Exam 1 REVIEW Answers
The exam will have 40 multiple choice questions and 3 short answer questions. Use this document to review for the exam.
When attempting to introduce a particular fragment of DNA into the genome of an animal cell which of the following methods would be most successful?
Answer: CRISPR/Cas9 recombination (Works because it has mechanisms to get into a nucleus of the cell)
Which of the following describes how DNA microarrays have helped advance genomic studies?
Answer: They allow the expression of many or even all of the genes in the genome to be compared at once. (you must know what you are targeting when using microarrays, but you can multiplex gene testing with the technology)
Which of the following statements correctly describes how RNA interference (RNAi) reduces the expression of selected genes?
Answer: Synthetic double stranded RNA molecules trigger the breakdown of a gene’s messenger RNA (stops translation before it starts by preventing the RNA from binding to ribosomes)
What is the critical difference between microarray technology and RNA sequencing technology?
Answer: RNA seq does not require knowledge of the genome’s sequence before the study begins (works by extracting RNA and building it into copy DNA (cDNA), adding adapters so that the cDNA will be recognized by the sequencer, florescent signals give you the information on the sequence of the genome which allows you to map out the sequence)
Which of the following statements correctly describes one of the main differences between embryonic stem cells and adult stem cells?
Answer: Embryonic stem cells can give rise to all cell types in the organism, and adult stem cells cannot. (adult stem cells give rise to regeneration and repair)
The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Which of the following best explains the reason for the differences?
Answer: X chromosome inactivation in the embryo is random and produces different patterns (one X chromosome in female is always turned off, which is called a Barr body, and which one gets turned off in each organism is random)
Which of the following processes is used to convert adult cells into pluripotent stem cells (iPS)?
Answer: A retrovirus is used to introduce four specific master regulatory genes. (Yamanaka factors)
In the form of gene therapy used successfully for severe combined immunodeficiency syndrome, SCID-X1, how is the genetic engineering of human cells achieved?
Answer: By isolating the patient’s bone marrow cells, infecting them with genetically engineered viruses, and injecting them back into the patient’s bone marrow.
Which of the following tools of DNA technology is incorrectly paired with its use?
Answer: DNA ligase - cutting DNA, creating sticky ends of restriction fragments (DNA ligase glues DNA together)
Information within sequence databases, such as GenBank, could be used to perform which of the following tasks?
Answer: Construct a tree to determine the evolutionary relationships between various bird species
Humans have 23 paris of chromosomes, and chimps have 24 pairs of chromosomes. Which of the following best explains the difference in chromosome number between humans and chimps?
Answer: The common ancestor of humans and chimps had 24 pairs of chromosomes. During human evolution, two human chromosomes fused end to end.
Which of the following statements is most consistent with the model of evolutionary relatedness represented in the phylogenetic tree?
Salamanders are a sister group to the group containing lizards, goats, and humans.
Short Answer Questions
Think about all the genetic tools we discussed in this chapter and how they can apply to criminal forensics. Now, explain to me why genetic tools alone can’t be trusted.
What are some genetic tools?
PCR - known gene, you can tell how it changes within a sequence
Sequencing - don’t have to know anything, can use total genetic information
Microarray - must know every protein, able to sequence the whole genetic sequence
The best tool to use for a forensic examination (aka a drop of blood) is sequencing, because you don’t know anything about the samples. Next, you need suspects with known genomes in order to compare to the unknown sequence, which a large limitation because you can’t really use the whole general population as your suspect pool. Each person’s DNA is unique but there can be overlap between individuals, especially in twins. This is why DNA tools alone cannot be trusted, because there can be a lot of overlap between genomes that can’t immediately be determined. There are also warrants that need to be signed in order for the suspects to consent to have their genome information registered and/or shared, and there are cases where DNA found in a crime scene that don’t really account for contextual information (aka, a wife was murdered by her husband, the DNA of the husband was found at their house, but that makes sense since he is literally living in the house, so additional information will be provided).
Below are the amino acid sequences (using single letters) of three short segments of the FOXP2 protein from the five species. These segments contain all amino acid differences between the FOXP2 proteins of these species. Compare the anim
What were the key evolutions in sequencing technology? What were the consequences of these evolutions in terms of ability to use sequencing in medicine or research? Any thoughts on where we are going next?
The first sequencer, Sanger sequencing, utilized sequencing by synthesis where each nucleotide had its own test tube and they had to be added up to find the total sequence. Illumina synthesis combined the nucleotides in order to track the different florescent signals for each nucleotide so that the sequence could be tracked all at once (on test tube). After illumina, nanopore took things one step further by switching from synthesis to direct sequencing. As the DNA is being built, electrical signals can be used to read the sequence in real time. The consequences of this evolution in technology is their use in pharmacogenetics, as the technology improved the time to sequence the genome got significantly shorter (from 13 years in Sanger to 6 hours in nanopore). It is also much more robust to sequence the genome directly from the source instead of relying and being confined to human input and error. Additionally, the technology has become a lot less expensive over time (hundreds of billions of dollars for Sanger, compared to five thousand dollars for a readily available nanopore sequencing kits), making the sequencing technology more readily available to both pharmaceutical companies and the general public. In the future, the scale of the genome sequenced can become much more minuscule, whereas the past technology has looked at the whole human genome, we may be able to look at the DNA for a single cell within the human body.