Unit 5 DNA, RNA and Protein Synthesis

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1 Unit 5 DNA, RNA and Protein Synthesis Standards Addressed BIO.B Compare cellular structures and their functions in prokaryotic and eukaryotic cells BIO.A Describe and interpret relationships between structure and function at various levels of biological organization (i.e., organelles, cells, tissues, organs, organ systems, and multicellular organisms). BIO.A Explain how carbon is uniquely suited to form biological macromolecules. BIO.A Describe how biological macromolecules form from monomers. BIO.A Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction. Essential Questions Why is DNA called the blueprint of life? How is structure related to function at all biological levels of organization?

2 DNA and RNA (Follows pages 1 7 in the reading packet) Central Dogma of Molecular Biology 1. DNA is found in. 2. However, another nucleic acid carries the instructions from DNA to the ribosomes (where proteins are manufactured) and this other nucleic acid is. 3. The phrase DNA RNA Protein is called the. DNA 4. In the 1920 s, studied two different strains of bacteria. He injected the bacteria into mice. The mouse injected with the lethal strain died and the mouse with the other strain did not. 5. In Griffiths experiment, he deduced that something in the S-strain was transferred to the harmless strain, making the R-strain deadly. 6. In the 1940 s, the scientific team lead by tried to answer Griffith s question. 7. The ultimate answer of the team lead by Avery was that is the material. 8. In the 1950 s, two additional scientists used radioactive tagged viruses to confirm DNA was the. 9. State Erwin Chargaff s Rules. 10. and are given credit for discovering DNA structure of. 11. The discovery of the structure of DNA was based on the work of. 12. The structure of the double helix is like a spiral staircase. There are three parts of a DNA nucleotide, the, the and a. 13. Which two bases pair up in the DNA molecule? 14. These base pairs are called bases. DNA Replication 15. DNA replication is the process in which is. 16. An enzyme breaks the bonds between the separating the two sides of the DNA molecule. 17. Each side is read by another enzyme and is used to two new strands.

3 RNA 18. RNA is a acid. 19. Complete the chart below describing the differences between DNA and RNA. Differences Between DNA and RNA DNA RNA Number of Strands (chains) Base differences Type of sugar 20. List the three main types of RNA and give their function. a. b. c.

4 History of DNA Structure and Function Transformation Which Molecule? What Kind of Molecule? Avery 1. Pauling / Corey 2. Transformation Which Molecule part 2? X-Ray Diffraction? 1952 Base-pair Rules Hershey / Chase Chargaff Bacteriophage Double Helix 1953 RNA Sidney Brenner

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9 RNA and Protein Synthesis I. The Structure of RNA A. Consists of a long strand of nucleotides B. Nucleotides consist of,, and a. C. The sugar is. D. Bases are,, and. E. Strand is single stranded. II. Functions of RNA A. Many different functions depending on the type of RNA it is B. All RNA molecules are involved in. III. Types of RNA a. Assembles amino acids into proteins A. Three main types a. (mrna) b. (rrna) c. (trna) Messenger RNA IV. produced sequence of in RNA Transcription A. Transcription process by which RNA molecules are from copying part of the nucleotide DNA into a complementary sequence Transfer RNA

10 B. Transcription requires the enzyme called RNA polymerase. 1. RNA polymerase binds to DNA and separates the DNA strands. 2. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA. 3. RNA polymerase starts at a promoter, which is a specific base sequence signal that tells the enzyme to bind and make RNA. There are also stop regions which signal termination. C. RNA Editing 1. RNA molecules require editing, like a rough draft of a paper. 2. While still in the nucleus, introns are cut out of RNA. Introns are sequences of nucleotides what are not involved in coding for proteins 3. After removal of introns, exons are what remains behind. Exons are coding sequences; they are expressed in proteins. 4. Once the introns are cut out, the exons are joined together to form final mrna molecule. V. Translation (or Protein Synthesis) A. mrna is transcribed (copied) from the DNA in the nucleus and released into the cytoplasm. 1. sequences of bases in mrna serves as instructions for the order in which amino acids should be joined together to make protein. B. Translation cell uses information from mrna and decoding it into proteins, takes place in cytoplasm. C. mrna attaches to the ribosome; then each codon is moved through the ribosome. 1. Codons consist of 3 consecutive nucleotides that specify a single amino acid D. trna delivers the proper amino acid to the ribosome. (Each trna molecule carries only one type of amino acid and has three unpaired bases called an anti-codon. Each anti-codon is complementary to only one mrna codon.) E. In the polypeptide assembly line, ribosomes create peptide bond between the amino acids brought to the ribosome by the trna and trna is released.

