BIOS 390 Week 1 Quiz Study Guide (LATEST UPDATE) | Download To Score An A

BIOS 390 Week 1 Quiz Study Guide BIOS390 – Molecular Diagnostics Week 1 (TCO 1) The basic principles of genetics contributed by Gregor Johann Mendel are: 1. The principle of segregation 2. T he principle of independent assortment (TCO 1) The Augustinian monk, Gregor Johann Mendel, crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6018 yellow and 2002 green (8020 total). The allele for green seeds has what relationship to the allele for yellow seeds? • Yellow is dominant over the green seeds, where as green seeds is recessive. (TCO 1) In 1953, James Watson and Francis Crick proposed • The double helix as a model for the structure of DNA. Question Set 2 (TCO 1) In 1928, Frederick Griffith discovered that Streptococcus pneumonia caused pneumonia in mice. In his experiments, mice were injected with different strains of treated and untreated bacteria. Which of the following is not likely to have occurred in the series of experiments by Griffith? • Live S bacteria inject into mice -die • Live R bacteria inject into mice-Live (do not have the capsule) • Heat killed S bacteria inject into mice-live • Mixture of live R bacteria and heat killed S bacteria injected into mice-Die (TCO 1) In 1928, Frederick Griffith injected living S (smooth) Streptococcus pneumonia into mice, and the mice died. When he injected living R (rough) Streptococcus pneumonia into mice, the mice lived. When he injected heat-killed S bacteria into mice, the mice lived. What was the result when he mixed heat-killed S bacteria with live R bacteria and injected this mixture into mice? • Mixture of live R bacteria and heat killed S bacteria injected into mice – The mice Die. • Griffith concluded that there was transformation which shows the role of DNA as a genetic material. (TCO 1) In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty used an in vitro agglutination assay to demonstrate that purified DNA was sufficient to cause transformation of cells, and that the transforming factor could be destroyed by • An enzyme called deoxyribonuclease that degrades DNA. Question Set 3 (TCO 1) Beadle and Tatum’s “one gene-one enzyme” hypothesis was later revised to the • “One gene – one polypeptide hypothesis” (TCO 1) In the 1950s, Hershey and Chase conducted a now-famous experiment to determine whether DNA or protein carried the hereditary information in bacteriophage T2. What method did they used to selectively label the DNA and protein components of bacteriophage T2? • Alfred Hershey and Martha Chase used radioactive sulfur and phosphorous to trace the fates of protein and DNA, respectively, of T2 phages that infected bacterial cells. They wanted to see which of these molecules entered the cells and could reprogram them make more phages. (TCO 1) The classic experiment performed by Alfred Hershey and Martha Chase revealed • When the proteins were labeled (batch 1), radioactivity remained outside the cells; but when the DNA was labeled (batch 2), radioactivity was found inside the cells. Bacterial cells with radioactive phage DNA released new phages with some radioactive phosphorus. • The researchers concluded that Phage DNA entered bacterial cells, but phage proteins did not. Hershey and Chase concluded that DNA, not protein, functions as the genetic material of phage T2. • The Hershey-Chase experiment was a landmark study because it provided powerful evidence that nucleic acids, rather than proteins, are the hereditary material, at least for viruses Question Set 4 (TCO 2) The phosphodiester linkage between adjacent nucleotides to form a DNA or RNA chain occurs by a reaction involving the removal of and pyrophosphate. • occurs by a condensation reaction involving the removal of H2O and pyrophosphate (TCO 2) The sugar in the DNA nucleotides is • a 5-carbon sugar (deoxyribose) (TCO 2) What forms the “backbone” of a nucleic acid? • a chain of sugar and phosphate groups, linked through phosphodiester bonds Question Set 5 (TCO 2) Which of the following did Watson and Crick know when they were trying to determine the structure of DNA? All except 6 and 8 applies… (TCO 2) The predominant form of DNA in vivo is B-DNA (TCO 2) Watson and Crick noted that DNA’s structure is interesting because it suggested a possible copying mechanism. What about DNA’s structure facilitates copying? The strands of the double helix are complementary. Question