DNA
What are nucleic acids?
Why is it important?
Structure of DNA
Scientists
Nucleic Acid
• Nucleic Acids are large complex molecules
containing genetic material
• Made of nucleotides
– sugar, phosphate group, and nitrogen base
Two types:
1. Deoxyribonucleic Acid- DNA
2. Ribonucleic - RNA
• DNA carries instructions that regulate cells
activities
• RNA–uses information from DNA to make
proteins
Nucleic Acids
• Nucleotides:
– Phosphate
– 5 carbon sugar (deoxyribose
in DNA, ribose in RNA)
– Nitrogen Base (Adenine,
Thymine, Guanine,
Cytosine)
What is DNA?
• DNA- deoxyribonucleic acid
• DNA contains the genetic information
that makes you, you… animals,
animals and plants, plants…
• DNA is composed of:
– Double helix
– Phosphate group
– 5 carbon sugar (deoxyribose)
– Nitrogen containing base
– Weak hydrogen bonds
Make up a
Nucleotide
Why is DNA Important?
• DNA is in all living things
• It is found in the cytoplasm of bacteria
and in the nucleus of protists, fungi,
plants, and animals.
The Structure of DNA
• Nucleotides- subunits (monomers) that
make up DNA
– Phosphate group
– 5 carbon sugar (deoxyribose)
– Nitrogen containing base (nitrogenous base):
• Adenine
• Guanine
S
P
Thymine
Cytosine
(A – T)
(G – C)
* Weak hydrogen bonds hold bases together
The Structure of DNA
• Double helix- two strands of nucleotides
twisted around each other, like a
winding staircase
• Complementary base pairs- the
sequence of bases on one strand that
determines the sequence of the other
strand
– Adenine
– Cytosine
Thymine
Guanine
The Structure of DNA
• So, if the sequence on one side is:
A
T
C
G
G
C
A
T
T
A
5’
The Structure of DNA
3’
A
Label:
-Phosphate (P)
-5 carbon sugar
(S)
C
-Correct base
pairs
(A, T, C, G)
-Draw hydrogen
bonds
5’
3’
The Sequence of DNA
• The sequence (order) of nucleotides
determines an individuals traits
• If the nucleotide sequence of nitrogenous
bases (adenine, guanine, cytosine, thymine)
are in a similar order, the more related two
things are
– This concept is used in forensic science and is
called DNA fingerprinting
The Structure of DNA
*Note about bases:
– Pyrimidines- single ring of carbon
• Tymine and Cytosine
– Purine- two rings of carbon
• Adenine and Guanine
A purine must always bond with a
pyrimidine!
DNA Discoveries and Scientists
• Alfred Hershey and Martha Chasediscovered that DNA stores genetic
information in living cells
• James Watson and Francis Crickpieced together the structure of DNA
• Rosalind Franklin—developed X-ray
pictures of DNA
• Chargaff- noticed the rules for base
pairing (Adenine- Thymine and Cytosine –
Guanine)
Why is DNA important?
• DNA is the basis of genetic material and
serves as the template for making proteins.
• Proteins make:
– your eye color and hair color
– antibodies in your blood
– enzymes vital to your metabolism
– skin and muscles
• Proteins make you, you!