Warm Up

•On the note card▫Write your name.▫Your favorite topic about last semester.▫The things you did best last semester.▫Your grade last semester.▫What do you hope to be different for this

semester.▫What do you hope to improve on this

semester.▫What is your goal for this semester.

Evolution UnitNotes #1: The Earth’s History

3 Experiments for vital force:

1) Redi – do flies come from meat?

Spontaneous generation: early idea that life could be

produce from non-living substances using vital force

Vital force: an invisible substance in the air that could give rise to new life from the nonliving world

2) Spallanzani – does vital force produce life in water (straight necked flask)?

3) Pasteur – does vital force produce life in water (curved necked flask)?

Measuring the Earth’s Age

Radiometric Dating = calculating the age of an object by measuring proportions of radioactive isotopes

Radioactive Isotope = an unstable form of an element that decays into simpler elements and gives off energy (radiation)Ex/ Carbon-14 decays into Nitrogen & Potassium-40 decays into Argon-40Half-life = the amount of time it takes for one half of a given radioactive isotope to decay (specific to the substance)Potassium 40

Half-life = 1.3 billion years

Argon 40

~4.5 billion years old

So how did life begin? (take 2)Spontaneous Origin

Spontaneous Origin = the process of life developing from non-living chemical interactions

1) Simple Organic molecules were formed in the atmosphere. (Ammonia, Methane, Hydrogen gas, Water, but NO Oxygen gas)2) Sun light, volcanic heat, lightning, etc energized the molecules creating larger and more complex substances.

The first building blocks of life became available

Testing the idea:

1920 – Oparin & Haldane suggest early atmosphere contained organic molecules & lacked oxygen1953 – Miller & Urey test the primordial soup model

Vocab• Take a sheet of paper and

fold into 3 columns.• Column 1: Vocab Word• Column 2: Definition in 8

words or less.• Column 3: Picture

▫ If there is no picture.▫ Draw and example or▫ Draw something that

relates.

• TODAY’S VOCAB (DUE TUES)

• Biogenesis• Spontaneous Generation• Isotope• Atom• Microspheres • Coacervates• Radiometric dating

HW:

•Get an 8.5 x 11 inch 3 subject notebook.•Go on Mr. E’s website at

www.losal.org/lahs and use instructions to make a cover page for Unit 8.▫Due Wednesday

Read p282 – 286 answer #1-5 on p.286

Prokaryotes, the oldest organisms

Scientists study fossils to discover clue of what early life was like

Fossils = mineralized bone, tooth, shell or imprints of organisms

The oldest fossils are microscopic and date 3.5 billion years old from Australia

Early prokaryotes survived without oxygen, in fact oxygen was toxic to some.Cyanobacteria were some of the first

prokaryotes to show and they were photosynthetic

Cyanobacteria began adding oxygen to the atmosphere through photosynthesisToday 21% of the Earth’s atmosphere is oxygen

Eukaryotes from Prokaryotes

Eukaryotes show up in the fossil record 1.5 billion years ago

The Theory of Endosymbiosis

One of the main differences between prokaryotes and eukaryotes= Mitochondria & Chloroplasts

Proposes that these organelles are the descendents of symbiotic, aerobic eubacteria.

Later a photosynthetic prokaryote entered a symbiotic relationship with a larger cell

The larger host cell would gain protection from toxic oxygen

Supporting Evidence: Both organelles contain their own circular DNA and can replicate on their own.