Miss Magargal’s Biology class Protein Synthesis Unit Test: Practice Guide Answers Part A: Complete the following questions: 1.) What is the difference between protein synthesis in Prokaryotes & Eukaryotes? All living things undergo the process of transcription and translation because they have the same DNA molecules. They differ in the number and arrangement and the location of where protein synthesis takes place. 2.) Where is the DNA located in a Prokaryote? in the cytoplasm. Where is the DNA located in a Eukaryote? in the nucleus 3.)What is the function of a ribosome? site of protein synthesis 4.)What is the difference between proteins made by free-­‐floating ribosomes and proteins that travel through the endomembrane system? free-­‐floating ribosomes remain in that cell, whereas, proteins that travel through the endomembrane leave by secretory vesicles. 5.)What organelle would you find both DNA and RNA? nucleus 6.)What are the three types of RNA? mRNA, tRNA, rRNA. What are their functions? a. mRNA Function: transcribes a copy of the DNA code to the ribosome b. tRNA Function: is the an anticodon & carries a specific amino acid to mRNA c. rRNA Function: makes up the ribosome 7.)What is a codon? Every 3 letters in mRNA What is the importance of a codon? It matches with an anticodon [carries a specific amino acid] in the cytoplasm on the ribosome. In translation, an mRNA codon is recognized by its complementary tRNA. 8.)What is the monomer of a protein? Amino acids 9.)What is an anticodon? tRNA What is the importance of an anticodon? It carries a specific amino acid 10.)What is transcribed from DNA? mRNA Where? In the nucleus 11.)What step of protein synthesis occurs at the ribosome? Translation Amino acids are linked together to form what? Proteins=polypeptides to be used by the cell for new cell parts 12.)Describe the process of transcription. DNA serves as a template for mRNA. mRNA molecules move to the ribosomes, tRNA molecules bring amino acids to the ribosome. 13.) What is the function of the rough endoplasmic reticulum in the endomembrane system? It aids in the production of membrane and secretory proteins. 1 Miss Magargal’s Biology class 14.) What is the function of the golgi apparatus in the endomembrane system? It modifies, sorts and packages the proteins for export from the cell. 15.)Describe the process of translation. It occurs at the ribosome directly by mRNA and linking amino acids. Instructions coded by DNA are translated into proteins which express an organism's physical traits. 16.)What is the difference between DNA replication = DNA makes DNA and DNA transcription= DNA makes mRNA? [DNA replication takes place in the nucleus, while DNA transcription takes place in the cytoplasm.] 17.)Why can’t DNA leave the nucleus? It’s double stranded What leaves? mRNA Where does it go? To the ribosome 18.) How many chains is DNA? 2 How many chains is mRNA? 1 19.) What is a mutation? Mutations can spontaneously occur during DNA replication. If they occur during meiosis, they can be passed from parents to their children. What are they caused by? These changes can be caused by environmental factors such as ultraviolet radiation from the sun, exposure to chemicals, or can occur if a mistake is made as DNA copies itself during cell division. 20.) What are the three types of point mutations? What is the result of each? a. Missense Result: the change of a single base pair causes the substitution of a different amino acid in the resulting protein. This amino acid substitution may have no effect, or it may render the protein nonfunctional. b. Silent Result: It does not cause a change in the phenotype of the organism. c. Nonsense Result: A change in the sequence of amino acids of a protein by producing a stop codon 21.) What is a frameshift mutation? What is the result of it? This mutation results from the insertion or deletion of nucleotides into the original sequence, which causes the reading frame of the sequence to change. 22.) If the bold nucleotide in the sequence changes to C, what happens? Nothing: same amino acid= tyrosine What if it changes to a G? it changes to a stop codon & stops protein synthesis UGG GGC GCU UAU AAG 2 Miss Magargal’s Biology class Part B: Use the presented case study and vocab to answer the following essay question: 23.) Use the following terms to answer the question: intron, mRNA, mutation, protein synthesis A researcher identifies the codon, or nucleotide sequence, GCU in a strand of mRNA inside a nucleus after being transcribed from DNA. In the genetic code, GCU codes for the amino acid Alanine (using the codon wheel). When the mRNA is utilized for protein synthesis, will Alanine appear in the protein? If yes, explain why If no, explain why not. If both can happen, explain why! Both could be an answer depending upon where the protein synthesis begins. A start codon begins protein synthesis by reading mRNA and translating it into proteins, the process continues until a stop codon is reached. If a mutation changes the DNA, the mRNA is also changed. Depending upon the type of mutation alanine may or may not be affected. Introns are parts of the DNA or RNA that does not code for proteins. Part C: Fill in the blanks, and describe the process of Protein Synthesis: 24.) Describe two similarities and two differences between transcription and translation in a eukaryotic cell. Similarities: RNA is made from DNA, and during translation, protein are made from RNA. Newly created proteins float in the cytoplasm. Differences: In Eukaryotic cells, transcription and transcription occur in separate locations in the cell. It’s more complex in eukaryotic cells because of the organelles. Part D: Use the graphic to answer question: 25.) Identify, in order, the cell structures involved in the synthesis and transport of secretory proteins (endomembrane system) throughout the cell. Secretory Vesicle
nucleus>>>>>RER>>>>>Golgi>>>>>> vesicle>>>>>>> out of cell Good Luck Studying!!!!! 3