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Name________________________________Class____________________Date____________________

From DNA to Proteins

Study Guide B

Answer KeySECTION 1. STRUCTURE OF DNA

Nucleotide: Refer to the Visual Vocab in Section 2 for visual answers. Students should label: phosphate group; nitrogen-containing base; and deoxyribose sugar.

1. 42. the phosphate group and the deoxyribose

sugar; the nitrogen-containing base3. that it was of uniform width4. by building models5. The sugar-phosphate backbone is on the

outside. Inside the structure, a base with two rings always pairs with a base with only one ring.

6. A; GDNA Double Helix: drawing should include sugar-phosphate backbone; nitrogen-containing bases; and hydrogen bonds

7. The sugar-phosphate backbone is like the twisting handrails of the staircase, and the nitrogen-containing bases are like the steps that connect the railings to each other.

8. Because A only pairs with T and C only pairs with G, the amount of A will be equal to the amount of T, and the amount of C will be equal to the amount of G.

SECTION 2. DNA REPLICATION1. the process by which DNA is copied during

the cell cycle2. nucleus3. S stage4. so that every cell will have a complete set of

DNA following cell division5. something that serves as a pattern6. ATCCATG7. Proteins help unzip the DNA strand, hold

the strands apart, and bond nucleotides together.

8. hydrogen bonds connecting base pairs9. because each molecule consists of one old

strand and one new strand10. Enzymes unzip the helix.11. DNA polymerase binds nucleotides together

to form new strands that are complementary to the original strands.

12. Two identical DNA molecules result.13. DNA polymerase is an enzyme that makes

DNA by forming bonds between nucleotides. The “-ase” ending signals that it is an enzyme. The first part of the word tells that the enzyme makes DNA by stringing together lots of monomers to form polymers.

14. Replication is the process by which DNA is copied during the cell cycle. Accept any reasonable answer. Students may compare replication to making copies on a copier.

15. Share the best bumper stickers with the class.

© Houghton Mifflin Harcourt Publishing Company

Holt McDougal Biology i From DNA to ProteinsStudy Guide B

Study Guide B continued

SECTION 3. TRANSCRIPTION1. replication (nucleus)2. transcription (nucleus)3. translation (cytoplasm)4. Contains the sugar ribose5. Has the bases A, C, G, and T6. Typically single-stranded7. RNA polymerase8. A large transcription complex, including

RNA polymerase and other proteins, assembles at the start of a gene and begins to unwind the DNA. Using one strand of the DNA as a template, RNA polymerase strings together a complementary strand of RNA. The RNA strand detaches from the DNA as it is transcribed, and the DNA zips back together.

9. mRNA: intermediate message that is translated to form a protein; rRNA: forms part of ribosomes; tRNA: brings amino acids from the cytoplasm to a ribosome to help make the growing protein

10. Both occur within the nucleus of eukaryotic cells, are catalyzed by large enzymes, involve unwinding of the DNA double helix, involve complementary base pairing of the DNA strand, and are highly regulated by the cell.

11. Replication occurs only once during each round of the cell cycle and makes a double-stranded copy of all the DNA in a cell. Transcription occurs repeatedly throughout the cell cycle to make proteins, rRNAs, and tRNAs as needed by a cell. Transcription makes a single-stranded complement of only a particular DNA sequence.

12. mRNA is a form of the DNA message that tells the cell what type of protein to make. rRNA is a key component of ribosomes. tRNA transfers, or carries, amino acids from the cytoplasm to the ribosome.

13. the process of copying a sequence of DNA to produce a complementary strand of RNA

SECTION 4. TRANSLATION1. the process that converts an mRNA message

into a polypeptide, or protein2. sequences of three nucleotides that code for

an amino acid3. RNA4. the order in which nucleotides are read; they

are read as a series of three, nonoverlapping nucleotides

5. arginine (Arg)6. stop codon7. UGG8. glycine (Gly)9. Ribosomes, tRNA molecules

10. amino acid, anticodonCycle Diagram:A. An exposed codon attracts a complementary tRNA bearing an amino acid.B. the ribosome forms a peptide bond between the amino acids. It breaks the bond between the first amino acid and tRNA.C. the ribosome pulls the mRNA strand the length of one codon. The first tRNA exits the ribosome, and another codon is exposed.

11. codons12. anticodon13. Stop codons indicate where translation is to

stop. (Students may mention that methionine is also a start codon.)

