1. Describe the structure of DNA.
Name:
Date: Period:
Chapter 12 Study Guide
Relate “DNA” to “nucleotide.”
Explain the meaning of the term “deoxyribonucleic acid.”
Explain how the sugar molecules glucose, ribose, and deoxyribose are different.
List the four nucleotides in DNA.
Explain why nucleotides are also known as “nitrogen bases.”
Label the 3 main parts of the nucleotide below.
Describe the backbone of the DNA molecule.
Explain why DNA contains sugar in its structure (hint: carbon ring).
Differentiate between the bonds holding together the sugar-phosphate backbone and the bonds holding together nucleotides in a base pair.
Identify the nucleotide in question #6 as a purine or a pyramidine.
Differentiate between purines and pyramidines in terms of their structure.
According to base-pairing rules, write the complementary sequence for: A C C G C T A T A C G G G C G.
Explain why there are always equal numbers of purines and pyramidines in a DNA strand.
Briefly describe Griffith’s contribution to our current understanding of DNA.
Briefly describe Hershey and Chase’s contribution to our current understanding of DNA.
Explain why Hershey and Chase used bacteriophages in their experiment.
Describe what Chargaff found when he analyzed a sample of DNA.
Briefly describe Franklin’s contribution to our current understanding of DNA.
Describe the structure of DNA.
Describe the function of DNA.
Explain why the order of nucleotides is important.
Which base does adenine always pair with?

2. Explain how Watson and Crick’s model explained Chargaff’s data.
Explain how Watson and Crick’s double helix model explained Franklin’s data from photo 51.
Explain how Watson and Crick’s model explained Chargaff’s data.
Identify the time in a cell’s life when it would need to replicate its DNA.
Relate “template” to “replicate.”
Explain why DNA replication is considered a chemical reaction (TWO-PART ASWER).
At the time of Watson and Crick’s discovery, it was known that DNA was a self-replicating molecule. Describe how Watson and Crick’s model explained how DNA could replicate itself. (TWO-PART ANSWER.)
Explain why DNA replication requires enzymes.
List the two enzymes involved in DNA replication.
Describe the role of helicase in DNA replication.
Describe the role of DNA polymerase in DNA replication.
Explain how DNA polymerase knows which base to add to the new strand during replication.
Explain why DNA replication is a nearly-perfect copying process.
Use the strand below as a template to construct a complementary strand.
C C G C G A G A A A T A C T A G A G T A C C A A A G A T T A C A
Identify the enzyme the does the job described in question #31.
Explain why cells need DNA.
Explain what “protein synthesis” means.
List the two parts of protein synthesis.
Identify the first step of protein synthesis.
Relate “transcription” to “mRNA.”
Explain why mRNA must be made in order for protein synthesis to occur.
Explain why mRNA must be chemically different from DNA.
G G C

3. 39. Complete the chart below showing the differences between DNA and mRNA.
40. Explain how RNA polymerase knows where to start transcribing a gene.
41. Transcribe the DNA strand below into mRNA, starting at the promoter and going all the way to the end.
C C G C G A A U G A T A C T A G A G T A C C A A A G A T T A C A
Predict where mRNA will go after it leaves the nucleus.
Identify the second part of protein synthesis.
Relate “translation” to “mRNA.”
Describe the role of ribosomes in the process of translation.
Relate “mRNA” to “codon.”
Relate “codon” to “amino acid.”
Describe the role of tRNA in the process of translation.
Complete the table below about mRNA and tRNA.
50. Explain why genes usually start with the codon “AUG.”
51. Explain how tRNA brings the correct amino acid to the ribosome.
DNA
mRNA
Able to leave nucleus? (Yes/No)
Number of strands
Nucleotides it contains
Sugar it contains
# of genes
Process that makes it
Enzyme that makes it
mRNA
tRNA
Involved in transcription, translation, or both?
Main job
Contains codons or anticodons?

4. 52. Transcribe the following DNA sequence into mRNA:
T A C C T C G C A T G G A A T A T T
53. Translate the above mRNA sequence into a chain of amino acids. Use the codon chart below.
54. Identify the four different codons that could code for the amino acid threonine.
55. During transcription, the codon UCU is incorrectly transcribed as “UCC.” Explain why this would not affect the final protein that is produced.

5. Name:
Date: Period:
Mutation Study Guide
List three sources of DNA mutation.
Explain how radiation causes DNA mutation.
Relate “DNA polymerase” to “DNA mutation.”
Explain what it means to say that most mutations are “neutral.”
Explain why most mutations are neutral.
Differentiate between gene mutations and chromosomal mutations by completing the chart below.
7. Explain why chromosomal mutations are more severe than gene mutations.
8. List the two types of gene mutations.
9. Differentiate between point and frameshift mutations by completing the chart below.
10. Explain why frameshift mutations are more severe than point mutations.
Gene Mutation
Chromosomal Mutation
Number of genes affected (one or many)
Types (nondisjunction, point, frameshift)
Disorders/diseases (sickle-cell anemia, Down syndrome, cystic fibrosis)
Point
Frameshift
Number of genes affected
Caused by substitution, insertion, or deletion?
Number of amino acids affected (zero, one, or many)

6. 11. Give an example of a point mutation.
12. Give an example of a frameshift mutation.
13. Differentiate between Down syndrome and Turner syndrome in terms of how they affect chromosomes.
14. Transcribe and then translate the DNA strand below.
DNA: G T T A C A A T G G U C A C G
mRNA:
Protein:
Mutate the DNA strand from question #14 by deleting the last letter of the first codon. Re-write the mutated DNA strand below. Then, transcribe and translate it.
mutated DNA:
mutated mRNA:
mutated protein:
16. Identify the type of mutation you did in question #15, and defend your answer.
Give an example of a beneficial mutation found in humans.
Relate “mutation” to “variation.”