Transcript Prokaryote to Eukaryote

Your Objectives
• Learn how plants and
animals evolved from protists
• Learn examples of how
organisms maintain
homeostasis
• Learn how plants and
animals use chloroplasts and
mitochondria for energy
• Learn how enzymes are
important for cellular
reactions
• Learn how cells copy their
DNA and divide as the cell
grows
• Learn how plants have
adapted to different
conditions to become
different from one another
A Trip Through Geologic Time
3.5 Billion years ago (how many human
lifetimes is this?)
Average human lifespan? About 70 years
How many lives would this be?
3,500,000,000 years
=
50,000,000 human lifespans
50,000,000 human lives
Doesn’t sound like a lot?
OK, the typical lifespan of a bacteria is a few
hours to a few days at most… so if you
think about how many “lives” bacteria have
had to evolve, you have to multiply
3,500,000,000 by 365 (if you assume a
cell lives for an entire day)
That’s 12,775,000,000,000,000 times
During that time…
• Anyway, we have fossils that show
photosynthetic, prokaryotic cells existed
3.5 billion years ago.
• Later, actually, about 7 hundred million
years later, there was a sudden increase
in diversity, and It seems that some large
Prokaryotes made the first big leap into
more complex life
Here’s how we think it happened…
Cells, like amoeba, eat other cells all the time. It is likely
that one cell ate another, and the other cell was never
destroyed, simply continued life, ADAPTING to the new
environment.
This would mean that one
organism…
• Lives inside another organism…
• Endo = inside
• Sybiont = together
• Incredibly, that other organism continued
life inside the other…even reproducing
itself?
How do we know?
• Scientific research has shown that chloroplasts
and mitochondria have their own ribosomes –
NOT the ribosomes of the “host” cell that are
similar to the ribosomes in prokaryotes.
• IN ADDITION, both chloroplasts and
mitochondria reproduce INDEPENDENTLY of
the cells that contain them.
Evidence continues to mount
So…
• The evidence shows that there were
organisms that behaved like mitochondria,
that lived in an oxygen-free environment,
and organisms that behaved like
chloroplasts that released the oxygen we
breathe into the atmosphere.
• They live on in our cells, a part of them,
but still have the characteristics of the
original organism…
Making Coacervates
• In the next lab we are going to simulate a
“primordial soup”.