

The BREAK DOWN of large and complex molecules into small and simple ones.

Small and Simple Molecules

Molecules used to build large and complex molecules.

Large and Complex Molecules

Molecules that can be broken down into small and simple ones.

Growth and Development in Unicellular Organisms

A unicellular organism must increase the volume of its cytoplasm, involving gaining more cytosol and organelles.

Cytosol

The liquid of the cell.

Organelles

The machinery of the cell.

Cell division and Specialization.

A multicellular organism must undergo what?

Cell Specialization

Cells specialize into different types of tissues.

Levels of Organization

Atom → molecule → macromolecule → organelle → cell → tissues → organ → organ system → organism.

Genetic Information

Comes in the form of a molecule called DNA.

DNA

Stands for deoxyribonucleic acid.

RNA

Genetic information found in viruses, including retroviruses.

Viruses

Do not exhibit some of the other characteristics of life and are classified as non-living.

Stimuli

Changes in the environment that living things respond to.

Internal Environment

The environment inside the organism.

External Environment

The environment outside the organism.

Response to Change

Brings the organism back to equilibrium or homeostasis.

Homeostasis

A constant internal state.

Charles Darwin

The British naturalist who came up with a mechanism for evolution.

Evolution

A mechanism explained by Charles Darwin through natural selection.

Natural Selection

The mechanism for evolution proposed by Charles Darwin.

Mutations

Random changes in DNA that cause individuals to differ in genetically determined traits.

Adaptations

Traits that allow organisms to SURVIVE and REPRODUCE better than others.

Fitness

Individuals with traits or adaptations that allow them to SURVIVE and REPRODUCE better than others are said to have more fitness.

Cells specialize into different types of tissues.