Bio 99: Molecular Biology

DNA/RNA is the less stable molecule because:

RNA, because it has a 2'OH group

Hershey and Chase's experiment demonstrated that DNA is the hereditary information. Which experimental result allowed them to conclude this?

Radioactive phosphorus was found in the bacterial pellets.

Which of the following is not a component of a ribonucleotide?

Thymine

One step of the Hershey/Chase experiment involved blending the virus/cell mixtrue before centrifugation and probing the pellet for radioactivity. Why was the blending step necessary?

To separate the bacteria from the bacteriophages.

Which of the following is not a feature of the DNA helix proposed by Watson and Crick?

Two grooves of equal dimensions

In the following pathway, mutation of enzyme II would result in the accumulation of __________ and the mutant would require __________ in the media in order to grow.

ornithine, citrulline

Which of the following types of RNA are involved in translation? Select all that apply.

tRNA, mRNA, rRNA

Each nucleosome contains:

A histone octamer composed of two copies of each of the following proteins: H2A, H2B, H3 and H4.

The first evidence for nucleosome formation came from digesting chromosomal DNA with a non-specific nuclease. Gel electrophoresis of the DNA after the reaction revealed:

A ladder of protected fragments about 200 bp apart.

Which of the following is not a way nucleosome formation affects DNA?

Binding of H1 destabilizes the nucleosome, alleviating the transcriptional repression exerted by the binding of nucleosome histones.

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? Select the best answer.

A DNA probe because it is more stable than RNA.

Of the proteins associated with chromatin, which of the following represents the largest component?

Histones

Which of the following is not true regarding protein coding DNA in humans?

Human protein coding genes are mostly exon sequences.

Which of the following are examples of auxotrophs? Select all that apply.

-A yeast cell that is unable to synthesize the amino acid leucine. -A neurospora strain that requires lysine from the environment in order to grow.

Which of the following are true regarding nucleic acid hybridization?

-It is possible to visualize a region of genomic DNA using a fluorescent probe. - It is possible to hybridize a DNA strand to an RNA strand. -It is possible for DNA from different species to hybridize.

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. -The existence of introns can lead to multiple variations of proteins encoded by a single gene.

Avery found that DNA was necessary and sufficient for bacterial transformation. Which of the following experimental results support this statement? Select all that apply

-Removal of DNA from cell extracts prevented transformation -DNA alone will cause transformation to occur

Which of the following are reasons why the "one gene, one enzyme" hypothesis is not completely accurate? Select all that apply.

-Some enzymes require more than one gene to be functional. -Some genes synthesize RNAs that do not produce proteins. - Some genes are capable of making multiple different enzymes.

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 genome of a healthy individual who does not have CFTR. -The genome of a CFTR patient known to have the specific truncation you are trying to identify.

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 would allow you to accomplish this?

-Using an RNA probe complementary to the region removed by the truncation. -Using an DNA probe complementary to the region removed by the truncation.

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

Chromatin consists of:

DNA and protein

Which of the following was observed by Erwin Chargaff?

DNA isolated from different tissues of the same species have the same base composition.

Genomics is the field dedicated to the study of:

DNA on a cellular scale.

Choose the answer that has the information flow of the central dogma in the correct order.

DNA, transcription, RNA, translation, protein

Which of the following will lower the Tm of a given DNA strand? Select all that apply.

Decreasing the buffer concentration from 50mM NaCl to 5mM NaCl.

The genomes of many organisms have been sequenced. What benefits or uses could result from this information?

Genome-based personalized medicine. Trace our evolutionary history. Elucidate genetic patterns related to diseases. Identify genes that can improve agricultural yield.

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? Select all that apply.

Heat killed non-virulent bacteria is added to a live virulent bacteria strain.

The contacts between the DNA and the histones of the nucleosome are:

Mainly between the conserved histone folds and the phosphate backbone of the DNA helix.

Which of the following does not describe an aspect of the Human Genome Project?

Overlapping clones from YAC and BAC libraries were identified by hybridization and organized into long contiguous stretches called contigs. Landmark sequences on the contig called sequence tagged sites (STS) were used to aid in ordering the contigs. The contigs were sequenced using a shotgun method, and the resulting sequences were assembled by computer.

A deoxyribonucleotide is composed of (select all that apply):

Pentose with 3' OH Phosphate group Nitrogenous base

Successive nucleotides of a DNA chain are joined by:

Phosphodiester bond between the 3 carbon of one nucleotide and the 5 carbon of the next

Which of the following is not a reason why proteins were thought to be the cell's carrier of genetic information?

Protein synthesis only requires proteins.

The carbons of the pentose group of DNA and RNA nucleotides are identical except for:

The functional group attached to C2

Which of the following is not a reason why H. influenzae was chosen to be the first genome sequenced.

The genome sequence had already been partially uncovered.

Which of the following is not true of histone tails?

They have enzymatic properties that can covalently modify DNA.

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?

Yes, because DNA and RNA nucleotides are similar.

The human genome is mostly composed of:

transposons and retrotransposons that are mostly inactive