Study Guide A. Answer Key

Transcription

1 From DNA to Proteins Answer Key SECTION 1. IDENTIFYING DNA AS THE GENETIC MATERIAL 1. Mice lived 2. Mice died 3. Mice lived 4. Mice died 5. S 6. bacteria 7. DNA; DNA; DNA 8. protein 9. radioactive 10. radioactive 11. DNA 12. virus SECTION 2. STRUCTURE OF DNA 1. Refer to Visual Vocab in Section 2 for a visual answer. 2. four 3. the phosphate group; the nitrogen-containing base 4. uniform 5. building models 6. outside; one 7. A; G 8. Refer to Figure 2.4 for a visual answer. 9. sugar-phosphate backbone; nitrogencontaining bases 10. c; c SECTION 3. DNA REPLICATION 1. copied 2. nucleus 3. S stage 4. cell 5. pattern 6. ATCCATG 7. a, b, e 8. hydrogen 9. old; new 10. a; Refer to Figure 3.1 for a visual answer. 11. c 12. b 13. hundreds of 14. errors 15. nucleotides SECTION 4. TRANSCRIPTION 1. replication; nucleus 2. transcription; nucleus 3. translation; cytoplasm 4. deoxyribose; ribose 5. T; U 6. double; single 7. RNA polymerase 8. i, gene, DNA; ii, RNA polymerase; iii, detaches from 9. trna; rrna; mrna 10. All five statements: Both 11. i. Replication; ii. Transcription; iii. Replication; iv. Transcription 12. protein; ribosomes; amino acids 13. DNA; RNA SECTION 5. TRANSLATION 1. polypeptide (or protein) 2. three 3. RNA 4. nucleotides 5. arginine (Arg) 6. stop codon 7. UGG 8. glycine (Gly) 9. Ribosomes; trna molecules 10. small 11. large 12. amino acid; anticodon 13. A, iii; B, ii; C, i 14. codons 15. anticodon 16. stop codon SECTION 6. GENE EXPRESSION AND REGULATION 1. b, d 2. transcription 3. promoter Holt McDougal Biology i From DNA to Proteins

2 continued 4. operon; genes 5. d 6. e 7. a 8. c 9. b 10. genes 11. starts 12. eukaryotic 13. protein 14. exon; tail; cap; intron 15. exon; intron 16. transcribed SECTION 7. MUTATIONS 1. Gene mutations: a, c; Chromosomal mutations: b, d 2. chromosomal mutation 3. unequal 4. attaches to 5. a, A T G C G T C C A T G A; b, Answers will vary. See Figure 7.2 for visual answer; c. Answers will vary and may be an insertion or a deletion. See Figure 7.2 for visual answer. 6. d 7. e 8. c 9. b 10. a 11. germ 12. no 13. mutagen 14. thymine 15. DNA 16. a Holt McDougal Biology ii From DNA to Proteins

3 Section 1: Identifying DNA as the Genetic Material KEY CONCEPT DNA was identified as the genetic material through a series of experiments. VOCABULARY bacteriophage MAIN IDEA: Griffith finds a transforming principle. Check the appropriate boxes to indicate the results of Griffith s experiments that are listed below. Results Experiments Mice Lived Mice Died 1. Injected mice with live R bacteria. 2. Injected mice with live S bacteria. 3. Killed S bacteria and injected them into mice. 4. Mixed killed S bacteria with R bacteria and injected them into mice. Circle the word or phrase that best completes the statement. 5. The S / R form of bacteria caused disease in the mice. 6. Griffith concluded that there must be a transforming principle that changed harmless bacteria into disease-causing bacteria / mice. Holt McDougal Biology 1 From DNA to Proteins Section 1: Identifying DNA as the Genetic Material

4 continued MAIN IDEA: Avery identifies DNA as the transforming principle. 7. Avery and his team isolated Griffith s transforming principle and performed three tests to learn if it was DNA or protein. In the table below, check the appropriate boxes to show the results of each type of test. Avery s Question DNA Protein What type of molecule does the transforming principle contain? Are the chemical elements in the transforming principle more similar to DNA or protein? Will transformation fail to occur after adding an enzyme that destroys DNA, or after adding an enzyme that destroys protein? MAIN IDEA: Hershey and Chase confirm that DNA is the genetic material. 8. A bacteriophage has two main structures: a DNA molecule and a coat. 9. In their first experiment, Hershey and Chase tagged bacteriophages with sulfur. Protein contains sulfur, but DNA does not. 10. In their second experiment, Hershey and Chase tagged bacteriophages with phosphorus. DNA contains phosphorus, but protein contains very little phosphorus. 11. Radioactivity was only present in the bacteria that were infected with phosphorus-tagged bacteriophages. This result indicated that the bacteriophages had entered the bacteria, but the protein had not. Vocabulary Check Fill in the blank with the word or phrase that best completes sentence. 12. A bacteriophage is a type of that infects bacteria. Holt McDougal Biology 2 From DNA to Proteins Section 1: Identifying DNA as the Genetic Material

