DNA structure Flashcards
(21 cards)
what has the DNA helix structure contain
major and minor grooves to form receptors for drugs
what is the central dogma
DNA makes RNA which makes proteins
what is DNA present in
chromatin
what are the three forms that DNA can present itself as
A form, B form and Z form
characteristics of A form
its more tightly coiled, tRNA takes this form
has right handed helices
characteristics of B form
- its the most common
- has right handed helices
- has a major form (large group of bases are exposed)
- has a minor form (small group of bases are exposed)
characteristics of Z form
- left handed helices
- (formed when there are alternating purine - pyrimidine) bases
- present in small amounts
what are the nucleotide units linked by
3’ - 5’ phosphodiester bonds
what types of bases are adenine and guanine
purine bases (double ring structures)
what types of bases are cytosine and thymine
pyrimidine bases (single ring structures)
what does tRNA fold into
an A- from helix (A from nucleic acid)
what is a Holliday junction
a four stranded DNA junction which is formed when DNA from two different chromosomes come together.
what are Holliday junctions important for?
for repairing damage
where are tetraplex DNA formed at
at the telomeres
I bacterial DNA what is supercoiling of the DNA caused by?
DNA gyrase which uses ATP
what is the basic building block of chromatin
nucleosome
what is DNA complexed with
histones and made into a fibre called chromatin
how many histone units is DNA bound around
8 histone subunits
2X 2A, 2B, 3 and 4
where does histone 1 bind to
the outside and linker DNA
what is the combined loop of DNA around histones called
nucleosomes
what is chromatin (condensed to a 30nm chromatin fibre)
multiple nucleosomes coiled together and then stacked on top of each other.
