Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Chapt 21-23
Transcription, translation, regulation of gene expression
| Question | Answer |
|---|---|
| What is transcription? | RNA synthesis |
| What is translation? | protein synthesis |
| What are the types of RNA? | mRNA, rRNA, tRNA |
| What is the function of mRNA? | messenger |
| What is the function of rRNA? | production of ribosomes |
| What is the function of tRNA? | transfer; brings amino acids to ribosomes and starts translation |
| This DNA helps synthesize RNA. | the template strand |
| This DNA is identical to the RNA produced. | the coding strand |
| These are codons that encode for specific amino acids. | RNA triplets |
| What is the degenerate code? | multiple codons encode for specific amino acids |
| What does the start codon do? | AUG sequence that encodes for methionine; starts translation |
| What does the stop codon do? | UAA, UAG, or UGA sequence that does not encode for an amino acid; stops translation |
| This type of base-pair mutation changes the codon so that it encodes for a different amino acid. | missense mutation |
| This type of base-pair mutation changes the codon to encode for stop instead of an amino acid. | nonsense mutation |
| This type of base-pair mutation does not cause any change in the amino acid translation or protein synthesis. | silent mutation |
| This type of mutation shifts the entire sequence to give different triplets, and other types of mutations. | insertion/deletion; frameshift mutation |
| What are NTPs? | nucleotide ribonucleoside triphosphates; ATP, GTP, CTP, UTP |
| What is a promoter sequence? | the binding site for RNA polymerase that determines the transcription start site |
| What does RNA polymerase do? | unwinds DNA and synthesizes RNA 5'->3' |
| This part of RNA polymerase promotes initiation. | σ (sigma) subunit |
| This part of the promoter sequence is called +1. | start point |
| What are the steps of transcription? | RNA polymerase binds to DNA, initiation/pre-initiation, elongation, termination |
| What are the consensus sequences? | Pribnow Box/-10 sequence (TATAAT), -35 sequence (TTGACA) |
| What happens in Rho factor termination? | the Rho factor (a protein that unwinds new RNA from DNA template) binds to termination sequences |
| What happens in non-Rho termination? | RNA transcribes the G-C rich sites -> hairpin loop formation -> dissociation of RNA from DNA |
| Transcription in bacteria step #1 | RNA polymerase binds to promoter and begins unwinding DNA |
| Transcription in bacteria step #2 | initiation: NTPs added 5'->3' until σ subunit falls off |
| Transcription in bacteria step #3 | elongation: RNA polymerase continues to unwind/rewind DNA and add NTPs to RNA, forming temporary RNA-DNA hybrids |
| Transcription in bacteria step #4 | termination: Rho or non-Rho |
| What is RNA polymerase I? | RNA polymerase involved in eukaryotic transcription found in nucleolus and transcribes rRNA |
| What is RNA polymerase II? | RNA polymerase involved in eukaryotic transcription found in nucloplasm and transcribes mRNA |
| What is RNA polymerase III? | RNA polymerase involved in eukaryotic transcription found in nucleoplasm and transcribes tRNA and 5S rRNA |
| What is the core promoter? | the minimum sequence needed to begin transcription with RNA polymerase I, surrounds start point |
| What is the upstream control element? | a sequence upstream of the core promoter where transcription factors can bind to enhance transcription with RNA polymerase I |
| What is Inr? | the iniatior sequence for transcription with RNA polymerase II that includes the start point and surrounding pyrimidines |
| What is the TATA box? | the TATA sequence at -25 that is preserved during transcription with RNA polymerase II |
| What is BRE? | transcription factor 2 (TF2) B recognition elements; where transcription factors bind to initiate transcription with RNA polymerase II |
| What is DPE? | downstream promoter element; sequences where transcription factors can bind to enhance transcription with RNA polymerase II |
| What are Boxes A, B, and C? | sequences found downstream of the promoter that allow transcription factors to bind to enhance transcription with RNA polymerase III |
| Pre-initiation (using RNA polymerase II) step #1 | transcription factor II D (TFIID) recognizes and binds TATA box |
| Pre-initiation (using RNA polymerase II) step #2 | TFIID recruits TFIIA and TFIIB to form ABD complex |
| Pre-initiation (using RNA polymerase II) step #3 | ABD complex recruits RNA polymerase II (RNApolII)/TFIIF |
| Pre-initiation (using RNA polymerase II) step #4 | TFIIE and TFIIH (helicase) also bind to form pre-imitation complex with RNApolII/TFIIF and ABD complex |
| Pre-initiation (using RNA polymerase II) step #5 | TFIIH phosphorylates RNApolII to begin initaion |
| What is the primary transcript? | pre-m, t, rRNA; the unprocessed result of transcript |
