Bio UNIT 5

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Chap 17 SI A biologist inserts a gene from a human liver cell into the chromosome of a bacterium. The bacterium then transcribes and translates this gene. The protein produced is useless and is found to contain many more amino acids than does the protein made by the eukaryotic cell. Explain Why.

Everything is expressed in bacteria. In humans introns are taken out so that in the bacteria they would express both exons and introns making forth a longer protein that does not function properly. In other words, if the protein is expressed then the protein has more amino acids and it my fold incorrectly causing all the proteins to interact with each other. Normally introns are cut of the mRNA before the strand leaves the nucleus and only exons are translated into amino acids which form the protein. If introns are not cut out (like in the case of bacteria) the amino acids they code are expressed as well. This all makes the protein “useless” needless to say.

Ch 18 – Ch 18.4 #1 A certain mutation in E coli changes the lac operator so that the active repressor cannot bend. How would this affect the cell’s production of B-galactosidase

When a certain mutation occurs in the E coli changing its lac operator, so that the active repression cannot bind, it affects the cell’s production by repeatedly producing B-galatosidase. Two enzymes that is used for lactose utilizing are permease and transacetylase; they will continue making those enzymes without lactose which could waste a cell’s reserves. Usually the active repressor binds with the operator causing it to physically block RNA polymerase from transcribing the genes when it isn’t needed. Since there is a mutation ( the active repressor cannot bind) it cannot bind to an operator; consequently, the active repressor becomes useless. Moreover, B-galatosidade will start to mass produce even thought it is not needed since the active repressor and operator can no longer prevent RNA polymerase.

Ch 18 STS Explain how the excessive or inappropriate use of antibiotics poses a health hazard for a human population.

An antibiotic is a substance, such as penicillin, produced by certain fungi, bacteria, and other organisms, that can destroy or inhibit the growth of other microorganisms. Antibiotics are used for treatment of infectious diseases. Antibiotics kill the cells that are not antibiotic resistant. So if you use too much of them only these cells are left and you have a bunch of super resistance bacteria that withstands antibiotics. In otherwords. Some bacteria have learned to outsmart the antibiotic and have repreoduced a generation of stronger and resistant bugs. Consequently, there are some serious infectious diseases that are no longer responding to antibiotics. If an infection does respond, it often requires five to ten times the amount of the drug that used to be effective.
When a child is continually treated with antibiotics, the bacteria in his or her body may eventually be able to survive the drugs, making it much harder to cure an infection. Too much antibiotic can kill helpful bacteria in the body.

Ch 20 SI You hope to study a gene that codes for a neurotransmitter protein in human brain cells. You know the amino acid sequence of the protein. Explain how you might a) identify the genes expressed in a specific type of brain cell, b) identify the gene for the neurotransmitter, c) produce multiple copies of the gene for study, and d) produce a quantity of the neurotransmitter for evaluation as a potential medication.

A) Loose packaging, transcription factors, and undigested mRNA would show you the genes expressed in a specific type of brain cell.

B) If you know the amino acid sequence, you would know the nucleotide sequence in mRNA by working backwards. To do that you would fine the codons and then find the RNA through trial and for the codons. Once you have the RNA you use a complimentary RNA probe. It is a small piece of RNA so it becomes radioactive and you can see where it goes and it’ll attack to the DNA strand where the gene is.

C) To be able to produce multiple copies of the gene for study, you could use a technique called PCR (Polymerase Chain Reaction). In this technique, the DNA strand is heated for a short amount of time so that it separates a single strand into two parts. It will start to cool down and the primers will bond to each of the two DNA strands once the strand is separates into two pieces. Next, the RNA polymerase will add nucleotides to each strand to the 3′ end of each primer; consequently, you will end up with two separate strands which doubled from the original amount of only 1 strand. The amount of gene copies to double through each cycle is what PCR will result to. Thermal cycle is a tool that could make this happen.

To produce a quantity of the neurotransmitter for evaluation as potential medication, you would have to use DNA cloning involving bacteria. cDNA is needed before cloning eukaryotic cell because bacteria don’t go through RNA processing. During the process of cDNA, the enzyme reverse transcriptase makes DNA from RNA( making cDNA). cDNA is DNA with no introns which is equivalent to bacterial DNA. Now you can insert that cDNA into the bacteria to clone it. During the cloning stage, it deals with isolating the gene and the vector which has ampR (ampicilin resistance). With the help of restriction enzymes to create a sticky end so that the end could combine, the gene is inserted into the vector making a recombinant. The new recombinant goes into the bacteria; however, some will be competent and non competent making recombinant and not recombinant bacteria. Once that is done, you the bacteria on an agar plate with ampR which destroys non recombinants vectors; consequently, the neurotransmitters will multiply which produces enough for medication.


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