Section: the Structure of DNA

Name______Class______Date______

Skills Worksheet

13.1 Active Reading

Section: The Structure of DNA

Read the passage below. Then answer the questions that follow.

In 1928, bacteriologist Frederick Griffith worked with two strains of Streptococcus pneumoniae. The first strain was enclosed in a capsule made of polysaccharides. The capsule helped make the microorganism able to cause disease. The second strain of S. pneumoniae lacked the polysaccharide capsule and did not cause disease.

Griffith knew that mice infected with S bacteria grew sick and died, while mice infected with R bacteria were not harmed. To determine if the capsule on the S bacteria was causing the mice to die, Griffith injected the mice with dead S bacteria. The mice remained healthy. Griffith then prepared weakened S bacteria by raising their temperature until the bacteria were “heat-killed,” meaning they were dead but maintained the capsule.

When Griffith injected the mice with the heat-killed S bacteria, the mice still lived. He then mixed the harmless live R bacteria with the harmless heat-killed S bacteria. Mice injected with this mixture died. Somehow, the harmless R bacteria underwent a change and became live, pneumonia-causing S bacteria. This phenomenon is now called transformation, a change in genotype caused when bacterial cells take up foreign genetic material.

Skill: Reading Effectively

Read each question, and write your answer in the space provided.

1.What does the term strain refer to in the first sentence?

______

2.What effect might the polysaccharide capsule have on a bacterium contained within the capsule?

______

3.What does the term transformation mean?

______

Active Reading continued

4.What effect did an injection of R bacteria have on the mice Griffith studied?

______

5.What effect did an injection of heat-killed S bacteria have on the mice Griffith studied?

______

6.What effect did an injection of live R bacteria mixed with heat-killed S
bacteria have on the mice?

______

In the space provided, write the letter of the phrase that best completes the
statement.

_____7.In order to determine whether the disease-causing properties of the S bacteria could be passed to the harmless R bacteria, Griffith injected mice with

a.heat-killed S bacteria.

b.live R bacteria.

c.heat-killed R bacteria.

d.Both (a) and (b)

Skills Worksheet

CH13.2 Active Reading

Section: Replication of DNA

Read the passage below. Then answer the questions that follow.

The process of making a copy of DNA is called DNA replication. The process can be broken down into three steps.

Step 1: Before replication can begin, the double helix must unwind. This is accomplished by enzymes called DNA helicases, which open up the double helix by breaking the hydrogen bonds that link the complementary nitrogenous bases. Once the two strands of DNA are separated, additional proteins attach to each strand, holding them apart and preventing them from twisting back into their double-helical shape. The two areas on either end of the DNA where the double helix separates are called replication forks because of their Y shape.

Step 2: At the replication fork, enzymes known as DNA polymerases move along each of the DNA strands, adding nucleotides to the exposed nitrogenous bases according to the base-pairing rules.

Step 3: The process of DNA replication produces two DNA molecules, each composed of a new and an original strand. The nucleotide sequences in both of these DNA molecules are identical to each other and to the original DNA molecule.

Skill: Reading Effectively

Read each question, and write your answer in the space provided.

1.What is replication?

______

2.When does replication occur?

______

3.What must occur before replication can begin?

______

Active Reading continued

Skill: Interpreting Graphics

4.The figure below shows DNA replicating. In the space provided, describe what is occurring at each lettered section of the figure.

Part a. Part b. Part c.

Part a. ______

______

Part b.______

______

Part c. ______

______

In the space provided, write the letter of the term or phrase that best completes the statement.

____5. DNA helicases and DNA polymerases are alike in that both are

a.nucleotides.

b.nitrogenous bases.

c.enzymes.

d.Both (a) and (b)

Skills Worksheet

CH13.3 Active Reading

Section: RNA and Gene Expression

Read the passage below. Then answer the questions that follow.

Like DNA, ribonucleic acid (RNA) is a nucleic acid—a molecule made of nucleotides linked together. RNA differs from DNA in three ways. First, RNA consists of a single strand of nucleotides instead of the two strands found in DNA. Second, RNA nucleotides contain the five-carbon sugar ribose rather than the sugar deoxyribose found in DNA nucleotides. And third, RNA has a nitrogenous base called uracil—abbreviated as U—instead of the base thymine (T) found in DNA. No thymine (T) bases are found in RNA. Like thymine, uracil is complementary to adenine whenever RNA base-pairs with another nucleic acid.

