 |
|
|
||||
|
|
|
|
||
|
AGR 3303 (3 credits) University of Florida - Fort Lauderdale  |
|
||||||||
|
||||||||
|
||||||||
| Below is exam #1 for 1993, Molecular genetics |
||||||||
|
||||||||
|
AGR 3303 - Genetics 27 Sep 1993 University of Florida - Fort Lauderdale Exam #1: MOLECULAR GENETICS
Read these carefully. One and only one response (a, b, c, d, or e) most completely and correctly answers the question, or completes the statement. Circle the appropriate response and turn in this exam. Please make sure your circle is unambiguous.
1. Double-stranded DNA which is rich in G-C base pairs will have: a higher composition of repetitive sequences b higher composition of unique sequences c lower melting point compared with DNA which is rich in A-T base pairs d higher melting point compared with DNA which is rich in A-T base pairs e none of the above 2. The normal human metabolic pathway makes substance Z from substance X, as shown below. If Enzyme A were defective, what would be the most probable consequence? Enzyme A Enzyme B X > Y > Z a Enzyme B would go ahead and complete the synthesis of Z b Substance X would accumulate in the body c Enzyme A would accumulate in the body d Enzyme B would not be produced e Substance Y would accumulate in the body 3. Enzymes: a reduce the energy of activation b are proteins d speed up chemical reactions d occur in the nucleus e all of the above 4. Which statement is most true? a The phenotype determines the genotype. b The genotype determines the phenotype. c The environment is determined by the genotype interacting with the phenotype. d The phenotype is determined by the genotype interacting with the environment. e The genotype is determined by the environment interacting with the phenotype. 5. Darwin and Wallace proposed a theory of natural selection to explain the variation among species. This explanation was incomplete, because something important was not explained. What was unexplained? a the genetic basis of variation b a basis for the inheritance of acquired characteristics c an hypothesis of pangenesis d realization that species are not fixed e realization that the earth was more than 6000 years old 6. Which sentence describes the general relationship between a polypeptide and its respective mRNA? a The number of amino acids in mRNA is three times the number of bases in the polypeptide. b The number of amino acids in the polypeptide is three times the number of nucleotide pairs. c The number of bases in mRNA is three times the number of amino acids. d The presence of wobble makes it impossible to predict a numerical relationship between the units in a polypeptide and its respective mRNA. e The code is ambiguous, which makes it impossible to predict a numerical relationship between a polypeptide and its respective mRNA. 7. Alien beings are discovered on a distant galaxy. Their genetic material is double-stranded DNA, with the same nitrogenous bases (A, T, G, and C) as earth-based DNA. The aliens' genetic code is based on a linear sequence of triplet codons, with no overlap, just like on earth. However, in contrast to earth-based molecular biology, there is no degeneracy in the alien genetic code. Therefore: a aliens may have more nonsense codons than earthlings b aliens may have more amino acids than earthlings c aliens have 64 possible triplet codons d any one of the above is possible e none of these interpretations fit the evidence 8. The Watson-Crick model of DNA structure was: a the first direct proof that DNA is the molecule of life b based on X-ray crystallography c predicted from triplet binding d the Central Dogma of molecular biology e all of the above 9. The bacteria of Avery et al. (1944) were transformed by a substance which remained active: a after treatment by heat and protease b after treatment by DNase c spontaneous creation d when radioactive 32P was detected e all of the above 10. Double-stranded DNA is allowed to replicate one cycle in a radioactively-labelled medium. If one half of the resulting daughter double strands were 100% labelled, and the other half were 0% labelled, this would be evidence for: a conservative replication b dispersive replication c semiconservative replication d semidispersive replication e cannot be determined 11. A cell-free protein-synthesizing system is used to link amino acids in a polypeptide chain. All necessary enzymes and other chemicals are included. A heteropolymer mRNA template is used, consisting of only two kinds of nucleotides (e.g., G and U), in long random sequences (e.g., GGGUGUUUUGUGUUGGUGU . . . . . . , etc.). Without knowing the coding dictionary, what is the maximum number of different kinds of amino acids which could be linked? a 1 b 2 c 4 d 8 e 20 12. What has molecular biology added to the knowledge of genetics a proof that genes act as particles b proof that genes are made of chemicals c proof that genes are located in the chromosomes d proof that both the female and the male parent contribute to the characteristics of the offspring e proof of the inheritance of acquired characteristics 13. A given piece of single-stranded DNA reads 5' GCCTAGCC 3'. Which of the following pieces of single-stranded DNA could form a normal, complementary double helix with the original piece? a 5' GGCTAGGC 3' b 5' CGGAUCGG 3' c 5' CCGATCCG 3' d 5' CGGATCGG 3' e 5' GGCUAGGC 3' 14. Where would you expect to find the genetic information describing the potential characteristics of Tyrannosaurus rex? a Only in its germ cells, i.e., primary spermatocytes or oocytes. b In virtually every cell of its body. c Depends on the characteristic; eye color genes would be found in its eyes, hemoglobin genes in its erythrocytes. d In the ribosomes. e In an island laboratory, off Costa Rica. 15. Hemoglobin and collagen are two proteins which show the quaternary (IVo or fourth) level of protein structure. The quaternary level is important in explaining the action of genes for hemoglobin and collagen because: a all enzymes are proteins b all proteins are enzymes c in these instances the normal product of the gene can compensate for a defective product d in these instances the normal product of the gene cannot compensate for a defective product e collagen and hemoglobin are monomeric proteins 16. Translation: a occurs in the nucleus b involves highly repetitive DNA c occurs in the ribosomes d is the process which produces mRNA e none of the above 17. Frameshift mutations demonstrate that: a The DNA code is a triplet b The DNA code has commas c Most codons do not specify an amino acid d There is an intermediate molecule, mRNA e None of the above 18. Sickle-cell anemia is caused by: a a violation of collinearity b a defective hemoglobin c a defective enzyme d a nonsense mutation e all of the above 19. Human insulin can be produced by bacteria, using human DNA. This proves that: a the infectious agent from phage contains P, not S b the infections agent from phage contains S, not P c the genetic material is DNA d DNA is a double helix e people are endosymbionts of mitochondria 20. What molecule is transcribed from the DNA template, is single stranded, is typically a large molecule, and has a short half-life (high turnover)? a tRNA b polypeptide c rRNA d antisense codon e mRNA 21. What can you say about an organism with the following base composition? A (adenine)=23% T (thymine)=17% G (guanine)=24% C (cytosine)=16% a Its genetic material is probably double-stranded DNA b This organism has collinearity between the pyrimidines and the purines c This organism must have much repetitive DNA d This organism must have single-stranded DNA e None of the above is compatible with the evidence 22. A gene can be defined as: a an inherited factor that determines a biological characteristic of an organism b a linear array of amino acids c the product of transcription d the product of translation e all of the above 23. How are nucleotides attached in single-stranded DNA? a hydrogen bonding between the bases b covalent bonding between the sugars c covalent bonding between phosphate and sugar d hydrogen bonding between the sugars e none of the above 24. Which of the following is a nucleotide of DNA: a deoxyribose + uracil + phosphate group b ribose + pyrimidine + phosphate group c deoxyribose + guanine + phosphate group d deoxyribose + nitrogenous base e none of the above 25. The human genetic disease phenylketonuria (PKU) results in mental retardation. The mental retardation effect can be diminished by restricting the amount of phenylalanine in the diet. PKU is an example of: a a toxic byproduct of blocked metabolic pathway b a defective enzyme c a genetic abnormality d a disease whose severity involves the interaction of a gene and the environment e all of the above |
|
|||
| (return to top) | |||