Welcome to the cell biology blog. This
blog is for students in the cell biology course at The Master's College, but
anyone is free to join. My name is Dr Francis and I teach the cell biology
course. Please feel free to contact me at jfrancis@masters.edu if you have
questions about this blog.
What are cells? Cells are often
distinguished from viruses, but recent discoveries of some very large viruses
suggest that this distinction is becoming more and more fuzzy.
Also, is there such a thing as unicellular
life? Can cells and do some organisms exist as single cells? Well I might be
going out on a limb but I do not believe that unicellular life exists. That
is certainly a statement that is subject to a lot of interpretation. Let me
explain.
First, single cells do exist, and some
appear to lead independent lives, for instance creatures we call microbes like
bacteria or paramecium. So what then does the term unicellular mean? It is a
term used to distinguish free living independent cells from those which live in
tissues, or the multicellular condition. Cells which live in this multicellular
state live in close contact with other cells. But I would argue that all cells
live in close contact with other cells.
So how likely is it that you are going to
find microbes living alone, in a true unicellular state. Take a pinch of soil;
you will find thousands of creatures living there, many interacting with each
other. Consider an amoeba or paramecium or other pond organism. How many of
these creatures do you know who live in their own private pond?!
But really, lets get down to the nitty
gritty, could you not isolate a single bacterium and give it a nice petri dish
with lots of nutrients in the corner of your room? But wait a minute, about
every 30 minutes, this guy will generate his own friends, within a few hours a
full grown microbial party will be in force. I am wondering just how easy it is
to isolate a single living bacterium. How would you do it?
I challenge the
microbiology students every year and tell them I will give them an A in the lab
course if they can isolate and stain a single bacterium on a single microscope
slide. What would you have to do to accomplish this task? ( I might give some
credit just for a protocol for how you would do this).
Lets face it. Life is multicellular at
every level. But wait. What about those pond organisms? they seem independent.
More and more studies are showing that most of these critters carry bacteria
around. There is even one strain that lives with a bacterium in its
macronucleus. Why in the world would you want to carry a bacterium in your
macronucleus? I have asked a lot of people, and no one has given me a
satisfactory answer. I have gotten some weird looks ….as if the person is
thinking, what the heck is a macronucleus and why do I care?
A lot of single celled pond organisms eat
bacteria or algae. But there
is one pond organism Paramecium bursarium which eats algae and bacteria but also
knows how to ingest some algae and not digest them; instead it keeps them as
energy harvesting slaves! Whoa! How does it know to eat some critters and digest
them and eat other critters an not digest them? Remember this is a small
creature with no brain and no nervous system.
So the questions for
the blog today are:
1 Investigate the Mimi virus and explain
how it is like cells but also different from cells. Is this a true virus in
your opinion?
2 Mimi virus is infected with viruses. What are these viruses and what could they being doing inside Mimi virus?
3 What
is a macronucleus and why would you want to live there? cheap rent?
cozy?
4 How would you
isolate a single bacterial cell on a microscope slide?
5 How
can Paramecium eat algae but not digest it?
6 What is the advantage to being multicellular?
Blog responses are due Feb 4.
