Who was most influential? Erwin Chargaff – 1:1 ratio of A to T – 1:1 ratio of C to G Linus Pauling – Laws of chemical bonding that show location of atoms in molecules ( ) – Measured helical proteins Rosalind Franklin – A and B form of DNA – Distance of one repeat in A form DNA helix – Confirmed A/G and C/T pairings – Paired anti-parallel strands Maurice Wilkins – Studied DNA before Watson, Crick and Franklin – Helped get Franklin hired at King’s College – Took is own x-ray images of DNA after Franklin – Realized that needed both experiments, mathematical models and physical models to understand structure of DNA. – Later designed a camera that took more detailed pictures James Watson and Francis Crick – Put all of the facts together – Watson – the only biologist – knew that DNA had to pass on information and explained this in model. A pairs with T C pairs with G

Today you will be Code breakers and learn how to break the code for creating new DNA strands and how the code in DNA is broken to produce and make proteins!!

Do you remember the basic form of DNA?

DNA Replication DNA needs to replicate itself for the purpose of cellular division Cells need to be created: To replace cells that have died like skin cells. How often to you scratch your skin and see dead cells? To create a cell (sperm or egg cell) to reproduce a new organism

Steps to DNA replication DNA is unwound and unzipped by enzymes The DNA code is read by DNA polymerase which adds the corresponding nucleotide (Nitrogenous base, sugar and phosphate) Example Adenine is added to Thymine and Cytosine is added to Guanine

DNA before Replication

Both DNA Strands are read and a new identical DNA strand is created. If the original DNA strand was ATCGCCGTTA The corresponding strand created would be TAGCGGCAAT What strand would be created if the original strand was AAAACCGGATTT? The strand would be TTTTGGCCTAAA You are so SMART!!!!!!!!!!!

Lets try a few more What DNA strand would be created from the following DNA strand? AATTACGCGGCCC Did you say TTAATGCGCCGGG How about TATATACCGATTTA Did you say ATATATGGCTAAAT Great!!!

The DNA Polymerase serves as a proof reader to correct any mistakes Mistakes occur in 1/10,000 nucleotides added. An error creating a DNA could cause a disease to occur or the wrong directions given in another part of the cell. Fun Fact… There are some people who lack DNA polymerase and do not have anyone to correct the errors in the DNA made. They are more susceptible to getting cancer when DNA is damaged from exposure to UV rays.

How is the code read in the DNA to create proteins and give directions other places in the cell? I need 4 volunteers.

To make Proteins Step 1 Transcription(make mRNA) The code to create proteins which lies in the DNA must be carried to a place where there are materials for the proteins to be created. Where are proteins created? DNA is copied to mRNA because DNA is too big to leave through the nuclear pores. If DNA was not copied the code could not be transferred to the place it can be created.

mRNA is created mRNA is created very similarly to how DNA is replicated except for mRNA does not have Thymine Instead it has uracil so when there is an A in a DNA strand the mRNA would have a U. The DNA molecule is split open by RNA polymerase RNA polymerase looks for a specific code that tells it when to start creating RNA called a promoter. The corresponding Nitrogenous bases are added as well as the sugar and phosphate attached.

Can you break the DNA code? If the DNA sequence was ATTCGGCCATT what would the mRNA sequence be that was created? ___________________________ Did you say UAAGCCGGUAA Yeah!!

Lets try a few more If the DNA sequence was ATTCCGCCGG What would the mRNA sequence be? Did you say UAAGGCGGCC? How about TTCCGCGCGCCGAA? Did you say AAGGCGCGCGGCUU Great!!!

Not all sections of DNA that are copied are used to make proteins. Those sections of DNA used to create proteins are called exons Those sections not used to create proteins are called introns and are cut out of the mRNA before the protein is made.

Translation:is when proteins are made from the mRNA TrNA (Transfer RNA) is great at breaking codes. There is a specific code for every three letter nitrogenous base sequence These three letter sequences are called codons. Each codon tells which amino acid to add to the protein.

Three letter Codes are Codons.

For example…. GUU signals a transfer mrNA molecule to bring Valine a specific type of amino acid. If the three letters were GCC the tRNA would bring Alanine and add it to the protein. Just like building blocks make a wall Different amino acids create a unique protein

If I gave you the RNA sequence of CGGGUAUUAUGUGAAUGA what series of Amino Acids would be created into a protein? Did you say Arginine,Valine,Leucine, Cytosine and Glutamine? YOU ROCK!!!!!

Lets try one more….. If I gave you the MrNA strand of CGUAGUAGAAGGGCGUGA what Amino Acids would you bring together? Arganine, Serine, Argenine, Argenine,Alanine FABULOSO!!!!!

Amino Acids connect to make proteins

Here is a great picture of the whole process….

To review, I will give you the player…. You will tell me what is does in the process and where it hangs out. First for DNA replication DNA strand Enzymes DNA polymerase Nucleotide Nitrogenous Base Phosphate

Now for transcription and translation DNA strand Nuclear Membrane RNA polymerase MrNA TrNA Ribosome Codon Amino Acid Protein

Your Job……. Create 2 comic strips: 1 comic must illustrate how DNA is created for creating new cells It must include all major players involved They must talk about their role in the process in your own words They must be pictured in the location they do their job.

The other comic…. Illustrates transcription and translation (How mRNA is created and the code from a DNA molecule allows a unique protein to be made) This comic must represent each player involved…. Each player must talk about their individual role in the process Each player must be located in the environment they do their job.

This will be due Next Monday/Tuesday…. You will have a work day Wednesday/Thursday