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AGR 3303 (3 credits) University of Florida - Fort Lauderdale  |
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| Below is exam #2 for 1998, Molecular genetics, with bonus
points for Mendelian |
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| Multiple choice (88
pts.) Please read these carefully. One and only one response (a, b, c, d,
or e) completely and correctly answers the question, or completes the statement. Circle
the appropriate response and turn in this exam. Make sure your circle is unambiguous. 1. What can you say about an organism with the following base composition? A (adenine)=23% T (thymine)=24% G (guanine)=17% C (cytosine)=16% a Its genetic material is probably double-stranded RNA b This organism has collinearity between the pyrimidines and the purines c This is mitochondrial DNA d This organism must have single-stranded DNA e None of the above is compatible with the evidence 2. Which of the following is a nucleotide of DNA: a deoxyribose + thymine + phosphate group b deoxyribose + nitrogenous base c ribose + pyrimidine + phosphate group d deoxyribose + uracil + phosphate group e none of the above 3. 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 ribosome b enzyme c polypeptide d all of the above e none of the above 4. Based on the Watson-Crick model of the double helix: a DNA is proven to be the molecule of life b structure reveals function c the mitochondrion is an ancient cell invader d all of the above e none of the above 5. What has molecular biology added to the knowledge of genetics a proof that genes are located in the chromosomes b proof that both the female and the male parent contribute to the characteristics of
the offspring c proof of epigenesis d proof of the inheritance of acquired characteristics e proof that genes are made of chemicals 6. The normal human metabolic pathway makes substance Z from substance X, as shown
below. If both Enzyme A and B were functional, what would be the most probable
consequence? Enzyme A Enzyme B X à Y à Z a Substance Y would accumulate in the body b Substance X would accumulate in the body c Enzyme B would accumulate in the body d Enzyme A would not be produced e Enzyme B would go ahead and complete the synthesis of Z 7. Frameshift mutations are observed because: a The DNA code is commaless b The DNA code has stop codons c The DNA code is a triplet d All of the above e None of the above 8. Human insulin can be produced by bacteria, using human DNA, thus: a human DNA is a transforming principal b the DNA contains S, not P c there is base pair complementarity d DNA is a double helix e bacteria are endosymbionts of people 9. Which statement is true of the double helix? a. AT pairs involve two hydrogen bonds b. purine pairs with pyrimidine c. heating causes the strands to separate d. all of the above e. none of the above 10. If an experiment had used radioactively labeled human insulin DNA, in a microbial synthesis, what would you expect to find in the insulin protein produced (think carefully about this): a. radioactive S would occur in the insulin b. radioactive P would occur in the insulin c. both radioactive P and S would occur in the insulin d. neither radioactive P or S would occur in the insulin e. insulin would not be produced 11. RNA polymerase is active in: a. replication b. transcription c. translation d. all of the above e. none of the above 12. Why is forensics evidence from DNA more useful than other kinds of substances, such as fiber, glass, and fingerprints? a DNA evidence can be based on minute sample quantities b the DNA message can be very complicated and specific to one in billions c DNA evidence is ubiquitous d all of the above e none of the above 13. A gene can be defined as: a a unit particle of inheritance b a region of the chromosome c a chemical which determines characteristics d all of the above e none of the above 14. There are no systems currently available for cloning RNA. To prepare probes for detection of plant viruses whose genome consists of RNA, phytopathologists resort to synthesizing and cloning DNA copies from viral RNA. Indicate which one of the following enzymes can be used to synthesize DNA copies from RNA templates. a. Ribonucleate H b. Reverse transcriptase c. DNA polymerase I d. S1 nuclease e. none of the above 15. The polymerase chain reaction (PCR) is the name of a powerful technique used for exponential amplification of DNA. Which is a stage of the PCR cycle:
16. There are three main types of vectors for cloning fragments of DNA. Choice of the vector depends upon the size of the DNA fragments to be cloned. You are attempting cloning the entire genome of Bacillus subtilis. After isolating and digesting DNA from this bacterium the average fragment size of the resulting DNA fragments is 7-50 kb. Indicate which one of the three vector types listed below would ideal for cloning DNA fragments within this size range
17. Indicate from the choices below which one refers to the transfer of DNA from an agarose gel onto a solid support such as a nylon membrane.
18. Plasmid vectors constructed from the Ti plasmid of the crown gall bacterium Agrobacterium tumefasciens are used to transform plants with genes conferring useful traits from other organisms. Indicate from the choices below which groups of plants can been successfully transformed with this vector system
23. Fill in the blank (10 pts.) Genetic information in the _______________________ template is transcribed to a short-lived intermediate molecule, _______________________ which is translated to the gene product, an amino acid polymer (_______________________), using an adapter molecule, _______________________ to decode the message. Other important players to know include RNA polymerase, nucleoside triphosphates, and promoter sequences (transcription) and ribosomes (translation). As with replication, transcription and translation involve initiation, chain elongation, and termination. Among eukaryotes, these processes occur as: _______________________ in the nucleus, _______________________ in the cytoplasm; among _____________________s, these processes are linked in time and place, and are faster. Prokaryotic genes can be nested within other genes. Transfer RNA helps understand some features of the genetic code. The triplet code is , _______________________ which is explained by the wobble hypothesis. Punctuation signals are the termination codons (nonsense triplets). The triplet nature of the code was first proven based on , _______________________ (nonsense) mutations, which lead to a change in the reading of the mRNA, leading to premature chain termination. Organellar DNA (mitochondrion and chloroplast) has a slightly different coding dictionary, suggesting that mitochondria and chloroplasts are prokaryotic _______________________. 24. Fill in the blank (10 pts.) In humans the _______________________ is the heterogametic sex, having both an X and a Y sex-determining chromosome; the _______________________ have two X chromosomes. (The remaining _______________________ chromosomes are _______________________). Genes located on a sex chromosome are called sex-linked; because the , _______________________ chromosome contains very little information (other than a sex determining factor), sex-linkage essentially always involves the , _______________________ chromosome. Important recessive, sex-linked traits in humans include hemophilia, color blindness, and muscular dystrophy. Because males have only one copy of sex-linked genes (hemizygous), the recessive traits are expressed in the male if he receives a copy of the gene from his mother. Females rarely express sex-linked traits, because they rarely receive a copy of the _______________________ allele from both parents. Consequently, one can refer to "female carriers" of a sex-linked trait. Another sex-linked trait, coat color in cats, shows an unusual pattern. Calico cats are females whose X chromosomes differ allelically for the coat color gene. According to the Lyon hypothesis, one or the other of the female's _______________________ is randomly inactivated to form a _______________________ body. This occurs independently for different cells during the early divisions of _______________________, and all daughter cells retain the same inactivated X chromosome; the allele on the active X chromosome conveys a coat color to the patch that developed from one of the early cells. Short answer (you can use arrows to extend your answers (41 pts.) to the reverse side of the pages; please be neat) 25. List the three basic allelic relationships that we discussed in class, plus the technical term for the masking interaction of separate genes controlling the same trait. Finally, as a fifth concept, include the word which is used for multiple genes. Give a brief definition of each of these five concepts. (15 pts.) 26. Explain in a few words mechanisms by which the chromosomes maintain the continuity of genetic information and also allow for new genetic combinations to occur. (5 pts.)
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