TEXTBOOK: From Bacteria to Plants

Chapter One: Living Things

Section 2 “The Origin of Life.” Pg. 25-27

Bellwork 10-17

• ***According to the textbook

• 1. How was the atmosphee different during early earth?

• 2. What do we know about the first living organism?

• 3 How do you feel about spontaneous generation now?

The Origin of Life

Earth’s EarlyAtmosphere

Atmosphere was different than today.

Nitrogen, water vapor, carbon dioxide, and methane were most abundant gases.

We couldn’t have survived b/c there was no oxygen. However, it is believed that some life forms did live on Earth about this time.

Today’s Atmosphere

Mainly nitrogen and oxygen, smaller amounts of the other gases.

Life forms on Earth 3.6 billion years ago.

Scientists believe that early life forms arose on Earth.  

They did not need Oxygen to survive.

Unicellular organisms.Probably lived in the oceans.

We can only hypothesize:

Life’s ChemicalsScientists believe that the first life

forms did arise from nonliving materials, even if they don’t today.

• From existing materials on Earth• From materials that got here by

meteorite

                         

Stanley Miller

An experiment was conducted where scientist recreated the conditions of early earth.

They added electricity to simulate lightning and found that there were small chemical units that could possibly form carbohydrates, proteins, and nucleic acids—the building blocks of life.

The First Cells:How they started.

Scientists theorized that over time small chemical units of life formed gradually over millions of years in Earth’s waters.

    Some formed together to form

chemical building blocks that are found in cells.

Some large chemicals accumulated and became the first cells.                                           

OTHER IDEA

• Meteorite hit earth which contained the same amino acids as Miller used. This makes his experiment important today.

• A series of giant meteorites essentially sterilized the planet about 3.8 billion years ago.

• Rocks 3.5 billion years old contain microfossils of primitive one-celled organisms without a nucleus ("prokaryotes") resembling bacteria and blue-green algae,

Fossils

traces of ancient organisms that have been preserved in rock.

Fossils they have found support their hypothesis about the beginning of life.

• Here's a fossil of a creature that is now extinct, but lived about 300 million years ago in the sea - a Trilobite.

• Much warmer climates in

earth's past have led to the

creation of fossil fuels. These are

fuels that are literally the fossilized

remains of former jungles.

• Woolly Mammoths Scientists

continue to find frozen remains of these creatures as

the ice cover in northern Siberia

retreats,.

Heterotrophs and Autotrophs developed over time.

Autotrophs contributed to Oxygen in the atmosphere.

ICE MAN—how do we know so much? We find it!

• September 19, 1991, Ötzi • Alps near the Austria• Found a dead mountaineer, only head

sticking out of the ice.• Well preserved, people thought dead only

short time.• Body was 4000 years old• 5 feet 4 inches tall,

               

Carrying

• 14 arrow and bag

• Ice pick• An axe with a copper

blade and yew shaft • A bow and a quiver of

arrows, two with flint arrow heads

• A small dagger in a scabbard

• A back pannier made of hazel rods, larch boards and birch bark

• Other smaller items, such as cords and flints

                                 

Fragments from clothes

• A fur cap

• A upper garment made of pieces of fur sewn together

• Fur leggings held up by a belt

• A soft leather loincloth

• Leather shoes, with a inner net of grass cords

last hours of this man's life

• The Neolithic people were farmers, growing varieties of wheat and barley. Two grains of barley and some wheat chaff were found in the iceman's clothing.

• They had domesticated animals (such as dogs, goats, pigs and cattle) and hunted wild animals such as ibex, deer and birds.

• Ötzi's mummification was so complete and happened so rapidly (experts think he froze and was encased in a glacier soon after death) that even his internal organs remain intact. In fact, scientists have been able to examine his stomach contents and intestines to learn about diet in the Neolithic period. They even know what he ate for his last meal!

Inside stomach

• they found pollen inside his colon– died in spring or early summer

• eating his last meal: unleavened wheat bread, an herb or another green plant, and meat.

• Finding this type of bread in Ötzi's intestinal tract suggests contact with an agricultural community.