DNA Transcription

Today we reviewed replication and began discussing the central dogma and DNA Transcription.
Thought Questions:

1. What are the main differences between DNA replication and DNA transcription?
2. Why do cells do replication, why do they do transcription and how are the reasons different?
3. Why is the Central Dogma important?

Central Dogma: Gene--->mRNA---->Protein---->Trait  (Where does the environment come into play?)

The 2 main jobs of DNA are: 1. code for proteins (which result in traits). 2. Inheritance (pass along genetic information to offspring)

TRANSCRIPTION: (Basic Transcription video)
Jeopardy Game (Basics and Transcription are the only categories you need look at! the basic section still covers some things we've not discussed yet)

What is it?
Transcription is making a 'copy' of a gene to make a protein. (Many genes may be transcribed at one time, but not all of them).
What are the steps?
1. RNA polymerase unzips the DNA double helix at the beginning of a gene (where does it bind? -the promoter!).
2. Complementary Nucleotides (which have a sugar (ribose in RNA!), the phosphate group, and the nitrogenous bases) are brought in.
3. RNA polymerase connects the sugar-phosphate backbones of the nucleotides by covalent bonds.
4. Hydrogen bonds have formed between the nitrogenous base portions of the mRNA and DNA so these are broken
5. mRNA leaves the nucleus via pores to go to the ribosomes (where translation occurs!)

Here is the ppt on central dogma and transcription!

Central dogma transcription only from lvilleDrFox

Here is another document to help you review Transcription (don't worry about Translation yet!!). Don't forget Cells, Scope lab, and DNA replication!

03 transcribe and translate a gene (1) from lvilleDrFox

DNA structure and Homework for Monday

On friday we began talking about the Structure of DNA (Deoxyribonucleic Acid)

The 3 main parts of a DNA molecule are:



1. The Sugar: Ribose







2. A Phosphate group:  (what do you think the X stands for?)







3. A Nitrogenous Base (Adenine, Guanine, Cytosine, Thymine and Uracil - this is a special one that is in RNA only)

One of each of these together makes up a Nucleotide:

As we begin to build a DNA molecule, how are the nucleotides connected to each other to build the rung of the ladder? 

Hydrogen Bonds! What are the numbers of the Carbons in the ribose sugar? What Carbon is the "1st" Phosphate group connected to? The 5' (five prime) Carbon. The phosphate of the next nucleotide is connected by the 3' Carbon. This is way when we discuss DNA we say it goes in the 5' to 3' direction. How are the nucleotides bonded to each other (i.e. the sides of the ladder)? Covalent bonds.

Why would you want the middle to be Hydrogen, and therefore weaker, but the sides be Covalent bonds (stronger)? 

Finally, your homework for Monday is to continue with the handout on DNA structure and replication. If you finish that one you should then begin the 2nd DNA handout (it has the website from BioTeach on the top).