Chapter 11 Pre-Class Assignment
Proto-oncogenes: (select all correct choices)
- can be mutated by cigarette smoke to become triggers for cancer. - promote cell division.
The second meiotic division resembles mitosis because:
- chromosomes decondense during telophase II. - sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells. - microtubules attach from opposite directions to the centromere of each sister chromatid pair. - the daughter cells have the same number of chromosomes as the parent cells. ** All of these choices are correct. **
During meiosis I:
- nonsister chromatids exchange maternal and paternal DNA. - chromosomes undergo reductional division. - sister chromatids are not separated. - bivalents are formed during prophase I and are taken apart during anaphase I. ** All of these choices are correct. **
Sexual reproduction results in an increase in genetic diversity because:
- of both recombination during prophase I and random orientation of bivalents during metaphase I. - during metaphase I, the bivalents line up in a random orientation so that gametes inherit a random set of maternally and paternally derived chromosomes. - during fertilization, the gametes that fuse are random so that a large number of chromosomal combinations are possible in the new organism. - during prophase I, genes that are paternally and maternally derived are recombined on the chromosomes so that the gametes have chromosomes that are different from the parents' chromosomes. ** All of these choices are correct. **
Reproduction by cell division:
- results in two daughter cells that are genetically identical. - persists in mature plant cells for continued growth. - continues in mature adult humans to replace damaged and worn-out cells. - is asexual reproduction. ** All of these choices are correct. **
Cell division is regulated by:
- signals that indicate a sufficient size of the cell. - signals that indicate that DNA has been replicated. - signals about the nutritional status of the cell. - growth factor signals. ** All of these choices are correct. **
Tumor suppressors can oppose oncogenes by:
- slowing cell division. - instructing defective cells to die. - blocking the action of an oncogene. - repairing mutations. ** All of these choices are correct. **
Match each of the following terms with its definition.
1. the physical breakage and reunion of non-sister chromatids during prophase I ----------> crossing over 2. the region of a chromosome where sister chromatids remain attached ----------> centromere 3. chromatids in a bivalent that do not share a centromere ----------> non-sister chromatids 4. a four-stranded structure of homologous chromosomes in alignment ----------> bivalent 5. the microtubule organizing center ----> centrosome 6. paired chromosomes that share the same set of genes ----------> homologous chromosomes 7. cross-like structures found in bivalents as a consequence of crossing over ----------> chiasmata 8. alignment of homologous chromosomes during prophase I ----------> synapsis
Which of the following statements is NOT true about sister chromatids?
They are formed when the prokaryotic circular chromosome attaches at the plasma membrane.
Which of the following is NOT true about gametes?
They are genetically identical to other gametes formed during meiosis.
The centrosome:
is the microtubule organizing center for the mitotic spindle.
