dna organization in chromosomes Flashcards
Describe bacterial and viral chromosomes
single nucleic acid molecule, devoid of associated proteins, smaller than eukaryotic chromosomes
What are the characteristics of viral dna?
Nucleic acid, either DNA or RNA, circular or linear, inert until released into host, can package DNA into small volume
What are the characteristics of bacterial chromosomes
double stranded dna associated with HU and H1 dna binding proteins
What does supercoiling do
compacts dna
why are polytene chromosomes useful?
very large and can be visualized by light microscopy
What are puff regions?
Uncoiled areas of polytene chromosomes that have a high level of gene activity
what is chromatin composed of?
nucleosomes with histones h2a, h2b, h3, and h4
what are the levels of chromatin structure
nucleosomes, solenoid, chromatin fiber, metaphase chromosome
What are the different histone modifications?
Acetylation, methylation, and phosphorylation
Euchromatin vs heterochromatin
euchromatin - uncoiled and actively transcribed
heterochromatin - condensed and inactive
C banding vs G banding
C - only centromeres are stained
G- due to differential staining along the length of each chromosome
What is repetitive dna and its categories?
Sequences repeated many times in eukaryotic chromosomes
includes highly repetitive, and middle repetitive dna
What is satellite DNA?
highly repetitive, includes telomeres and centrosomes, the latter of which mediates chromosomes migration during mitosis and meiosis
what does moderately repetitive dna include?
VNTFs, mini satellites, microsatellites,
These sequences are often used for forensic analysis
retrotransposons- generated via RNA intermediate, include SINES and LINES that are dispersed throughout genome rather than tandemly repeated
How much of the human genome consists of protein encoding genes?
A very small amount
Highly repetitive and moderately repetitive DNA constitute up to 40% of the human genome
Pseudogenes - part of single copy non coding regions.
