Posts Tagged ‘biology’

Snow Days Inspire Innovation!

Posted: February 4, 2011 in chemistry, helpful hints
Tags: ,

Hey guys,

I’ll just assume you all have been missing me as much as I’ve been missing you! I hope you all are snuggled up with a good book (i.e. your biology textbook) and enjoying the surprise winter break. If you have running water, I’ll be there in an hour to borrow your shower…

I thought a biology blog might be a good way to keep us updated throughout the semester, and especially for now when we’ll be crunched to stay on schedule and cover all the required material. Please feel free to post information, provide feedback, and contribute in unique ways!

Hint: As you read through, make absolutely certain you understand every word/phrase used. If you don’t know the meaning of something used in context, LOOK IT UP. Don’t just continue past! To make for more condensed reading, I have chosen not to define concepts easily found in your book.

So from chemistry (continue reading through the notes, and I’ll also be posting more!) we’re scheduled to move on to cell structure and function. This includes cell theory, a description of various critical components, and a synthesis of how everything works together as a living organism. In multicellular creatures such as ourselves, our individual cells must then also be connected, both physically and functionally, to create a whole that seems itself irreducibly complex. For example, YOU don’t respire, your CELLS respire. You merely breathe; which allows oxygen to be disbursed to each individual cell, inside of each of which many semi-autonomous organelles called mitochondria actually perform the biochemical conversion of the glucose you eat into ATP fuel (think of it like an energy-storing battery) with the help of that oxygen.

Wow! Let’s back up a bit. While your body seems to work as a whole, it is composed of some trillions of individual cells – all derived from that single sperm-infused egg in your mama’s belly. Even though each (with one important exception) contains your entire genome, various “specialties” arise during your development and eventually lead to over 260 differentiated cell types that spontaneously organize into an integrated, functional system. In some (e.g. animal), but not all multicellular forms, cells may lose their individual identity to maintain that whole. Before we study the body systems, though, it is important to understand how each individual cellular unit works. In addition, it is important to keep in mind that most of life exists as single-celled organisms. And most of these are prokaryotic! For the purposes of this class, we’ll be focusing on eukaryotic cells like ours. However, I would like you to study, and be able to describe, the defining characteristics – and differences between – prokaryotes and eukaryotes in general.

Professor Wolfe (great lecturer) gives an overview of cells

Good cell overview with structure and function
Fun virtual tour (a bit technical in parts, but extremely informative) of the cell

I encourage you to play around on this website as you study
More great biology resources and videos can be found on Professor Wolfe’s website
Here are some tutorials with sample test questions from one of my favorite study sites

As we study the cell, you’ll notice that a major theme is the difference between the outside environment and the inner conditions required to maintain life. Homeostasis is the maintenance of the proper pH, temperature, osmotic pressure, etc. for optimal performance. The structure of the cell membrane itself is wonderfully crafted to very efficiently promote homeostasis. That is, it provides an effective barrier between external and internal environments – it is a selective, semi-permeable membrane. To fully appreciate this concept, one must be familiar with the chemical and physical concepts of diffusion and osmosis.

Osmosis and diffusion
Cell membrane basic structure and function
Excellent basic overview of cell membrane transport

Don’t forget that you already know all about diffusion and osmosis – why do salad bars and buffets keep veggies in water baths? To take advantage of osmosis (water in = fresh, plump appearance!)….but don’t be fooled! Where do you think the vitamins, antioxidants, and minerals are going due to diffusion? That’s right: If you want these nutrients, you’re probably better off drinking the water than eating the food (don’t really try that, by the way). And what about when you spend too long in the bathtub? You get all wrinkly because the same thing is happening to you! The bath water is hypotonic to your cells, which means that water diffuses (via osmosis!!) INTO your cells; you look wrinkly because they are becoming so individually overloaded that they are folding back upon one another as they swell.