lecture 3 (chapter 11) Flashcards
viral chromsome characteristics
- either DNA OR RNA, single OR double stranded
- circular
baterial chromosome characteristics
- circular, double-stranded DNA compacted into nucleoid
- DNA is assocated with HU and H-NS DNA-binding proteins
__ and ___ contain their own DNA
mitochondria, chloroplasts
mtDNA characteristics
- double stranded (no chromosomal proteins)
- introns absent
- most genes are encoded on one strand
cpDNA characteristics
- circular, double-stranded, free of associated proteins found in eukaryotic DNA
- has BOTH introns and duplications
in vertebrate mitochondrial DNA, the two DNA strands vary in density. This implies…
that one strand is enriched in A’s and G’s while the other strand is enriched in T’s and C’s
chromatin at interphase
eukaryotic chromosomes uncoil and decondense into chromatin
chromatin during interphase
chromatin is dispersed throughout nucleus and replicated
chromatin during cell division
coils and condenses back into visible chromosomes
histone proteins
`
responsible for the first level of DNA packing in eukaryotic chromatin
histone proteins contain large amounts of
lysine and arginine
twists and turns of DNA superhelix encircle _
histones
nucleosome consists of
DNA wound around a protein core of eight histones
to allow replication and gene expression, chromatin must:
- relax compact structure
- expose regions of DNA to regulatory proteins
- have a reversal mechanism for inactivity
acetylation enzyme
histone acetyltransferase (HAT)
acetylation
addition of acetyl group to positively charged amino group on side chain
acetylation changes net charge of protein by
neutralizing positive charge
methylation enzyme
histone methyltransferase (HMT)
methylation adds methyl groups to _ and _ residues in histones
argnine, lysine
phosphorylation enzyme
kinase
phophorylation adds phosphate groups to _ groups of amino acids _ and _ in histones
hydroxyl (-OH), serine, histidine
CpG island
region of DNA where many cytosine guanine dinucleotides are present
methylation of the cytosine within polynucleotide chains of DNA;
- forms 5-methyl cytosine
- negatively correlated with gene activity
satellite DNA
many repeats of short sequences
* found at regions flanking centromeres