SECTION 5. MUTATIONS1. point mutation/substitution; frameshift

mutation2. gene duplication; translocation3. chromosomal mutation4. unequal crossing over5. the attachment of a piece of one

chromosome to a nonhomologous chromosome

6. Answers will vary.7. Answers will vary.8. noncoding regions9. premature stop codon

10. no change11. lack of regulation12. altered splice site13. germ cells/gametes14. no15. an agent in the environment that can change

DNA16. UV light can cause neighboring thymine

nucleotides to break their hydrogen bonds to adenine and bond with each other instead.

17. a change in an organism’s DNA18. a frameshift mutation

Section 1: Structure of DNA

Study Guide BKEY CONCEPTDNA structure is the same in all organisms.

VOCABULARY

nucleotide base pairing rules

double helix

MAIN IDEA: DNA IS COMPOSED OF FOUR TYPES OF NUCLEOTIDES.In the space below, draw a nucleotide and label its three parts using words and

arrows.

1. How many types of nucleotides are present in DNA?________________________________________________________________

2. Which parts are the same in all nucleotides? Which part is different?________________________________________________________________________________________________________________________________


Holt McDougal Biology 4 From DNA to ProteinsStudy Guide B


MAIN IDEA: WATSON AND CRICK DEVELOPED AN ACCURATE MODEL OF DNA’S THREE-DIMENSIONAL STRUCTURE.3. What did Franklin’s data reveal about the structure of DNA?

________________________________________________________________

4. How did Watson and Crick determine the three-dimensional shape of DNA?________________________________________________________________

5. How does DNA base pairing result in a molecule that has a uniform width?________________________________________________________________

MAIN IDEA: NUCLEOTIDES ALWAYS PAIR IN THE SAME WAY.6. What nucleotide pairs with T? with C?

________________________________________________________________In the space below, draw a DNA double helix. Label the sugar-phosphate backbone, the nitrogen-containing bases, and the hydrogen bonds.

Vocabulary Check7. Explain how the DNA double helix is similar to a spiral staircase.

________________________________________________________________________________________________________________________________

8. How do the base pairing rules relate to Chargaff ’s rules?________________________________________________________________________________________________________________________________



Section 2: DNA Replication

Study Guide BKEY CONCEPTDNA replication copies the genetic information of a cell.

VOCABULARY

replication DNA polymerase

MAIN IDEA: REPLICATION COPIES THE GENETIC INFORMATION.1. What is DNA replication?

________________________________________________________________

2. Where does DNA replication take place in a eukaryotic cell?________________________________________________________________

3. When is DNA replicated during the cell cycle?________________________________________________________________

4. Why does DNA replication need to occur?________________________________________________________________

5. What is a template?________________________________________________________________

6. If one strand of DNA had the sequence TAGGTAC, what would be the sequence of the complementary DNA strand?________________________________________________________________

MAIN IDEA: PROTEINS CARRY OUT THE PROCESS OF REPLICATION.7. What roles do proteins play in DNA replication?

________________________________________________________________

8. What must be broken for the DNA strand to separate?________________________________________________________________

9. Why is DNA replication called semiconservative?________________________________________________________________



12.11.10.

______________________________

______________________________

______________________________


Use words and diagrams to summarize the steps of replication, in order, in the boxes below.

MAIN IDEA: REPLICATION IS FAST AND ACCURATE.

Vocabulary Check13. Explain what DNA polymerase is by breaking the word into its parts.

________________________________________________________________

14. Write a short analogy to explain what replication is.________________________________________________________________

Be Creative15. People sometimes like to display bumper stickers that relate to their trade or

field of study. For example, a chemist may have a bumper sticker that says “It takes alkynes to make the world.” Then, chemists or other people who know that an alkyne is a molecule that contains carbon atoms joined by a triple bond get a nice little chuckle out of the play on words. Use your knowledge of DNA replication to write a bumper sticker.________________________________________________________________________________________________________________________________



1. _______________

DNA RNA Proteins

3. __________________________________________

2. ______________________________

Section 3: Transcription

Study Guide BKEY CONCEPTTranscription converts a gene into a single-stranded RNA molecule.

VOCABULARY

messenger RNA (mRNA)

RNA ribosomal RNA (rRNA)

transcription transfer RNA (tRNA)

RNA polymerase

MAIN IDEA: RNA CARRIES DNA’S INSTRUCTIONS.Label each of the processes represented by the arrows in the diagram below. Write where each of these processes takes place in a eukaryotic cell in parentheses.

