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84 Cards in this Set
- Front
- Back
What is a gene? |
A segment of DNA that is transcribed into a RNA molecule that has a function within the cell |
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What does mRNA include for protein-encoding genes? |
All the information specifying the amino acid sequence of a polypeptide |
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When do RNA transcripts typically undergo processing? |
Before becoming fully functional |
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What is transcription? |
The process of converting DNA into RNA |
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How is RNA transcription carried out? |
By immobile protein complexes that reel in the DNA |
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What is an exon? |
A protein coding segment |
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What is splicing? |
The removal of introns and joining of exons in an RNA molcule |
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What controls splicing? |
Consensus sequences |
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What is a consensus sequence? |
(Usually) short sections of DNA/RNA that are common at different locations and important for specific functions |
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What is a promotor? |
A region of a gene, upstream of the transcribed section, where RNA polymerase binds, and transcription will begin |
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What is a transcription factor? |
Proteins that facilitate binding of RNA polymerase by altering the structure/form of DNA at the promoter and bind to consensus sequence |
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What is an enhancer? |
DNA sequences |
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What is an activator? |
Protein |
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What do activators do? |
Bind to enhancers to promote the transcription of a gene |
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What is an operon? |
Set of functionally related genes under the control of one promoter and only found in prokaryotes |
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What are prokaryotes classified as? |
Bacteria |
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What is an RNA polymerase? |
An enzyme, unwinds and separates double-stranded DNA at the position where transcription occurs |
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Where does transcription begin? |
At promotors |
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What allows coordinated gene expression? |
Prokaryotic operons |
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What has a variety of consensus sequences? |
Eukaryotic promotors |
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What do transcription factors recognize? |
Eukaryotic promotors |
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How is a transcription bubble formed? |
When transcription factors unwind DNA |
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What binds to RNA polymerase? |
Many transcription factors |
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What acts as a distance from the promotor? |
Enhancers and activators |
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Where are enhancer sequences found? |
Upstream of the promotor |
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How many exons does a typical gene consist of? |
Eight |
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What does an estimated 80% of the human genome possibly undergo? |
Transcription to produce noncoding RNA |
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What are the three fundamental types of RNA? |
1. mRNA 2. rRNA 3. tRNA |
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What are happens to noncoding RNA? |
They are not translated into protein |
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What is mRNA? |
Messenger RNA - encodes for polypeptide sequences |
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What is rRNA? |
Ribosomal RNA - aids in polypeptide synthesis |
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What is tRNA? |
Transfer RNA - carries amino acids to the ribosome |
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What is siRNA? |
Small Interfering RNA |
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What is miRNA? |
Micro Interfering RNA |
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What do siRNA and miRNA bind to? |
Complementary RNA and target it for destruction/degredation or block translation |
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What is the function of rRNA? |
Translation (ribosomal structure and catalytic activity) |
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What is the function of tRNA? |
Delivery of amino acids to ribosome during translation |
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What is the function of siRNA and miRNA? |
Sequence-specific inactivation of mRNA |
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What does RNA polymerase I transcribe? |
rRNAs |
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What transcribes mRNAs? |
RNA polymerase II |
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What transcribes tRNAs? |
RNA polymerase III |
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T or F: RNA polymerase is a processive enzyme |
True |
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T or F: Histone modification does not affect gene expression |
False |
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What is a key change in the transformation of silent to active chromatin? |
The acetylation of histones |
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Is DNA backbone positively or negatively charged? |
Negatively |
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How is chromatin decondensed? |
The action of the chromatin-remodeling complex |
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What occurs in chromatin remodeling? |
DNA is loosened from the histone so that it can slide along the nucleosome |
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What are the two methods in which transcription in prokaryotes is terminated?
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1. Hairpin loop 2. Rho |
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How is prokaryotic mRNA processed? |
Immediately translated |
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How is eukaryotic mRNA processed? |
Needs to travel from nucleus to cytosol (location in the ribosomes) |
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What are three factors of mRNA? |
1. mRNA can be modified ("processed") 2. Variety of gene products can be generated gene 3. Expression can be regulated |
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What are the three ways that mRNA can be processed? |
1. Addition of 5' methyl cap 2. Addition of 3'm poly (A) tail 3. Splicing |
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What are the factors of the addition of 5' methyl cap in mRNA processing? |
Eukaryotic mRNAs receive a 5' methyl cap Protection from exonucleases that would attack the 5' end |
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What are the factors of the addition of 3' poly (A) tail in mRNA processing? |
The 3' end receives a poly (A) 3' tail Attachment of poly (A) binding proteins Protection from exonucleases that would attack the 3' end |
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What is poly (A)? |
A binding protein bound to poly (A) |
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What does a consensus sequence trigger poly (A) polymerase to do? |
A consensus sequence triggers poly (A) polymerase to create the poly (A) tail that is then bound to poly (A) - BP |
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When does splicing commence? |
Before transcription ends |
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What are the factors of splicing in mRNA processing? |
Prior to translation, introns needs to be removed and exons joined together |
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What is splicing? |
Splicing is the removal of introns and joining of exons in an RNA molecule |
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What is splicing controlled by? |
It is controlled by consensus sequence that are recognized by the spliceosome |
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What is a spliceosome? |
Complex made of snRNA and proteins |
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What is an different way of RNA splicing? |
Alternative splicing |
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What is one of the explanations as to why humans have over 100,000 proteins created from only 20,000 genes? |
Alternative splicing |
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What limits gene expression? |
mRNA turnover |
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What is lincRNA? |
Large intervening noncoding RNA |
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What is snRNA? |
Small nuclear RNA |
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What is snoRNA? |
Small nucleolar RNA |
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What is the function of lincRNA? |
Transcriptional control |
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What is the function of snRNA? |
RNA splicing |
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What is the function of snoRNA? |
Sequence-specific methylation of rRNA |
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What is the function of siRNA and miRNA? |
Disrupt the synthesis of proteins by either degrading mRNA or blocking translation |
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What does RNAi mean? |
RNA interface |
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What is the purpose of RNAi? |
Regulation of gene expression |
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What is the average length of an RNAi? |
20 - 25 nucleotides (small) |
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What are the two types of RNAis? |
1. siRNA 2. miRNA |
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RNAi is a potential what? |
Therapeutic strategy |
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What is the current obstacle of RNAi? |
Effective delivery to target sites |
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What are the problems with the effective delivery of RNAi to target sites? |
RNA is subject to nuclease degradation RNA is unable to cross cell membranes |
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What are the potential solutions to the problem with RNAi? |
Direct delivery (injection at target site) Chemical modifications Lipid or polymer based nanocarriers |
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How can lipid or polymer based nanocarriers solve the problem of RNAi? |
Need to optimize for delivery to target site, uptake of nanocarrier, and release of RNA once in the cells |
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T or F: RNA is a nonversatile molecule |
False |
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What does RNA have properties similar to? |
Proteins |
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How is RNA similar to proteins? |
Can catalyze reactions Can adopt complex tertiary structures |
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What ways can RNA nucleotides base pair? |
Watson-Crick base pairing Nonstandard base pairing |