Nucleic Acids | OAT
Nucleotides
• Nucleosides consist of a:
o 5-carbon sugar
o Nitrogenous base
• To make it a nucleotide, we must
add a phosphate group
Nucleosides and Nucleotides
A nucleoside is formed from the combination of
(b) a 5-carbon sugar and (c) a nitrogenous base.
Adding in (a) a phosphate group makes the
molecule a nucleotide.
•
There are 5 nitrogenous bases we
will use:
o Adenine
o Guanine
o Cytosine
o Thymine
o Uracil
Nucleic Acid
Nucleic acids are polymers of nucleotides. They
are joined by phosphodiester bonds (indicated by
pink arrow) between the phosphate group on one
nucleotide and the 5-carbon sugar’s 3rd carbon on
another nucleotide.
•
We denote nucleic acids as a
sequence of their nucleotides,
abbreviated by their first letter
o For example, a nucleic
acid consisting of
nucleotides with adenine,
guanine and cytosine
would be denoted AGC
Nucleic Acids
• Nucleic acids are polymers of
nucleotides
• The bonds joining the monomers
are phosphodiester bond
o They form between the
phosphate group on one
nucleotide and the 3rd
carbon on another
nucleotide’s 5-carbon
sugar
Sample Nucleic Acid
This acid, consisting of adenine, guanine, and
cytosine-containing nucleotides, would be
denoted AGC.
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© 2017 J Co Review, Inc., Accessed by Guest on 06-16-2017
Nucleic Acids | OAT
•
•
But why did we label the
molecule from top-to-bottom?
o Why AGC and not CGA?
We write nucleotides 5’ 3’
o To understand this, let’s
focus in on the guanine in
our AGC chain
And, let’s number
the carbons of
guanine’s pentose
Close-Up of Guanine in the Previously
Illustrated Nucleic Acid
Guanine is highlighted in blue, while adenine
and cytosine are in green and red, respectively.
•
•
•
•
•
The suffix –osine indicates a
nucleoside
i.e. adenine is a nitrogenous base,
and adenosine is its nucleoside
Nucleic Acids in the Body
• DNA and RNA are nucleic acids
o More on this later
• Also, ATP, NADH, and FADH2
are all nucleotides
o We will see these
molecules later in this
chapter
Adenosine Triphosphate (ATP)
Since we write nucleic acids 5’
3’, the nucleotide stemming off
guanine’s 5-carbon will appear
before guanine
o Adenine, which stems off
guanine’s 5-carbon, will
appear before guanine
And, nucleotides stemming off
guanine’s 3-carbon will appear
after guanine
o Cytosine, which stems off
guanine’s 3-carbon, will
appear after guanine
This gives our sequence: AGC
Suffixes
• Don’t be confused with suffixes
• The suffix –ine indicates a
nitrogenous base
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© 2017 J Co Review, Inc., Accessed by Guest on 06-16-2017