| What are the 4 types of rRNA? | 25-28S, 5.8S, 5S, 18S |
| Which of the 4 types of rRNA make up the large ribosome subunit? | 25-28S, 5.8S, 5S |
| Which of the 4 types of rRNA make up the small ribosome subunit? | 18S |
| This contains separate genes for each rRNA. | the transcriptional unit |
| These separate repeated transcriptional units. | nontranscribed spacers |
| These separate genes for each rRNA. | transcribed spacers |
| What is pre-rRNA? | the RNA with all RNAs still connected by spacers |
| What is mature rRNA? | the separate rRNAs which result from RNA cleavage and degradation of spacers |
| What is a spliceosome? | a complex made up of 5 kinds of RNA and 200+ proteins |
| What are the types of snRNPs? | U1, U2, U4/U6, U5 |
| What are the splice sites? | GU (5'), AG (3') |
| What is the branch site? | A located within intron |
| tRNA processing step #1 | leader sequence on 5' end of pre-transcript is cut off |
| tRNA processing step #2 | nucleotides at end of 3' end replaced with CCA so it can attach to an amino acid |
| tRNA processing step #3 | bases are chemically modified |
| tRNA processing step #4 | hairpin loops form |
| tRNA processing step #5 | introns are cut out |
| How is mRNA processed? | 5' cap added, 3' poly A tail added, and splicing |
| What does the 5' cap do? | protects the mRNA from degradation, aids in attachment to ribosome |
| What does the 3' poly A tail do? | protects the mRNA from degradation, aids in nuclear export |
| mRNA splicing step #1 | snRNP U1 binds 5' splice site |
| mRNA splicing step #2 | snRNP U2 binds branch site |
| mRNA splicing step #3 | snRNP U4/U6 bind to form loop (spliceosome) |
| mRNA splicing step #4 | 5' splice site is cleaved -> UG binds A branch site (Lariat structure) |
| mRNA splicing step #5 | 3' splice site is cleaved |
| mRNA splicing step #6 | exons joined by exon junction complex (EJC) |
| mRNA splicing step #7 | introns are degraded |
| What do introns do? | act as spacers, increase frequency of DNA cross-overs, allow for alternative splicing |
| What is alternative splicing? | 1 gene can lead to multiple polypeptides |
| This is made up of a tRNA and an amino acid. | aminoacyl tRNA |
| These aid in translation, and there are 3 types: IFs, EFs, and TFs. | protien factors |
| Where is the mRNA binding site? | in the small ribosome subunit |
| Where is the A site? | in the large ribosome subunit |
| Where is the P site? | in the large ribosome subunit |
| Where is the E site? | in the large ribosome subunit |
| How do tRNAs move through the ribosome? | A->P->E |
| What is the anticodon? | the codon on the tRNA that binds to the mRNA codon it matches in order to add its amino acid to the growing polypeptide |
| What does the aminoacyl tRNA synthetase do? | it makes aminoacyl tRNA |
| Aminoacyl tRNA synthesis step #1 | amino acid and ATP attach to binding sites on enzyme |
| Aminoacyl tRNA synthesis step #2 | ATP hydrolyzes 2 phosphates (pyrophosphate), and amino acid attaches to remaining AMP |
| Aminoacyl tRNA synthesis step #3 | tRNA takes place of AMP on enzyme |
| Aminoacyl tRNA synthesis step #4 | new aminoacyl tRNA is released |
| What is the wobble position? | the #3 spot on the anticodon that allows the anticodon to base pair with bases it normally would not pair with |
| What is I? | inosine, a nucleotide found only in tRNA that is able to bind with A, C, or U |
| What are the 3 types of protein translation factors? | initiation factors, elongation factors, release factors |
| Initiation process in bacteria step #1 | GTP binds IF2 |
| Initiation process in bacteria step #2 | GTP/IF2 recruits IF1 and IF3 |
| Initiation process in bacteria step #3 | GTP/IF2/IF1/IF3 bind to 30S |
| Initiation process in bacteria step #4 | mRNA and initiator tRNA (fmet) are recruited into GTP/IF2/IF1/IF3 complex, and IF3 is released -> 30S initiation complex |
| Initiation process in bacteria step #5 | GTP hydrolysis -> IF1 and IF2 released, 50S binds -> 70S initiation complex |
| Initiation process in eukaryotes step #1 | eIF2/GTp binds initiator tRNA (met) |
| Initiation process in eukaryotes step #2 | eIF1A and 40S bind to eIF2/GTP/initiator tRNA |
| Initiation process in eukaryotes step #3 | mRNA is recruited |
| Initiation process in eukaryotes step #4 | eIF4F binds |
| Initiation process in eukaryotes step #5 | tRNA binds start codon (AUG in Kozak sequence) |
| Initiation process in eukaryotes step #6 | GTP hydrolysis -> initiation factors released leaving 40S initiation complex (mRNA, initiator tRNA, 40S) |
| Initiation process in eukaryotes step #7 | 60S binds -> 80S initiation complex |
| What is the Kozak sequence? | ACCAUGG |
| What are the bacterial initiation factors? | IF1, IF2, IF3 |
| What are the eukaryote initiation factors? | eIF2, eIF1A, eIF4F |
| What are the elongation factors? | EF-Tu, EF-Ts, EF-G |
