Molecular biology of the gene 1

1st set of flashcards

role of histone H1

linker histone - binds to linker DNA and nucleosome-associated DNA, impacts entry/exit angle of DNA to cause tighter packaging

what impacts whether the solenoid or zigzag form of the 30nm chromatin fibre forms

length of linker DNA, H1 variants

describe the higher order packaging of the 30nm chromatin fibre

forms loops of 40-90kb that are held at the base by chromosome scaffold which contains topoisomerase II and SMC proteins

what can chromatin loops act to do

delineate active regions of the genome

role of scaffold associated regions of DNA (SARs)

mark chromatin boundaries

what does condensation of chromosomes cause

early mitosis

role of condensins

hydrolyse ATP to coil chromosomes

what causes bacterial DNA to be more compact

chromosome is negatively supercoiled

what does the dynamic interaction of nucleosomes allow

DNA binding proteins bind in sequence-specific way

mechanism of non-homologous end joining

Ku protein detects breaks and binds DNA ends, Ku:DNA complex dimerise and align duplexes, nuclease, polymerase, ligase join fragments

5 types of DNA repair

direct reversal, base excision repair, nucleotide excision repair, double strand break repair, translation synthesis

what does base deamination result in

base transition causing mismatch

what is the repair mechanism for x-ray chemical adducts

homologous recombination

how can the nucleiod be unfolded

by agents acting on RNA and protein

what do nucleosome remodelling complexes catalyse

sliding of DNA along histone octamer to cause decondensed chromatin

how does lysine acetylation affect chromatin structure

neutralises positive charge of histones which relaxes packaging

2 roles of histone variant H2AZ

gene expression, chromosome segregation