Extra Credit GENED Assessment Test (Liberty University) Questions With Complete Solutions

1. What is 3'polyA tail? - ANSWER -large string of adenine nucleotides added to the last nucleotide of the transcript -helps with transport of mRNA out of nucleus, with increasing stability of mRNA and with translation 2. Stop Codons - ANSWER signal termination of translation 3 of them 3. tRNA - ANSWER -transports amino acids to ribosomes -amino acid on one end, anticodon on other end 4. Ribosomal Subunits - ANSWER -small and large -subunits join together just before translation occurs -has binding sites for mRNA and 3 tRNA's 5. Translation: Initiation - ANSWER -brings all translation components together at the start of codon (AVG) -initiator tRNA attaches to the start codon 6. Elongation - ANSWER -polypeptide increases in length -exits a E site, arrives a A site 7. Termination - ANSWER -occurs at a stop codon -requires release factor proteins -dissociates into 2 subunits 8. Housekeeping Genes - ANSWER -govern functions that are common to many types of cells -active in many cell types for routine functions 9. Where is gene expression controlled? - ANSWER cell 10. 2. Transcriptional Control Factors help... - ANSWER help RNA polymerase bind to a promoter 11. 2. Transcriptional Control Initiation Complex - ANSWER joining of several transcription factors at a promoter that helps pull double-stranded DNA apart for transcription to begin 12. 2. Transcriptional Control Activators - ANSWER proteins that speed up transcription dramatically 13. 3. Post-Transcriptional Control - ANSWER primary mRNA converted to a mature mRNA -addition of poly-A tail and guanine cap -removal of introns and splicing of eons --the same mRNA can be spliced in different patterns to generate slightly different proteins upon translation 14. The longer the mRNA is available in the cytoplasm, the more______can be translated. - ANSWER gene product 15. 4. Translational Control - ANSWER -differences in the poly-A tails and/or guanine caps may determine how long a mRNA is available for translation -specific hormones may also effect longitivity of mRNA 16. Post-Translational Control - ANSWER -some proteins must be activated after synthesis -many proteins function only for a short time before they are degraded or destroyed by the cell 17. Translocation - ANSWER -during translation: elongation -everything moves over one codon worth -ex: P site goes to E site 18. Gene Expression - ANSWER process of using a gene sequence to synthesize a protein depends on different types of RNA, mRNA, tRNA, rRNA 19. Transcription: General - ANSWER -takes place in nucleus in eukaryotic cells -part of DNA and serves as a template for mRNA formation 20. Translation: General - ANSWER -takes place in cytoplasm of eukaryotic cells -sequence of mRNA bases determines the sequence of amino acids in a polypeptide -tRNA's bring amino acids to ribosome 21. How is mRNA formed? - ANSWER transcription 22. Function of mRNA - ANSWER serves to carry genetic information from DNA to the ribosomes for protein synthesis 23. Primary RNA - ANSWER -direct product of transcription in eukaryotic cells -contains both intron and exon segments of DNA 24. Introns - ANSWER intra gene segments which get removed 25. Exons - ANSWER remain in mRNA 26. What is 5' cap? - ANSWER -guanine nucleotide connected to the first nucleotide of the primary RNA transcription -helps during translation and also transports the mRNA into the cytoplasm 27. Escherichia coli - ANSWER -can use various sugars as a source of energy -can quickly adjust its end expression based on which sugar is available and will metabolize it 28. Operon - ANSWER cluster of genes usually coding for proteins related to a certain metabolic pathway 29. Promoter - ANSWER sequence of DNA where transcription begins 30. Operator - ANSWER sequence of DNA where a repressor protein binds 31. Promoters: Prokaryotic vs. Eukaryotic - ANSWER prokaryotes: single promoter can serve several genes eukaryotes: each gene has its own promoter 32. Eukaryotic Gene Expression: 5 Different Levels - ANSWER 1. Pre-transcriptional control 2. Transcriptional control 3. Post-transcriptional control 4. Translational control 5. Post-translational control 1. Pre-Transcriptional Control - ANSWER -DNA methylation and chromatin packing are used to keep genes turned off -genes located within heterochromatin are inactive -active genes found in euchromatin 2. Transcriptional Control - ANSWER -depends on interaction between certain proteins and particular DNA sequences -proteins are called transcription factors/activators -DNA sequences called promoters/enhancers