Fill in the table below to contrast DNA and RNA.

DNA RNA

4. Contains the sugar deoxyribose

5. Has the bases A, C, G, and U

6. Typically double-stranded




MAIN IDEA: TRANSCRIPTION MAKES THREE TYPES OF RNA.7. What enzyme helps a cell to make a strand of RNA?

________________________________________________________________

8. Summarize the three key steps of transcription.________________________________________________________________________________________________________________________________________________________________________________________________

9. Write the basic function of each type of RNA in the chart below.

Type of RNA Function

mRNA

rRNA

tRNA

MAIN IDEA: THE TRANSCRIPTION PROCESS IS SIMILAR TO REPLICATION.10. List two ways that the processes of transcription and replication are similar.

________________________________________________________________

11. List two ways that the end results of transcription and replication differ.________________________________________________________________

Vocabulary Check12. How does the name of each type of RNA tell what it does?

________________________________________________________________________________________________________________________________________________________________________________________________

13. What is transcription?________________________________________________________________



Section 4: Translation

Study Guide BKEY CONCEPTTranslation converts an mRNA message into a polypeptide, or protein.

VOCABULARY

translation stop codon anticodon

codon start codon

MAIN IDEA: AMINO ACIDS ARE CODED BY MRNA BASE SEQUENCES.1. What is translation?

________________________________________________________________

2. What is a codon?________________________________________________________________

3. Would the codons in Figure 5.1(located in chapter 8 of the textbook) be found in a strand of DNA or RNA?________________________________________________________________

4. What is a reading frame (look up in textbook)?________________________________________________________________

Refer to Figure 5.1 (located in chapter 8 of textbook) to complete the table below.

Codon Amino Acid or Function

5. AGA

6. UAG

7. tryptophan (Trp)

8. GGA

MAIN IDEA: AMINO ACIDS ARE LINKED TO BECOME A PROTEIN.

9. _______________ and _______________ are the tools that help a cell translate an mRNA message into a polypeptide.



Ribosome assembles on start codon of mRNA strand.

A.

B.C.

When the ribosome encounters a stop codon, it falls apart and the protein is released.


10. A tRNA molecule is attached to an _______________ at one end and has an _______________ at the other end.

Fill in the cycle diagram below to outline the steps of translation.

Vocabulary Check11. What are AGG, GCA, and GUU examples of?

________________________________________________________________

12. What is a set of three nucleotides on a tRNA molecule that is complementary to an mRNA codon?________________________________________________________________

13. What do codons code for in addition to amino acids?________________________________________________________________



Section 5: Mutations

Study Guide BKEY CONCEPTMutations are changes in DNA that may or may not affect phenotype.

VOCABULARY

mutation frameshift mutation

point mutation mutagen

MAIN IDEA: SOME MUTATIONS AFFECT A SINGLE GENE, WHILE OTHERS AFFECT AN ENTIRE CHROMOSOME.1. List two types of gene mutations.

________________________________________________________________

2. List two types of chromosomal mutations.________________________________________________________________

3. Which type of mutation affects more genes, a gene mutation or a chromosomal mutation?________________________________________________________________

4. What leads to gene duplication?________________________________________________________________

5. What is a translocation?________________________________________________________________

Below is a string of nucleotides. (1) Use brackets to indicate the reading frame of the nucleotide sequence. (2) Copy the nucleotide sequence into the first box and make a point mutation. Circle the mutation. (3) Copy the nucleotide sequence into the second box and make a frameshift mutation. Use brackets to indicate how the reading frame would be altered by the mutation.

A G G C G T C C A T G A

6.

7.



result incoding regions 9.

10. mayoccur

in

Pointmutations 11.

resultin8. 12.

no change

nonfunctional protein


MAIN IDEA: MUTATIONS MAY OR MAY NOT AFFECT PHENOTYPE.Fill in the cause-and-effect diagram below to explain how a point mutation may or may not affect phenotype.

13. For a mutation to be passed to offspring, in what type of cell must it occur?________________________________________________________________

MAIN IDEA: MUTATIONS CAN BE CAUSED BY SEVERAL FACTORS.14. Can DNA polymerase catch and correct every replication error?

________________________________________________________________

15. What is a mutagen?________________________________________________________________

16. How does UV light damage the DNA strand?________________________________________________________________________________________________________________________________

Vocabulary Check17. What is a mutation?

________________________________________________________________

18. If a nucleotide is deleted from a strand of DNA, what type of mutation has occurred?________________________________________________________________



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