NAME ________________________________
BLOCK ______________
BIOLOGY 12: CHAPTER 25/26.1 - REVIEW WORKSHEET
DNA REPLICATION, PROTEIN SYNTHESIS, & RECOMBINANT DNA
A. DEOXYRIBONUCLEIC ACID (DNA)
1. Where are the genes found in a cell? Name the two groups of nitrogenous bases found in chromosomes.
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2. List the three subunits of every nucleotide found in nucleic acid. What are the specific pairings of the bases in DNA?
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3. The two _________________ of DNA twist about one another to form a ______________ helix with the two strands held
together by _____________________ bonds between the purines and pyrimidines.
4. How does the structure of unwound DNA compare to that of a ladder?
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5. Name the two scientists that first determined the structure of DNA.
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6. List the three basic functions that DNA, as a hereditary material, must be able to do.
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7. a) What is the function of helicase?
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b) What is the function of DNA polymerase?
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c) List the steps required in DNA replication?
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8. Why is DNA replication said to be semiconservative? Which enzyme “proofreads” the replicated DNA?
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9. What does the concept, one gene - one enzyme, mean?
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10. What is the difference between transcription and translation?
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11. What is the specific type of RNA that is used to produce the correct order of amino acids in a polypeptide?
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12. The genetic code is arranged into ___________________.
13. a) Define a codon. ______________________________________________________________________________________________
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b) There are three general categories of codons. Explain what each type does and give a specific example of each.
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iii) ___________________________________________________________________________________________________________________
14. Is the genetic code considered essentially universal?
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B. PROTEIN SYNTHESIS
1. During transcription, a segment of _________ unwinds, and complementary ______ nucleotides pair with the ___________
nucleotides of the template strand.
2. What enzyme is used to join the RNA nucleotides together? ____________________________________
3. a) Distinguish between introns and exons. What happens during mRNA processing?
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b) What is the role of ribozymes in processing?
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4. What is the function of tRNA? What is found attached to the “head” of each tRNA molecule? What is found at each
end of the tRNA molecule?
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5. a) What are the two types of molecules found in each of the two subunits of a ribosome?
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b) Where is each component molecule made/processed?
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c) Where are the subunits assembled and then transferred?
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6. a) List the three steps of translation (in sequential order).
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b) The codon that stands for the amino acid ____________________ will begin the first stage of protein synthesis.
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7. How many tRNA molecules will attach to a ribosome at one time?
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8. Define a polyribosome. What is the advantage of forming them?
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9. The ______________________ of each tRNA is complementary to a particular codon in __________________.
10. During translation, the order of mRNA codons determines the order in which ____________ and their attached amino
acids come to a ribosome to determine the sequence of amino acids in a polypeptide.
C. GENE MUTATIONS
1. Define gene mutations. Are they always deleterious?
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2. a) Categorize the following gene mutations as P (point mutations) or F (frameshift mutations)
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_____ Deletions
_____ Substitutions
3. a) Distinguish among missense mutations, silent mutations, and nonsense mutations.
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b) i) What type occurs in sickle cell hemoglobin? _____________________________________________
ii) Explain how sickle cell disease occurs.
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4. a) What are transposons? What organisms are they found in?
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b) Explain the two types of transposition.
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5. a) What is a mutagen?
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b) What are the two categories of mutagens? Give an example of each.
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c) Does exposure to mutagens necessarily guarantee a mutation? Why or why not?
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D. COMPLETION AND SHORT ANSWER QUESTIONS
1. All nucleotides are made up of three parts: a base, a sugar, and a ___________.
2. In DNA, the base adenine (A) is always paired with a base symbolized by the letter ____.
3. DNA is a ____________ stranded helix with the nucleotides found on the ________________.
4. DNA replication is referred to as __________________ because each new double helix is made up of an old strand and a
new strand.
5. A mutation is a change in the sequence of _________ within a DNA molecule.
6. During transcription, DNA serves as a ______________ for mRNA formation.
7. A __________ consists of three adjacent bases that code for one amino acid.
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E. RECOMBINANT DNA
1. Production of identical copies through asexual means is called ___________.
2. Small accessory rings of DNA that can be used as a vector are called ____________.
3. The two enzymes needed to introduce foreign DNA into vector DNA are _____________ and ___________________________.
4. ___________ ________ can bind to foreign DNA by complimentary base pairing.
5. A human gene inserted into a bacterium should not contain ___________.
6. List 3 possible uses for recombinant DNA in the future.
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7. Explain the process used to create recombinant DNA.
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