Rules for warm-up• Warm-ups are to be started as soon as the bell

rings.▫One weeks worth of Warm-ups should fit on

one side of a sheet of paper.▫Mr. E will stamp warm-up if you have been

working since the bell rang.• Warm-ups will be collected every two weeks.

•Warm up 1/29: Describe the experiments of Redi, Spallanzani, and Pastuer. What were these three scientists trying to show?

Evolution UnitNotes #2: The First Organisms

Warm up 1/29: Describe the experiments of Redi, Spallanzani, and Pastuer. What were these three scientists trying to show?

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 oxygen

•1953 – Miller & Urey test the primordial soup model

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 are some of the oldest

prokaryote fossils: they were photosynthetic autotrophs

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

HW:

Classwork: Deep Time

Homework: Due ThursdayRead p279 – 283 answer #2-4 on p.281 Answer #1,2 on p. 286

Cover Page: Due TomorrowDon’t Forget a page for your name.

Evolution UnitNotes #3: Eukaryotes & Heredity

Warm-up 1/30: What comprised the Earth’s early atmosphere?Where the first organisms prokaryotes or eukaryotes? Heterotrophs or Autotrophs? Why?

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. (mitochondria)

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

The larger host cell would gain protection from toxic oxygen

The Origin of Heredity

Why is RNA needed? Why not go straight from DNA to Protein?

Support:

Current theories suggest RNA was the first genetic material not DNA

RNA can form many shapes

Ribozyme = a RNA molecule with the ability to catalyze a specific reaction

RNA can store information as well as act as a catalyst

These molecules can replicate themselves as well

Early cell like structures could have accumulated/collected RNA molecules with different abilities

Reverse Transcriptase = a ribozyme capable of copying RNA into DNA form which could have helped the transition into cells using DNA

Radiometric Dating Review

•Mr. Eisenberg has a sample 100 grams of Carbon-14 which has a half life of 6,000 yrs.

•How much is left after 6,000 yrs?/ 12,000 yrs?

• If you find 25 grams of Mr. E’s C-14, How old is the sample?

•Mr. Eisenberg has 1000 grams of a highly radioactive isotope with a half life of 90 minutes.▫How long until only 1/16 th of the original

sample is radioactive?▫What happens to the other 15/16th?▫Mr. E come in at 8:00 am and finds 20

grams of this substance is radioactive. At what time was 40 grams radioactive?

•Answers▫360 Min or 6 hours▫It becomes a stable isotope.▫6:30 am

Homework: Due ThursdayRead p279 – 283 answer #2-4 on p.281 Answer #1,2 on p. 286

•Homework: Due FridayRead p 284-290 Problems p. 296 #3-5Problems p. 290 #1-5

Homework

Read p.297 – 301Answer Questions #1,3,6-8 on p301

Quiz Friday covering Monday through today’s notes