DNA and RNA Molecule Test Exam

Non-coding RNAs are RNA molecules that do not encode polypeptides. Some ncRNAs bind to DNA, or another RNA molecule through complementary base pairing. Select functions commonly carried out by ncRNAs. - Alteration of protein function or stability - Ribozyme - Blocker - Scaffold - Decoy - Guide ncRNAs that contain binding sites for multiple components can act as a(n) scaffold for the formation of a complex. RNA molecules that do not encode polypeptides are called non-coding RNAs. Select ways in which the binding of an ncRNA to a protein may affect the protein's function. It may affect the ability of the protein to bind another molecule. It may affect the stability of the protein. It may affect the ability of the protein to act as a catalyst. Select the molecules to which ncRNAs commonly bind. Proteins mRNA Small molecules DNA The ncRNA in RNaseP functions as an endonuclease that cleaves a tRNA. What function is this ncRNA carrying out? Ribozyme Match each ncRNA function to its correct description. Scaffold - Some ncRNAs contain binding sites for multiple molecules Guide - Some ncRNAs function to deliver a molecule to a specific site Ribozyme - Some ncRNAs have catalytic function Blocker - Some ncRNAs prevent cellular processes from occurring Decoy - Some ncRNAs bind to other ncRNAs and sequester them The ncRNA Hox transcript antisense intergenic RNA is also known as HOTAIR. Why was C. elegans used as the experimental organism in experiments carried out by Mello and Fire? It is relatively easy to inject with RNA. Expression of many of its genes had already been established. An ncRNA that binds to a protein and brings it to a specific site in the cell's DNA is performing what function? Guide The phenomenon in which double-stranded RNA causes the silencing of mRNA is called RNA interference When an ncRNA binds to a(n) protein, it can alter its ability to act as a catalyst, or its ability to bind to another molecule. RNA molecules with catalytic function are called ribozyme. Where is RNA interference found? In most eukaryotic species Select the roles played by the ncRNA HOTAIR. Repression of gene transcription Alteration of chromatin structure MicroRNAs influence gene expression by inhibiting translation of mRNA. Mello and Fire studied the effects of injected RNA on the expression of specific mRNA in C. elegans. Select the sources of RNA that promote RNA interference. small-interfering RNAs microRNAs The term RNAi stands for which of the following? RNA interference Which of the following regulatory RNAs originate from genes normally found in the genome? miRNAs only The phenomenon of RNA interference is carried out by: both animals and plants Approximately how many human genes are estimated to encode miRNAs? 2,000 MicroRNAs play a key role in regulating gene expression particularly during embryonic development in animals and plants. Which type of RNA is exogenous? siRNA RNA interference is mediated by: miRNA and siRNA List the steps of RNA interference in the correct sequence. 1. Pre-miRNAs and pre-siRNA are cleaved by dicer. 2. Double-stranded RNA associates with proteins to form the RNA-induced silencing complex (RISC). 3. One strand of the dsRNA is degraded. 4. Single-stranded miRNA or siRNA allows RISC to bind to complementary mRNA sequences. 5. RISC may inhibit translation or direct degradation of the mRNA. Which molecule is exported from the nucleus? pre-miRNA MicroRNAs are ______ RNAs that are transcribed from ______ sources. non-coding; endogenous What percentage of human protein-encoding genes are thought to be regulated by miRNAs? 60% Select possible sources of siRNAs. Viral RNA Made by researchers Which type of RNA might originate in a virus? siRNA The protein complex that contains a double-stranded RNA molecule and degrades mRNA is called RNA-induced silencing complex Which of the following statements correctly describes gene regulation through RNA interference? miRNAs associated with a RISC enzyme bind to mRNAs thus inhibiting translation Which molecule is first folded into a hairpin in the mechanism of RNA interference? pri-miRNA Which of the following regulatory RNAs originate from genes normally found in the genome? miRNAs only The signal recognition particle: facilitates the process of protein secretion Which molecule is made up of two complementary RNA molecules that base pair with each