Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?
A) Cancer cells are no longer density-dependent.
B) Cancer cells are no longer anchorage-dependent.
C) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
D) Transformation introduces new chromosomes into cells.
C
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The formation of the bivalent during meiosis
A. is required for the pairing of homologous chromosomes. B. contributes to the genetic diversity of a species. C. ensures that the resulting haploid cells will have the same combination of homologous chromosomes as the original diploid cell. D. aids the alignment of sister chromatids in a single row along the metaphase plate. E. occurs during meiosis II.
Which of the following are examples of integrators?
a. brain, spinal cord b. muscles, glands c. sensory cells in eye, tongue, and ear d. bones e. none of these
Subtelomeres are blocks of homologous DNA sequences close to the ends of chromosomes
In a worldwide population of humans, when sequences of chromosomes 4q and 10q subtelomeres were analyzed only 17 4q and 8 10q haplotypes were found among African, European, and Asian groups. Which of the following might be among the results or conclusions of this analysis? A) finding that few or no interchromosomal exchanges can occur among these chromosomes B) a conclusion that all haplotypes were present before the human population migrated from Africa C) reporting that haplotype polymorphism shows no response to natural selection D) finding greater than 80% variation between homologous ends of chromosomes in humans E) a conclusion that assigning chromosomal origin of repeat arrays by using specific restriction enzymes is possible only in a population with the same ethnic origin
Which two cellular organelles in eukaryotes have both electron transport systems and chemiosmotic mechanisms?
a. Ribosomes and endoplasmic reticulum b. Chloroplasts and endoplasmic reticulum c. Chloroplasts and mitochondria d. Mitochondria and nuclei e. Nuclei and Golgi apparatus