Messenger RNA (mRNA) – copies the coded message from DNA in the nucleus and carries the message to the ribosome. Transfer RNA (tRNA) – transfers amino acids to ribosomes during protein synthesis. Ribosomal RNA (rRNA) – contains most of the RNA in the cell, responsible for ribosome function. b. Where does transcription take place?
c. The ribosome moves on down the mRNA, making room for the next incoming tRNA and amino acid. When it reaches a stop codon, it stops production of the protein. Universal Genetic Code 1. Is it the codon or the anticodon that codes for the amino acid? codon 2.
Controlling the Code: molecules at work The lac operon 2. (a) Write a description of the role of the operator in B-gal production. • What is the operator? The operator is a segment of DNA located between the promoter and the enzyme genes. It acts as a switch by determining whether RNA polymerase can attach to the promoter and start transcribing.
Cell division stops until p53 binds to DNA and repairs the damage. C. p53 is an example of an oncogene, and its expression causes uncontrolled cell division. D. activation of p53 leads to inhibition of the S-phase cyclin-CDK complex. 6. All of the following statements correctly describe M-Cdk, EXCEPT: A. M-Cdk causes the cell to enter S phase and begin DNA replication.
The enzyme that is responsible for replicating molecules of DNA by attaching complementary bases in the correct sequence is called ____________________ ____________________. 27. Enzymes called ____________________ are responsible for unwinding the DNA double helix by breaking the hydrogen bonds that hold the complementary strands together. 28. Errors in nucleotide sequences are called ____________________.
Marshall Nirenberg and Heinrich Matthaei used mRNA made up of repeating uracil nucleotides in a cell free extract. They obtained amino acid chains consisting of phenylalanine. What did they learn when they asked the question, ”What happens when mRNA made up of only cytosine, alanine, and guanine are placed in a cell free extract?” 10. Explain how the structure of tRNA helps it to deliver the correct amino acid to the corresponding mRNA codon at the ribosome. Sketch the structure of a tRNA molecule, making sure to label the amino acid and the
DNA specifies the synthesis of proteins, However, a gene does not build a protein directly, instead it dispatches instructions in the form of RNA, which then programs protein synthesis. This molecular chain of command is from DNA in the nucleus then to RNA then to protein synthesis in the cytoplasm. The two main stages are transcription and translation, transcription is the transfer of genetic information from DNA into an RNA molecule, translation is the transfer of the information from RNA into a protein. Describe each stage of the flow of information starting with DNA and ending with a trait. Information will always start with DNA then it will travel to the RNA and then the protein.
] Protein Synthesis Bodies ! Cells ! DNA ! Bodies are made up of cells ! All cells run on a set of instructions spelled out in DNA DNA !
21. Describe the process of translation. Describe how mRNA translates the message into a protein? How are the amino acids brought to the ribosome? 22.
Gizmo Warm-up The Building DNA Gizmo™ allows you to construct a DNA molecule and go through the process of DNA replication. Examine the components that make up a DNA molecule. 1. What are the two DNA components shown in the Gizmo? The DNA components shown in the Gizmo are phosphate molecules and deoxyribose sugars 2.