Agenda Intro to DNA Awesome DNA song(s) Make DNA origami If you missed the test, please see me

DNA DeoxyriboNucleic Acid

DNA is the Genetic Material of Chromosomes

Levels of Structure Chromosomes are long DNA molecules packed together DNA is composed of 2 strands Each strand is a long string of nucleotides

DNA is the blueprint Contains the codes for what makes us, well, us We are really just scratching the surface in understanding the ways DNA works

Some basics about DNA We have a lot of it- every cell contains about 6.5 feet of DNA (if you were to run each molecule end to end) The total length of DNA in our body would go the sun and back ▫70 times!

Our Understanding of It Is Changing Rapidly Old ViewNew View DNA is mostly genes Each segment of DNA is a gene that codes for a protein Rest of DNA is “junk” <1% of DNA are actually coding genes The rest controls the expression of genes or play as-of- yet undiscovered roles

What We Have a Good Understanding Of The structure of DNA (shape, how it is stored etc.) How DNA is replicated How proteins are made from genes The sequence of DNA

What We Barely Understand What a lot of the non-coding DNA does Genetic links in things like heart disease/cancer The exact details on how gene expression works How DNA came to be, chromosome came to be etc. Much, much more

Our Knowledge of DNA is Changing RAPIDLY! Our understandings now is very different from when I was in college which is different from when I was in HS. Our understanding will have changed if you take biology in college The old adage “50% of what you are learning is wrong- the problem is we don’t know which 50%”

DNA Structure Double helix consisting of 2 strands wrapped around each other Discovered by Watson and Crick AND Rosalind Franklin

Rosalind Franklin Provided the scientific evidence that allowed Watson and Crick to suggest the double helix Often goes un- credited and since she had died – couldn’t share in the Nobel prize

Nucleotide A single piece of the DNA strand Made of 3 parts ▫Deoxyribose (sugar) ▫Phosphate ▫Base (A,G,C or T)

The helical backbone of 1 strand Alternates between the sugar (deoxyribose) and the phosphate group The base sticks out into the middle

Double-Stranded The bases bond with each other to hold the strands together ▫The base from one strand bonds with the base from the other forming a base pair They coil into a double-helix

Hydrogen Bonds Between Base Pairs A T G C Allows strands to separate relatively easily ▫To allow new DNA to be made ▫To allow gene to be expressed

The Nucleotide Bases

More about DNA The genetic material in EVERY living thing ever observed Though it is packaged differently, the basic mechanisms of DNA are similar in all living things ▫Bacteria have only 1 chromosome, it forms a circle, much less DNA than us

Fun Facts About DNA Humans have about 3 billion base pairs in every cell (on each strand, so 6 billion nucleotides) If you printed the DNA sequence it would take 200 NYC phone books. Typing 60 words per minute 8 hours a day would take you 50 years to type a person’s DNA sequence All humans share 99.9% of our DNA Your great^x grandparent was a Neanderthal (1- 4% of our genes are thought to be Neanderthal genes)