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Chapter 14Section 2

Activity- Earth’s timeline

Materials: 1 ruler, 1 sheet of paper, colored pencils or markers

Instructions: Draw a horizontal line that will

represent the timeline of Earth’s History

The far left side starts at the current estimated formation of the Earth, mark 4.6 Billion Years ago

The far right side represents present day

Place these key events where your group estimates they happened and include a date, ex 2.6Bya, 100Mya, 14,000 yrs

Work in groups of 4 Do not talk to other groups

1. 1st flowering plants

2. 1st Life

3. Multicellular organisms

4. Invasion of Land

5. 1st Eukaryotes

6. 1st Photosynthetic bacteria

7. Extinction of Dinosaurs

8. Last of the Glaciers recede from temperate zones

9. Homo Sapiens appeared

10. Continents appear essentially as they do today

11. 1st Aerobic Bacteria

4.6 ByaFormation of Earth

3 Bya1st Photosynthetic bacteria

4Bya

3Bya

2Bya

1Bya

3.8 Bya1st Life

800 MyaMulticellular Organisms

300 MyaInvasion of land

250 Mya1st flowering Plants

65 MyaExtinction of Dinos

20 MyaContinents appear as they do today

160,000 yrsHomo sapiens

15,000 YrsLast Glaciers Recede

2.1 Bya1st Aerobic Bacteria

1.6 Bya1st Eukaryotes

+Warm up question

1. What does the 1st flask contain?

2.How does the broth change during the experiment? -use complete sentences

Broth is boiled

1 yr passes, broth remains clear

Curved neck is removed

One day passes, broth becomes cloudy

+The Formation of Earth

Our solar system began as a swirling mass of gas and dust 5 Billion years ago

Most material was pulled together by gravity and formed the sun

Planets formed through repeated collisions of space debris

Earth formed to roughly it’s size today over a 400 Million year period

+How did the Oceans form?

4 billion years ago, the Earth could be described as a very large, hot rock without a trace of water on its surface

As the Earth cooled to below 100oC oceans were formed when water vapor condensed and formed liquid water.

Water on the young Earth came from two sources Outgassing from within the Earth

process whereby gases are released from molten rock in the mantle of the planet by volcanic activity

Bombardment by comets

+First Organic CompoundsAll elements found in organic compounds

existed on Earth when it was formed but how were they assembled into compounds?

Early atmosphere contained:Ammonia NH3

Hydrogen gas H2

Water vapor H2OHydrocarbons CH4

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Alexander I. Oparin and John Haldane – 1920’sOparin hypothesized that at high

temperatures these formed simple organic compounds Amino acidsEnergy supplied by lightning and U.V.

rays

These ultimately resulted in macromolecules essential for life

How did elements form into the 1st organic compounds?

+The Miller-Urey experiment

1. A solution of simple chemicals is heated producing an “atmosphere”

2. Electrical sparks simulate lightning, provides energy for synthesis of new compounds

3. A condenser cools atmospheric gases, collect in “ocean”

4. Condensate is analyzed

Stanley L. Miller (1930 - ) Harold Urey (1893 – 1981)

Hypothesis: Organic chemical compounds can be generated under conditions similar to those that existed on primitive Earth

Conclusion: The chemical building blocks of life (amino acids, ATP, nucleotides) could have been generated in the atmosphere of early Earth

+Molecules to cell like structures In solutions of simple organic chemicals cell-

like structures will spontaneously form

Microspheres – spherical, composed of many proteins. Mimic a cell membrane

Coacervates – collections of droplets that are composed of molecules of different types. Amino acids, lipids, and sugars

+Cell Like properties(coacervates/microspheres)

Ability to take up substances from their surroundings

Growth

Budding to form smaller structures

NO HERHEREDITARY CHARATORISTICS