1. HW #5 Read pages 423-428 Pg. 428 section 17-2 answer Q 1-4
Aim: How did life begin ?
HW #5
Read pages
Pg. 428 section 17-2 answer Q 1-4

2. Billions of years ago, life on Earth is thought by many scientists to have begun as simple, single organisms. About a billion years ago, increasingly complex multi-cellular organisms began to evolve.

3. Do Now:KWL (What is Life ?)

4. Conditions of Primitive Earth
Early Earth would have been very different and inhospitable compared to the Earth today.
Hot atmosphere, boiling water, etc.
Atmosphere - early atmosphere probably completely different in composition from present Earth (H2, He, ammonia and methane)
H2 He CH4 NH3

5. Evolution of the Present Atmosphere
Atmosphere - Envelope of gases that surrounds the Earth. Used by life as a reservoir of chemical compounds used in living systems. Atmosphere has no outer boundary, just fades into space. Dense part of atmosphere (97% of mass) lies within 30 km of the Earth (so about same thickness as continental crust).
Chemical Composition Today - Nitrogen (N2)- 78%, Oxygen (O2)- 21%, Carbon Dioxide (CO2) %, plus other miscellaneous gases (H2O for one).

6. Today the atmosphere is 21% free oxygen.
Talk to your partner and explain how oxygen is produced.
Photochemical dissociation – breakup of water molecules by ultraviolet light
And
Photosynthesis – carbon dioxide and water + sunlight = organic compounds and O2

7. The heterotroph hypothesis describes the possible change of the earth’s atmosphere to support life, as we know it.
Miller discharged an electric spark into a mixture thought to resemble the primordial composition of the atmosphere From the water receptacle, designed to model an ancient ocean, Miller recovered amino acids. Subsequent modifications of the atmosphere have produced representatives or precursors of all four organic macromolecular classes.
Give Handout
What is the research question?
What is the hypothesis?
What is the data?
What is the conclusion?

8. Organic compounds are compounds found in living things
Organic compounds are compounds found in living things. They contain carbon, Hydrogen and Oxygen
Nucleic acids
Carbohydrates
Proteins
Lipids

9. Stanley Miller's (and subsequent) experiments have not proven life originated in this way, only that conditions thought to have existed over 3 billion years ago were such that the spontaneous (inorganic) formation of organic macromolecules could have taken place.

10. KWL
Go back and fill in the L column

11. Aim: How do we define Life ?
What do living things do that non-living things cannot do?
Life began with the formation of organic molecules.
Groups work together to come up with life functions.
Life is defined by what living things can do.

12. Life Functions
Digestion breakdown of food to simpler molecules which can enter the cells
Circulation the movement of materials within an organism or its cells

13. Life Functions
Movement - (locomotion) change in position by a living thing
Excretion - removal of waste products by an organism (wastes may include carbon dioxide, water, and urea in urine and sweat)

14. Life Functions
Respiration - process which converts the energy in food to ATP (the form of energy which can be used by the cells)
Reproduction - the making of more organisms of one's own kind -- not needed by an individual living thing but is needed by its species

15. Life Functions
Regulation - the control of the various activities of an organism (mostly involves the nervous system and endocrine glands in complex animals)
Synthesis - the production of more complex substances by combining two or more simpler substances
Do Crossword puzzle

16. Uni-cellular protozoan
All living things perform life functions from the smallest organism to the largest
Whale Shark
Uni-cellular protozoan

17. Digestion
We know that all living things perform the same life functions but lets see how they are different.
Digestion in a paramecium is going to be a little different than digestion in a cow.
We call these adaptations.

18. Circulation and Movement
Circulation - Getting materials to all parts of the organism is going to be different in a single celled organism than in a large organism.
Movement - Paramecium moves by the rhythmic movement of cilia.
What moves humans? Muscle and bones with the coordination of the nervous system.

19. Excretion
Paramecium get rid of wastes by diffusion and humans get rid of wastes by the kidneys

20. Respiration
Fish use gills to get the oxygen out of the water and into their bodies.
Land animals use lungs to get the oxygen out of the atmosphere and into there bodies.
Bird lungs have adapted many sacs.

21. Paramecium Conjugation
Reproduction
From the simplest organism in a water environment to the most complex organism on land, reproduction is necessary for the survival of the species but not necessary for the survival of the individual.
Marsupial birth
Paramecium Conjugation

22. Regulation Phototropism in plant shoots
Regulation involves the coordination of many systems, including endocrine and nervous.
Phototropism in plant shoots

23. All cells synthesize compounds for use in and out of the cell
Synthesis
All cells synthesize compounds for use in and out of the cell