Biology 1202B Lecture Notes - Lecture 6: Francis Crick, Nucleic Acid Double Helix, Chloroplast Dna
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Question 1
1 pts
Cystic fibrosis is caused by nonsense and missense mutations in the CFTR gene, which encodes for a chloride channel. You are studying cystic fibrosis patients to determine what mutation they possess in the CFTR gene. The difference between the mutant and wild type CFTR genes can be uncovered by examining the CFTR:
| DNA | |
| mRNA | |
| protein | |
| tRNA |
Question 2
1 pts
You decide to identify the CFTR mutation by analyzing the genomic DNA of your patients compared to healthy individuals. You specifically are looking to see whether a specific 3' gene truncation has occurred in the patients. You will determine this using hybridization techniques with samples from healthy and CF patients. Which of the following will allow you to accomplish this?
| Using an RNA probe complementary to the region not removed by the truncation. | |
| Using an RNA probe complementary to the region removed by the truncation. | |
| Using an DNA probe complementary to the region not removed by the truncation. | |
| Using an DNA probe complementary to the region removed by the truncation. |
Question 3
1 pts
You would like to ensure that this experiment (to determine whether patients have a specific CFTR gene truncation using hybridization) is properly controlled. Which of the following samples must you test?
| The genomic DNA of a healthy individual who does not have cystic fibrosis. | |
| The genome of a CFTR patient known to have the specific truncation you are trying to identify. | |
| The genome of a CFTR patient with a missense mutation but full length gene. | |
| The genome of a healthy individual married to a CFTR patient with the specific truncation you are trying to identify. | |
| The genome of a patient with muscular dystrophy, which can be due to a trucation in the dystrophin gene. |
Question 4
1 pts
To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?
| As both are composed of nucleic acids, using either would result in identical results. | |
| An RNA probe because RNA has uracil bases. | |
| An RNA probe because it could also be used in a translation experiment. | |
| A DNA probe because it is more stable than RNA. | |
| A DNA probe because RNA cannot bind to DNA. |
Question 5
1 pts
Which of the following will lower the Tm of a given DNA strand?
| Increasing the percentage of GC base pairs. | |
| Raising the pH of the solution from neutral to basic. | |
| Decreasing the buffer concentration from 50mM NaCl to 5mM NaCl. | |
| None of the above. |
Question 6
1 pts
One step of the Hershey/Chase experiment involved blending the virus/cell mixture before centrifugation and probing the pellet for radioactivity. Why was the blending step necessary?
| To collect the bacteria at the bottom of the tube. | |
| To break open the bacteria to release the genome. | |
| To separate the bacteria from the bacteriophages. | |
| To be able to detect the radioactivity. |
Question 7
1 pts
Imagine Hershey/Chase had used an RNA virus (genome composed of RNA) instead of a DNA virus in their experiment. Would radioactivity still have been found in the pellet?
| No, because only DNA can be labeled with radioactivity. | |
| No, because the RNA genome would not enter the bacteria upon infection. | |
| No, because while DNA and RNA nucleotides are similar, they are not identical. | |
| Yes, because DNA and RNA nucleotides are similar. | |
| Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly. |
Question 8
1 pts
Griffith and Avery's transformation experiments allowed us to identify that DNA is our genetic information. Which of the following scenarios would result in bacterial cells that are capable of killing mice upon injection?
| Heat killed non-virulent bacteria is added to a live virulent bacteria strain. | |
| Heat killed virulent bacteria is added to a heat killed non-virulent bacteria strain. | |
| A heat killed virulent bacteria that is treated with a nuclease, is then added to a non-virulent bacteria strain. | |
| Heat killed mouse cells are added to a non-virulent bacteria. |
Question 9
1 pts
The human genome consists mostly of non-coding DNA. Which of the following are benefits of this?
| Random DNA mutations generally won't affect RNA and protein function. | |
| It is faster to duplicate the genome when these are present. | |
| The existence of introns can lead to multiple variations of proteins encoded by a single gene. | |
| It is unlikely transposons would exist in the genome if there was too much protein coding DNA. |
Question 10
1 pts
Andrew Murray's sister, Andrea, is adding to her brother's work on chromosomes. She is using cells that are unable to synthesize adenine (âade) and histidine (âhis). The plasmid she is currently working with consists of an origin of replication and the Ade gene.
Following her transformation of the plasmid into her yeast, what media will the cells be plated on to select for cells that have picked up the plasmid?
| Media containing histidine | |
| Media containing adenine | |
| Media lacking adenine | |
| Media lacking histidine |
Chapter 10
1.Outline the history of our knowledge on DNA up to Watson and Crick. What were the main contributions made by each researcherâs key experiment?
2.Explain the setup of the Hershey and Chase experiment, what would the results have been if protein was the genetic material?
3.Draw the structure of a DNA nucleotide, labeling each main component correctly. How does an RNA nucleotide differ?
4.If a section of double stranded DNA contains 19% Adenine, how much Thymine is present?
5.You are a researcher studying the genetic basis of heart attacks and have been working to determine the expression levels of different genes that might contribute to cancer formation. You obtain the DNA methylation status of five genes of interest (the data are shown in the table below). The plus (+) sign indicates the level of DNA methylation; more plus signs correlates with increased methylation levels.Based on this information which genes would you predict to have the highest rate of transcription?
| Gene | Methylation levels |
| 1 | ++ |
| 2 | +++++ |
| 3 | +++ |
| 4 | ++ |
| 5 | + |
What are the characteristics of the 3 main DNA forms?
Chapter 11
What are the different types of chromatin?
What are the structures and important roles for telomeres and centromeres?
What are the differences found between eukaryotic chromosomes and mitochondrial?
Chapter 12
Explain each of the different models of replication.
If you grow a culture of bacteria in media with radioactive nucleotides so that all DNA in the cells include radioactive nucleotides and then place the bacteria in new non radioactive media. After two rounds of replication what proportion of the DNA molecules will contain radioactivity?
Summarize the similarities and differences between rolling-circle replication, theta replication and linear eukaryotic replication.
What are the functions of the different DNA polymerases found in eukaryotic cells?
Draw a replication fork and include all key components and orientations. (Leading/lagging strands, DNA helicase, RNA primer and DNA gyrase)
What is the Holliday model of recombination and what are the necessary steps?
Chapter 13
What are the different types of RNA and what roles do they play?
Describe the properties and functions of each of the RNA polymerases and how they differ depending on the organism.
Describe in detail the process and mechanisms of transcription in both prokaryotes and eukaryotes.
Chapter 14
What are the primary purposes of each of the three post transcriptional modifications that occur in eukaryotic cells.
What is alternative splicing and what role does it play in the cell?
How is ribosomal RNA processed after transcription?
How do siRNA and miRNA work, describe/draw out the process in detail.