The Characteristics of Life. History: Spontaneous Generation or Abiogenesis- 1 st proposed by...

The Characteristics of Life

The Characteristics of Life History:

Spontaneous Generation or Abiogenesis-

•1st proposed by Aristotle

•held that complex, living organisms are generated by decaying organic substances,

•e.g. that mice spontaneously appear in stored grain or maggots spontaneously appear in meat.

The Characteristics of Life History:•Was widely believed until the 19th century.

•Several scientists performed experiments that disproved spontaneous generation

•Francisco Redi

•Lazzaro Spallanzani

•Louis Pasteur

Redi’s Experiment

Francisco Redi

1668

Spallanzani’s Experiment

Lazzaro Spallanzani

1746

Pasteur’s Experiment

Louis Pasteur

1859

The Characteristics of Life History:

Biogenesis- is the process of life forms producing other life forms

• e.g. a spider lays eggs, which form into spiders.

•The term is also used for the assertion that life can only be passed on by living things.

The Characteristics of Life

How can you tell if something is alive?

The Characteristics of Life

Biologists have devised a list of 5 characteristics that define life.

Something can be considered alive ONLY if it displays ALL 5 of the characteristics.

The Characteristics of Life

Anything that possesses all 5 of the characteristics of life is called an organism.

The 5 characteristics of life are:

1. Cellular Organization celltissueorgansystemorganism

2. Growth & Development

3. Reproduction

4. Adaptation to environment – response to a stimulus

5. Maintenance of Homeostasis

The Characteristics of Life

Organization:

All living organisms have an organized structure

Ex. -Cells form tissues

-Tissues form organs

-Organs form organ systems

The Characteristics of Life

All living organisms grow and develop during their life spans.

Growth & Development:

The Characteristics of Life

Growth: an increase in the size of an organism due to an increase in the size and number of cells

Development: all of the changes that take place throughout the life span of an organism

The Characteristics of Life

Reproduction:All living organisms are able to produce live offspring.

The Characteristics of Life

Adaptation to environment:

All living organisms are able to adapt to their surroundings.

They are able to react, or respond to an environmental condition, or stimulus.

The Characteristics of Life

Maintenance of Homeostasis:

All living organisms are able to maintain a relatively constant internal environment.

Homeostasis: The regulation of an organism’s internal environment to maintain conditions suitable for life.

The Characteristics of Life

Are bacteria alive?

How about viruses?