The Characteristics of Life

What does it mean to be alive?

What is the name of the science that studies living or once living

organisms?BIOLOGY

The Traits of Life• Cellular Organization • Growth and Development• Metabolism (Obtain and Use Energy)• Homeostasis • Reproduction • Responsiveness & Sensitivity Adapt Through Evolution • Heredity

Cells

• Cell is a basic unit of life which itself is much more complex than it’s environment.

• Some life is only one-celled or unicellular.

• Much of life is multi-cellular. They have different types of cells have different special functions within the organism.

• Each life form begins from one cell, which then will split to form different type of cells which make up different tissues and organs.

• Complex organization patterns are found in all living organisms.

1. Living Organisms are made up of Cells.

a.) CELL: Collection of living material enclosed within a barrier

b.) cells are basic unit of life

c.) Unicellular: made up of one cell

d.) Multicellular: made up of many cells

Unicellular

Multicellular

Growth & Development

• All organisms grow and change.

• Growth means to get bigger in size.

• Development involves a change in the physical form of an organism.

• All species have a life span.

Metabolism: Obtain & Use Energy • All organisms use energy

(heat, light, & chemical). The sum of the chemical energy they use is called metabolism. This energy is used to carry out everything they do.

• Living organisms need energy to grow, develop, repair damage, and reproduce.

• Autotrophs (plants) use energy from the sun for photosynthesis, to make their own ‘food’ (glucose).

• Heterotrophs (animals) must ingest food for this purpose.

• Metabolism The total of all chemical reactions in an organism. Anabolism + Catabolism = Metabolism • Anabolism: The process of building up complex substances from simpler substances like in photosynthesis (making sugars) and protein production.• Catabolism: The process of breaking down complex substances into simpler substances to release energy: like digestion & cellular respiration.•All organisms produce waste of some kind.

Homeostasis • Maintaining internal stable

state of conditions in the body that are necessary for life.

• These include temperature, water balance, pH balance, oxygen, carbon dioxide heartbeat, salts (electrolytes), blood sugar, and other such things.

• All the organ systems of body are important in maintaining these balances.

Thermoregulation

Living things maintain a stable internal environment

HOMEOSTASIS: internal balance

Examples: sweating, panting, shivering, eating drinking, urinating, etc.

Sensitive & Responsive

• A process that enables organisms to become better suited to their environment.

• All organisms are sensitive to changes in their environment (stimuli) often respond with a change in their adaptations or the way they survive.

• If a population has a major change that is passed on to future generations then it can evolve into another species over time.

Reproduction • Reproduction is the process of

producing new organisms of the same type as they receive genes from their parent(s).

• In sexual reproduction the new organism will have some characteristics from the mother, and some from father. Universal genetic code carry hereditary information in the form DNA in the male and female sex cells.

• In asexual reproduction, the new organism is an exact copy of the first. A single parent organism reproducing by itself.

Living Organisms Reproduce: a.) produce offspring which resemble parents

b.) asexual reproduction: has only one parent

c.) sexual reproduction: requires two parents

Asexual

Sexual

Where Do Living Things Come From?

• It was common knowledge for thousands of years that simple organisms could come from dust, mud and food left out.

• This idea was called “spontaneous generation.”

• From the time of the ancient Romans, through the Middle Ages, and until the late nineteenth century, it was generally accepted that some life forms arose spontaneously from non-living matter.

How Did This Happen?• Every year the Nile River

flooded leaving behind nutrient rich soil that enables people to

grow that year’s crops.

However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times.

How Did This Happen?

• Conclusion:

It was perfectly obvious to the people back then that muddy soil gave rise to the frogs.

How Did This Happen?

• In many parts of Europe, medieval farmers stored grain in barns with thatched roofs. As a roof aged it started to leak. This could lead to spoiled or moldy grain, and of course, there were lots of mice around.

How Did This Happen?

• Conclusion:

It was obvious that the mice came from the moldy grain.

How Did This Happen?

• In many parts of Europe, medieval farmers stored grain in barns with thatched roofs. As a roof aged it started to leak. This could lead to spoiled or moldy grain, and of course, there were lots of mice around.

Hello, Francesco Redi

• Italian Doctor most well-known for his experiment in 1668 which is regarded as a one of the first steps in refuting spontaneous generation.

Redi’s Experiment

Jar-1• Left open Maggots developed• Flies were observed laying eggs on the meat in the open jarJar-2• Covered with netting Maggots appeared on the netting• Flies were observed laying eggs on the nettingJar-3• Sealed No maggots developed

Louis Pasteur

Louis Pasteur was a French chemist who finally disproved the Theory of Spontaneous Generation in the mid 1800's.

Life comes only from life!