DNA structure and packaging Flashcards
Basic DNA structure
what are the purine bases
Adenine and Guanine
what are the purine bases
adenine and Guanine
Bigger bases
what are the pyrimidine bases
cytosine and thymine
small bases but long name
what are the characterisitics of purines
what allows us to identify them
two rings and one NH3 group
what differs adenine from guanine
both of double ring strucutre and NH3 group but guanine also has a double bond to O
what are the charecterisitics of pyrimidines
they have one ring and at least one double O bond
what differs cytosine from Thymine
Thymine has 2 double O bonds while cytosine has 1
All base pairs must have 2 double O bonds
Base pairing rules?
A pairs with T
G pairs with C
bases interact with H bonds
How many bonds does each base pair have?
Adenine with Thymine has 2 while Guanine with Cytosine has 3
because Guanine has an extra NH3 group to adenine
how is DNA packaged?
DNA strand->Nucleosome->Beads on a string-> chromatin-> chromosome
How is DNA packaged during transcription
Beads on a string
easier to acces genes
How is DNA packaged most of the time
Chromatin
How is DNA packaged during mitosis/Meisosis
chromosome
what is a nucleosome
It is when 8 histone proteins are bound together with DNA
why does DNA interact with Histones?
DNA is negatively charged because of phosphate groups while histone tails are rich in lysine and arginine which makes them positively charged