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Transcription and Translation in Eukaryotes and Prokaryotes, Exams of Biology

A wide range of topics related to transcription and translation in both eukaryotic and prokaryotic cells. It discusses the process of rna polymerase binding to the promoter region, the formation of the pre-initiation complex, the differences between prokaryotic and eukaryotic transcription, the role of the 5' cap and poly(a) tail in mrna processing and stability, the mechanisms of splicing and termination, and the differences between mrna translation in prokaryotes and eukaryotes. The document also touches on various other topics such as dna packaging, mitosis and meiosis, and the identification of different forms of dna. Overall, this document provides a comprehensive overview of the fundamental processes of gene expression in living organisms.

Typology: Exams

2023/2024

Available from 08/25/2024

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Bio Core II Exam 1 | Actual Exam
Questions | 100% Correct Answers |
Verified 2024 Version
which of the following statements regarding a DNA double helix is always true? - ✔✔the amount of
adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of
cytosine
working in a coroner's office, you are investigating the mysterious death of a person found in the
wooded area in the spring of the year. during a cellular analysis of this body, you learn that the levels of
mRNA that can be obtained from critical tissues are very low, and you find mushrooms in the contents of
the stomach. after examination of the mushrooms, you learn that they are a species of Aminita, and a
search of the Internet reveals that a toxin in this fungus inhibits RNA polymerase. However this isn't very
specific information. to be more certain of the cause of death in this case, you would need to verify that
the alpha-aminitin inhibits which eukaryotic RNA polymerase? - ✔✔RNA polymerase II
a prokaryotic mRNA transcript is - ✔✔translated as it is being transcribed
in eukaryotes, transcription is initiated by the formation of a pre initiation complex of transcription
factors and RNA polymerase at the TATA box of the promoter. give the correct order of the steps below: -
✔✔A: the TFIID complex containing the TATA box binding proteins binds to the TATA box
B: TFIIA and TFIIB bind to the initiation complex
E: TFIIF binds to RNA polymerase and this complex adds to the complex assembling at the TATA box
D: TFIIE and TFIIH bind to the complex, and the helicase function of TRIIH produces a small bubble in the
double-stranded DNA
C: RNA polymerase begins transcribing the sense strand of the DNA producing a complementary RNA
which form of DNA is a left-handed double helix - ✔✔Z-DNA
which of the following catalyzes the synthesis of ribosomal RNA in eukaryotes - ✔✔both RNA
polymerase I and III
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Download Transcription and Translation in Eukaryotes and Prokaryotes and more Exams Biology in PDF only on Docsity!

Bio Core II Exam 1 | Actual Exam

Questions | 100% Correct Answers |

Verified 2024 Version

which of the following statements regarding a DNA double helix is always true? - ✔✔the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine working in a coroner's office, you are investigating the mysterious death of a person found in the wooded area in the spring of the year. during a cellular analysis of this body, you learn that the levels of mRNA that can be obtained from critical tissues are very low, and you find mushrooms in the contents of the stomach. after examination of the mushrooms, you learn that they are a species of Aminita, and a search of the Internet reveals that a toxin in this fungus inhibits RNA polymerase. However this isn't very specific information. to be more certain of the cause of death in this case, you would need to verify that the alpha-aminitin inhibits which eukaryotic RNA polymerase? - ✔✔RNA polymerase II a prokaryotic mRNA transcript is - ✔✔translated as it is being transcribed in eukaryotes, transcription is initiated by the formation of a pre initiation complex of transcription factors and RNA polymerase at the TATA box of the promoter. give the correct order of the steps below: - ✔✔A: the TFIID complex containing the TATA box binding proteins binds to the TATA box B: TFIIA and TFIIB bind to the initiation complex E: TFIIF binds to RNA polymerase and this complex adds to the complex assembling at the TATA box D: TFIIE and TFIIH bind to the complex, and the helicase function of TRIIH produces a small bubble in the double-stranded DNA C: RNA polymerase begins transcribing the sense strand of the DNA producing a complementary RNA which form of DNA is a left-handed double helix - ✔✔Z-DNA which of the following catalyzes the synthesis of ribosomal RNA in eukaryotes - ✔✔both RNA polymerase I and III