11 F. Polypeptide chain grows until ribosome reaches a stop codon, then the chain is released. VI. The Genetic Code A. Proteins are made by joining amino acids into polypeptide chains. B. There are 20 amino acids. C. RNA codes for 3 bases at a time or the word in the genetic code is 3 letters long. D. A series of 3 bases is called a codon E. With 4 different bases, there is a possible 64 three-base codons available to code for amino acids.

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20 Topic 6: DNA and its Processes DNA Structure Deoxyribonucleic acid (DNA) is an important biomolecule that contains our genetic code. Here is a diagram of the double helix model of DNA. Note that the monomers/building blocks of DNA are called nucleotides. Each nucleotide contains three parts Sugar (deoxyribose) Phosphate group Nitrogenous base (4 kinds) DNA Replication In order for new cells to pass on the genetic code, DNA must be copied inside of cells. In eukaryotic cells, this takes place inside of the nucleus, which stores the cell s DNA. In prokaryotes, the process of copying DNA occurs in the cytoplasm. Regardless of location, the process is known as replication. Two daughter strands are formed. 1. The double helix is opened up by breaking the weak hydrogen bonds 2. An enzyme (DNA polymerase) comes in and adds new bases to the open strand a. It follows base pairing rules: Adenine pairs with Thymine (straight letters A-T go together) and Cytosine pairs with Guanine (curvy letters G-C go together) 3. At the end, two identical strands of DNA are formed. 4. These strands are said to be complementary to each other because they follow the base pairing rules RNA Structure Ribonucleic acid (RNA) is a similar molecule to DNA. However, it has some key differences. Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) Number of strands 2 1 Sugar Deoxyribose Ribose Base pairs A-T G-C A-U G-C In addition to those differences, there are three different types of RNA. These different types have various shapes and functions. Messenger RNA (mrna) carries the transcripted message from DNA to the ribosome to make proteins Ribosomal rna (rrna) is a component of the ribosome and the site of protein synthesis Transfer RNA (trna) brings the amino acids to the ribosome for protein synthesis

21 Transcription This occurs in the nucleus of eukaryotes. In the process of transcription, an mrna transcript is made using the double helix as a template. The double-stranded molecule of DNA separates along the hydrogen bonds. An enzyme called RNA polymerase adds in corresponding base pairs. However, instead of using Thymine to match up with Adenine, Uracil is used. For RNA, the base paring rules are A-U and G-C. At the end of this process, one piece of mrna is created. It is complementary to the strand of DNA is was formed from. Translation This process occurs in the cytoplasm. In the process of translation, the piece of mrna is read by the ribosome in groups of three letters (codons). Each 3-letter portion of mrna is referred to as a codon and codes for a specific amino acid. These codes match up to the anticodons on the bottom of the trna molecules. The corresponding trna molecule brings in the correct amino acid (building block of proteins). The ribosome joins the amino acids together to make a protein. The diagram on the left shows replication, transcription, and translation all happening in the cell. The diagram on the right shows a chart of the 64 codons that make up the genetic code and the 20 amino acids that match up. Each 3-letter portion of mrna is referred to as a codon and codes for a specific amino acid. These codes match up to the anticodons on the bottom of the trna molecules. Mutations Many different types of mutations can occur. They can either affect a few nucleotides (point mutations) or affect large portions of DNA (chromosomal mutations). These will ultimately affect the shape and size of the protein constructed, and the appearance of the cell or organism.

22 AMOEBA SISTERS: VIDEO RECAP DNA VS. RNA AND PROTEIN SYNTHESIS Amoeba Sisters Video Recap: DNA vs RNA and Protein Synthesis Whose Show Is This? Directions: DNA shouldn t get all the credit! For this page, you will need to watch the video clip Why RNA is Just as Cool as DNA. Label the two cartoons below. For the following comments, write a D inside the speech bubble if for DNA, R inside the speech bubble if for RNA, or BOTH if the statement applies to both. 1. I am single stranded. 2. I am found only in the nucleus of eukaryote cells (exception during mitosis when nucleus is temporarily disassembled). 3. I am a nucleic acid. 4. I am arranged as a double helix or twisted ladder. 5. I have the sugar ribose. 6. I have the sugar deoxyribose. 7. I include the bases Guanine, Cytosine, and Adenine. 8. In eukaryote cells, I travel out of the nucleus to a ribosome. 9. I have the base Thymine. 10. I have the base Uracil. There are 3 types of RNA. Fill in any missing information in the chart below: Type: mrna 11. Type: 12. Type: 13. Stands for: Stands for: Transfer RNA Stands for: transfers message.