5 Section 2: Structure of DNA KEY CONCEPT DNA structure is the same in all organisms. VOCABULARY nucleotide double helix base pairing rules MAIN IDEA: DNA is composed of four types of nucleotides. 1. In the space below, draw a nucleotide and label the phosphate group, the nitrogen-containing base, and the deoxyribose sugar. 2. How many types of nucleotides are present in DNA? 3. All nucleotides have two parts that are the same: the deoxyribose sugar and. The third part,, is different. MAIN IDEA: Watson and Crick developed an accurate model of DNA s three-dimensional structure. Circle the word or phrase that best completes the statement. 4. Franklin s data revealed that the structure of DNA is uniform / variable in width. 5. Watson and Crick determined the three-dimensional shape of DNA by building models / building genomes. 6. DNA base pairing results in a molecule that has a uniform width. A sugarphosphate backbone is on the inside / outside. Inside the structure, a base with two rings always pairs with a base with one / two ring(s). Holt McDougal Biology 3 From DNA to Proteins Section 2: Structure of DNA

6 continued MAIN IDEA: Nucleotides always pair in the same way. 7. The T nucleotide pairs with the nucleotide, and the C nucleotide pairs with the nucleotide. 8. In the space below, draw a DNA double helix. Label the sugar-phosphate backbone, the nitrogen-containing bases, and the hydrogen bonds. Vocabulary Check 9. The DNA double helix is similar to a spiral staircase: the is like the twisting handrails of the staircase, and the are like the steps that connect the railings to each other. Select from the lettered list to fill in the blanks in the sentence below. 10. The base pairing rules of DNA relate to Chargaff s rules. The base pairing rules state that A only pairs with T and C only pairs with G. Therefore, the amount of A will be the amount of T, and the amount of C will be the amount of G. a. less than b. more than c. equal to Holt McDougal Biology 4 From DNA to Proteins Section 2: Structure of DNA

7 Section 3: DNA Replication KEY CONCEPT DNA replication copies the genetic information of a cell. VOCABULARY replication DNA polymerase MAIN IDEA: Replication copies the genetic information. Fill in the blank or circle the word or phrase that best completes the statement. 1. DNA replication is the process by which DNA is copied / observed during the cell cycle. 2. DNA replication takes place in the centrosome / nucleus of a eukaryotic cell. 3. DNA is replicated during the M stage / S stage of the cell cycle. 4. DNA replication needs to occur so that every cell / organism will have a complete set of DNA following cell division. 5. A template is something that serves as a. 6. Suppose that one strand of DNA has the sequence TAGGTAC. Write down the sequence of the complementary DNA strand. MAIN IDEA: Proteins carry out the process of replication. 7. Circle all of the roles that proteins play during DNA replication. a. They help unzip the DNA strand. b. They hold the DNA strands apart. c. They attach nucleotides to the nucleus. d. They remove nucleotides from the DNA strands. e. They bond nucleotides together. Holt McDougal Biology 5 From DNA to Proteins Section 3: DNA Replication

8 continued 8. In order for the DNA strands to separate, the bonds connecting base pairs must be broken. 9. DNA replication is called semiconservative because each molecule consists of one strand and one strand. Place the following sentences in the correct order to summarize the steps of replication. Draw a diagram showing each step. a. Enzymes unzip the helix. b. Two identical DNA molecules result. c. DNA polymerase binds nucleotides together to form new strands that are complementary to the original strands MAIN IDEA: Replication is fast and accurate. Circle the word or phrase that best completes the statement. 13. Human chromosomes have only one / hundreds of origin(s) of replication, where the DNA is unzipped so replication can begin. 14. DNA polymerase has a proofreading function that enables it to detect errors / enzymes and correct them. Vocabulary Check 15. The suffix -ase indicates an enzyme. A polymer is a string of repeating structural units. DNA polymerase is an enzyme that makes DNA by forming bonds between. Holt McDougal Biology 6 From DNA to Proteins Section 3: DNA Replication

