5 Written questions
5 Matching questions
- Use the following information to answer the following questions.
InDrosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The four sequestered cells at one end are most probably destined to become
C) the legs of the adult fly.
D) the germ cells of the adult.
E) wing primordial.
- One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Which of the following best describes this phenomenon? A) inherited predisposition to mutation
B) susceptibility to chemical carcinogens
C) inherited inability to repair UV-induced mutation
D) embryonic or fetal cancer
E) inherited cancer taking a few years to be expressed
- Viral envelopes can best be analyzed with which of the following techniques?
A) transmission electron microscopy
B) staining and visualization with the light microscope
C) immunofluorescent tagging of capsid proteins
D) antibodies against specific proteins not found in the host membranes
E) use of plaque assays for quantitative measurement of viral titer
- To cause a human pandemic, the H5N1 avian flu virus would have to
A) become much more pathogenic.
B) spread to primates such as chimpanzees.
C) arise independently in chickens in North and South America.
D) become capable of human-to-human transmission.
E) develop into a virus with a different host range.
- Which of the following is most closely identical to the formation of twins?
A) therapeutic cloning
B) embryo transfer
C) organismal cloning
D) cell cloning
E) use of adult stem cells
- a C) organismal cloning
- b D) become capable of human-to-human transmission
- c D) antibodies against specific proteins not found in the host membranes
- d C) inherited inability to repair UV-induced mutation
- e D) the germ cells of the adult
5 Multiple choice questions
- A) translation rate
- D) other transcription factors
- A) differentiated cells retain all the genes of the zygote
- B) increased chromatin condensation
- A) nothing; they self-assemble
5 True/False questions
In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to
A) the attachment of methyl groups to cytosine following birth, which changes the type of hemoglobin produced.
B) pseudogenes, which interfere with gene expression in adults.
C) histone proteins changing shape during embryonic development.
D) identical genes that generate many copies of the ribosomes needed for fetal globin production.
E) nonidentical genes that produce different versions of globins during development. → E) nonidentical genes that produce different versions of globins during development
DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. What is the purpose of transferring the DNA from a gel to a nitrocellulose paper?
A) to attach the DNA fragments to a permanent substrate
B) to prepare the DNA for digestion with restriction enzymes
C) to separate the two complementary DNA strands
D) to separate out the PCRs
E) to transfer only the DNA that is of interest → A) to attach the DNA fragments to a permanent substrate
Which of the following best describes siRNA?
A) a molecule, known as Dicer, that can degrade other mRNA sequences
B) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
C) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits
D) a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns
E) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor → B) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
How does a bacterial cell protect its own DNA from restriction enzymes? A) by adding histones to protect the double-stranded DNA
B) by forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching
C) by adding methyl groups to adenines and cytosines
D) by reinforcing the bacterial DNA structure with covalent phosphodiester bonds
E) by using DNA ligase to seal the bacterial DNA into a closed circle → C) by adding methyl groups to adenines and cytosines
The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.
In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which
of following best fits these observations?
A) Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage.
B) The viral envelope is not required for infectivity, since the envelope does not enter the nucleus.
C) The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the genome is all that enters the nucleus.
D) Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus.
E) The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate. → C) The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the genome is all that enters the nucleus.