Skill: Recognizing Similarities and Differences

Read each question, and write your answer in the space provided.

1.In the spaces provided, write D if the statement is true of DNA. Write R if
the statement is true of RNA. Write B if the statement is true of both DNA
and RNA.

_____a.consists of a single strand of nucleotides

_____b.is made of nucleotides linked together

_____c.contains deoxyribose

_____d.has the nitrogenous base uracil

_____e.contains ribose

_____f.is a nucleic acid

_____g.consists of a double strand of nucleotides

_____h.contains a base that pairs with adenine

An analogy is a comparison. In the space provided, write the letter of the term or phrase that best completes the analogy.

_____2.RNA is to U as DNA is to

a.C

b.G

c.T

d.A

Assessment

CH13.1 Quiz

Section: The Structure of DNA

In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

_____1.In 1928, the experiments of Griffith demonstrated transformation of

a.harmless bacteria into disease-causing bacteria.

b.disease-causing bacteria into harmless bacteria.

c.heat-killed S bacteria into R bacteria.

d.S bacteria into heat-killed R bacteria.

_____2.In 1952, Hershey and Chase used a bacteriophage to determine that genetic material is made of which of the following?

a.protein c. DNA

b.RNA d. 35S

_____3.Avery’s experiments showed that

a.DNA is responsible for transformation.

b.proteins are responsible for transformation.

c.bacteriophages are responsible for transformation.

d.infectious bacteria are responsible for transformation.

_____4.Each nucleotide in a DNA molecule consists of a

a.sulfur group, a five-carbon sugar molecule, and a nitrogen base.

b.phosphate group, a six-carbon sugar molecule, and a nitrogen base.

c.phosphate group, a five-carbon sugar molecule, and an oxygen base.

d.phosphate group, a five-carbon sugar molecule, and a nitrogenous base.

_____5.In 1953, Watson and Crick built a model of DNA with the configuration of a

a.single helix.

b.double helix.

c.triple helix.

d.circle.

In the space provided, write the letter of the description that best matches the term or phrase.

_____6.radioactive sulfur

_____7.adenine

_____8.Chargaff

_____9.cytosine

Assessment

13.2 Quiz

Section: Replication of DNA

In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

_____1.DNA is replicated before

a.crossing-over. c. cell death.

b.cell division. d. transformation.

_____2.Which of the following happens last in replication?

a.Two new DNA molecules form.

b.Two original strands of DNA separate.

c.A replication fork forms.

d.DNA polymerase adds nucleotides to each DNA strand.

_____3.The areas where DNA separates during replication are called

a.helicases. c. replication forks.

b.polymerases. d. proofreaders.

_____4.Replication forks tend to

a.slow down replication.

b.increase errors during replication.

c.speed up replication.

d.be more plentiful in prokaryotic DNA.

_____5.At the end of replication, each new DNA molecule is composed of

a.two new strands of DNA.

b.two original strands of DNA.

c.either two new or two original strands of DNA.

d.a new and an original strand of DNA.

_____6.Which of the following proofreads the new DNA molecules during replication?

a.DNA polymerases c. DNA helicases

b.replication forks d. the original strand of DNA

In the space provided, write the letter of the description that best matches the term or phrase.

_____7.replication forks

_____8.DNA polymerases

_____9.DNA replication

10. DNA helicasesAssessment

CH13.3 Quiz

Section: RNA and Gene Expression

In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

_____1.During transcription, the genetic information for making a protein is rewritten as a molecule of

a.messenger RNA. c. transfer RNA.

b.ribosomal RNA. d. translation RNA.

_____2.All organisms have a genetic code made of

a.two-nucleotide sequences. c.four-nucleotide sequences.

b.three-nucleotide sequences. d.five-nucleotide sequences.

_____3.In a cell, the equipment for translation is located in the

a.cytoplasm. c. plasma membrane.

b.nucleus. d. centrioles.

_____4.Like DNA, RNA contains which of the following?

a.phosphate c. thymine

b.uracil d. deoxyribose

_____5.In eukaryotes, translation ends when

a.the codon site becomes vacant.

b.tRNA detaches from mRNA.

c.a stop codon is reached.

d.mRNA leaves the nucleus.

In the space provided, write the letter of the description that best matches the term or phrase.

_____6.anticodon

_____7.mRNA

_____8.RNA polymerase

_____9.tRNA

_____ 10. DNA

Holt Biology1DNA, RNA, and Proteins