DNA strands are considered antiparallel because the strands are oriented in opposite directions. each nucleotide strand has a 5'-3' or 3'-5' directionality. What is the basis of this DNA polynucleotide directionality? - ✔✔the phosphodiester linkage points of the nucleotides: linking the 5' carbon and 3' - OH group of each unit bacterial mRNAs are polycistronic, whereas eukaryotic mRNAs are monocistronic. Polycistronic means that - ✔✔bacterial mRNAs contain coding information for multiple genes a cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. these mRNAs however were transcribed from the same gene in the cell nucleus. which mechanism below could best account for this? - ✔✔exons from the same gene could be spliced in different ways to make different mRNAs different mRNA molecules can have poly(A) tails of different lengths and this affects the lifetime of the mRNA molecule in the cell. Longer poly(A) tails means the mRNA is present for a greater time in the cell. why do you think this is? - ✔✔the poly(A) tail protects the mRNA from being degraded by 3' exonucleases in humans, the cell that is fertilized by a sperm is the - ✔✔secondary oocyte self-cleaving RNAs that function catalytically are called - ✔✔ribozymes a rho-independent terminator - ✔✔forms a hairpin loop during termination which of the following steps is responsible for the production of an active spliceosome during the splicing of introns? - ✔✔dissociation of the U4 snRNP from the spliceosome complex is the activating step leading to removal of the intron, the formation of a "lariat" and an mRNA with the intron spliced out the following figure shows the transcribed region of a typical eukaryotipicprotein coding gene. what is the size in bases (bp) of the fully processed, mature mRNA? assume a poly(A) tail of 200 A's in calculations - ✔✔ 376 (200 A's, + 100 + 50 + 25 exon bps)

roughly 6 feet of eukaryotic DNA are in each cell and are compacted by proteins called histones. why are histones highly positively charged proteins? - ✔✔DNA has negatively charged phosphate backbone describe the packing of chromatin from the 10-nm to the 30-nm fiber stage. what is the role of histones?

  • ✔✔in the 10 nm stage, chromatin has the characteristic "beads on a string" morphology. the "beads" are nucleosomes. nucleosomes consist of a histone core (eight histone proteins; 2 each of H2A, H2B, H3, and H4) + DNA wound around the core, condensing the DNA 6 - fold. binding of histone H1 to the linker DNA at one end of the nucleosome and to the middle of the DNA segment wrapped around the core histones, causes further condensation to the 30 nm stage, giving a "zig-zag" pattern rosalind franklin's data was shown to watson and crick by Wilkins and was the catalyst for their correct double helical model of DNA for which they would eventually win the Nobel prize. given what you know, briefly summarize what actions in this case may have been unethical - ✔✔franklin's data was shown without her permission to watson and crick and they used it to propose their model without properly acknowledging her work looking at a nucleotide, determine whether from DNA or RNA - ✔✔DNA has thymine and lacks hydroxyl group RNA has uracil and has hydroxyl group be able to number the carbons in the sugar (1' to 5') and draw Watson crick base pair involving a shown base, show hydrogen bonds, just draw base pairs - ✔✔be able to recognize A, T, G, C and draw a A&T or G&C pair in eukaryotes, mRNA is processed before it can be translated into a polypeptide. a mature mRNA has a 5' cap, a poly(A) tail and introns excised out by splicing. what are two known functions of the 5' cap - ✔✔protection from degradation translation initiation if the 5' cap is not added to an mRNA, what do you think might be two possible outcomes for that mRNA transcript based on the cap's functions? - ✔✔mRNA might be degraded too soon (because cap protects from exonucleases) mRNA might not get translated (because cap is recognized by translation factors)