Set 6 (TCO 2) As DNA denatures, its absorption of UV light increases, a phenomenon known as the hyperchromic shift. The purine and pyrimidine bases in DNA strongly absorb ultraviolet light. (TCO 2) The melting temperature (Tm) of DNA is The temperature at which the DNA strands are half denatured, meaning half double- stranded, half single-stranded, is called the melting temperature(Tm). The amount of strand separation, or melting, is measured by the absorbance of the DNA solution at 260nm. (TCO 2) When two strands of DNA from different sources are hybridized in the lab, what provides the chemical stability for holding the two strands of DNA in a double helix structure? hydrophobic interactions (base-stacking) and hydrogen bonds Question Set 7 (TCO 2) Hairpin loops, base-paired stems, and bulges make up what part of RNA’s structure? Base-paired stems in RNA form an A-type double helix. A hairpin loop is an unpaired loop of messenger RNA (mRNA) that is created when an mRNA strand folds and forms base pairs with another section of the same strand. The resulting structure looks like a loop or a U-shape. A stem-loop structure is formed in an RNA sequence when a short neighboring sequence consists of complementary nucleotide sequence relative to its flanking regions. These sequences have a high tendency to entangle and make a stem-loop like structure. Importantly, the strength of this stem-loop structure depends upon the nature and number of nucleotide bonds present. Generally, the more is the GC content of this stem-loop binding, the more stable it is because GC bonds are comprised of triple hydrogen bonds. (TCO 2) Base-paired stems in RNA Base-paired stems in RNA form an A-type double helix. (TCO 2) A GU wobble is an example of noncanonical base pair Question Set 8 (TCO 2) A particular RNA chain can be misfolded and become trapped in a misfolded structure in the absence of RNA chaperones. Transfer RNA (tRNA) is a small RNA chain of about 80 nucleotides that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation The ribosome binds mRNA and carries out protein synthesis. Several ribosomes may be attached to a single mRNA at any time. (TCO 2) The term ribozyme describes what property of RNA molecules? catalytic (TCO 2) There is a tremendous versatility of functional RNA products involved in a wide range of cellular processes. One of the key contributing factors to this versatility is The key to RNA's versatility is its chemical structure. It's made from just 4 simple building blocks, yet RNA can take on a nearly infinite variety of shapes. And its three-dimensional shape in part determines what an RNA molecule can do. Contributing to the versatility of RNA function is the ability of RNA to form complementary base pairs with other RNA molecules and with single-stranded DNA. The ability of RNA to make specific base pairs is key to understanding its role in everything from post-transcriptional gene silencing to translation. Question Set 9 (TCO 2) A retrovirus, such as HIV-1 Retroviruses have an enzyme, called reverse transcriptase, that gives them the unique property of transcribing their RNA into DNA after entering a cell. The retroviral DNA can then integrate into the chromosomal DNA of the host cell, to be expressed there. HIV is a retrovirus. In the case of HIV, viral protein integrase then inserts the HIV DNA into host DNA. (TCO 2) Subviral RNA particles, such as viroids and satellite RNAs, differ from viruses in that viruses are non-living and cannot die. Viroids retain their ability to cause infections after being treated with powerful proteolytic chemicals that would destroy all proteinaceous material. -RNA virus virions are recovered as ribonucleoproteins -Viroids are recovered as naked RNA -(however, weak associations with replicating proteins, movement proteins, of the cell) -Viruses are parasites of the cell's translation system -Viroids are parasites of the cell's transcription system -Virus genomes encode genes that are translated into proteins; RNA viruses replicate in the cytoplasm -Viroids do not encode proteins; viroids replicate in specific subcellular organelles, not the cytoplasm -Viruses replicate with linear transcription templates -Viroids have a circular template for at least some replicative transcription -Virus genome size >2500nt -viroid "genome" size 246-401nt Virus acronyms end in "V" Viroid acronyms end in "Vd" (e.g., PSTVd) Question