Q&A Hero

Q: Describe the major cellular and molecular events that mark the entry of mitosis from G2.

Q: What is the significance of CDK?

Q: Why do cancer researchers study molecular events associated with mitosis?

Q: Chronic myelogenous leukemia appears to be associated with a chromosomal rearrangement. Which chromosome(s) is(are) involved, and what is the name of the rearrangement?

Q: Chronic myelogenous leukemia appears to be associated with a chromosomal rearrangement. How is a chromosomal rearrangement responsible for this disease?

Q: Provide a definition of cancer at the anatomical level.

Q: Provide a definition of cancer at the genetic level.

Q: What is the name of the protein that appears to regulate the entry of cells into an S phase? This protein is also known as the "guardian of the genome." A) p34 B) p102 C) cyclin D) p53 E) phosphokinase

Q: In sporadic cases of retinoblastoma, how many gene mutations are thought to be necessary in the same cell for a tumor to develop? A) one B) two C) four D) six E) There is insufficient information to answer this question.

Q: Mutant versions of genes that are normally involved in promoting the cell cycle are known as ________. A) tumor suppressors B) proto-oncogenes C) oncogenes D) malignant genes E) attenuators

Q: The retinoblastoma protein (pRB), like p53, serves as a(n) ________ in regulating the cell cycle. A) tumor suppressor B) tumor enhancer C) up regulator D) oncogene E) pseudooncogene

Q: A protein functions as a cell-cycle regulator that causes cell death (apoptosis) to a damaged cell. What is the symbol given to this protein? A) p34 B) p102 C) cyclin D) p53 E) phosphokinase

Q: What is the name of the protein that combines with cyclins to exert local control of the cell cycle? A) cyclin-dependent kinase B) phosphatase C) ATPase D) integrase E) hexokinase

Q: Which of the following general mechanisms appear to be involved in the formation of cancer cells? A) genomic instability, DNA repair failure, chromatin modifications B) inversions, operon formation, methylation C) RNA failure, DNA phosphorylation, phosphorylation of adenyl cyclase D) transdetermination, mutation, allosteric interactions E) suppression, tabulation, projection

Q: Driver mutations provide a growth advantage to a tumor cell. Which type of mutation is known to accumulate in cancer cells but has no direct contribution to the cancer phenotype? A) alteration mutations B) passenger mutations C) carrier mutations D) indirect mutations E) insignificant mutations

Q: Caenorhabditis elegans is extremely useful as an experimental organism because it has relatively few cells, and, for the most part, each embryonic cell's fate is developmentally fixed.

Q: Drosophila and Arabidopsis use different sets of nonhomologous master regulatory genes to establish the body axis and specify the identity of structures along such an axis.

Q: A homeobox gene is one that produces a group of repetitive base sequences such as a VNTR.

Q: Segmentation genes, such as the pair-rule class, are inherited through mitochondrial DNA in Drosophila.

Q: In Drosophila, maternal-effect genes are influential in determining the anterior-posterior organization of the developing embryo.

Q: Genetic involvement in development appears to be achieved, at least in part, by variable gene activity.

Q: Differentiation is the process whereby a cell's determined state is expressed.

Q: Determination is the process whereby a cell's eventual developmental fate is set.

Q: What significant conclusion has the classic work on the eyeless and Pax6 genes provided in terms of developmental mechanisms?

Q: During development, many genes act in such a way as to decrease the number of alternative developmental pathways that a cell can follow. Usually there are two alternative developmental paths for a cell to follow. What is the term given to genes that act in this fashion?

Q: Give a brief definition of a homeobox.

Q: The bicoid gene of Drosophila generates embryos with two posterior regions. What is the likely aspect of embryonic development that the bicoid gene probably controls?

Q: From a human developmental standpoint, what is the significance of Hox genes?

Q: What is the significance of the homeodomain?

Q: It is presently believed that the asymmetric distribution of substances in the egg, positioned by the mother, is responsible for establishing the determined state. Which general term describes such molecular positioning?

Q: Do Hox gene clusters exist in humans? If so, how many are known to exist?

Q: Mutations in the selector genes sometimes form structures in the wrong segment, transforming the antenna of a fly into a leg, for example. What are such mutations called?

Q: Which class of genes controls the developmental identity of segments along the anterior-posterior axis?

Q: A gene that specifies the fate of a particular anatomical segment in Drosophila is called a(n) ________.

Q: Molecular/structural orientations (gradients) in an egg are thought to play a significant role in development. What is the origin of such gradients? What evidence indicates that the maternal genotype is involved in providing such gradients?

Q: What is the general order of genes involved in determining early Drosophila development?

Q: How do segment polarity genes relate to pair-rule genes?

Q: Provide a brief description of segment polarity genes, including their regulation and their molecular and developmental effects.

Q: In Drosophila, what is the order of function of the segmentation genes?

Q: Which functions earlier in development: maternal-effect genes or zygotic genes?

Q: Experiments involving nuclear transplantation in amphibians indicate that nuclei derived from blastula are more likely to support development of complete and normal adults compared with those derived from later stages of development. What do these experiments tell us about the process of development?

