DNA is a long, double-stranded nucleic acid made of nucleotides, functioning as the primary informational molecule for storing genetic information about polypeptides. It consists of two complementary polynucleotide chains forming a double helix, held together by hydrogen bonds between nitrogenous bases. RNA serves various roles in protein synthesis and, in some viruses, acts as the primary genetic material instead of DNA.

2. • Classified as aClassified as a Nucleic AcidNucleic Acid
• Long, double stranded molecule madeLong, double stranded molecule made
up of monomers know asup of monomers know as nucleotidesnucleotides
• DNADNA

3. Nucleic acids, built by polymerizing nucleotides,Nucleic acids, built by polymerizing nucleotides,
function primarily as informational moleculesfunction primarily as informational molecules
for the storage and retrieval of information aboutfor the storage and retrieval of information about
the primary sequence of polypeptides.the primary sequence of polypeptides.
Store and Retrieve Genetic InformationStore and Retrieve Genetic Information
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4. Deoxyribonucleic acid serves asDeoxyribonucleic acid serves as
a cellular database by storinga cellular database by storing
an immense amount ofan immense amount of
information about all theinformation about all the
polypeptides a cell canpolypeptides a cell can
potentially makepotentially make
Ribonucleic acid occurs inRibonucleic acid occurs in
several different formsseveral different forms
(messenger RNA, ribosomal(messenger RNA, ribosomal
RNA, transfer RNA) and isRNA, transfer RNA) and is
needed to convert DNAneeded to convert DNA
information into polypeptideinformation into polypeptide
sequences. In some viruses,sequences. In some viruses,
RNA serves as the primaryRNA serves as the primary
database with no DNAdatabase with no DNA
involvement.involvement.

6. • Basic unit of DNABasic unit of DNA
• Three PartsThree Parts
Deoxyribose sugarDeoxyribose sugar
Phosphoric acidPhosphoric acid
Nitrogen baseNitrogen base

7. Many nucleotidesMany nucleotides
are piecedare pieced
together to make atogether to make a
DNA moleculeDNA molecule
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8. There are four different basesThere are four different bases
found in DNA. Because eachfound in DNA. Because each
base contains at least twobase contains at least two
nitrogen atoms, they are callednitrogen atoms, they are called
nitrogenous bases.nitrogenous bases.

9. There are twoThere are two
classes of bases:classes of bases:

10. DNA consists of two polynucleotideDNA consists of two polynucleotide
chains wound around each other tochains wound around each other to
form a double helix. The two chainsform a double helix. The two chains
are held together by complementaryare held together by complementary
base pairing; that is, specific bondingbase pairing; that is, specific bonding
between A and T bases and betweenbetween A and T bases and between
G and C bases on the two strandsG and C bases on the two strands..

11. A DNA chain consists ofA DNA chain consists of
nucleotides joined by bondsnucleotides joined by bonds
between phosphate and sugarbetween phosphate and sugar
This makes up the sides of theThis makes up the sides of the
DNA “ladder”DNA “ladder”

12. In complementary baseIn complementary base
pairing, the two DNApairing, the two DNA
chains are heldchains are held
together by hydrogentogether by hydrogen
bonds betweenbonds between
nitrogen bases!nitrogen bases!

13. Complementary baseComplementary base
pairingpairing involves specificinvolves specific
hydrogen bondinghydrogen bonding
between A and T basesbetween A and T bases
(two bonds) and between(two bonds) and between
G and C bases (threeG and C bases (three
bonds).bonds).
These paired basesThese paired bases
form the rungs ofform the rungs of
the DNA ladder!the DNA ladder!

14. Do you know your DNA???Do you know your DNA???
Go to the Biology Place to test yourself!Go to the Biology Place to test yourself!

15. DNA is the Master Molecule ofDNA is the Master Molecule of
Diversity. Its simple structure holdsDiversity. Its simple structure holds
the key to millions of different geneticthe key to millions of different genetic
codes for all of the species of life oncodes for all of the species of life on
Earth. In the days to follow you willEarth. In the days to follow you will
see how DNA carries out its role assee how DNA carries out its role as
the Master Molecule!the Master Molecule!