Contributed by:
We will be discussing the structure of DNA in this article. Deoxyribonucleic acid is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses. DNA and ribonucleic acid are nucleic acids.
2.
DNA stands for
Deoxyribonucleic acid
3.
DNA Structure
DNA consists of two molecules that are
arranged into a ladder-like structure
called a Double Helix.
A molecule of DNA is made up of millions
of tiny subunits called Nucleotides.
Each nucleotide consists of:
1. Phosphate group
2. Pentose sugar
3. Nitrogenous base
4.
Phosphat
e
Nitrogeno
us
Base
Pentos
e
Sugar
5.
The phosphate and sugar form the
backbone of the DNA molecule,
whereas the bases form the “rungs”.
There are four types of nitrogenous
bases.
6.
A T
Adenine Thymine
C G
Cytosine Guanine
7.
Each base will only bond with one
other specific base.
Adenine (A)
Form a base
Thymine (T)
pair.
Cytosine (C)
Form a base
Guanine (G)
pair.
8.
Base-Pair Rule
Adenine <==> Thymine
Guanine <==> Cytosine
The sides of the DNA
ladder are phosphate &
sugar held together by
hydrogen bonds
9.
DNA Structure
Because of this complementary base
pairing, the order of the bases in one
strand determines the order of the
bases in the other strand.
11.
Base Pair Rule
One side: A T A T C A T G C G G G
Other side:
12.
DNA Structure
To crack the genetic code found in
DNA we need to look at the sequence
of bases.
The bases are arranged in triplets
called codons.
AGG-CTC-AAG-TCC-TAG
TCC-GAG-TTC-AGG-ATC
13.
DNA Structure
A gene is a section of DNA that codes for
a protein.
Each unique gene has a unique sequence
of bases.
This unique sequence of bases will code
for the production of a unique protein.
It is these proteins and combination of
proteins that give us a unique phenotype.
14.
How the Code Works
The combination of A,T,G,C determines what
traits you might have, for ex.
C A T C A T = purple hair
T A C T A C = yellow hair
15.
Think of the bases of DNA like
Letters form words....
Words form sentences....
*endless
combinations
17.
Let's Review What We Know
About DNA
1. DNA stands for: De _____ ribo ______ acid
2. What is the shape of DNA? _______________
3. Adenine always pairs with _______________
4. The sides of the DNA ladder are deoxyribose and _____
5. Guanine always pairs with _____________
6. What is the complimentary sequence: A A T G C A
7. The two sides of DNA are held together by _______
8. DNA is composed of repeating subunits called
9. What are the 4 bases that make up the rungs of the DNA
ladder? _______________________________________
+1-315-636-4485
+91 98151-74050 
