Chapter 15: Eukaryotic Gene Expression Flashcards
what is known as the hallmark of cancer?
uncontrolled proliferation
activation and repression of gene expression is a
delicate balancing act for an organism
regulation of gene expression in bacteria is linked to
metabolic need
in eukaryotes regulation of gene expression has several
levels of regulation
what forms chromatin?
histone and nonhistone proteins
nucleosomes are
repeating DNA-histone complexes
compact chromatin inhibits which processes?
- DNA replication
- DNA repair
- transcription
what is known as a space that is occupied by an individual chromosome?
discrete domain
what is known as channels between chromosomes that contain little to no DNA?
interchromatin compartments
transcriptionally active genes are located…
at the edge of chromosome territories next to channels
where is RNA processing machinery found?
in the interchromatin compartments
chromosome alterations include…
- chromatin conformation
- histone modification
an example of chromosomal conformations is
H2A to H2AZ
examples of histone modifications include
-covalent bonding
-acetylation
-
acetylation decreases…
the positive charge of histones
Histone acetyltransferase enzymes (HATs)
- catalyze histone acetylation
- are associated with increased transcription
histone deacetylases (HDACs)
- remove acetyl groups from histone tails
- recruited to genes by transcription repressor proteins
examples of chromatin alterations include…
- histone modification
- DNA methylation
- chromatin remodeling
chromatin remodeling involves
repositioning or removal of nucleosomes on DNA
DNA methylation plays a role in gene expression by
repressing gene expression
what are the two types of promoters?
- focused core promoters
2. dispersed core promoters
list five core promoter elements
- initiator element
- TATA box
- TFIIB recognition element (BRE)
- motif ten element (MTE)
- downstream promoter element (DPE)
transcription factors serve to
increase or reduce levels of transcription
what is an example of a gene that can be regulated due to the interplay of promoters, enhancer elements, and transcription factors?
Metallothionein 2A gene (MT2A)
MT2A gene product is a
protein that binds to heavy metals and protects cells from toxic effects
what initiates the formation of the pre-initiation complex (PIC)?
IID protein binding to TATA box
define coactivators…
serve as bridge between activators and GeneralTranscriptionFactors
define enhanceosomes…
large complexes of activators and coactivators that direct transcription activation
exons
code for amino acids
introns
do NOT code for amino acids
variants of a protein are known as
isoforms
what are the 5 different ways pre-mRNAs can be spliced?
- cassette exons
- alternative splice site
- intron retention
- alternative promoters
- alternative polyadenylation
what is the most common type of alternative splicing in plants, fungi and single celled eukaryotes?
intron retention
transcription of what signal terminates transcription?
polyadenylation
alternative splicing increases…
number of proteins made from each gene
term that defines when the number of proteins an organism makes exceeds the number of genes in a genome
proteome
RNA-binding proteins act by
binding or hiding splice sites to promote use of alternative sites
term used for genetic disorders that are caused by mutations that disrupt RNA splicing
spliceopathies
what is an example of a spliceopathy?
myotonic dystrophy
what is known as the total amount of mRNA that a cell has for translation?
steady-state level of mRNA
exoribonucleases are
enzymes that degrade RNA by removal of terminal nucleotides
what are the enzymes that degrade the poly-A tail?
deadenylase
exosome complex destroys mRNA in a
3’ to 5’ manner
decapping enzymes
remove 5’ cap
XRN1 exoribonuclease destroys mRNA in a
5’ to 3’ manner
mRNAs are cleaved internally by
endoribonucleases
sncRNAs have two subtypes which are
siRNAs and miRNAs
siRNAs…
cleave mRNA
miRNAs…
inhibit translation
RNAi is a mechanism by which
ncRNAs guide post-transcriptional silencing
kinases are
enzymes that catalyze the addition of phosphate groups
phosphatases are
enzymes that remove phosphates
protein degradation regulation is done via
ubiquitin-mediated protein degradation
proteasome
unwinds and removes ubiquitin tags
