DNA Replication-- Summary

The following are the summary of what happens during DNA replication:

1. Starting from the origin of replication (ori), helicase unwinds the the double helix. Single-stranded bonding proteins (SSBPs) bind to the single stranded DNA to keep them apart.
2. RNA polymerase constructs RNA primers on both leading and lagging strands
3. • The leading strand is continuously elongated by DNAP III.
   • The lagging strand is elongated discontinuously. Each okazaki segment is primed with RNAP, and then elongated by by DNAP III. DNAP I replaces the RNA primer with DNA, and DNA ligase joins the fragments together by catalyzing the formation of phosphodiester bonds.
4. This process continues until the replication fork meets the replication fork of another replication bubble, or when the end of the DNA strand is reached.

Waves Basics

Basics

• A wave is a disturbance in a medium that carries energy.
• Two points are in phase if they have the same motion at all times
• Two points are completely out of phase if their motions are always opposite
• Superwaves are created when two identical waves move toward each other

Path Length and Path difference

• Path length: the distance from a point to the source of a wave
• Path difference(Δ): the difference between the path lengths of two different waves
• If two point sources vibrate in phase with each other, they would be in-phase at points where Δ is a whole number multiple of λ

Waves at Boundaries

• The frequency of a wave never changes
• Snell's law: n×sin(θ) is constant (n is the index of refraction)
• If a wave travels from a faster medium to a slower medium, the transmitted wave becomes inverted

Interference from two point-sources

• If a point P is very far away from the two sources, then Δ= d×sin(θ), where d is the separation between the sources, and θ is the angle between the perpendicular bisector of the sources and the line joining P and the midpoint of the two sources

Young's double slit experiment:

• Problem: to have two point sources of light that are coherent
• The first slit acted as a point source of light
• The double slit acted as two point sources of light
• On the screen, the bright fringes are where the antinodal lines are
• The dark fringes are where the nodal lines are

Interference of thin films:

• Use the theory of "waves at boundaries" and path difference to do these problems
• n₁×λ₁=n₂×λ₂

A Busy Winter Break

There are actually a lot of things that I need to do during this winter break. This means that I cannot just waste days playing games and doing nothing; I cannot afford to waste the valuable time.

So I decided to make this post to remind myself of all the things that I need to do:

University Applications:

• Engineering essay (600 words)
• Engineering extracurricular activities
• Engineering academic achievements
• What is a folly act?
• What defines you as you?
• What is an educated person?
• Write a reference letter for yourself

School

• Study for physics
• Study for calculus
• Prepare for physics presentation
• Work on philosophy essay

I Think, Therefore I Am

The quote "I think, therefore I am" is Rene Descartes' famous cogito argument, and it is extremely important in epistemology. Using his own Method of Doubt, Descartes doubted everything that was provided by the fallible senses, as well as anything that could be part of a dream or an illusion created by an evil genius. This left him with one thing that he could be sure of— his existence. He reasoned that even if everything around him was an illusion, his mind must exist because otherwise he would never have been fooled. This quote is an extremely important argument in rationalism— as it is purely based on reason— and it is also relevant to solipsism. It illustrates Descartes' method of doubt, which is to doubt anything that comes from our senses or anything that could be an illusion.

Not A Priority

A lot of things have happened last month. I dropped one of my courses, I started following a new television show, and I have encountered many thought-provoking things.

However, clearly I didn't take the time to document any of these onto this blog or anywhere else. Even when I had spare time, I would always choose another activity over writing a blog post.

Why? I think one reason is my preference for thoroughness. Whenever I thought of updating the blog, I would want to make a super-long post that would outline my thoughts with great detail; I would never allow myself to write a 2-sentence blog post. But thoroughness is costly— it takes time. I have time to make a post, but obviously not enough to spend 2-3 hours in a single session. And since I do not have the habit of writing a post chunk by chunk, I just never wrote anything.

Also, I have started to think that perhaps it's not always necessary to write everything down. Why can't I just go through everything in my head?

Besides, school really is busier than last year, and also a lot more important. In my final year, almost all my marks matter, and I have to spend a lot of time and effort to prepare for tests and to go over assignments.

So unfortunately, this trend probably wouldn't change until sometime next year. Blogging isn't a priority right now.

A Few Complaints

The administrative team of my school constantly brags about how the school is one of the highest-ranked schools in the school board. However, these rankings are merely based on the scores on standardized tests, and in actuality have little to do with how "good" the school is.

This post is going to outline all the major flaws that I find with the school.

Nightmare: Snakes and Death

September 27th
This dream was a bit more mystical than the one during the night before; it's a lot harder to put it into context.

For some reason I was walking in an area with a lot of trees, with many poisonous snakes on the ground. Of course, I couldn't actually tell whether they were poisonous or not, but they had black bodies plus some weird yellow patterns on their skin, so I assumed they were. Also, these snakes were all very large. They were perhaps as thick as a person's leg.