BIO206H5 Lecture Notes - Lecture 10: Ribosomal Rna, Tryptophan, Transfer Rna

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ceruleanporcupine379

4 Nov 2015

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The energy of this bond is later used to link the amino acid covalently to the growing polypeptide chain. Rnas (rrnas: the small ribosomal subunit matches the trnas to the codons of the mrna, while the large subunit catalyzes the formation of the peptide bonds that covalently link the amino acids together into a polypeptide chain. These two subunits come together on an mrna molecule near its 5 end to start the synthesis of a protein. The mrna is then pulled through the ribosome like a long piece of tape. Its amino acid is then linked to the peptide chain held by the trna in the neighboring p site. Next, the large ribosomal subunit shifts forward, mov- ing the spent trna to the e site before ejecting it. This initiator trna always carries the amino acid methionine: this methionine is usually removed later by a specific protease. In eukaryotes, an initiator trna, charged with methionine, is first loaded into the.

Related Questions

The energy for protein synthesis comes from which of the following?

	a.	The ATP used in the synthesis of aminoacyl-AMP molecules that are then converted to aminoacyl-tRNAs
	b.	The GTP that is bound to initiation factors used in the initiation and translocation phases of translation
	c.	The high energy C-N bond of the amino acid
	d.	a, b, and c
	e.	a and b

The enzymatic process of "charging" a molecule of tRNA is similar to other enzyme catalyzed reactions. Which of the following correctly describes such similarities?

	a.	Formation of an acyl-adenylate intermediate coupled to the hydrolysis of pyrophosphate in fatty acid activation is similar to reactions involved in the "charging" of tRNA.
	b.	Proofreading and correcting abilities that prevent incorporation of the wrong molecule are analogous to the action of DNA polymerase.
	c.	The aminoacyl-tRNA synthetase is a relatively non-specific enzyme (i.e., it can activate many different amino acids) and, in this respect, is similar to ribonucleotide reductase.
	d.	a and b.
	e.	b and c.

22. What is probably the single most important distinction between bacteria and eukaryotes?

a. transcription

b. the separation of the cell's genetic material from the surrounding cytoplasm

c. the existence of ribosomes

d. RNA processing in bacteria

e. antibiotics

23. Which one does NOT characterize an open reading frame (ORF)

a. Uses six reading frames during translation

b. Contains a start codon

c. Contains a stop codon

d. Its length is in multiples of 3 nucleotides

e. It should have the number of codons for a protein or on average ~250 codons in length.

24. Nested intronic genes lie within the non-coding intronic region of a larger gene, and occur in the human genome.

a. True

b. False

25. How would you characterize this statement: EF-Tu will hydrolyze GTP only if the codon:anticodon & tRNA:amino acid matchings are correct

a. Transcription; initiation steps

b. Transcription; termination steps

c. Translation: initiation steps

d. Tanslation: elongation steps

e. Spliceosome

26. Regarding the transcription unit architecture of the Escherichia coli genome, which one is FALSE?

a. Each of the 4,661 transcription units comprised an average of 1.1 modular units.

b. 3,010 transcription units (~65%) are monocistronic.

c. 1,652 transcription units (35%) contain more than one ORF (polycistronic)

d. The largest transcription unit is equivalent to 16 ORFs with numerous introns.

e. 398 transcription units (~9%) are nested within each other in opposite transcriptional orientation

27. Regarding RNA interference (RNAi), which one is FALSE?

a. It is a common and conserved mechanism in eukaryotic cells.

b. Originally discovered in bacteria and plant viruses.

c. A form of primitive immunity to protect the genome.

d. Pre microRNA (miRNA) genes have been found in introns.

e. Recent research shows that exogenous plant miRNAs in food can regulate the expression of target genes in mammals.

28. Aminoacyl-tRNA synthetases

a. Recognize the 3âUTR

b. The genes for these enzymes fall into the family of inducible genes

c. The enzymes are imported into the nucleus

d. Covalently attaches an amino acid to the appropriate tRNA. This takes place in the cytoplasm.

e. Forms the peptide bond during protein synthesis

29. What is the process by which complementary RNAs are made from a DNA template?

a. translation

b. transcription

c. protein synthesis

d. transduction

e. transliteration

cyanbee225

1. You have the following prokaryotic DNA sequence: 5â²-GGACTAGACAATAGGGACCTAGAGATTCCGAAA-3â² 3â²-CCTGATCTGTTATCCCTGGATCTCTAAGGCTTT-5â² If the top strand is the template strand which sequence below is the correct mRNA transcript? A. 5â²-GGACUAGACAAUAGGGACCUAGAGAUUCCGAAAâ3â² B. 5'-UUUCGGAAUCUCUAGGUCCCUAUUGUCUAGUCC-3' C. 5'-CCUGAUCUGUUAUCCCUGGAUCUCUAAGGCUUU-3' D. None of the above are correct

2.Starting in the cytoplasm with a fully mature mRNA explain the process of translation initiation and then elongation and termination to me.

3.Prior to export from the nucleus, pre-mRNA must be processed. What specifically does this entail?

4.The biosynthetic pathway for the two amino acids E and H is shown schematically in the figure. You are able to show experimentally that E inhibits enzyme V, and H inhibits enzyme X. The most logical hypothesis regarding the regulation of Enzyme T would be that it is most likely subject to feedback inhibition by E alone. True or False?

5. A. kinase B. ligase C. polymerase D. oxido-reductase E. Phosphatase F. protease G. nuclease H. ATPase 1. Removes a phosphate group from a molecule 2. Hydrolyzes ATP 3. Hydrolyzes bonds between nucleotides 4. Adds phosphate groups to molecules 5. Catalyzes reactions in which one molecule is oxidized and another is reduced 6. Hydrolyzes peptide bonds 7. Joins two ends of DNA together 8. Catalyzes the synthesis of polymers such as RNA and DNA

6. Looking at the figure showing the change in reaction rate for two different enzymes that both utilize the same substrate, answer the following questions. a. What is the approximate Vmax for enzyme B ? b. What is the approximate Vmax for enzyme A ? c. What is the approximate Km for the enzyme which has a higher affinity for the substrate uM.

7. Answer the following question either yes or no (spell out the word, do not abbreviate as y or n). Looking at the following coupled reaction: Luciferase luciferin + O 2 ==========> oxyluciferin + light âG = + + Mg2+ ATP <=> AMP + PPi âG = - - - a. Based on your knowledge of free energy change and reactions would this coupled reaction occur ? b. Would changing the second step from ATP<=> AMP + PPi âG = - - - to ATP <=> ADP + Pi âG = - change your answer

7.Spontaneous reactions by definition will happen instantaneously. Why false?

8. Each of the following questions apply to the image of the channel protein. The purple sphere is a charged ion. Type your response to each question in the blank provided. a. Based you on what you know about cells and ions, what does the tri-lobed red and white molecule represent (although there aren't anywhere near enough of them shown) ? b. Since the question stated the purple sphere was a charged particle, using what you know about the tri-lobed red and white molecule what is the charge of the purples sphere c. On the extracellular space, on the right side of the purple sphere, there are two tri-lobed red and white molecules in close proximity to one another. The red of one appears to be attracted to the white of the other. What type of bond is this ? d. Based on your knowledge of proteins that interact with the membrane and the properties of the membrane, to what family of amino acids would the amino acid marked by A. most likely belong? ?

BIO206H5 Lecture Notes - Lecture 10: Ribosomal Rna, Tryptophan, Transfer Rna

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