Bio Topic 7 review
Nucleosomes help to regulate transcription in eukaryotes Outline the effect of acetylation of nucleosome tails on rates of gene expression
Acetylation of histones allows DNA to be available for transcription while methylation of DNA prohibits DNA from being available for transcription
Transcription occurs in a 5' to 3' direction Describe elongation of transcription, including the role of nucleotide triphosphate and the direction of transcription
Elongation is when RNA polymerase moves down the template, or anti-sense, strand of DNA and adding the matching RNA nucleotides, replacing T with U, and adding on the 3' end of the growing strand.
: Gene expression is regulated by proteins that bind to specific base sequences in DNA• Outline the role of enhancers, silencers and promoter-proximal elements in regulation of gene expression.
Enhancers are a region of non-coding DNA that binds to activator proteins that speed up transcription. Silencers are a region of non-coding DNA that binds to repressor proteins that slow transcription. Promoter-proximal elements are a region of non-coding DNA that
The environment of a cell and of an organism has an impact on gene expression •Outline two examples of environmental influence on gene expression.
Exposure to sunlight changes DNA (thymine dimers) and these changes causes the gene for melanin to be expressed. Siamese cats have temperature-dependent tyrosinase. If this mutation of tyrosinase is at warmer temperatures, it does not allow for melanin to be deposited (light belly, back) while melanin is deposited at cooler temperatures (ears, feet, nose). Diet can activate expression of obesity genes. Smoking activates expression of cyclins to speed up the replacement of dying cells.
Splicing of mRNA increases the number of different proteins an organism can produce. • Outline an example of alternative splicing the results in different protein products
From the book, tropomyosin has 11 exons total. Removal of certain exons allows for different types of muscle cells to express only the form of tropomyosin that works for that cell type. Skeletal muscle removes exon 2 whereas smooth muscle cells remove exons 3 and 10.
Gene expression is regulated by proteins that bind to specific base sequences in DNA define gene expression
Gene expression is when DNA is transcribed into mRNA and then the mRNA is translated into protein based on the needs of the cell.
Eukaryotic cells modify mRNA after transcription list 2 major differences in gene expression between prokaryotic cells and eukaryotic cells
In prokaryotes since there is no nucleus, transcription and translation can occur simultaneously whereas in eukaryotes transcription occurs, the transcript or mRNA leaves the nucleus and then it undergoes translation. In eukaryotes post-transcriptional modifications occur to make the mRNA able to undergo translation whereas in prokaryotes post-transcriptional modification is unnecessary.
Eukaryotic cells modify mRNA after transcription • List two major differences in gene expression between prokaryotic cells and eukaryotic cells
In prokaryotes since there is no nucleus, transcription and translation can occur simultaneously whereas in eukaryotes transcription occurs, the transcript or mRNA leaves the nucleus and then it undergoes translation. In eukaryotes post-transcriptional modifications occur to make the mRNA able to undergo translation whereas in prokaryotes post-transcriptional modification is unnecessary.
Transcription occurs in a 5' to 3' direction Describe the initiation of transcription, including the role of the promoter, transcription factors, the TATA box and RNA polymerase
Initiation begins when RNA polymerase binds near the promoter region of the gene. The TATA box is located in the promoter region on DNA and helps give a place for the DNA to be unwound allowing RNA polymerase to bind. Transcription factors simply bind to the DNA also aiding in RNA polymerase binding.
Gene expression is regulated by proteins that bind to specific base sequences in DNA outline the environment regulation of the breakdown of lactose in E coli.
Lactose absent, repressor binds to gene to prevent transcription of lactase (the enzyme that breaks down lactose). Lactose present, repressor is removed from gene so lactase can be transcribed.
Eukaryotic cells modify mRNA after transcription •Describe the three post-transcriptional modifications of pre-mRNA in eukaryotes.
Methylguanosine cap - added at the end in order to give a "buffer" on the end similar to how telomeres act. Poly-A tail - again similar to telomere function. Splicing - introns are removed and exons are fused together to make mature mRNA.
eukaryotic cells modify mRNA after transcription describe the three post-transcriptional modifications of pre-mRNA in eukaryotes
Methylguanosine cap - added at the end in order to give a "buffer" on the end similar to how telomeres act. Poly-A tail - again similar to telomere function. Splicing - introns are removed and exons are fused together to make mature mRNA.
Gene expression is regulated by proteins that bind to specific base sequences in DNA state 2 reasons why gene expression must be regulated
Proteins that are only necessary during certain environmental conditions do not need to waste energy in being expressed all the time. Gene expression is a critical part of cellular differentiation as well as the process of development.
Transcription occurs in a 5' to 3' direction describe termination of transcription, including the role of the terminator
Termination is the part of transcription when RNA polymerase recognizes the terminator sequence on DNA and releases itself from the DNA and then the mRNA is free to undergo post-transcriptional modifications.
The environment of a cell and of an organism has an impact on gene expression • Describe the use of twin studies to measure the impact of environment on gene expression.
The use of twin studies has taught us more about the significance of nature vs nurture. Twin studies allow professionals to asses the differences in twins (genetically and individually)
Splicing of mRNA increases the number of different proteins an organism can produce. Describe the process of alternative RNA splicing.
This allows a single gene to code for multiple protein so while the entire gene is transcribed, when it undergoes post-transcriptional modification, different exons can be spliced along with introns resulting in proteins with different amino acid sequences and possibly different functions.
Nucleosomes help to regulate transcription in eukaryotes •Outline the effect of methylation of nucleosome tails on rates of gene expression.
gene pithing highly condensed heterochromatin are usually not expressed. Also, chemical modifications to histone proteins and DNA can influence chromatin structure and gene expression