| Elongation process step #1 | aminoacyl tRNA binds |
| Elongation process step #2 | EF-Tu binds to GTP and aminoacyl tRNA -> binds to codon in A site |
| Elongation process step #3 | GTP hydrolysis -> EF-Tu released and recycled by EF-Ts |
| Elongation process step #4 | peptide bond formation |
| Elongation process step #5 | EF-F/GTP binds ribosome |
| Elongation process step #6 | GTP hydrolysis -> moves tRNAs to E and P sites/mRNA (translocation) |
| Elongation process step #7 | EF-G/GDp is released and recycled |
| Elongation process step #8 | elongation continues |
| Termination process step #1 | stop codon in A site (UAG, UAA, UGA) -> release factors/GTP recruited to stop codon |
| Termination process step #2 | GTP hydrolysis -> translation complex dissociation |
| What is induction? | a catabolic pathway where the production of something induces the gene regulation pathway in bacteria |
| what is an example of an induction pathway? | the lac operon |
| What is end-product repression? | an anabolic pathway where the product inhibits more synthesis of the product |
| What is an example of end-product repression? | the trp operon |
| What does a regulatory gene do? | it encodes for the repressor protien that binds to the operator to regulate gene expression |
| What is the lac operon? | lac Z, lac Y, and lac A sequences |
| What is P-lac? | the lac operon promoter |
| What is the operator? | the sequence next to the promoter that regulates transcription |
| Why is the lac operon inducible? | because the default state is off and it's induced to the on state by the presence of lactose |
| Why is the lac repressor a negative/inhibitory regulator? | when there is no lactose present, the active repressor binds to the operator to block transcription |
| What is CAP? | the catabolite activator protein that binds to cAMP to regulate the lac operon |
| When is CAP used to regulate the lac operon? | when there is no glucose present and there is high [cAMP] |
| Regulation with CAP step #1 | cAMP binds to CAP -> CAP is activated |
| Regulation with CAP step #2 | activated CAp binds the CAP recognition sequence in the operon |
| Regulation with CAP step #3 | RNA polymerase is recruited |
| Regulation with CAP step #4 | transcription |
| Regulation with CAP step #5 | the lac genes are turned on |
| What are chromosome puffs? | sites of chromatin decondensation/increase transcription |
| What is the histone code? | specific histone modifications that activate or silence genes |
| What are proximal control elements? | separate DNA sequences near promoter where the regulatory transcription factors bind |
| What are distal control elements? | separate DNA sequences far away from the promoter where regulatory transcription factors bind |
| What are enhancers? | where activators bind to activate/enhance/increase transcription |
| What are silencers? | where repressors bind to silence/decrease transcription |
| Enhancer process step #1 | activator proteins bind enhancer |
| Enhancer process step #2 | DNA bends |
| Enhancer process step #3 | coactivators (SWI/SNF, HAT) stimulate histone acetylation and chromatin remodeling |
| Enhancer process step #4 | activators bind mediator complex -> positions TFs and polymerase |
| What is the mediator complex? | RNA polymerase + TFs |
| What are response elements? | inverted repeats near the promoter that allow distant genes with similar functions to be controlled together |
| Coordinated gene regulation involving hormones step #1 | hormone receptors (HR) in cytoplasm bind hormone and enter the nucleus |
| Coordinated gene regulation involving hormones step #2 | bind the hormone response elements they match on all strands of DNA having the matching sequences |
| What do hox genes do? | determine the body axes in embryonic development in Drosophila |
| How are genes regulated at the post-transcriptional level? | chemical modifications, cleavage, binding to UTRs, alternative splicing, mRNA degredation/lifespan |
| What is RNAi? | RNA mediated-interference at the transcriptional level |
| RNAi gene regulation step #1 | double stranded RNA (dsRNA) is introduced into the cell |
| RNAi gene regulation step #2 | dicer cleaves dsRNA into single-stranded RNA (siRNA) |
| RNAi gene regulation step #3 | RISC complex binds siRNAs to form siRISC complex |
| RNAi gene regulation step #4 | one siRNA is degraded |
| RNAi gene regulation step #5 (if siRNA inhibits transcription) | siRNA looks for matching DNA in the nucleus |
| RNAi gene regulation step #5 (if siRNA binds mRNA in the cytoplasm) | slicer degrades the mRNA if the siRNA is 100% complementary, translation is inhibited if the siRNA is partially complementary |
| How are genes regulated at the post-translational level? | chemical modification, cleavage, protein targeting/sorting, ubiquitin-targeted degredation involving proteosomes |
Created by:
653527423
Popular Science sets