Holt, Rinehart, and WInston Modern Biology California
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| Studied a bacterium called Streptococcus pneumoniae. He used two strains of the bacterium. First he injected live R cells into a mouse and it does not die. Second he injected live S cells and the mouse dies. Third he kills S cells with hear and inject them into a mouse. The mouse lives. Lastly he kills S cells with heat, mixes them with live R cells, and injects it into a mouse. The mouse dies. Griffith concluded that heat-killed virulent bacterial cells release a hereditary factor that transfers disease-causing ability to live harmelss cells. This type of transfer is called transformation. | ||
| Tested whether the transformiing agent in Griffith's experiment was protein, RNA, or DNA. The scientists used enymes to seperately destroy each of the three molecules in heat killed S cells. They used protease enzyme to destroy protein, an enzyme called RNase to destroy RNA, and an enzyme DNase to destroy DNA. Then they mixed three seperate batches of heat-killed S cells with live R cells and injected mice with the mixtures. Avery found that the cells missing protein and RNA were able to transfrom R cells into S cells and kill the mice. However, cells missing DNA did not transform R cells into S cells. Therefore, DNA is responsible for the transformation. | ||
| They tested where DNA or protein was the hereditary material viruses transfer when viruses enter a bacterium. Viruses that infect bacteria are called bateriophages. Hershey and Chase used radioactive isotopes to label the protein and the DNA in the phage. They used radioactive sulfur to label protein and radioactive phosphorous to label DNAS. Then they allowed the phages to seperately infect Escherischia coli bacteria. Then they removed the phage coats. They used a centrifuge to seperate the phage from E. coli. They found that viral DNA and little of the protein entered the E. coli cells. They concluded that DNA is the hereditary molecule in viruses. | ||
| They tried to determine the structure of DNA. They used X-ray diffraction photos of DNA crystals produced by Rosalind Franklin and Maurice Wilkins. | ||
| 5c sugar, phosphate group, and a nitrogenous base. | ||
| between sugar and phosphate molecules | ||
| between nitrogenous bases | ||
| adenine, guanine | ||
| thymine, cytosine | ||
| Created the base pairing rule. Pairs of bases are called complementary base pairs. The order of the nitrogenous bases is called the base sequence. | ||
| the process by which DNA is copied in a cell before it divides. First helicase seperates the DNA strands. The Y shaped region is the replication fork. Then enzymes called DNA polymerase add complementary nucleotides. When one strand is new and the other old, it is called semi-conservative replication. When mistakes occur, the base sequence of the two DNA molecules are different. This is called a mutation. | ||
| gaps are joined by this enzyme during DNA replication | ||
| replication begins at one point. Two replication forks are formed. They have one circular chromosome. | ||
| chromosome long, not circular. Replication begins at many points or orgins. | ||
| have repair functions that proofread DNA | ||
| DNA acts as a template for the synthesis of RNA. It takes place in the nucleus. RNA polymerase binds the gene's prmoter and causes DNA to unwind. Complementary RNA nucleotides are added and joined. When RNA reaches the termination signal, the DNA and new RNA is released by the polymerase. | ||
| RNA directs the assembly of proteins. Occurs in ribosomes. Ribosomal subunits, mRNA, and tRNA carry methionine bind together. The tRNA carrying the amino acid binds to the codon. Peptide bonds from between amino acids. FIrst tRNA detaches and leaves. Polypeptide chain grows longer. When a stop codon is reached the process stops. Ribosome complex falls apart and polypeptide is released. | ||
| forms proteins based on info in DNA and carries out by RNA | ||
| has ribose instead of deoxyribose. Has the base uracil instead of thymine.Single stranded. Shorter in length than DNA. 3 types: mRNA: carries instructions from a gene to make protein. Carries the genetic message from DNA in the nucleus to ribosomes in the cytosol. rRNA: part of ribosomes. Protein synthesis occurs in ribosomes. tRNA: transfers amino acids to the ribosome to make proteins. | ||
| three nucleotide sequence in mRNA that encodes an amino acid or signifies start or stop signals. | ||
| AUG, Methionine | ||
| stop translation UAA, UAG, or UGA | ||
| three nucleotides on RNA that are complementary to the sequence of a codon in mRNA | ||
| translation of an mRNA occurs only after transcription is finished. | ||
| translation can begin on an mRNA even before transcription | ||
| entire gene sequence of the human | ||
| turning on of a gene | ||
| Discovered how genes control the metabolism of the sugar lactose Escherichia coli. Won Nobel Prize for their discovery. | ||
| disaccharide that is composed of two monosaccharides glucose and galactose. When present, it induces E. coli to produce 3 enzymes | ||
| genes that code for the polypeptides. | ||
| a DNA segment that is recognized by the enzyme RNA polymerase. Initiates transcription. | ||
| serves as a switch by controlling access of RNA polymerase to the promoter. | ||
| series of genes that code for specific products. When turned off, the lactose is absent. | ||
| coded for by regulatory genes. Attachment causes the block of RNA polymerase advancement and transcription cannot occur so the lac operon is "turned off" | ||
| a molecule that initiates gene expression. Lactose acts as an inducer by binding to the repressor protein and causes it to change shape and detach from the operator. | ||
| lac operon for gene expression | ||
| pre-mRNA formation occurs in nucleus. Pre- mRNA contains both introns and exons. molecule of mRNA is formed when introns are removed. Remaing exons are spliced, or joined and results in a mRNA strand with only exons. It leaves the nucleus and enters cytoplasm to begin protein manufacturing. | ||
| uncoiled form of DNA | ||
| transcribed but not translated | ||
| when expressed, transcribed and translated | ||
| regulatory proteins in eukaryotes | ||
| sequences of DNA that are locataed far from the promoter. Activator and enhancer in contact with RNA polymerase and transcription factors at the promoter activate transcription. AFTER gene expression in eukaryotes. | ||
| determine where anatomical structures will develop | ||
| genes thaht regulate cell growth, cell division, and the ability of cells to adhere one another. | ||
| mutation of proto-oncogene will turn into oncogene. A gene that can cause uncontrolled cell proliferation. | ||
| spread of cancer cells beyond original site | ||
| any substance that can induce or promote cancer | ||
| agents that cause mutations | ||
| grow in skin and tissues that line organs | ||
| grow in bone and tissue muscle | ||
| grow in tissues of the lymphatic system, can cause leukemia |
