Nucleic Acids Flashcards
What is the Central Dogma of Molecular Biology?
• DNA stores information which is: Transcribed to make RNA.
• RNA is modified and used as a template:
Translated to make protein
What are the building blocks of DNA and RNA?
*5-‐carbonsugar
examples – ribose (RNA)
– deoxyribose (DNA)
*Nitrogenous bases
Purines: Adenine and Guanine: 2 rings
Pyrimidines: Cytosine, Thymine & Uracil: 1 ring
- Nucleotide di-‐ and triphosphates (such as ADP and ATP)
Nucleotide di-‐ and triphosphates (such as ADP and ATP) are high energy compounds due to the energy associated with _______bonds. The high energy bonds in nucleotide phosphates (NTPs) provide the energy necessary for nucleic acid synthesis. ___ and _____are also used as a source of energy for MANY reactions.
.
Nucleotide di-‐ and triphosphates (such as ADP and ATP) are high energy compounds due to the energy associated with anhydride bonds. The high energy bonds in nucleotide phosphates (NTPs) provide the energy necessary for nucleic acid synthesis. ATP and GTP are also used as a source of energy for MANY reactions.
Important carbon designations on the sugar residue:
• Carbon 1 (1’) covalently linked to a base (______bond)
• Carbon 1 (1’) covalently linked to a base (glycosidic bond)
Important carbon designations on the sugar residue:
• Carbon 2 (2’)
– _____group in RNA,
– no oxygen in DNA (deoxy–)
• Carbon 2 (2’)
– hydroxyl group in RNA,
– no oxygen in DNA (deoxy–)
Important carbon designations on the sugar residue:
• Carbon 3 (3’)
– ______group in both DNA and RNA REQUIRED for polymerization of nucleic acids, joined to the 5’ carbon through a _____ bond.
• Carbon 3 (3’)
– hydroxyl group in both DNA and RNA REQUIRED for polymerization of nucleic acids, joined to the 5’ carbon through a phosphodiester bond
Important carbon designations on the sugar residue:
• Carbon 5 (5’) linked to one or more phosphates, joined to carbon 3 of an adjacent nucleotide through a __________bond.
• Carbon 5 (5’) linked to one or more phosphates, joined to carbon 3 of an adjacent nucleotide through a phosphodiester bond.
Structure of DNA:
• DNA is a polar molecule with a 5’ and 3’ end.
The free _____ group is at the 5’ end. The free ____ group at the 3’ end.
• DNA is a polar molecule with a 5’ and 3’ end.
The free phosphate group is at the 5’ end. The free hydroxyl group at the 3’ end.
Structure of DNA:
• Nucleotides in DNA are joined by ______bonds.
• Bases are linked by ______ bonds.
• Nucleic acids are described in a number of ways
- Nucleotides in DNA are joined by phosphodiester bonds.
- Bases are linked by glycosidic bonds.
- Nucleic acids are described in a number of ways
By convention, if no end designation is made, DNA is always assumed to be written __ to ___.
By convention, if no end designation is made, DNA is always assumed to be written 5’ to 3’. (5’—TACG—3’ is the same as TACG).
If a nucleotide sequence is to be written backward, the ends MUST be designated. How would TACG be written backwards?
3’—GCAT—5’ (these are the same molecules)
Occasionally you will see the location of the phosphate groups indicated, for example TACG may be written ____.
pTpApCpG
Occasionally you will see the type of nucleic acid indicated, for example a DNA sequence of TACG may be written ______or an RNA sequence of UACG may be written _______.
dTdAdCdG
rUrArCrG
What are two characteristics of DNA Structure and the Double Helix?
• Antiparallel – the two strands are opposite in direction
• Complementary – A always base pairs with T.
G always base pairs with C (via hydrogen bonds)
A::T Base Pairing – __H bonds
G::C Base Pairing – __H bonds
A::T Base Pairing – 2H bonds
G::C Base Pairing – 3H bonds
DNA Structure and the Double Helix:
• DNA is twisted like a spiral staircase
• Double helix forms ___ and _____ grooves, important for regulatory proteins (gene expression regulation)
major and minor
DNA Structure and the Double Helix:
• Hydrophilic sugar—_______backbone is one the outside of the helix, and contains a net NEGATIVE charge.
• Hydrogen-‐bonded base pairs are ______ and form the_____of the helix. It’s perpendicular to the axis of symmetry.
• DNA has domains that are hydrophilic, and hydrophobic. It is an amphipathic molecule and DIRECTIONAL.
DNA Structure and the Double Helix:
• Hydrophilic sugar—phosphate backbone is one the outside of the helix, and contains a net negative charge.
• Hydrogen-‐bonded base pairs are hydrophobic and form the “stairs” of the helix. It’s perpendicular to the axis of symmetry.
• DNA has domains that are hydrophilic, and hydrophobic. It is an amphipathic molecule.
Normally a right-handed helix, called _____ or __-DNA. It is a rarer form that contains a high GC content.
Watson-Crick DNA or B-DNA
Left-handed helix, called _-DNA (function unknown, possibly important for gene regulation).
Z-DNA
How many H-bonds does AT bonds have?
2
How many H-bonds does CG bonds have?
3
