Warning: Contains Biology by Paul B. '11

As you hopefully already know, I am a sophomore in Course 20 here at MIT. Because we say everything here in numbers, Course 20 actually means that I am a biological engineering major. Moreover, even though I’ve planned on being Course 20* since before coming to MIT**, MIT students tend to all take the same core curriculum as freshmen. This not only provides all students with a common core of foundational scientific knowledge, it also prevents students from being pressured into declaring a major too early too.

But now that I’m a sophomore, I get to start taking exciting Course 20 classes!

…well, sort of.

I say “sort of” because although three of my five classes this term are recommended and required for a Course 20 degree, only one of them is, strictly speaking, Course 20.

But that’s actually part of the point of biological engineering: it is a highly interdisciplinary field, especially here at MIT; and it is continuing to evolve from the various fields that originally gave birth to it. Bioengineering is still incredibly ground-breaking, with new research pushing the limits of our knowledge every day – and that’s why I’m so excited to be part of bioengineering here at MIT, where so many fantastic discoveries have already been made.

* This is actually over-simplifying things slightly. Originally I wanted to study biomedical engineering, which tends to incorporate a lot of things from Course 2 (mechanical engineering) as well as Course 20. So for a while I contemplated declaring Course 2 or Course 2A (mechanical engineering with a particular focus; I would have chosen biomedicine, like Melis) instead of Course 20. Yet ultimately I decided that Course 20, which is just straight up pure biological engineering, was the right choice for me personally.

** For the prospective students applying, do not worry about what you list as your “intended major” on your application form. Because of MIT’s centralized, “single-door” admissions policies, all applicants are reviewed by the Admissions Office equally no matter what you put down. That question’s only purpose is to help the Admissions Office get a sense of what your passions are and how you have explored them before applying (for example, competing in science fairs, attending engineering summer camps, participating in FIRST, or doing research).

It’s also perfectly fine to put down “Undecided” if that’s what you honestly are. I know several friends who put that down on their application and got in. Don’t let anyone tell you that being unsure about your future stop you from being admitted to MIT – who really expects 17-year-olds to be 100% sure about what they want to do for the rest of their lives, anyway?

As I was saying, though, I’m taking three “Course 20” classes this term:

• 20.110 – Thermodynamics of Biomolecular Systems
• 5.12 – Organic Chemistry I
• 7.03 – Genetics

20.110 and 7.03 both have homework assignments – problem sets – due tomorrow. I’ve been making good progress on them so far. But because I realized I haven’t talked about my academics all that much this term, I thought I would give you a brief insight into some of the questions that have been on my mind lately.

First, from the 7.03 problem set, Question 1:

Growth on glycerol in yeast requires a functional electron transport system. Some of the enzymes in this electron transport system are encoded in chromosomes residing in the nucleus and some in the mitochondrial DNA. This situation means that a strain unable to grow on glycerol could have a mutation in the nuclear DNA, the mitochondrial DNA, or both. For the nuclear notation, a wild type strain is GLY1+ and a strain that has a mutation in a nuclear gene preventing growth on glycerol is gly1-. For the mitochondrial genome notation a strain can be ρ+ or ρ- where the strain that is ρ+ can grow on glycerol and the strain that is ρ- can not. Thus, a wild type strain is GLY1+ ρ+ and a glycerol non-grower could be gly1- ρ+, GLY1+ ρ-, or gly1- ρ-. You have known haploid stocks of strains with these four genotypes to characterize any new strain.

When you cross a ρ- strain with a ρ+ strain the resulting diploid is ρ+.

a) You isolate a haploid strain that can not grow on glycerol and want to know what its
genotype is with respect to the nuclear GLY1 and mitochondrial ρ DNA. What
strains would you cross it by to distinguish whether its genotype is gly1- ρ+, GLY1+ ρ-, or gly1- ρ- ?

b) In a cross of gly1- ρ+ x Gly+ ρ- what would be the glycerol genotype and
phenotype of the four meiotic products?

And from the 20.110 pset, Question 3:

When raindrops fall, they are distorted slightly from a spherical shape due to drag forces on the sphere. Consider a droplet that is initially 1 mm in diameter. Its surface area is increased by a factor of 1.75 while falling. What is its change in free energy during the process (do not include the change in potential energy)? If this free energy were converted into heat, would the temperature of the drop change appreciably? The surface tension of water is γ = 72 dyne/cm and the heat capacity of water is 4.1 J/gm/K.

As you can see, problem sets are a lot different from high school homework. There are (usually) fewer problems, but they’re each individually more difficult and more likely to make you want to tear your hair out. Moreover, they generally can’t be answered just by using some formula you copy out of your chem textbook – you actually have to think outside the box and applying what you learned in lecture and from the text.

But that’s what MIT’s all about. We wouldn’t be here if it weren’t challenging.