other? pre-siRNA In RNA interference, RISC stands for RNA-induced silencing complex. In bacteria and archaea, the SRP directs proteins to the plasma membrane. The RNA-protein complex that targets proteins for secretion is called the signal recognition particle. Which of the following is an RNA-protein complex? SRP Where does the SRP direct proteins to in eukaryotic cells? ER membrane A peptide must contain a sorting signal called an ER signal sequence to be directed to the ER membrane. The RNA component of the signal recognition particle (SRP) stimulates certain proteins to hydrolyze GTP. If this function of SRP RNA did not work properly, what would you expect to happen? SRP would not be released from the ER membrane The signal recognition particle is composed of RNA and protein. The CRISPR‐Cas system in bacteria and archaea is similar to our body’s immune system. Consistent with its role in providing protection against infection, the CRISPR locus contains segments that are derived from bacteriophage DNA. CRISPR stands for clustered, regularly interspaced, short palindromic repeats. The ER signal sequence is found in: proteins that need to be directed to the ER membrane The CRISPR-Cas mediated defense process can be divided into three phases: 1. adaptation; 2. Expression; and 3. Interference. Order the steps in the targeting of a polypeptide to the ER membrane by SRP. Start with the first step at the top. 1. Translation of a polypeptide begins 2. SRP binds to an ER signal sequence in the polypeptide and causes translation to pause 3. SRP binds to an SRP receptor in the ER membrane 4. The GTP-binding proteins with SRP and SRP receptor hydrolyze their GTP causing the release of SRP 5. Translation resumes and the polypeptide is threaded into the ER lumen An immune type system in prokaryotes that protects against foreign invaders is called the CRISPR-Cas system. The CRISPR locus in prokaryotes contains a series of: repeated sequences Place the steps in the expression phase of the CRISPR-Cas system in order. Start with the first step at the top. 1. The genes encoding pre-crRNA and tracrRNA are transcribed 2. tracrRNAs bind to pre-crRNA due to complementary base pairing 3. pre-cRNA is cleaved into many small molecules 4. Each tracrRNA-cRNA complex binds to a Cas9 protein Which phase of the CRISPR-Cas defense system is depicted in this figure? Expression Consistent with its role in providing protection against infection, the CRISPR locus contains segments that are derived from DNA Select the three phases of the CRISPR-Cas response. Interference Adaptation Expression During adaptation, what proteins in the CRISPR-Cas system are involved in recognizing and cleaving bacteriophage DNA into small pieces? Cas1 Cas2 What phase of the CRISPR-Cas defense system is depicted in this figure? Interference In the CRISPR-Cas defense system, what triggers the expression phase? A subsequent bacteriophage infection What causes abnormal expression levels of ncRNAs, potentially leading to human disease? Epigenetic changes that alter the expression of ncRNA genes Mutations in ncRNA genes During the interference phase of the CRISP-Cas defense system, each spacer within a ______ is complementary to one of the strands of the bacteriophage DNA. crRNA miRNAs can act as both tumor suppressors and oncogenes. True or false: Since they don't encode proteins, ncRNAs cannot cause disease. False What percentage of miRNAs are expressed in the brain? 70% miR-1 regulates the expression of genes that encode ion channel proteins, which are involved in signaling between cardiac muscle cells. Which ncRNA is associated with the formation of arterial plaques? miR145 What class of ncRNAs is most prevalent in affecting plant behavior? miRNAs Levels of expression of which type of ncRNAs have been found to differ between normal and cancer cells in nearly all forms of human cancer? miRNAs Abnormal expression levels of miRNAs have been found in early all neurological disorders in which they have been investigated. An miRNA called miR-1 is associated with the development of heart arrhythmias. Which processes are known to be affected by ncRNAs in plants? Germination Timing of flowering Seed development Development of stomata During the interference phase of the CRISP-Cas defense system, each spacer within a ______ is complementary to one of the strands of the bacteriophage DNA. crRNA