Name__________________________ Class _______________ Date _____________


Reading Guide


Section 13–1 RNA (pages 362–365)


The Role of RNA

1. Complete the table to contrast the structures of DNA and RNA.




Number of Strands











2. On the lines provided, identify each kind of RNA.

a.                                               b                                                  c.                            



RNA Synthesis

For Questions 3–8, complete each statement by writing the correct word or words.

3.      The process of using DNA to produce complementary RNA molecules is called                ____________________________________.

4.      The sequence of                                                                                                               in mRNA complements the sequence in the DNA template.

5.      In eukaryotes, RNA is formed in the                                                                                and then travels to the         

6.      The enzyme                                                                                                                     binds to DNA during transcription.

7.      _____________________                                                                                              are portions of RNA that are cut out and discarded.

8.      _____________________                                                                                              are spliced together to make the final mRNA.


Section 13–2 Ribosomes and Protein Synthesis (pages 366–371)


The Genetic Code

Use the diagram to answer Questions 9–15. 

9. What are the words along the outside of the circle?



10.  What is a codon?



11.  For which amino acid is AAA a codon?



12.  What is the codon for tryptophan?



13.  For which amino acid is GGA a codon?



14.  What is a codon for alanine?



15.  What are three other codons for alanine?


16.  Circle the letter of the number of possible three-base codons.

a. 4                     b. 12                c. 64                d. 128


17.   Is the following sentence true or false? All amino acids are specified by only one

codon. _____________________________________


18.  Circle the letter of the codon that serves as the “start” codon for protein synthesis.

a. UGA             b. UAA           c. UAG           d. AUG


Phenylalanine   leucine      lysine     methionine


Use the diagram to answer Questions 19–21.

19.  What is the anticodon for leucine?        

20.   What is the codon for leucine? ___      

21.  List the amino acids in the order they would appear in the polypeptide coded for by this mRNA.




22.  What is the difference between

transcription and translation?




23.  Complete the table to describe the steps in protein synthesis




Beginning of translation


Assembly of polypeptide


Completing the polypeptide


24.  Describe the role of rRNA during translation.




The Molecular Basis of Heredity

25.  The instructions for assembling proteins are contained in the

a. genes.              b. ribosomes.                           c. exons.                      d.  introns.


26.  The way in which DNA, RNA, and proteins are all involved in putting genetic information into action in living cells is called

a.        translation.            b.transcription.             c.gene expression.       d.viral transfer


Section 13–3 Mutations (pages 372–376)


Types of Mutations

For Questions 27–34, match the term with its definition.



               27. The change of one base to another in a DNA sequence

               28. A change in one or a few nucleotides that occur at a single point in the DNA sequence

               29. Part of one chromosome breaks off and attaches to another

               30. A heritable change in genetic information

               31. A mutation that produces an extra copy of all or part of a chromosome

               32. A chromosomal mutation that reverses the direction of parts of a chromosome

               33. A kind of mutation that can change every amino acid that follows the point of mutation

               34. The addition of a base to the DNA sequence




A.  mutation

B.  substitution

C.  point mutation

D.  frameshift mutation

E.  insertion

F.   translocation

G.  inversion

H.  duplication



35.  What are mutations?



36.  Is the following sentence true or false? Chromosomal mutations result from changes in a single gene.  _______



37.  Mutations that involve change in one nucleotide in the DNA sequence are _________



38.  A mutation involving the insertion or deletion of a nucleotide is a(an) _____________



39.  Deletion can happen as a gene mutation or as a chromosomal mutation. What is the difference?



Effects of Mutations


40.The cellular machinery that replicates DNA inserts an incorrect base

a.most of the time.                              c.. roughly once in every million bases.

b. about half the time.                         d.roughly once in every 10 million bases.


41.Small changes in genes

a.   disappear quickly.                           c. prevent the next generation from


b.gradually accumulate over time.      d. do not affect future generations.


42.What happens when cells cannot repair the damage caused by a mutagen?




43.  A possible mutagen is

a.      an anticodon.              b.translocation.            c. hemoglobin.      d. ultraviolet light.


44.  Mutations are important to the evolution of a species because they

a.       happen over the long period of time that evolution requires.

b.      cut out and replace damaged or useless genes

c.       are a source of genetic variability.

d.      accelerate the transcription rate of DNA.


45.Cancer is the product of a mutation that

a. causes the uncontrolled growth of cells.

b.changes the structure of hemoglobin in the blood.

c. brings about stunted growth and severe pain.

d. causes a translocation in a pair of chromosomes.


Section 13-4Gene Regulation and Expression (pages 377–383)


Prokaryotic Gene Regulation

46.  How do prokaryotes conserve energy?



47.  How do DNA-binding proteins in prokaryotes regulate genes?



48.  What is an operon?



49.  What is the function of the genes in the lac operon of E. coli?



50.  How does a repressor protein turn off the lac operon?



51.  How does lactose turn on the lac operon?



52.  Complete the table to describe the role of each regulatory region or molecule in the operation of the lac operon.


Regulatory Region or Molecule

What It Does

Repressor protein




RNA polymerase







Eukaryotic Gene Regulation

53.  In what two ways is gene regulation in eukaryotes different from gene regulation in prokaryotes?





54.  What is a TATA box? What does a TATA box do?




55.  What are transcription factors and what do they do?



56.  Explain how gene regulation makes cell specialization possible.



57.  What is microRNA and how is it related to mRNA?



58.  Blocking gene expression by means of an miRNA silencing comlex is known as _________.