DNA STRUCTURE Flashcards
What is a polar molecule?
Molecule that contains atoms at either end with differing attractive forces to the electrons they share. This results in one end having a slightly negative charge whilst the other positive.
What are two examples of substances that are hydrophillic?
Ionic and polar molecules. (e.g. NaCl and urea)
What is a property of hydroxyl group?
Polar
What is a property of a methyl group?
Nonpolar
What is a property of a carbonyl group?
Charged, ionises to release H+ (acidic)
What is a property of an amino group?
Charged, accepts H+ to form NH3+ and is basic (because amino groups can remove H+ from solution)
What is a property of a phosphate group?
Acidic (charged and releases H+ into solution)
What is a property of a phosphodiester group?
Charged and present in DNA
What is a property of a sulfhydryl group?
Polar
Where is ‘extragenic ‘ information read from in DNA?
The surfaces exposed in the double helix
What is the extragenic information in DNA used for?
Used by proteins to read the code without unwinding the DNA helix and targeted by toxins and drugs that attack DNA
What conditions is A-DNA formed under and what conformation does it have?
Formed under dehydrating conditions and contains tipped bases with a deep major groove.
Why is RNA in the A form?
Extra hydroxyl group on the sugar is in the way and as result, the B form is unstable.
What is B-DNA and what conditions is it in?
This is the DNA double helix that is found under NORMAL conditions inside cells.
What is Z DNA and what conditions is it formed in?
Formed under high salt conditions and has lots of alternating C-G G-C pairs
If messenger RNA carries the code for only one polypeptide, what is it termed?
Monocistronic
If messenger RNA carries the code for more than one polypeptide, what is it termed?
Polycistronic
Between which types of bases in base stacking are interactions strongest?
Between purines
What is strange about base pairing in RNA?
Sometimes G pairs with U when two single strands of RNA pair or if RNA folds back on itself
Which properties of DNA are often used to help scientist manipulate and study DNA?
Solubility, Charge, Viscosity, UV absorption, Denaturation, Stability
In UV light absorption, where does Dye bind to in DNA to emit a blue light under UV?
The dye binds to the minor groove in AT rich regions
If there are more G-C bonds, what effect does this have on DNA?
Increases melting temperature and increases stability (linear relationship)
The phosphodiester bonds that link nucleotides in both RNA and DNA are broken by…… and join……
broken by mechancal shearing and join the 3’ hydroxyl of one nucleotide to the 5’ hydroxyl of the next
Do DNA binding proteins interact with the bases on the major or minor groove?
They interact on the major groove side because the backbones are not in the way.
