understanding dna deoxyribonucleic acid double helix: two strands twisted around each other like a...
TRANSCRIPT
Understanding DNA
Deoxyribonucleic Acid
Double Helix: Two strands twisted around each other like a winding staircase
Rosalind Franklin & Maurice Wilkins
James Watson & Francis Crick
very large linear molecules
very large linear molecules
examples: DNA and examples: DNA and RNARNA
examples: DNA and examples: DNA and RNARNA
sugar
phosphate
nitrogen
base
nucleotide
store genetic store genetic information, help to information, help to
make proteinsmake proteins
store genetic store genetic information, help to information, help to
make proteinsmake proteins
Nucleotides A. Sugar (deoxyribose) B. Phosphate Group C. Nitrogen Bases
A
B
C
Erwin Chargaff
A T
C G
Rules for Base Pairing:
B. Adenine = Thymine (A = T)
A. Cytosine Guanine (C G)
the lines between the letters are hydrogen bonds
* stores genetic information
What is the function of DNA?
C
G
A
A
T
G
Sugar
Phosphate Nitrogen
Bases
Fun Facts
If you wrote down all of the bases in one cell, you would fill a stack of 1,000 phone books with A's, T's, G's and C's
Fun Facts
If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.
DNA Replication
DNA ReplicationResults in two identical DNA
strands 1. DNA helicase separates
or“unwinds” complementary nucleotide strands.
2. DNA polymerases move along each DNA strand adding nucleotides at the replication fork.
3. Each DNA molecule is composed of one old and one new strand.
Errors
DNA polymerases act as proofreaders and make corrections if the wrong nucleotide is added.