Chap 17 RQ - Genectics
Which of these are molecular mechanisms that underlie epigenetic control of gene expression? (4)
- Covalent histone modification - Localization of histone variants - Chromatin remodeling - DNA methylation
Which are the three most common ways that the functions of regulatory transcription factors are controlled?
- Covalent modifications - Protein-protein interactions - The binding of a small effector molecule
TFIID binds to the _______ box and helps recruit RNA polymerase II to the core __________
- TATA (box) - (core) promoter
Place the steps in glucocorticoid hormone and receptor action in order, with the first step at the top. (5)
1. The glucocorticoid hormone diffuses through the plasma membrane. 2. The glucocorticoid hormone binds to the glucocorticoid receptors. 3. HSP90 is released from the glucocorticoid receptor. 4. Two glucocorticoid receptors form a homodimer and travel through a nuclear pore into the nucleus. 5. The homodimer binds to a glucose response element and activates transcription of the adjacent gene
What kind of protein is expected to enhance the ability of TFIID to initiate transcription?
Activator protein
Stretches of DNA of 1000-2000 bp in length containing a high number of methylation sites and found near gene promoters are called ______
CpG islands
5-methylcytosine is formed by ______
DNA methyltransferase
Select the most common process regarding methylation
Maintenance methylation
True or false: The methylation state of DNA is inherited during cell division
True
A regulatory transcription factor that enhances the rate of transcription is called a(n) ________
activator
Relative to the promoter for a gene of interest, regulatory elements are located ______
at various distances
A protein that increases the rate of transcription but does not directly bind to the DNA is called a(n) _______
coactivator
For Arabidopsis, flowering in spring due to exposure of colder temperatures in the winter is associated with ______ modification of _____ that occurs in the winter and persists into the spring
covalent; histones
The methylation of a previously unmethylated site is called ______
de novo methylation
Steroid hormones are synthesized by _______ glands and secreted into the bloodstream, ultimately affecting the transcription or expression of genes in target cells.
endocrine
Repressors bind to ________
silencers
A protein that influences the ability of RNA polymerase to transcribe a given gene is a(n) _______ _______
transcription factor
An epigenetic change occurring during development is the marking of histone H3 through a process called ______
trimethylation
During development, covalent modification of Histone H3 by ______ at position 4 is an activating mark but the same change at position 27 is a repressive mark
trimethylation
In general ______ CpG islands correlate with active genes, and ______ CpG islands correlate with suppressed genes.
unmethylated; methylated
An enhancer is a DNA element that is bound by a regulatory transcription factor, which leads to ______
up regulation
In which ways can methylation affect transcription? (2)
- Methyl-CpG binding proteins recruit other proteins that inhibit transcription - The methylation of CpG islands may prevent or enhance the binding of regulatory transcription factors to the promoter region
Which of these are environmental factors that promote epigenetic changes? (3)
- Temperature - Toxins - Diet
Gene regulation can occur during which of the following? (4)
- Transcription - Translation - RNA processing - Posttranslational modification
Plants and animals require a greater level of gene regulation than single-celled eukaryotes because of ______ (4 different reasons)
- developmental stages - multicellularity - more complex cell structure - different tissue types
Repressors inhibit TFIID by ______ (2)
- inhibiting the ability of TFIID to recruit RNA polymerase II to the core promoter - preventing the binding of TFIID to the TATA box
Transcription factors that affect the ability of RNA polymerase to begin the transcription process may work by ______
- regulating the binding of the transcriptional complex to the core promoter - controlling the switch from the initiation to the elongation stage of transcription
DNA sequences in eukaryotes that can be bound by regulatory transcription factors, which then affect the ability of RNA polymerase to transcribe a particular gene are called ______ (3)
- regulatory sequences - regulatory elements - control elements
Which are examples of how gene regulation benefits eukaryotic organisms?
- the ability to respond to changes in nutrient availability - the ability to respond to environmental stresses
In eukaryotes, DNA methyltransferase is an enzyme that attaches a methyl group to the _____ position of the ____ base
5 ; cytosine
As a result of a diet of royal jelly, queen bees develop differences in _____ when compared with worker bees.
DNA methylation
True or false: Regulatory elements must be located within 200 base pairs upstream from the core promoter.
False
General transcription factors are required for the binding of _______ ______ to the core promoter and its progression to the elongation stage
RNA polymerase
During Drosophila development, the protein complex trithorax group (TrxG) causes gene ________ , while polycomb group (PcG) complex causes gene _______
activation; repression
DNA methylation is the _____ attachment of methyl groups to DNA
covalent
Regulatory elements that inhibit transcription are called silencers and their effect on transcription is called ______ regulation.
down
Glucocorticoid response elements are located near ______ genes.
dozens of different
Steroid hormones are synthesized by ________ glands and secreted into the bloodstream, ultimately affecting the transcription or expression of genes in target cells
endocrine
A glucocorticoid response element functions as a(n) ______
enhancer
Activators bind to ______
enhancers
During embryonic development, many genes undergo ______ changes that enable them to be transcribed or cause them to be permanently repressed.
epigenetic
What type of mechanism is responsible for enabling the transcription of muscle-specific genes in an embryonic cell that will eventually give rise to muscle tissue?
epigenetic changes
Methylation of the cytosine in both strands is called ______ methylation, and methylation of only one strand is called _______
full; hemimethylation
Gene regulation means that ______
gene expression can be controlled so that genes can be expressed at high or low levels
Human nerve cells and muscle cells look quite different from each other due to differences in ______
gene regulation
Genes that code for proteins that are required in most cells of a multicellular organism are called ______
housekeeping genes
In genomic _______, specific genes are _______ during oogenesis or spermatogenesis, but not both.
imprinting; methylated
In a multicellular organism, housekeeping genes tend to be expressed ______
in most cell types
A process called _______ methylation seems to be the primary mechanism by which DNA in vertebrate and plant cells is methylated.
maintenance
The methylation of hemimethylated sites is called ______
maintenance methylation
CpG islands near the promoters of tissue-specific genes are often ______
methylated
The covalent attachment of a -CH3 group to DNA is known as DNA ______
methylation
The function of a regulatory transcription factor can be modulated by covalent modifications, such as the attachment of a ______ group
phosphate
If gene regulation acts to prevent translation, which molecule will not be produced?
protein
Following the binding of a hormone, two glucocorticoid ______ form a dimer and travel to the cell's ________
receptors ; nucleus
DNA sequences that are analogous to the operator sites found near bacterial promoters are called ________ elements or _______ elements
regulatory ; control
Regulatory transcription factors that prevent transcription from occurring are called _______
repressors
The function of TFIID is inhibited by proteins called ________, which prevent the binding of TFIID to the _______ box
repressors ; TATA
X-chromosome inactivation occurs in ______cells of ______ mammals
somatic; female
In genomic imprinting, following fertilization, if a gene is methylated only during spermatogenesis, ______
the allele from the father will be methylated in the somatic cells of the offspring, but the allele from the mother will be unmethylated
Genes that are highly regulated and may be expressed only in certain cell types are called ______ - ______ genes
tissue - specific