Biology 203: Final Exam Review Questions and Answers with Complete Verified Solutions Graded A 2024

What cellular events occur in the G1 phase of the cell division cycle? - normal growth and cell function What is the best way to describe homologous chromosomes? - they carry information for the same traits In some parts of Africa, the frequency of individuals who are heterozygous for the sickle-cell anemia allele is higher than the frequency in North America, presumably because this reduces the frequency of malaria. Such a relationship is related to what? - Darwin's theory of natural selection Red-green color blindness is an X-linked recessive trait in humans. Two people with normal color vision have a son with colorblindness. Given this information, the genotypes of the parents are ________________. - X^N X^n and X^N Y What investigator was responsible for determining that DNA contains equal amounts of adenine and thymine, and equal amounts of guanine and cytosine? - Erwin Chargaff What is a nondisjunction? - An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell When can nondisjunction occur? - In mitosis and meiosis, when sister chromatids fail to separate & in meiosis, when homologous chromosomes fail to separate. What syndrome is characterized by the XO chromosome abnormality? - Turner syndrome What kind of cell results when a diploid and a haploid gamete fuse during fertilization? - A triploid cell What type of chromosomal abnormalities is most likely to be viable in humans? - trisomy If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n - 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred? - A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n - 1 chromosomes, what type of error occurred? - A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell. What is the difference between a DNA and an RNA molecule? - DNA is usually double-stranded, whereas RNA is usually single-stranded. What nitrogenous base is found in DNA but not in RNA? - thymine In a nucleotide, the nitrogenous base is attached to the sugar's _________ carbon and the phosphate group is attached to the sugar's _________ carbon. - 1' ... 5' Nucleic acids are assembled in the ____________ direction. - 5' to 3' In a DNA double helix an adenine of one strand always pairs with a(n) ___________ of the complementary strand, and a guanine of one strand and always pairs with a(n) ____________ of the complementary strand. - thymine ... cytosine Who demonstrated that DNA is the genetic material of the T2 phage? - Hershey and Chase The radioactive isotope 32P labels the T2 phage's ___________. - DNA Hershey and Chase used ___________ to radioactively label the T2 phage's proteins. - 35S After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained __________ , which demonstrated that ___________ is the phage's genetic material. - labeled DNA ... DNA What catalyzes DNA synthesis? - DNA polymerase What is true about DNA synthesis? - Primers are short sequences that allow the initiation of DNA synthesis. Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis? - Phosphate groups What enzyme creates a primer for DNA polymerase? - Primase What is true about Okazaki fragments in E. coli? - They are formed on the lagging strand of DNA.