Fifth Lesson: Transcription Review and Translation Introduction

As we remember the “mechanistic work” of the cell is performed by proteins, yet the information to build proteins is encoded in the nucleotide sequence of DNA.  How do we take the data present within the nucleotide sequences of DNA into proteins?  Previously, we had discussed that there is an intermediate involved in this process called mRNA.  Only one of the strands of DNA contains the information required to build a functional protein (because of course, the DNA strands are complementary due to base-pairing rules).  A single-stranded molecule that is complementary to the protein-defining strand is first formed and this is the mRNA.  In other words the mRNA is complementary to the particular one strand in the DNA that contains the information required to form the given protein.  (In reality molecular biologists know exactly which strand of DNA is involved in protein formation and which strand is exactly considered the complementary strand that matches the exact sequence of mRNA.)  The process of forming this complementary strand is called Transcription.  (See Lesson 4 for more information)

(See also for visual: http://www.youtube.com/watch?v=ztPkv7wc3yU)

After the mRNA molecule is formed from Transcription, the next processed involved is called Translation.  Translation involves taking the sequence of the mRNA molecule and converting it into a protein.   Translation is performed by a very complex molecule comprised of both a special, different type of RNA, called rRNA, and proteins.   Together both the rRNA pieces and protein pieces form what is known as the ribosome.  Think of the ribosome has a hybrid engine: it has protein parts and rRNA parts that work together to form a functional unit, just like a hybrid engine usually has gasoline and electric parts that work together to produce energy.  The ribosome takes the information in the mRNA and converts it into a new protein.  This is a very complex process that I am going to divide between two sections, thus I will continue discussing this topic in the next section.

(The color portions are the protein part and the grey part are the rRNA part)


Additional Videos for Reference:
(Some of these maybe a little bit complicated but still offer visualizes for the points I make)

http://www.youtube.com/watch?v=Jqx4Y0OjWW4&NR=1

or