History of Life on EarthJanuary 12, 2009

What is the age of the Earth?a) 4,500 years old

b) 4,500,000 years old

c) 4,500,000,000 years old

d) 4,500,000,000,000 years old

Miller-Urey ExperimentShowed that, under certain

conditions, organic compounds could form from inorganic molecules

The experiment

Life’s Building Blocks

Hydrothermal Vents: energy from the vents could have fueled chemical reactions and the depth of the sea would have offered protection from solar radiation

Space: some meteorites that have hit the Earth’s surface contain amino acids

Really, Mrs. G? Space??

Meteorite Room TourFriday, 8 June 2007

                                                                                                                                                                                                                                                                                      

Kris Rhodes excitedly holds Allende, the oldest meteorite known, which

contains the first solids to condense out of the solar nebula over 4.556

Billion years ago! Allende also contains tiny diamonds from super

nova explosions of other solar systems. And last, but not least, it

contains amino acids not of our world.

http://www.nmnh.si.edu/rtp/students/2007/schedule07_mineral_tour_photo_meteorites.html

What process is used to estimate the age of fossil within strata, or layers of the Earth?

a. half-life

b. radioactive decay

c. radiometric dating

d. relative dating

Copralite = Dinosaur dunghttp://i.livescience.com/images/ig25_dinosaur_dung_09.jpg

What has shaped the geologic time scale of the Earth?

a. earthquakes

b. the formation of

the Earth

c. floods

d. mass extinctions

What do some scientists think provided the energy for chemical reactions that produced the first biological molecules?

a. meteors

b. heat from hydrothermal vents

c. ribozymes

d. microspheres

The First Cells Lipids make up cell

membranes Lipids do not mix with water In water, lipids can form tiny

spheres called microspheres. Microspheres may have been

the first step towards cellular organization

Endosymbiosis A mutually beneficial relationship in which one

organism lives within another Larger cells engulfed smaller cells, which then began

to live inside larger cells

Evidence for Endosymbiosis Size and structure: mitochondria are the

same size as most bacteria Genetic material: both chloroplast and

mitochondria contain their own DNA that is different from the DNA of their host cells

Ribosomes: both have ribosomes Reproduction: Like bacteria, chloroplasts

and mitochondria reproduce by simple fission

Which were the first animals to evolve and successfully live on land?a. arthropods

b. reptiles

c. amphibians

d. mycorrhizae

Tapping Timeline