23 AMOEBA SISTERS: VIDEO RECAP DNA VS. RNA AND PROTEIN SYNTHESIS Amoeba Sisters Video Recap: DNA vs. RNA and Protein Synthesis Protein Synthesis Summary Directions: Fill in any missing information in the summary chart below after watching Protein Synthesis and the Lean, Mean Ribosome Machines. Name of Process: Where is this process located (assuming eukaryote cell)? Is DNA directly involved in process? Which types of RNA are involved? End Result and Purpose Transcription mrna only 17. Translation 18. No, as DNA remains in the nucleus and this process is not in the nucleus

24 Worksheet: Mutations Practice There are three ways that DNA can be altered when a mutation (change in DNA sequence) occurs. 1. Substitution one base-pairs is replaced by another: Example: G to C or A to G C G T C 2. Insertion one or more base pairs is added to a sequence: Example: CGATGG CGAATGG GCTACC GCTTACC 3. Deletion one or more base pairs is lost from a sequence: Example: CGATGG CATGG GCTACC GTACC There are five possible results of a mutation. 1. Silent mutation: When a base pair is substituted but the change still codes for the same amino acid in the sequence: Example: TCT and TCC both code for the amino acid Serine 2. Substitution: When a base pair is substituted for another base pair a. If the substitution changes the amino acid, it is called a MISSENSE mutation: Example: TCT codes for Serine and CCT codes for Proline b. If the substitution changes the amino acid to a STOP, it is called a NONSENSE mutation. Example: GTGGTCCGAAACACC GTGGTCTGAAACACC Val-Val-Pro-Asn-Thr Val-Val-STOP c.if the substitution does not change the amino acid, it s called a SILENT mutation. Example: GTGGTCCGAAACACC GTGGTACGAAACACC Val-Val-Pro-Asn-Thr Val-Val-Pro-Asn-Thr 3. Codon Deletion or Insertion: A whole new amino acid is added, or one is missing from the mutant proton: Example: GTGGTCCGAAACACC GTGGTCTGCCGAAACACC Val-Val-Pro-Asn-Thr Val-Val-Cys-Pro-Asn-Thr 4. Frame Shift: When a deletion or insertion results in a different base pair being the beginning of the next codon, changing the whole sequence of amino acids Example: GTGGTCCGAAACACCT GTGGTCGAAACACCT Val-Val-Pro-Asn-Thr Val-Val-Glu-Thr-Pro

25 1. Below is the base sequence for the normal protein for normal hemoglobin and the base sequence for the sickle cell hemoglobin. Normal: GGG CTT CTT TTT Sickle: GGG CAT CTT TTT a. Transcribe and translate the normal and sickle cell DNA. b. Identify this as a point or frameshift mutation. Explain. c. If the base sequence read GGG CTT CTT AAA instead, would this result in sickle cell hemoglobin? Explain.

26 2. There are several types of genetic mutations. List two. What do they have in common? How are they different? Give an example of each. 3. A geneticist found that a particular mutation had no effect on the protein coded by a gene. What do you think is the most likely type of mutation in this gene? Why? 4. Name one amino acid that has more than one codon. Name an amino acid that has only one codon 5. Look at the following sequence: THE FAT CAT ATE THE RAT. Delete the first H and regroup the letters in groups of three- write out the new groups of three. Does the sentence still make sense? What type of mutation is this an example of? You have a DNA sequence that codes for a protein and is 105 nucleotides long. A frameshift mutation occurs at the 85 th base- how many amino acids will be correct in this protein? 6. Given the following three mrna sequences, 2 code for the same protein. Which two? #1. AGU UUA GCA ACG AGA UCA #2 UCG CUA GCG ACC AGU UCA #3 AGC CUC GCC ACU CGU AGU

27 Original DNA Sequence: mrna Sequence: Amino Acid Sequence: T A C A C C T T G G C G A C G A C T Mutated DNA Sequence #1: T A C A T C T T G G C G A C G A C T What s the mrna sequence? (Circle the change) What will be the amino acid sequence? Will there likely be effects? What kind of mutation is this? Mutated DNA Sequence #2: T A C G A C C T T G G C G A C G A C T What s the mrna sequence? (Circle the change) What will be the amino acid sequence? Will there likely be effects? What kind of mutation is this? Mutated DNA Sequence #3: T A C A C C T T A G C G A C G A C T What s the mrna sequence? (Circle the change) What will be the amino acid sequence? Will there likely be effects? What kind of mutation is this? Mutated DNA Sequence #4: T A C A C C T T G G C G A C T A C T What s the mrna sequence? (Circle the change) What will be the amino acid sequence? Will there likely be effects? What kind of mutation is this? Mutated DNA Sequence #5: T A C A C C T T G G G A C G A C T What will be the corresponding mrna sequence? What will be the amino acid sequence? Will there likely be effects? What kind of mutation is this?

28 1. Which type of mutation is responsible for new variations (alleles) of a trait? 2. Which type of mutation results in abnormal amino acid sequence? 3. Which type of mutation stops the translation of the mrna?