DNA DEOXYRIBONUCLEIC ACID. DNA IS THE GENETIC MATERIAL Only understood hundreds of years after...
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Transcript of DNA DEOXYRIBONUCLEIC ACID. DNA IS THE GENETIC MATERIAL Only understood hundreds of years after...
D N A
DEOXYRIBONUCLEIC ACID
DNA IS THE GENETIC MATERIAL
• Only understood hundreds of years after Mendel
• How do we know? Read about it before the test to answer the Level IV questions
DNA IS MADE OF NUCLEOTIDES
• 4 different bases, A, G, C and T
A STRAND OF DNA
• Sugar-phosphate backbone
DNA IS DOUBLE STRANDED
•Held together by Hydrogen bonds between bases• A T•G C
DNA FORMS A DOUBLE HELIX
• Suggested in 1953 by James Watson and Francis Crick• Don’t forget about Rosalin
d Franklin though
KEY DISCOVERIES OF DNA STRUCTURE
1. SEQUENCE OF NUCLEOTIDE BASES = CODE.
Stay tuned for C.O. 6.3 for more!
And there are 2 codes!
ATGCTAGGC +TACGATCCG
2. TWO COMPLEMENTARY STRANDS INCREASES ACCURACY
A G C T A C G C A T C
T C G A T G C G T A G
A G C T A C G C A T C
T C G A T A C G T A G
UV Radiation, Toxic Ooze, Etc.
A G C T A C G C A T C
T C G A T G C G T A G
A G C T A C G C A T C
T C G A T G C G T A G
A G C T A C G C A T C
T C G A T G C G T A G
Yay, I
didn’t get
cancer
3. EACH STRAND IS A TEMPLATE FOR BUILDING THE OTHER
DNA PACKAGING
• About 3,000,000,000 base pairs of DNA in every cell• Typing 60 wpm, 8 hours a day it would take you 50 years
to type out your genome
• Split into 23 pairs of chromosomes (46 total)
WHAT IS A CHROMOSOME?
• A very, very long sequence of DNA, coiled up very tightly• You have 23 pairs, one from mom, one from dad• Except if you are a guy instead of a pair of Xs you have
an X and Y
Why is this in an X? Stay tuned for C.O. 6.2!
UNDERSTANDING YOUR CHROMOSOMES
• Each chromosome contains thousands of genes, for a total of about 25,000• Genes actually make
up less than 1% of the DNA• What does the rest
do?• That’s what we’re
trying to find out! But it’s got something to do with gene expression!
DNA WRAPPING
• To understand how DNA is packaged, we will use pipe cleaners to represent segments of a chromosome• Each person begins with one pipe cleaner, which
represents about 8 million base pairs and 150 genes
DNA IS WRAPPED AROUND HISTONE PROTEINS
• We will use puffballs to represent histone proteins
WHY DOES THIS MATTER?
1. CONTROLS ACCESS TO THE DNA AND THUS THE EXPRESSION OF THE DNA
• E.g. epigenetics
Genes are accessible here
2. DNA MUST FIT IN A SMALL SPACE
• Amount of DNA in your body would go to the sun and back• 600 times!
• Each cell contains 5 feet of DNA packed into a nucleus with a radius of less than a hundredth of a millimeter
PACKAGE OUR DNA
• Wrap up your DNA in the histone proteins• Connect your DNA to the partners in your
group• Connect your group to the other groups in
the class• How small can we make our DNA!?
• ** not all that small because we used really large histone proteins to help you see what’s happening, but still!