Q: Maternal effects are cases of extrachromosomal inheritance in which the genotype of the mother influences the phenotype of her immediate offspring in a non-Mendelian manner. Provide a rationale for the molecular basis of a maternal effect.

Q: Three investigatorsNsslein-Volhard, Wieschaus, and Lewiswon the Nobel Prize for physiology and medicine in 1995 for work they did in 1970 with Drosophila. Briefly describe their findings.

Q: What kinds of general observations cause one to conclude that development is the result of variable gene activity?

Q: It is often said that development is a two-step process. What two steps are likely to be referred to here?

Q: Design an experiment that would allow you to determine if a particular nucleus in a Drosophila embryo is capable of directing development of an entire new fly.

Q: Provide a brief description of the variable gene activity hypothesis as it relates to development. What information is often provided in support of this hypothesis?

Q: Define determination and differentiation.

Q: How does determination relate temporally to differentiation?

Q: Provide an explanation of the differences between differentiation and determination. Provide examples of each process and indicate how each is involved in development.

Q: Which of the following is a fundamental characteristic of the Notch pathway? A) It works through nuclear signals involving the lac operon. B) It works through direct cell to cell contact. C) It allows mRNAs to accumulate in the posterior portion of the Drosophila embryo. D) It directs mRNAs to antisense systems in the posterior portion of all organisms. E) It provides symmetry to plant flowers.

Q: Mutations that eliminate a contiguous region in the Drosophila embryo's segmentation pattern are called ________. A) homeodomains B) gap genes C) compartment genes D) linkage genes E) segment genes

Q: In Drosophila, the sequential order of the function of segmentation genes is ________. A) gap, segment-polarity, pair-rule B) pair-rule, transdeterminal, gap C) transdeterminal, gap, pair-rule D) gap, pair-rule, segment-polarity E) segmentational, helical, spherical

Q: Immediately after fertilization of a Drosophila egg, the zygote nucleus undergoes a series of divisions. Subsequent nuclear migration generates a(n) ________. A) syncytium B) maternal effect C) homeodomain D) zygote E) cleavage nucleus

Q: Which general genetic process is believed to account for the variety of cellular structures and functions in eukaryotic cells? A) variable gene activity B) negative control exclusively C) maternal environmental activities D) intron processing E) RNA processing

Q: Which term refers to the regulatory events that establish a specific pattern of gene activity and developmental fate for a given cell? A) lysogen B) differentiation C) determination D) gradient regulated E) attenuation

Q: One of the earliest steps in the RNAi pathway involves the association of siRNA or miRNA molecules with an enzyme complex composed mainly of reverse transcriptase.

Q: The term spliceopathy would be a reasonable term to signify a genetic condition caused by a defect in the regulation of RNA splicing.

Q: Alternative RNA processing can result in different mRNAs that start with different exons.

Q: Alternative RNA processing generates different mRNAs, which can direct the synthesis of different polypeptides.

Q: An upstream activator sequence (UAS) can function at variable distances and in either orientation. However, it differs from an enhancer in that it cannot function downstream of the transcription starting point.

Q: Transcription factors are proteins with at least two functional domains"one that binds to DNA and one that binds to RNA polymerase or to other transcription factors.

Q: The CAAT (CAAT box) sequence appears to be critical to the ability of many eukaryotic promoters to facilitate transcription.

Q: Transcription in eukaryotes is generally influenced by enhancers just as in prokaryotes.

Q: Regulation of RNA transport through the nuclear membrane is as common in prokaryotes as in eukaryotes.

Q: In general, one could say that fewer levels of regulation are possible in prokaryotes than in eukaryotes.

Q: In what way is gene rearrangement related to gene regulation? Give an example.

Q: In some cases, genes undergo amplification (local, multiple duplications) when additional gene products are in high demand. Would you consider gene amplification as a form of genetic regulation in eukaryotes? Explain your answer.

Q: List three general pathways in which eukaryotic mRNA is typically degraded in eukaryotes.

Q: When transcription factors interact with DNA, is the resulting genetic control typically positive or negative?

Q: In what ways are eukaryotic transcription factors thought to function?

Q: List three major structural classifications of DNA-binding domains that are found in eukaryotic transcription factors.

Q: What evidence indicates that steroid hormones exert their influence at the level of DNA?

Q: What is meant by the term helix-turn-helix (HTH)?

Q: Describe the function and general nature of promoters in eukaryotes.

Q: What are zinc fingers, and why are they frequently encountered in descriptions of genetic regulation in eukaryotes?

Q: The human metallothionein IIA gene (hMTIIA) is transcriptionally regulated through the interplay of regulatory elements and transcription factors. What is the function of this gene, and how is it regulated by environmental circumstances?

Q: Approximately 5% of the cytosine residues are methylated in the genome of any given eukaryote. In what way is DNA methylation related to genetic regulation?

Q: Provide a general set of statements that describes an enhancer.

Q: Mutations in the promoter region of the β-globin gene indicate that some areas are more sensitive than others. When mutations occur in consensus sequences (modular elements such as GC box, CAAT box, TATA box), does transcription usually increase or decrease?