9 Section 4: Transcription KEY CONCEPT Transcription converts a gene into a single-stranded RNA molecule. VOCABULARY central dogma RNA transcription RNA polymerase messenger RNA (mrna) ribosomal RNA (rrna) transfer RNA (trna) MAIN IDEA: RNA carries DNA s instructions. Label the diagram below with each of the following processes: translation, transcription, and replication. For each process, write down whether it takes place in the nucleus or in the cytoplasm of a eukaryotic cell. 1. DNA RNA Proteins Place the following words and letters into the table below to contrast DNA and RNA. ribose deoxyribose double single U T DNA RNA 4. Contains the sugar Contains the sugar 5. Has the bases A, C, G, and Has the bases A, C, G, and 6. Typically -stranded Typically -stranded Holt McDougal Biology 7 From DNA to Proteins Section 4: Transcription

10 continued MAIN IDEA: Transcription makes three types of RNA. 7. The enzyme that helps a cell to make a strand of RNA is called. 8. The following sentences summarize the three key steps of transcription. Circle the word or phrase that best completes the sentence, i. A large transcription complex, including RNA polymerase and other proteins, assembles at the start of a gene / nucleus and begins to unwind the DNA / RNA. ii. Using one strand of the DNA as a template, DNA polymerase / RNA polymerase strings together a complementary strand of RNA. iii. The RNA strand attaches to / detaches from the DNA as it is transcribed, and the DNA zips back together. 9. Identify which type of RNA (mrna, rrna, and trna) performs each of the following functions. brings amino acids from the cytoplasm to a ribosome to help make the growing protein. forms part of ribosomes. is an intermediate message that is translated to form a protein. MAIN IDEA: The transcription process is similar to replication. 10. Check the appropriate boxes to identify whether each of the following processes is true of transcription, true of replication, or true of both transcription and replication. i. is catalyzed by large enzymes Transcription Replication Both ii. is highly regulated by the cell iii. involves complementary base pairing of the DNA strand iv. involves unwinding of the DNA double helix v. occurs within the nucleus of eukaryotic cells Holt McDougal Biology 8 From DNA to Proteins Section 4: Transcription

11 continued 11. Check the appropriate boxes to identify whether each of the following end results is true of transcription, true of replication, or true of both transcription and replication. i. makes a double-stranded copy of all the DNA in a cell Transcription Replication Both ii. makes a single-stranded complement of only a particular DNA sequence. iii. occurs only once during each round of the cell cycle iv. occurs repeatedly throughout the cell cycle to make proteins, rrnas, and trnas, as needed by a cell Vocabulary Check 12. The name of each type of RNA tells what it does. mrna is a form of the DNA message that tells the cell what type of to make. rrna is a key component of. trna transfers, or carries, from the cytoplasm to the ribosome. 13. Transcription is the process of copying a sequence of to produce a complementary strand of. Holt McDougal Biology 9 From DNA to Proteins Section 4: Transcription

12 Section 5: Translation KEY CONCEPT Translation 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. Fill in the blank with the word or phrase that best completes the sentence or answers the question. 1. Translation is the process that converts an mrna message into a. 2. A codon is a sequence of nucleotides that code for an amino acid. 3. Would the codons in Figure 5.1 in your textbook be found in a strand of DNA or RNA? 4. A reading frame is the order in which are read. Refer to Figure 5.1 in this section of your 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. Circle the word or phrase that best completes the statement. 9. Ribosomes / Vesicles and trna molecules / DNA polymerase are the tools that help a cell translate an mrna message into a polypeptide. Holt McDougal Biology 10 From DNA to Proteins Section 5: Translation

13 continued 10. The small / large subunit of a ribosome holds onto the mrna strand. 11. The small / large subunit of a ribosome has binding sites for trna. 12. A trna molecule is attached to a(n) sugar / amino acid at one end and has a(n) frame / anticodon at the other end. 13. Place the following sentences into the cycle diagram below to outline the steps of translation. i. The ribosome pulls the mrna strand the length of one codon. The first trna exits the ribosome, and another codon is exposed. ii. The ribosome forms a peptide bond between the amino acids. It breaks the bond between the first amino acid and trna. iii. An exposed codon attracts a complementary trna bearing an amino acid. Ribosome assembles at the start codon of mrna strand. A. C. B. When the ribosome encounters a stop codon, it falls apart and the protein is released. Vocabulary Check 14. AGG, GCA, and GUU are examples of. 15. A(n) is a set of three nucleotides on a trna molecule that is complementary to an mrna codon. 16. A indicates where translation is to stop. Holt McDougal Biology 11 From DNA to Proteins Section 5: Translation