Set 10 (TCO 2) Which of the following properties do you predict to be most critical to histone association with DNA? histones are positively charged (TCO 2) The term nucleosome means the core octamer of histones plus the linker histone and approximately 180 base pairs of DNA (TCO 2) The core octamer is composed of tetramer of histones H3 and H4, and two dimers of histones H2A and H2B Question Set 11 (TCO 2) A eukaryotic chromosome consists of a single molecule of double stranded DNA (TCO 2) What statement is not true about bacteriophages? (List things that are true about bacteriophages.) Bacteriophages are viruses specialized in parasitism of bacteria. They are used in genetic engineering as molecular cloning vehicles to insert recombinant DNA into bacteria. They were also used in the former Soviet Union to treat bacterial infections. Bacteriophages have a polyhedron-like capsid and DNA as genetic material. The “head” of the virus is connected to a tail that ends in small fibers that help the virus to attach to the bacterial cell wall and to inject its genetic material into the host. (TCO 2) What statement is not true about plasmid DNA? (List things that are true/factual about plasmid DNA. 1. plasmids are typically circular and double–stranded DNA molecule; but linear plasmids have also been reported. 2. Plasmids are smaller than an independent of nuclear chromosome measuring between 1,000 and 20,000 DNA base pairs. 3. Many plasmids also have genes responsible for phenotypic expression of the organism. 4. Every plasmid contains at least one DNA sequence that serves as an origin of replication, which enables the plasmid DNA to be duplicated independently from the chromosomal DNA 5. Plasmids are easy to cut open, without falling apart, and snap back into shape. This makes it easy to insert new DNA into plasmids. Once a new DNA is inserted, the modified plasmid can be grown in bacteria for self-replication to make endless copies. 6. They carry functions advantageous to the host such as: • produce enzymes which degrade antibiotics or heavy metals • produce restriction and modifying enzymes Question Set 12 (TCO 1) Sodium hydroxide denatures both proteins and nucleic acids, while phenol denatures proteins, but not nucleic acids. In the transformation experiments performed by Griffith with Streptococcus pneumoniae, what result would be expected if an extract of S-strain bacteria was treated with phenol? What would be expected if it was treated with sodium hydroxide? The mice would die DNA would be transformed from S to R The mice would live, sodium hydroxide breaks down proteins and DNA (TCO 1) Using the Hershey-Chase experiment as an example, list the hypothesis, observations, and the conclusion of this experiment. Who confirmed that DNA is the material causing the transforming principle? When? Hershey and Chase in 1952 (THEY got the nobel prize, not Avery who paved the way) What is bacteriophage? (virus that infects bacteria) a virus that takes over a bacterium's genetic machinery and directs it to make more viruses What kinds of phages did Hershey and Chase study? simple ones, DNA molecule surrounded by a protein coat How did Hershey & Chase confirm that the genetic material was in fact DNA causing the transformation? By using the simple phages it they needed to discover which part of the phage, the DNA or the protein actually entered the bacterium Hershey & Chase confirmed DNA is the genetic material causing the transformation: 1. by using simple phages. 2. protein contains sulfur but little phosphorous 3. DNA contains phosphorus and little sulfur 4. Their plan was to grow cultures that contained radioactive isotopes of sulfur or phosphorus then use them in 2 experiments two experiments Hershey & Chase did to find the transformation material: 1. bacteria were infected with phages that had radioactive sulfur in their protein. They used a blender to separate the bacteria from the phages that remained on the outside of the bacteria. No significant radioactivity was found. thus transformation did not happen with the protein 2. repeated this procedure with phages that had DNA tagged with radioactive phosphorus. This time radioactivity was clearly present inside the bacteria (TCO 1) Compare the chromosome theory of inheritance to the process of meiosis. chromosome theory of inheritance: the principle that genes are located on chromosomes and that patterns of