Chromosome Structure 2 Flashcards
what does the centromere consist of
highly repeated satellite DNA
what is the structure and function of telomeres
at the ends of chromosomes- made of multiple repeats of simple DNA sequences
believed to be responsible for protecting the coding DNA by acting as a buffer against damage
how are telomeres added to the ends of the chromosome
RNA containing enzyme telomerase
how do telomeres mark the aging process
number of repeats per telomere decreases with age
what are nucleosomes
protein spools- around which DNA is neatly wrapped
what are the two protein classes found in nucleosomes
histones and nonhistones
what is the general structure and function of histones
positively charged arginine or lysine rich protein. they interact with the ionic bonds in neg charged phosphate groups in the polynucleotide backbone
what are the five distinct histones
H1, H2A, H2B H3 and H4
which histones form the octameric core
H2A, H2B, H3, H4
what is a solenoid
a shape containing 6 nucleosomes- it is a stage of condensing DNA
what happens after a solenoid is formed
it is then folded into long loops
what is a miniband unit
occurs when the DNA loops of solenoids are arranged radially around the circumference of a single turn
how is a prokaryotic chromosome arranged
the dna is in a single closed circular molecule in the nucleoid. DNA folded into loops and then further into twists by DNA gyrase and topoismearase
