1. Ch. 14 – Origins of Life QUESTIONS OF THE DAY!!!!
What do you think were the very first organisms? Why?
What are the main elements that make up organisms?
What are the building blocks of protein?
What are the 4 biological macromolecules and what do they do?
What evidence do you think we have to determine how life started on earth?

2. Ch. 14 – Origins of Life The Cosmic Calendar…
If the history of the universe were condensed into a single calendar year

3. Ch. 14 – Origins of Life
Life as we know it appeared the last month in the last few days of the Cosmic Calendar

4. Ch. 14 – Origins of Life Earth’s Age 4.2-4.6 billion years old
1.8 billion years ago life began
Radioactive (radiometric) dating
Uses radioactive isotopes and their breakdown to estimate approximate age (Review Ch. 6)
Isotope: a radioactive atom w/different number of neutrons ( Carbon 12 is normal – 6 neutrons, 6 protons)
(Carbon 14 is radioactive – 8 neutrons, 6 protons)

5. Ch. 14 – Origins of Life
The isotopes release energy (radioactive) at a CONSTANT RATE. This determines the age.
The release of energy is radioactive decay.
The amount of time for ½ of the material to decay is called a HALF LIFE.
EX: A. Start with 100g B. Half life is 50 years
25 g is left How old is the material?

6. Ch. 14 – Origins of Life
Below is a graph representing the half life of Carbon 14 in animal tissue.

7. Ch. 14 – Origins of Life Miller and Urey
Experimented to determine primitive atmospheres and origins of amino acids
Primitive atmosphere of CH4, NH3, H2O, and H2 gases
Gases combined and made amino acids
Amino acids are the building blocks of protein.

8. Ch. 14 – Origins of Life
1st Organisms
Anaerobic, prokaryotes, and heterotrophs

9. Ch. 14 – Origins of Life

10. Ch. 14 – Origins of Life
Photosynthesis (sugar & oxygen) evolved (Autotrophs)(Ch.8)
Eukaryotes and aerobic respiration develop in response to photosynthesis (Ch. 8)

11. Ch. 14 – Origins of Life
Endosymbiosis – small things living in bigger things as a mutualistic relationship
Mitochondria
Chloroplasts

12. Ch. 14 – Origins of Life Fossil Record, Rock, and Early Life
Fossil: traces of dead organisms that have been preserved in rock.
Law of superposition
Layer of rock (sediment) are deposited on existing layers

13. Ch. 14 – Origins of Life
Cyanobacteria- the first organisms to undergo photosynthesis

14. Ch. 14 – Origins of Life
Cambrian EXPLOSION! – Oxygen increased so diversity in life increased! (many new species appeared)
More oxygen = more higher forms of animals
The graph to the right shows the increase of oxygen as earth has aged.

15. Ch. 14 – Origins of Life