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 RapidlyOld View New 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 causes genes to be activated or

expressed•What the 99% of DNA does or why it’s

there•Genetic links in things like heart

disease/cancer•How the environment affects our DNA•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•Theorized to be a

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 uncredited 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

What You Should Know about DNA structure•The basic structure of a nucleotide

•The basic structure of DNA•How DNA and RNA differ•Base-pair rules•How the structure suggests a replication method