DNA Reflection
•On one side of the paper:▫How do you think you did on the test?
▫If you had to grade yourself on your knowledge of Heredity, what would you give yourself and why?
▫What could you have done to be more prepared?
DNA on DNA (on other side of paper)
•What is the first thing that pops into your head when you hear “DNA”
•What do you already know about DNA?
•What do you want to know about DNA?
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 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 the base pairs hold the 2 strands together
•Allows strands to separate relatively easily▫To allow new DNA
to be made▫To allow gene to be
expressed
Storage of DNA
•In eukaryotes, DNA is coiled around histone proteins
•Controls access to the DNA
•Compacts DNA so lots of DNA can fit in a small nucleus
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)http://holykaw.alltop.com/17-interesting-facts-about-dna
Video not made by Mr. Mahon
•http://www.youtube.com/watch?v=wdhL-T6tQco
