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1 DNA REPLICATION & BIOTECHNOLOGY Biology Study Review DNA DNA is found in, in the nucleus. It controls cellular activity by regulating the production of, which includes It is a very long molecule made up of thousands of units called Nucleotides are made up of a group, a, and a base. These bases are,,, The bases are bonded together through a bond. is complementary to, and is complementary to. DNA Replication The double stranded DNA molecule unwinds and unzips between the nitrogenous base pairs with the enzyme Free nucleotides present in the nucleus start forming a This is done with the help of enzymes like may be required to begin a new section of DNA, because DNA polymerase can add nucleotides only to an existing piece of Later, the short RNA pieces ( ) will be removed and replaced with DNA nucleotides. One strand is made continuously, the strand, while the other is made in sections where are then stitched together by the enzyme Each new DNA has one old and one newly made complementary strand. This is called replication. It occurs in the nucleus during of interphase. RNA The RNA molecule is a nucleotide strand, not a double strand as in DNA. The sugar molecule in RNA is, not deoxyribose in DNA. The base takes the place of thymine. mrna, or, made in the nucleus, serves as a template for making trna, or, brings to growing protein chain. rrna, or, goes to, forms Only one side of DNA is used to make RNA because a different side of the DNA strand would end up making Transcription of RNA Transcription is the transfer of the from to. It happens in the nucleus. DNA is a template for the synthesis of mrna.

2 mrna molecules are to the of the DNA template. mrna moves from the nucleus to the mrna has, which are, that code for specific The original DNA codes are called There are never 2 amino acids for the same codon but there can be tons of codons for one amino acid. Translation of RNA Translation is the making of the chain using the as a blue print. mrna strand becomes associated with before protein formation begins. Specific pick up specific and bring them to the The first amino acid is always, which is what the start codon, AUG, codes for. Amino acids (there are 20 types) are lined up one at a time in the assembly area of the ribosome. The ribosome moves down the mrna, reading one at a time. With the aid of and, the amino acids are bonded together to form a polypeptide chain (protein chain) on the ribosome. Translation occurs in the When a ribosome reaches a stop codon,protein chain synthesis stops, ribosome, and the chain folds up to form a final with a Some proteins join other proteins to form larger protein molecules. Draw a picture of a ribosome translating mrna, the trna matching the codons with their anticodons, and the growing polypeptide chain. MUTATIONS Changes in can change the code, resulting in the formation of a different The mutant protein may have one amino acid changed, or many may be changed, depending on the type of mutation. : One nucleotide is for another. : One nucleotide is or, changing the way the entire DNA strand is read. This is because DNA is read in triplets, and if one is added or deleted, all of the downstream triplets will be affected. Causes of Mutations Any that can react with DNA can cause mutations. Example: tobacco smoke, benzene, etc. can cause mutations by damaging in actively

3 Things that can change the DNA code are called Many of these are also, things that can cause cancer. REGULATION OF GENE ACTIVITY Not all genes in a cell are active at one time. Regulation allows selective expression of certain genes in different types of cells or at different times in the same cell. Different body cells with the same DNA because different genes are and other genes are Regulation of gene activity is due to special and CLONING Cloning: Producing a group of offspring from the cells of an organism. It is a form of reproduction, and thus involves It can be artificially done in animals by inserting a of the animal to be cloned into a This zygote-like cell is then grown in a petri dish until a small clump of cells develops. Then it must be put into a of an animal to develop. Technically, are clones of each other, forming from a zygote that splits into two cells after the first mitotic division that then separates and grows into two twins. Plants are cloned using, which can be done with various plant parts (shoot, leaf, root cuttings) or by tissue culture. BIOTECHNOLOGY AND GENETIC ENGINEERING is the combination of DNA from two different organisms. is the transfer of genetic information from one organism to another. Transferred genes allow host organism to make new, because it has a new gene. Potentials: Could correct by replacing a faulty gene with a good gene; increase by making plants that produce to kill pests and lower the costs of making medically needed or Plasmids and Bacteria Plasmids are small circular which can be taken up by bacteria. They are used as vectors to get into a bacterium. The normal bacterial chromosome is too big to serve as a vector. Biologists choose plasmids because plasmids are within the bacteria and each daughter cell receives one, meaning the biologist doesn t have to continuously insert plasmids with foreign DNA into bacteria over and over again. are used to cut DNA in specific places called which have a specific nucleotide sequence in a bacterial plasmid and the - is used to cut the foreign DNA. This allows the foreign DNA segments and plasmid to be cut into Foreign DNA segments are inserted into the bacterial plasmid and the complementary nitrogenous bases join to form is used to allow foreign DNA to join to bacterial DNA and the plasmid

4 closes up again. It also helps to form between and in the to fuse DNA segments together. Scientists choose plasmids with an because it helps them to figure out which bacteria have taken up a plasmid vs. those which didn t take up a plasmid. We can also choose a plasmid which has the cutting site, or, in the middle of a gene. If foreign DNA is inserted into the cut and the plasmid ring closes, the gene is dysfunctional due to the foreign DNA in the middle. If the ring closes before taking up foreign DNA, the gene with the cut site will be able to work again. This is one of the ways biologists can tell if bacteria have taken up the right plasmid with the right foreign DNA. Restriction enzymes are naturally present in some cells and are used as a defense against because they cut up any foreign DNA that tries to enter the cell, making it harmless. In the lab, bacteria without plasmids are exposed to plasmids, which many bacteria take up due to If they take up a (has foreign DNA), they will show new traits. In the lab, bacteria must be grown and successful recombinants containing the desired gene must be selected out and multiplied. Characteristics produced by the foreign genes are expressed when they are inserted into the DNA. Recombinant organisms have altered DNA, which they can pass down to their. Plants & Animals Plants can have foreign genes introduced by turmor forming bacteria Agrobacterium tumifaciens, which inserts plasmids into plant DNA and forces plants to grow tumors, which the bacteria eats. However, humans can take out the tumor causing gene and make the bacteria insert other, foreign DNA in the plasmid, called the plasmid. List a benefit and risk of growing food-producing plants that make their own insecticide. o o Foreign genes in animals are usually inserted into fertilized eggs via or harmless viruses. Many tries are needed to get a successful recombinant. Technology: Electrophoresis A technique used to separate based on their Involves a tray with specialized gel and an which is turned on for a period of time. Several DNA samples which have been cut with the same are loaded into wells at the end of the tray. Because DNA is, it migrates towards the end of the tray when the electrical current is turned on. Smaller fragments move because they can pass through the gel more easily than larger ones. When electrical current is turned off, the fragments of DNA are towards the positive side and the fragments are towards the negative side. are needed to see DNA; different patterns in different lanes can show similarities and differences between DNA samples. It is good for comparing DNA and to find the

5 Technology: Polymerase Chain Reaction (PCR) PCR is a way to large amounts of from a small sample. Uses special DNA polymerase. DNA is to, are added and allow DNA to replicate when solution is cooled. Primers are small custom manufactured DNA segments that allow DNA polymerase to add nucleotides to create new strands where the desired gene to be replicated is. Can be repeated for several cycles, and DNA amount doubles each time. This process is good for getting enough DNA from, to a DNA fragment, to do, recombinant work, etc. HUMAN GENOME PROJECT Human Genome Project attempted to and to determine the genetic code of humans. It will enable us to: and Negative effects: Insurance companies might gain access to individual genetic information and discriminate based upon your genes and chances of getting a condition or disease. MORE STUDYING Check the Regents!