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. Anaerobic heterotrophic prokaryotes2. Aerobic eukaryotes3. Chemosynthetic prokaryotes4. Photosynthetic prokaryotes

Answer: 1, 3, 4, 2

Sequence of First CellsAnaerobicHeterotrophicProkaryotes

ChemosyntheticProkaryotes

PhotosyntheticProkaryotes

PhotosyntheticEukaryotes

AerobicEukaryotes

Endosymbiosis Occurs Here!

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