1. When a bacteria picks up DNA from the environment it is termed –
a. Conjugation
b. Saltation
c. Transformation
d. Flocculation
e. Transduction
2. Choose the appropriate letter and then tell me why: Binary fission involves the
replication of DNA, elongation of the cell, and dividing the cell in half.
a. This is true because…
b. This is false
3. Choose the appropriate letter and then tell me why: Genetic variation is necessary
for evolutionary adaptation. The two major sources of genetic variation in bacterial
cells are mutations and the incorporation of foreign genetic material into the
genome.
a. This is true
b. This is false
You guys worked hard to figure out what happens as a result of surface area
increasing slower than volume. Now, remember that eukaryote cells are MUCH
larger than prokaryotes (I tried to stress this in class). So the question is, why were
eukaryotic cells successful? Well, there were three innovations that led to their
success: the formation of the nuclear membrane, mitochondria, and chloroplasts.
The following activity is a THINKING one, so show me what you’re thinking about.
Try to answer the questions in order, they’re designed to have you build on
knowledge. Feel free to work with friends, neighbors, acquanteneces, but try to limit
it to people (aka try NOT to use the computer until you’re done). I can’t stop you, but
the exercise is meant to have you process information, not just spit info back to me.
Where did eukaryotes come from? There are some evolutionary times and events
and questions for you to answer interspersed in the timeline.
Earth 3 billion years ago: Anaerobic bacteria are happy as clams. There is no oxygen
gas in the atmosphere.
2.9 billion years ago: Anaerobic bacteria are not happy as clams. There is mayhem
and carnage and death and destruction because…
1. Why?
2.2 billion years ago: Aerobic bacteria have figured out cellular respiration and are
thriving. There are still anaerobic bacteria (those using anaerobic respiration) and
some that use fermentation. There are the two ways to get carbon into a cell too
(them same as we see today): autotrophs and heterotrophs.
2.1 billion years ago: Remember aerobic respiration? Good, keep it in your brain.
Now, know this: some bacteria were heterotrophs that ate
other bacteria by engulfing them. Look at the figure.
2. What is happening to the cell membrane here? Is the
surface area increasing or decreasing (circle one)
3. Why might natural selection favor bacteria that have periods where the
infolding hangs out longer than in other bacteria? (think of the MEMBRANE
and processes involved with the membrane)
So now, those infoldings on heterotrophs start to run together and the bacteria in
which the infoldings meet and contain the bacterial chromosomes are selected for.
4. Why is this an advantage? (Think of advantages of a membrane in general)
5. Guess what organelle just evolved?
Hopefully, you didn’t look to the this page: the answer the nucleus.
So the size of our cell has now increased some. The increased number of infoldings
have led to a nucleus and increased ATP production (aerobic cellular respiration)
6. How and why are size and energy demands correlated?
So now there are heterotrophs of various size that are in the primordial mix. One
larger heterotroph eats a smaller one and doesn’t get to digesting it right away. The
small heterotroph is an ATP making machine with all these infoldings! So good at
making ATP in fact, that some of that ATP leaks out. (predation in ancient Earth  )
7. From the perspective of each player (large and small bacteria) is this
leaking ATP a good or bad thing? Explain your answer.
Large:
Small:
9. Look up each of the following terms: competition, mutualism, parasitism,
commensalism, or predation and give a brief description (just a phrase). Circle
the one that describes the eventual relationship between the large and small
heterotroph
10. So now there is an ATP making machine “living” in the larger heterotroph.
What organelle did the small heterotroph evolve to?
The process that you just went through with the big and little heterotroph is called
PRIMARY ENDOSYMBIOSIS ( you have to know that). And the organelle that the
little heterotroph evolved to is the mitochondria.
11. What pieces of evidence would you want to see to confirm that
mitochondria were once their own entity?
12. Chloroplasts evolved in a similar way – propose the scenario that
describes its evolution (try not to look this up)- use your logic.
The moral of the story is
that EVERY CELL in your
body now is a product of
these HUGELY
IMPORTANT events in
evolutionary history. It also
means that the branches of
our tree