1) The nucleotide sequence of the attenuator region in the leader of the trp mRNA -
a) Contains features of a transcription termination site
Depurination - the loss of a purine base from a nucleotide
Deamination - the removal of an amino group from an organism, particularly from
an amino acid
attenuator region - region of RNA sequence that forms an alternate secondary
structures that govern the level of transcription of attenuated operons.
Transcription factors and other regulatory proteins that alter the chromatin
structure without altering the chemical structure of the histones are called: -
Chromatin-remodeling complexes
chromatin remodeling complexes - protein machines that use the energy of ATP
hydrolysis to change the position of the DNA wrapped around nucleosomes
The type of histone modification that decreases the positive charge of the histone
proteins and loosens the binding of the histone proteins to the DNA is: -
Acetylation; this will increase transcription rates
acetylation - addition of acetyl group
histone proteins - A simple protein bound to DNA, involved in the coiling of
chromosomes
, This process affects the expression of genes by changing chromatin structure and is
characterized by CpG sites and acts primarily on cytosine. - DNA Methylation
histone methylation - the condensing of chromatin structure (heterochromatin),
prevents transcription
DNA methylation - The addition of methyl groups to bases of DNA after DNA
synthesis; may serve as a long-term control of gene expression.
Chromatin Immunoprecipitation (ChIP) - can determine if proteins can bind to a
particular region of DNA in the chromatin of living cells
If glucose and lactose are both in the environment in an E. coli bacterial cell, the
regulation of the lac operon will allow which of the two to be processed first? -
Glucose will be processed and utilized first, and then once it is used up, lactose
will be utilized
lac operon - a gene system whose operator gene and three structural genes control
lactose metabolism in E. coli
Increases in DNA methylation can repress transcription in multiple ways: - a)
Methylated CpG sites in the vicinity of the promoter can interfere with
transcription
b) Methylated CpG sites attract methyl-CpG-binding proteins and other
remodeling complexes