14-3: Origin of Heredity
Hypothesis
• Testable explanation to a problem or a
question
Theory
• Summarizes a hypothesis or group of
hypotheses that have been supported with
repeated testing.
• It is valid as long as there is no evidence to
dispute it.
• EX. Cell Theory and Theory of Continental
Drift
Law
• Generalizes a body of observations
• Laws explain things, but they do not
describe them
• EX. Law of Gravity
First Life Forms
Role of RNA
• Amino acids linked to make a chain that
could make shapes like ribozymes (early
ribosome) which could replicate itself
First Life Forms - The First Cells
• Prokaryotes before eukaryotes
• 3 major trends all interrelated:
• Anaerobic  Aerobic
• Heterotrophic  Autotrophic
• Chemosynthetic  Photosynthetic
First Life Forms
The First Eukaryotes
• Endosymbiosis Theory
• Mitochondria and chloroplasts are thought to be
prokaryotic cells that were engulfed by a bigger cell
• Supporting Evidence:
• Both organelles contain their own DNA
• DNA is circular (like other prokaryotes)
• Can replicate on their own.
•
Put these in the order in which
they are thought to have
originated on Earth
1.
2.
3.
4.
Anaerobic heterotrophic prokaryotes
Aerobic eukaryotes
Chemosynthetic prokaryotes
Photosynthetic prokaryotes
Answer: 1, 3, 4, 2
Sequence of First Cells
Anaerobic
Heterotrophic
Prokaryotes
Chemosynthetic
Prokaryotes
Photosynthetic
Prokaryotes
Endosymbiosis Occurs Here!
Aerobic
Eukaryotes
Photosynthetic
Eukaryotes
Discovery Education-How Life
Formed on Earth
Class work
•
•
•
•
Read Pages 287-290
Answer Questions 1-5 on page 290
Write out questions or embed in answer.
Draw and label Endosymbiosis on page 290