Thursday, September 2, 2021

Nucleic Acids

Biology Index

Where are we going with this? The information on this page should increase understanding related to this standard:  Evaluate comparative models of various cell types with a focus on organic molecules that make up cellular structures.

Article includes ideas, images, and content from Troy Smigielski (2021-09)

Nucleic Acids
(Hmm… What now?)

So… yet one more biomolecule… Let's get going!

Nucleic acids function to store genetic information and provide instructions for building proteins.

Nucleic acids are made of nucleotides.

That means that the monomer for nucleic acids are nucleotides.


A nucleotide is made up of:

sugar + phosphate + nitrogenous base 

The nitrogen bases in DNA can be broken down into two categories: Purines and Pyrimidines.

Purines have 2 rings. Examples are Adenine (A) and Guanine (G).

Pyrimidines have 1 ring. Examples are Cytosine (C), Thymine (T), and Uracil (U).

Chargaff’s Rules

In nucleic acids…
…a purine will ALWAYS bond with a pyrimidine.
…the A pairs with T or U.
…the C pairs with G.

…the number of A and T is always the same.

…the number of C and G is always the same.

In each nucleotide, you have a sugar, a phosphate, and a nitrogen base.

The nitrogen base will be A, G, C, or T (in DNA).

If the base is A, then there will be a T on the other side of it.

Likewise for C and G

Two Kinds of Nucleic Acids

There are 2 kinds of nucleic acids:
DNA: locked inside the nucleus
RNA: can leave the nucleus

DNA = DeoxyriboNucleic Acid

RNA = RiboNucleic Acid

So… what's the the difference between DNA and RNA?

DNA: stuck in nucleus
  • Double-stranded (double-helix)
  • Main information molecule

RNA: can leave nucleus
  • Single-stranded
  • Functions mainly as a middle man for making proteins

How do nucleic acids apply to real life?

DNA is often used to convict or exonerate suspects from a crime. Most people have seen the TV show, CSI. DNA analysis is a common aspect of that show, just as it is in many major crime investigations.

How does it work? The DNA code is represented by bands that can be compared much like fingerprints are compared, but… You can't hide your DNA by wearing gloves!

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