Card Set Information
Backbone is comprised of?
repeating phosphate pentose units.
Sugar phosphate backbone
Oriented to the outside of the double helix
Doesnt contain information
free phosphate group on the 5' carbon of the terminal sugar
free hydroxyl on the 3' carbon of the terminal sugar
____________keeps neucleiotides bonded covalently
In what direction does the DNA and RNA synthesis proceed in
5' to 3' direction
Where is information found in DNA
Stacked on top of one another forming parallel planes
What is the orientation of the polynucleotide strands in the double helix?
Adenine bonds with
2 hydrogen bonds
Cytosine bonds with
Bases are stabilized with?
Primarily with Hydrogen bonds
Most DNA in cells is right or left handed helix?
Right handed helix
B form of DNA
-In B form the majority of time
-2 helical grooves (
-This is important because it is where
protein interacts with the nucleic acid.
protein acess to basse pairs
In very low humidity (and dehydrated samples), the B form of DNA changes to the A form. Also RNA-DNA and RNA-RNA helices exist in the A form.
Found in in vitro
Short DNA molecules of alternating purine and pyrimidine nucleotides
Adopt a left-handed helix conformation known as the Z form
Z DNA is also transiently formed shortly after transcription and, as such, is a tag for actively transcribed genes.
B DNA can_____ about it's long axis. Which is important why?
It can bend along its long axis
It is important in DNA- protein interactions and in the folding of DNA into compact condensed structures
DNA denaturation andrenaturation is important when?
During DNA replication and intranscription. It is also exploited in many techniquesin molecular biology and genomics.
It is a function of GC conent because it takes more energy because of the 3hydrogen bonds
As we increase the percentage of CG bonds the higher the Tm temperature.
Can RNA fold
Yes, it has many secondary structures
Function is derived from the 3 dimentional structure, and the 3 dimentional structure is specified by the amino acid sequence.
Three dimentional structure= conformation
They have a bias
What binds amino acids together is the peptide bond
Also use the term residue=amino acid within the peptide/polypeptide
Refers to interactions at a local level
Folding of localized regions of a polypeptide chain
Stabilizing non-covalent interactions, forming as example:
Non covalent interactions=random coil
H bonds (stabilizes)
R- group point outwards
Laterally packed strands
H-bonding between backbone of the beta strands
not very long
parallel or antiparallel
R groups points outwards
stabolilized by H bonds
Why is Proline compact?
Because ring structures forces a natural bend. In other words the bends are rich in glycine and proline
Long range of folding with a polypeptide chain
hydrophobic interactions between non polar side chains
hydrogen bonds between polar side chains
disulfide bond between cysterine residues
Provides a compact structure of alpha helices, beta sheets and turns
Some protein need association with other polypeptides
Potassium Ion Channel; nearly identical polypeptides that create the channel. It takes 4!
Usually>1 megadaltons in size 10's to 100's of polypeptides chains(as well as other macromolecules)
Motif and Domain
3 different motifs
a) coiled- hydrophobic residue
- found in very fibrous proteins
b) Ef Hand/ helix loop-helix motif
- ionic bonds involving a Ca
-Ca2+ binding protein
c) Zinc finger motif
-allows polypeptides to interact with DNA and RNA
- RNA and DNA binding proteins
Many polypeptides are composites of different combinations of motif/ domains
* concerve domain,interchange of domain....which create new protein