Major Points
1. "The central dogma":
DNA --> RNA --> Protein
2. The genetic code
3. The processes of transcription & translation
DNA Replication
Conversion between "Languages"
Instructions in DNA are expressed in a nucleotide "language" or
"code"
Proteins are expressions of a different "language" of amino acids
The process of conversion of nucleotide code to amino acids
is a process of "translation"
A Messenger Molecule
DNA can not be directly read into proteins
* It must be converted into a messenger nucleic acid, ribonucleic acid (RNA)
* Both molecules use the same nucleotide language or "code"
Therefore, conversion of DNA to RNA is a copying process (as done by a "scribe")
The process is called "transcription"
The Structure of DNA & RNA
Nucleic acids are made from nucleotides which have three parts:
* A nitrogen rich base
* A sugar molecule (DNA: deoxyribose RNA: ribose)
* A phosphate
* RNA replaces the base thymine (T) with uracil (U) which base pairs with
A
Nucleic Acids have Polarity
The phosphate forms a bridge between adjacent nucleotides
* It links the positions referred to as 5' and 3' to each other
* Transcription of DNA into RNA occurs in a 5' to 3' direction
- The start of the RNA has a free 5'
- The end of the RNA has a free 3'
The Process of Transcription
* RNA polymerase unwinds a segment of DNA (at a promoter)
* It begins making an RNA copy by base pairing with the DNA
* It moves along, continuing to copy
* At a special sequence it releases its RNA copy (termination)