Biochemistry - DNA Packaging

Thermal Dynamics of DNA

DNA structure must be stable enough to achieve necessary conformations but weak enough to break bonds to separate into single strands

DNA denaturation/melting

increasing temperature to break hydrogen bonds

DNA renaturation/annealing

increasing temperature to rejoin bonds

true or false: melting temperature is dependent on GC content of DNA and the higher the Tm value the more GC bonds present

true

true or false: for DNA renaturation the more complex the DNA the more time it takes to renature and a higher Cd value indicates longer time to renature

true

Cot curve - indicates area of repetitive and complex DNA regions

high up on y-axis (fraction reassociated) = highly repetitive/not unique region

steep slope fast Cot (revisit)

Hybridization

using probes to find DNA sequences that will specifically bind to it and then using those samples for testing

Chromatin

DNA is packaged in the nucleus in the form of chromatin; euchromatin gets transcribed and heterochromatin does not

Three components of chromosome

ARS (autonomously replicating sequence); centromere - attachment site of spindle fiber for mitotic division; telomeres

Chromatin to Chromosome Packing

chromatin wraps around histones which together are called nucleosomes and multiple nucleosomes are nucleofilaments which make up chromosomes

What histones does the nucleosome core contain?

2A, 2B, 3, and 4

true or false: histone 1 occupies the liner region between nucleosomes

true

Epigenetics - histones

modifications of core histones by reversible acetylation or methylation can impact gene expression and DNA packing as a result of environmental factors

What are the basic elements of a gene?