* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download HW10 Answer Key
Epigenetics in stem-cell differentiation wikipedia , lookup
No-SCAR (Scarless Cas9 Assisted Recombineering) Genome Editing wikipedia , lookup
X-inactivation wikipedia , lookup
Oncogenomics wikipedia , lookup
Neuronal ceroid lipofuscinosis wikipedia , lookup
Genetic engineering wikipedia , lookup
Protein moonlighting wikipedia , lookup
Long non-coding RNA wikipedia , lookup
Frameshift mutation wikipedia , lookup
Gene nomenclature wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genome (book) wikipedia , lookup
Gene desert wikipedia , lookup
Epigenetics of diabetes Type 2 wikipedia , lookup
Gene therapy wikipedia , lookup
Genome evolution wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Epigenetics of neurodegenerative diseases wikipedia , lookup
Helitron (biology) wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Gene expression profiling wikipedia , lookup
Alternative splicing wikipedia , lookup
Mir-92 microRNA precursor family wikipedia , lookup
Gene expression programming wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Microevolution wikipedia , lookup
Designer baby wikipedia , lookup
Gene therapy of the human retina wikipedia , lookup
Point mutation wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Primary transcript wikipedia , lookup
1) (10 Points) Compare and contrast the function of nucleosomes in the regulation of eukaryotic transcription to the function of the lac repressor in regulation of lac operon transcription. Nucleosomes and the lac repressor function similarly in regulation of transcription in that both inhibit transcription when bound to DNA near/on the promoter of genes and the binding of both can be altered in order to allow transcription to occur. They differ in several respects. For example, the lac repressor binds to a specific DNA sequence, the operator, whereas nucleosomes assemble on DNA of any sequence. They also differ in the mechanism that controls their binding to/assembly on DNA. The lac repressor is prevented from binding by the presence of lactose, which causes the lac repressor to change structure and become unable to bind to the operator DNA sequence. The presence of nucleosomes is regulated by "chromatin remodelling" proteins that act in several different ways to either remove nucleosomes from DNA, alter the location of nucleosomes (on or off of promoters), or alter the structure of nucleosomes (making promoter sequences more or less available) 10 points if inhibitory function and ability to be regulated are described. 5 points if effort is made but both aspects of regulation are not addressed or one or both statements are incorrect. Zero of no effort. 2) (10 Points) Two different cell types in an animal express slightly different forms of the same protein. This protein is encoded by a single gene. The two proteins are identical in sequence in their amino-terminal 200 amino acids and their carboxyl-terminal 200 amino acids but they differ in the sequence of their middle 100 amino acids. a) What stage of gene expression (see figure 18.1) is regulated to control expression of this gene? pre-mRNA processing or pre-mRNA splicing. mRNA splicing also accepted. 5 Points if correct. 2.5 for effort, 0 for no effort. b) Draw a figure that illustrates how the two proteins are encoded by a single gene. See next page for key. I've drawn three ways that I can think of that show understanding. Any one of these three is worth 5 Points. Otherwise, 2.5 for effort, 0 for no effort. pre-mRNA exon 1 intron 1 exon 2 intron 2 exon 1 exon 2 intron 3 exon 4 alternate splicing pathway one splicing pathway mRNAs exon 3 exon 1 exon 4 exon 3 exon 4 part of intron 1 or intron 2 exon 1 pre-mRNA intron 1 exon 2A one splicing pathway mRNAs exon 1 exon 2A exon 1 intron 1A intron exon 2B intron 2 alternate splicing pathway exon 3 exon 2A exon 3 exon 1 exon 2B exon 3 exon 3 intron 2A pre-mRNAs exon 1 intron 1B one splicing pathway mRNAs exon 1 exon 2A exon 3 exon 2B exon 3 intron 2B alternate splicing pathway exon 1 exon 2B exon 3 3) (10 Points) Gene X is transcribed in liver cells but not in muscle cells. If liver-cell-specific transcription of gene X is due to the function of an enhancer, how would a loss of function mutation in the enhancer affect transcription of gene X in liver and muscle? The enhancer functions in liver but not muscle, therefore, loss of enhancer function only affect liver cells. The mutation would prevent expression of the gene in liver cells and would have no effect in muscle cells. The gene would not be expressed in either cell types. 10 Points if correct (need to address the effect of the mutation in both cell types), 5 points for effort, zero for no effort. 4) (10 Points) Gene X is transcribed in liver cells but not in muscle cells. If liver-cell-specific transcription of gene X is due to the function of a silencer, how would a loss of function mutation in the silencer affect transcription of gene X in liver and muscle? The silencer functions in muscle but not liver, therefore, loss of silencer function only affects muscle cells. The mutation would allow expression of the gene in muscle cells and would have no effect in liver cells. The gene would be expressed in both cell types. 10 Points if correct (need to address the effect of the mutation in both cell types), 5 points for effort, zero for no effort. 5) (10 Points) Genes X and Z are located on the same chromosome but are separated by an insulator. Gene X is expressed in liver cells but not in muscle cells whereas gene Z is expressed in muscle cells but not in liver cells. If livercell-specific expression of gene X is due to the function of an enhancer and muscle-cell-specific expression of gene Z is due to the function of an enhancer, how would a loss of function mutation in the insulator affect transcription of genes X and Z in liver and muscle cells? The enhancer for gene X functions in liver but not muscle, whereas the enhancer for gene Z functions in muscle but not liver. The insulator normally prevents the gene X enhancer from affecting gene Z and also prevents the gene Z enhancer from affecting gene X. The mutation would allow both enhancers to affect the expression of the both genes: the liver enhancer would promote expression of X and Z in liver and the muscle enhancer would promote expression of X and Z in muscle. Both genes would be expressed in both cell types. 10 Points if correct (need to address the effect of the mutation in on both genes in both cell types), 5 points for effort, zero for no effort.