poly(A) polymerase is responsible for the addition of adenosine nucleotides to the 3' end of the mRNA transcript. if there was a mutation in the PAP enzyme turning it constitutively on, meaning it never stopped adding adenosines to mRNAs, what do you think might be some consequences for the mRNA and the cell overall? - ✔✔mRNA might never get degraded because polyA tail very long. too much of that protein might be made. OR around at the wrong time. could adversely affect cell. too much mRNA might be bad for cell as well. maybe lead to cell death disease etc. Descriptions of a series of mitotic events are provided in the table below. Write the name of the corresponding event on the left (i.e. which phase) and number the blanks to the right of each event according to when they occur, beginning with a 1 for interphase and ending with a 7 for the last event in the sequence. - ✔✔1: interphase - chromosome replication occurs 2: prophase - replicated chromosomes begin to condense and become visible under the microscope 3: prometaphase - the nuclear envelope breaks down, a developing mitotic spindle enters the former nuclear area, and kinetochores bind to centromeres 4: metaphase - chromosomes become aligned along the equatorial plane of the cell 5: early anaphase - sister chromatids begin to separate and migrate towards opposite poles of the cell 6: late anaphase - the migration of the daughter chromosomes to the two poles is complete 7: telophase or cytokinesis - the cytoplasm divides and the cell contents are separated into two separate cells list three differences, excluding mRNA processing, between prokaryotic and eukaryotic transcription - ✔✔1. initiation is different - transcription initiation complex in eukaryotes vs RNA pol + sigma factor in prokaryotes

  1. happens in nucleus in eukaryotes only
  2. mRNA cotranslated in prokaryotes only
  3. promoter regions different (-35 and - 10 in prokaryotes, core promoter and proximal elements in eukaryotes) know how to identify the different stages of mitosis and meiosis, how to find diploid chromosome number - ✔✔ex: 2N = 6 (we see 3 chromosomes present) Cell (a) shows three pairs of previously synapsed homologs disjoining and must therefore illustrate anaphase I of meiosis.

a cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. These mRNAs, however, were transcribed from the same gene in the cell nucleus. Which mechanism below could best account for this? - ✔✔exons from the same gene could be spliced in different ways to make different mRNAs in Rho-dependent termination, which of the following is true? - ✔✔the enzyme Rho unwinds the DNA- RNA hybrid different mRNA molecules can have poly(A) tails of different lengths, from a few A's up to 200 A's. what do you think is a consequence of these differences? why do you think this is? - ✔✔longer poly(A) tails allows the mRNA to be present for a greater time in cell which of the following statements is not correct - ✔✔only prokaryotic mRNAs are polyadenylated at their 3' ends during transcription the synthesis of the mRNA strand proceeds in which direction? - ✔✔5' to 3' only which one of the following is essential for RNA polymerase to bind an E. coli promoter? - ✔✔sigma factor which of the following can be described as 'a sequence that can be several thousand base pairs upstream of a eukaryotic promoter and which increases gene expression as much as 200-fold - ✔✔enhancer the DNA and histone proteins in a eukaryotic chromosome are compacted into structures called - ✔✔nucleosomes which of the following statements is true concerning true genetic chimeras? - ✔✔a and b (they may be hermaphrodites, they began as two separate zygotes) all the DNA in a human cell forms a single, very long chain - ✔✔false

all species have the same number of chromosomes in the nuclei of their cells - ✔✔false the drug colchicine inhibits the formation of spindle fibers. if you treat dividing cells with colchicine, what would you expect the result to be? - ✔✔chromosomes would duplicate in interphase (S phase) and enter mitosis aka normal interphase. However, the spindle apparatus would not form, so the chromosome would not be segregated and mitosis would not occur what are two mechanisms by which genetic variation is produced by meiosis? - ✔✔independent assortment and crossing over there are five substages of meiosis prophase I: leptonema, zygote, pachynema, diploma, and diakinesis. briefly summarize what happens during reach stage - ✔✔leptotene: the duplicated chromosomes start to condense and become visible zygotene: synapsis begins pachytene: synapsis is completed and crossing over occurs diplotene: synaptonemal complex disappears and chiasma is visible diakinesis: chromosomes pull further apart, but non-sister chromatids (tetrads) remain loosely associated at the visible chiasmata what is the key difference between anaphase I in meiosis and anaphase in mitosis - ✔✔homologous chromosome separate halving chromosome number vs sister chromatids separate in mitosis