inheritance are determined by the behavior of chromosomes during meiosis... essentially explained by the independent alignment and separation of homologs at meiosis I X-linked inheritance convinced most biologists that the chromosome theory of inheritances was correct! Question Set 13 (TCO 2) Distinguish between the terms “nucleoside” and “nucleotide.” What does dGTP stand for? A nucleoside consists of nitrogenous base which covalently attached to the sugar molecule. A nucleotide is consisting of nitrogenous base attached to the sugar molecule as well as the phosphate group. These are made up of 5 carbon sugars + nucleobase + phosphate In the nucleoside the phosphate group is not present. Nucleotides are the building blocks of the DNA and RNA. Nucleosides are formed when the nucleotides are broken down. These nucleosides have anti-cancer uses. Deoxyguanosine triphosphate (dGTP) is a nucleoside triphosphate, and a nucleotide precursor used in cells for DNA synthesis. The substance is used in the polymerase chain reaction technique, in sequencing, and in cloning. It is also the competitor of inhibition onset by acyclovir in the treatment of HSV virus. (TCO 2) When the base composition of DNA from a grasshopper was determined, 29% of the bases were found to be adenine. (a) What is the percentage of cytosine? (b) What is the % composition of each of the other two nucleotides in the DNA sequence? a) 21% b) A (29%) T(29%) C (21%) G (21%) Chargaff's rule -rule about base ratios percentages of A and T are equally the same, as are those of G and C (TCO 2) What determines the polarity of the two strands of DNA? Why are the two strands anti-parallel? DNA- double-stranded polynucleotide formed from two separate chains of covalently linked deoxyribonucleotide units. Stores cells genetic information Important structural features and characteristics of DNA: - Contains Nucleotides, chromatin, chromosomes - Double stranded and double helix - Phosphate group and carbohydrate join by phosphodiester bonds covalent and negatively charged - Nucleotides are covalently linked together into polynucleotide chains through the sugar phosphate backbone - Hydrogen bonds connect the bases (A-T, C-G) Hydrogen bonds hold the two DNA strands together in a DNA double helix. These bonds are formed of f the purines and Pyrimidines. The sugar phosphate backbone of a DNA strand is negatively charged. The strands are oriented to each other through a double helix. DNA is linked in a 5' to 3' direction, meaning that the bases must run from 5' to 3', making the two strands anti-parallel. DNA is a polar molecule because it has a negatively (-) charged phosphate group attached to the 5' end of the molecule and a negatively charge hydroxl group (OH) attached to the 3' prime end of the molecule. Question Set 14 (TCO 2) The 10 nm chromatin fiber in eukaryotes has been described as "beads on a string." What are the "beads" (be precise and detailed in your use of terminology) and what is the "string"? The chromatin packing in Eukaryotic chromosome from smallest to biggest: 1. DNA, the double helix 2. Histones 3. Nucleosomes, or "beads on a string" 4. 30-nm fiber 5. Looped domains 6. metaphase chromosome Nucleosome: -the basic unit of DNA packaging -the string between these beads is called "linker DNA" -consists of DNA wound twice around a protein core composed of two molecules each of the 4 main histones types. -the "histone tail" The amino end (N-terminus) of each histone extends outward from the nucleosome -during cell cycle, histones leave the DNA only briefly during DNA replication and transcription. (TCO 2) List 2 features that distinguish eukaryotic genomes from bacterial genomes Introns and chromatin are not found in bacterial genomes. (TCO 2) List the steps in eukaryotic DNA packaging. The chromatin packing in Eukaryotic chromosome from smallest to biggest: 1. DNA, the double helix 2. Histones 3. Nucleosomes, or "beads on a string" 4. 30-nm fiber 5. Looped domains 6. metaphase chromosome Nucleosome: -the basic unit of DNA packaging -the string between these beads is called "linker DNA" -consists of DNA wound twice around a protein core composed of two molecules each of the 4 main histones types. -the "histone tail" The amino end (N-terminus) of each histone extends outward from the nucleosome -during cell cycle, histones leave the DNA only briefly during DNA replication and transcription. Show Less