14 Section 6: Gene Expression and Regulation KEY CONCEPT Gene expression is carefully regulated in both prokaryotic and eukaryotic cells. VOCABULARY promoter operon exon intron MAIN IDEA: Prokaryotic cells turn genes on and off by controlling transcription. 1. Circle two reasons why gene expression is regulated in prokaryotic cells. a. Regulation allows the cells to live for a longer period. b. Regulation allows the cells to better respond to stimuli. c. Regulation allows the cells to promote gene recognition. d. Regulation allows the cells to conserve energy and materials. Circle the word or phrase that best completes the statement. 2. In prokaryotic cells, gene expression is typically regulated at the start of transcription / translation. 3. A(n) operator / promoter is a segment of DNA that helps RNA polymerase recognize the start of a gene. 4. An exon / operon is a region of DNA that includes a promoter, an operator, and one or more genes / introns that code for proteins needed to carry out a task. Complete the Cause-and-Effect Diagram describing the lac operon on the next page by putting the letter for each sentence into the appropriate box. a. Lactose binds to the repressor protein, and the repressor cannot bind to the operon. b. Lactose is broken down. c. RNA polymerase can transcribe the genes. d. RNA polymerase is blocked by the repressor. e. The genes are not transcribed. Holt McDougal Biology 12 From DNA to Proteins Section 6: Gene Expression and Regulation

15 continued medium without lactose added Bacteria growing in culture medium with lactose added The repressor continues to bind to the operator The 9. resulting transcript is translated into 3 enzymes. 6. MAIN IDEA: Eukaryotic cells regulate gene expression at many points. 10. The cells in your body differ from each other, because they express different sets of. 11. Transcription factors bind to the DNA and help RNA polymerase know where a gene. 12. A TATA box is a promoter that is found in almost all cells. 13. Sonic hedgehog is an example of a that helps control the expression of many other genes and plays an important role in establishing body pattern. Holt McDougal Biology 13 From DNA to Proteins Section 6: Gene Expression and Regulation

16 continued 14. The diagrams below represent unprocessed and processed mrna in a eukaryotic cell. Using the diagrams as a reference, fill in the legend with the corresponding element from the following list: cap, exon, intron, tail. Unprocessed mrna Legend Processed mrna Vocabulary Check 15. An exon differs from an intron. A(n) is a sequence of nucleotides that is expressed in a protein, whereas a(n) is an intervening sequence of nucleotides that will be removed during mrna processing. 16. A promoter is a DNA segment that allows a gene to be. Holt McDougal Biology 14 From DNA to Proteins Section 6: Gene Expression and Regulation

17 Section 7: Mutations KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype. VOCABULARY mutation point mutation frameshift mutation mutagen MAIN IDEA: Some mutations affect a single gene, while others affect an entire chromosome. 1. From the following list, select the two types of mutations that are gene mutations and select the two types that are chromosomal mutations. a. frameshift mutation b. gene duplication c. point mutation (substitution) d. translocation Gene mutations: Chromosomal mutations: 2. Which type of mutation affects more genes, a gene mutation or a chromosomal mutation? Circle the word or phrase that best completes the statement. 3. Gene duplication happens when there is equal / unequal cross-over event. 4. A translocation happens when a piece of one chromosome attaches to / detaches from a nonhomologous chromosome. Holt McDougal Biology 15 From DNA to Proteins Section 7: Mutations

18 continued 5. In the boxes below is a string of nucleotides. a. Use brackets to indicate the reading frame of the nucleotide sequence. b. Make a point mutation. Circle the mutation. c. Make a frameshift mutation. Use brackets to indicate how the reading frame would be altered by the mutation. a. A T G C G T C C A T G A b. A T G C G T C C A T G A c. A T G C G T C C A T G A MAIN IDEA: Mutations may or may not affect phenotype. Fill in the Cause-and-Effect Diagram using the phrases listed below to explain how a point mutation may or may not affect phenotype. a. altered splice site b. lack of regulation c. no change d. noncoding regions e. premature stop codon Point mutations may occur in nonfunctional protein coding regions may result in may 6. result in 10. no change 11. For a mutation to be passed to offspring, it must occur in the autosomal / germ cells. Holt McDougal Biology 16 From DNA to Proteins Section 7: Mutations

19 continued MAIN IDEA: Mutations can be caused by several factors. 12. Can DNA polymerase catch and correct every replication error? 13. An agent in the environment that can change DNA is called a. 14. UV light damages a DNA strand by causing neighboring nucleotides to break their hydrogen bonds to adenine and bond with each other instead. Vocabulary Check 15. A mutation is a change in an organism s. 16. If a nucleotide is deleted from a strand of DNA, what type of mutation has occurred? a. frameshift mutation b. gene duplication c. point mutation (substitution) d. translocation Holt McDougal Biology 17 From DNA to Proteins Section 7: Mutations