2. DNA structure
1. DNA nucleotide structure
2. The four bases in DNA
3. How DNA nucleotides are linked together by
covalent bonds into a single strand
3. DNA is a kind of nucleic acid
Sugar
DNA
Polynucleotide: made by a lot of
nucleotides…. Nucleotide: organic molecule.
Building block of nucleic acids
4. Aldopentose
The simplest form of sugar
Monosaccharide with 5 carbon
atoms and an aldehyde functional
group at position 1.
Monosaccharide
R = Side chain
5. • Electrons on the
alcohol oxygen are
used to bond carbon
#1
• The hydrogen (green)
is transferred to the
carbonyl oxygen
(green) to make a
new alcohol group
(green)
9. Nitrogenous base Ribonucleoside Deoxyribonucleoside
Adenine
Adenosine
A
Deoxyadenosine
dA
Guanine Guanosine
G
Deoxyguanosine
dG
Thymine Thymidine
dT
Uracil
Uridine
U
Cytosine
Cytidine
C
Deoxycytidine
dC
10. BASE + SUGAR + PHOSPHATE = NUCLEOTIDE
•Ester bond:
Carboxyl group
combines with the hydroxyl
from the phosphate group.
Very strong covalent bond.
•Glycosidic bond:
Bond between a
carbohydrate and another
group. Also a covalent bond.
11. • Covalent bonds connect the sugar of one
nucleotide to the phosphate group of the
next.
A covalent bond is a
chemical link between
two atoms in which
electrons are shared
between them.
14. • 1950’s Rosalind Franklin
& Maurice Wilkins
X-ray crystallography
• Watson & Crick (1953 described their model)
Saw the photos of R.Franklin and created a
model.
Sugar-phosphate backbone on the outside and
bases inside of the double helix. Nitrogen
bases aligned formed hydrogen bonds.
Complementary base pairs, due to size of bases
and ability to form hydrogen bonds with each
other.
