Bio 181 Grand Canyon University Exam 3

Bio 181 Grand Canyon University Exam 3 A frameshift mutation could result from - ANS - E) either an insertion or a deletion of a base. Which of the following does not occur in prokaryotic eukaryotic gene expression, bu ...

Bio 181 Grand Canyon University Exam 3 A frameshift mutation could result from - ANS - E) either an insertion or a deletion of a base. Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression? - ANS - C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end. Which of the following helps to hold the DNA strands apart while they are being replicated? - ANS - single-strand binding proteins Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the - ANS - bonding of the anticodon to the codon and the attachment of amino acids to tRNAs Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? - ANS - 8% What is the function of DNA polymerase III? - ANS - to add nucleotides to the 3' end of a growing DNA strand A new DNA strand elongates only in the 5' to 3' direction because - ANS - DNA polymerase can only add nucleotides to the free 3' end. How do we describe transformation in bacteria? - ANS - assimilation of external DNA into a cell What is the function of topoisomerase? - ANS - relieving strain in the DNA ahead of the replication fork Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? - ANS - DNA polymerase III Which of the following nucleotide triplets best represents a codon? - ANS - a triplet in the same reading frame as an upstream AUG An Okazaki fragment has which of the following arrangements? - ANS - DNA polymerase I, DNA polymerase III What do we mean when we use the term monohybrid cross and dihybrid cross? - ANS - a dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one. How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE ? a) 4 b) 8 c) 16 d) 32 e) 64 - ANS - b) 8 Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? a) no genes interacted to produce the parental phenotype. b) each allele affected phenotypic expression. c) the traits blended together during fertilization. d) one phenotype was completely dominant over another. e) different genes interacted to produce the parental phenotype. - ANS - d) one phenotype was completely dominant over another. When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? - ANS - 50% Which of the following is an example of polygenic inheritance? - ANS - skin pigmentation in humans Which of the following is false, regarding the law of segregation? a) it states that each of two alleles for a given trait segregate into different gametes b) it can be explained by the segregation of homologous chromosomes during meiosis c) it can account for the 3:1 ratio seen in the F2 generation of mender's crosses d) it can be used to predict the likelihood of transmission of certain genetic diseases within families e) it is a method that can be used to determine the number of chromosomes in a plant - ANS - e) it is a method that can be used to determine the number of chromosomes in a plant Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize a particular amino acid. The amino acid is not otherwise produced by humans. Therefore, the most efficient and effective treatment is which of the following? a) feed them the substrate that can be metabolized into this amino acid b) transfuse the patients with blood from unaffected donors c) regulate the diet of the affected persons to severely limit the uptake of the amino acid d) feed the patients the missing enzymes in a regular cycle, such as twice per week e) feed the patients an excess of the missing product - ANS - c) regulate the diet of the affected persons to severely limit the uptake of the amino acid The following question refers to the pedigree chart in Figure 14.2 above for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the genotype of individual II-5? a) WW b) Ww c) ww d) WW or ww e) ww or Ww - ANS - ww Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp pines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of a) incomplete dominance b) epistasis c) complete dominance d) pleiotropy e) codominance - ANS - b) epistasis Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century? a) individuals inherit particular chromosomes attached to genes b) mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis c) homologous chromosomes give rise to some genes and crossover chromosomes to other genes d) no more than a single pair of chromosomes can be found in a healthy normal cell e) natural selection acts on certain chromosome arrays rather than on genes - ANS - b) mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? - ANS - the gene involved is on the X chromosome Which of the following statements is true of linkage? a) the closer two genes are on a chromosome, the lower the probability that a crossover will occur between them b) the observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100% c) all of the traits that mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome d) linked genes are found on different chromosomes e) crossing over occurs during prophase II of meiosis - ANS - a) the closer two genes are on a chromosome, the lower the probability that a crossover will occur between them What does a frequency of recombination of 50% indicate? a) the two genes are likely to be located on different chromosomes b) all of the offspring have combinations of traits that mat