Make Robert Hooke Proud

[NOTE: for the take-home quiz assignment, scroll down to Friday's post]

As a class, we really bombed out on the micrograph question on the exam.  Oops.  

So now, as a class, we have an opportunity to learn and grow from that oops.  Your assignment, if you choose to accept it, is to create a portfolio of micrographs of each of the organelles that we have studied.  And, if you choose to accept it, your efforts will be rewarded with up to 5 scaled points back on your Unit 1 exam. 

If you embark on this journey of retribution, you will:

• Use the internet to collect micrographs showing the following organelles: plasma membrane, nucleus, mitochondria, chloroplast, golgi apparatus, rough endoplasmic reticulum, and lysosome.
• For each organelle, show several labeled micrographs pointing it out.
• In writing, explain how you would identify the organelle in an unlabeled diagram.

This assignment, if you choose to accept it, is due Monday, Oct. 19th.  It may be typed.

Biology = Awesome

Just stumbled upon this article from Wired magazine, which is chock full of amazing, real images that biologist have accrued with their powerful microscopes.  Apparently, lens maker Nikon holds an annual competition for the best photo produces through microscopy.  The article has the best of the best from the past 35 years - very cool.  Check it out!

The image above is a double transgenic mouse embryo - it looks like both the developing mouse (in pink) and the mother's placenta (green) have been genetically altered to glow their fluorescent colors under the microscope.  Incidentally, that's the same technology a team of neuroscientists used to make the nerve cells appear rainbow colored - as in the image that makes up the blog's banner.

In another note, I have made an executive decision to give everybody an opportunity to recoup some points on their unit exam by doing a little research on microscopy... more details to come on Tuesday.
Enjoy your three day weekend!

Practice identifying cell parts in micrographs

Boston University has an excellent catalog of electron micrographs that highlight the different cell parts.  This is great practice for you in identifying cell parts.  The site can be found here:

BU Histology Catalog

If you scroll down to where it says "know the structure, function, and location of:", it lists different organelles.  If you click on the arrow next to each organelle, it will take you to an annotated micrograph pointing out the organelle.  

Note that this resource comes from the BU medical school.  I hope that gives you an idea of the caliber of the IB program - we need doctoral program resources to tackle it!  This is good.


[Note - if you are looking for the pre-lab homework for lab#1, scroll down to the post for Friday, Oct 2]

Plants: More like you than you know

Today, we looked at Elodea, a freshwater pond plant, under the microscope to observe some of its large organelles - the cell wall, chloroplasts, and central water vacuole.  Although on the surface plants look quite different from us, when you get down to it, we really have a lot in common.  After all, we're both Eukaryotes (we have nuclei), and our cells share many of the same organelles - mitochondria, endoplasmic reticuli, golgi apparati, plasma membranes, ribosomes - plants have them all too.


Here's a light micrograph of Elodea (another nice thing about light microscopy is that it produces color images):

And here's a nifty electron micrograph of a plant cell, with less color but much more detail:

Homework
R4 should complete their annotated drawings of Elodea to turn in tomorrow.  R6 should complete the homework on Prokaryotes posted on Monday, September 21st.


Please note that there will be a quiz on cell parts (2.2 and 2.3) on the Tuesday we get back from our long weekend.


Best,
Mr. Hill

Our cells "inner skin"

Today, we learned about the endomembrane system, a network of "inner skins" that organize the cell and manage the production and secretion of sensitive chemical substances such as hormones, neurotransmitters, enzymes, and other proteins.

For review, here is the helpful animation I showed in class: Tutorial of the Endomembrane System.

[UPDATE 10/1: I have added the Lecture notes.  They can be found here: Endomembrane System Lecture]

Homework
Continue to work on your assessment statements, particularly 2.4.7, which is largely based on today's lecture.  You may refer to textbook pages 70-73 for more information.

All pictures are from real electron microscopy of cells (mostly liver cells).  It might be advantageous to follow the lead set by James in R4 by printing the micrographs and pasting them directly into your notebook.  In your class journal, identify the structures and state evidence for why you think it is that structure.  In other words, be thoughtful: how do you know?

1. What structure is shown below?  How do you know?

2. What structure is shown below?  How do you know?

3.  Five structures are labeled in the diagram below.  Identify them and state evidence. [9/24: Note - I updated this with the labeled micrograph in order to alleviate some of the confusion we had in class in annotating the diagram.  The questionable organelle IV was in fact the rER.]

Prokaryotes are EVERYWHERE

Did you know that humans, on average, have about three pounds of E.coli and other bacteria living in their gut?  Considering that most bacteria are fewer than 10 micrometers in length and have a weight to match, that's a lot of bacteria!

Today, in R4, groups of students worked to debrief a textbook reading about prokaryotes and answer the question of how single-celled bacteria survive.  You should now be able to draw and label a diagram of E. coli, one of the most abundant prokaryotic species, and annotate the diagram with the functions of each of the major structures.

The textbook diagrams, however, are misleadingly clear.  In reality, the parts of E. coli aren't quite so easy to pick out.  But all the parts we discussed are there - check it out:

Homework
Your assignment is to answer the questions below about this particular prokaryote.  Use looseleaf or an index card.

1. Determine the length of this prokaryote using the scale bar.  Show your workings.
2. Identify the structures labeled I, II, III, and IV.
3. Explain how I, II, III and IV enable the prokaryote to live.

This is due Tuesday for R4 and Friday for R6.  Remember that R4 has a short quiz tomorrow.