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DNA Modifying EnzymesEukaryotic and prokaryotic cells possess multiple mechanisms to repair DNA and control damage to their genomes. These include base excision repair (BER) and nucleotide excision repair (NER) that excise and replace damaged nucleotide bases and helix-distorting lesions, respectively. Many of the enzymes involved in NER are also active in transcription-coupled repair (TCR) processes. In addition, mismatch repair (MMR) enzymes act to replace mismatched nucleotides and repair insertion/deletion loops. Furthermore, there are two types of double-stranded DNA break repair, homologous recombination (HR) and non-homologous end-joining (NHEJ).
Base excision repair proteins correct DNA lesions and ensure that mutations are not propagated. The process of base excision repair is achieved via specific and sequential enzyme activity. Damaged bases are first identified and removed by DNA glycosylases/AP lyases, which break beta-N glycosidic bonds to create an abasic (AP) DNA site. Depending on the initial events of base removal, repair proceeds through either the short patch (1 nucleotide) or long patch (2-10 nucleotides) repair pathways. This involves the AP site being recognized by endonuclease enzymes which nick the damaged DNA, and recruit DNA polymerases to fill the gap in the DNA. Base excision repair is completed by DNA ligase sealing the nick between the two strands.
Nucleotide excision is an additional DNA repair mechanism which removes nucleotides that have been damaged by chemicals or ultraviolet radiation. Nucleotide excision generates a short single-stranded DNA gap, which is subsequently used as a template by DNA polymerase. In addition to base and nucleotide excision repair molecules, mismatch repair (MMR) enzymes act to replace mismatched nucleotides and repair insertion/deletion loops. Genotoxic stress can introduce DNA double-strand breaks (DSBs), which are repaired by either homologous recombination or non-homologous end-joining. The Mre11/Rad50/Nbs1 (MRN) complex, along with members of the Rad51 family of proteins, are involved in double-strand break repair during homologous recombination. R&D Systems offers quality DNA enzyme products which include DNA glycosidases, endonucleases, polymerases, ligases, and more.
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What happens to the affinity between the substate and enzyme when the enzyme becomes denatured?
Affinity decreases as the enzyme's geometry is modified by being denatured. It will no longer properly fit the active site.
Why their structure shape is so important (hintactive site)?
The shape of the active site is very important because it determines the efficiency of the specific enzyme. If an active site shifts, the substrate can no longer bind to an enzyme's active site, therefore causing inefficiency. We say that the enzyme is undergoing denaturation.
What is azocasein?
Azocasein is a synthetic substrate used in enzyme assays to measure protease activity. It is a derivative of casein, a protein found in milk, that has been modified with an azo dye to allow for easy detection of enzymatic activity. When proteases cleave azocasein, the azo dye is released, causing a color change that can be quantified spectrophotometrically.
What is the theory the synthesis of each enzyme is catalyzed by one specific gene?
The theory you are referring to is the "one gene-one enzyme" hypothesis proposed by Beadle and Tatum in the 1940s. This theory suggested that each gene is responsible for encoding a specific enzyme, which catalyzes a specific biochemical reaction in an organism. Although it has been modified over time, the concept remains fundamental to our understanding of how genes encode proteins and their functions in cells.
What enzyme and cell organelle are required for protein synthesis to work?
Protein synthesis requires the enzyme ribosomes and the cell organelle called the endoplasmic reticulum. Ribosomes are the cellular machinery responsible for translating mRNA into proteins, while the endoplasmic reticulum is where newly synthesized proteins are folded and modified before being transported to their final destination in the cell.
What happens to the affinity between the substate and enzyme when the enzyme becomes denatured?
Affinity decreases as the enzyme's geometry is modified by being denatured. It will no longer properly fit the active site.
An enzyme whos activity is affected when a molecule binds to a certain site other than the active site is called?
Allosterically modified
Why their structure shape is so important (hintactive site)?
The shape of the active site is very important because it determines the efficiency of the specific enzyme. If an active site shifts, the substrate can no longer bind to an enzyme's active site, therefore causing inefficiency. We say that the enzyme is undergoing denaturation.
One gene controls the synthesis of one?
protein. This process involves transcription, where the gene is copied into mRNA, and translation, where the mRNA is used to assemble amino acids into a protein. The protein produced carries out specific functions in the cell or organism.
What is azocasein?
Azocasein is a synthetic substrate used in enzyme assays to measure protease activity. It is a derivative of casein, a protein found in milk, that has been modified with an azo dye to allow for easy detection of enzymatic activity. When proteases cleave azocasein, the azo dye is released, causing a color change that can be quantified spectrophotometrically.
What is lipolyzed fat?
In short, they are enzyme modified fats, used to enhance dairy flavor. They are natural dairy flavors made with the use of lipase enzyme and cultures to treat fresh milk/cream/butter (i.e. Lipolyzed Butterfat or Lipolyzed Cream). The lipase enzyme causes milkfat to split into free fatty acids liberating the flavors from volatile compounds lactones and methyl ketones. To destroy the culture bacteria and the enzyme, the lipolyzed product is heated after lipolysis.
What is the theory the synthesis of each enzyme is catalyzed by one specific gene?
The theory you are referring to is the "one gene-one enzyme" hypothesis proposed by Beadle and Tatum in the 1940s. This theory suggested that each gene is responsible for encoding a specific enzyme, which catalyzes a specific biochemical reaction in an organism. Although it has been modified over time, the concept remains fundamental to our understanding of how genes encode proteins and their functions in cells.
Why beadle and tatums one gene one enzyme hypothesis has been modified scince they presented it in the 1940s?
The one gene-one enzyme hypothesis has been modified to the one gene-one polypeptide hypothesis because not all proteins are enzymes. Proteins can have various functions beyond enzymatic activity, such as structural roles. Additionally, some genes may encode for multiple protein products through alternative splicing, post-translational modifications, or other mechanisms.
What stores and makes RNA in the nucleus?
RNA is transcribed in the nucleus by an enzyme called RNA polymerase, using DNA as a template. The RNA is then processed, modified, and transported out of the nucleus for translation into proteins.
Why has beadle and tatoms one gene - one enzyme hypothesis been midified since the presented it in 1940s?
Tatum and Beadle proposed the "one gene one enzyme" theory. One gene code is responsible for the production of a single protein. "One gene one enzyme" is modified to "one gene one polypeptide" because the majority of proteins are composed of multiple polypeptides.
What was the first practical use of a restriction enzyme in production of what?
The first practical use of a restriction enzyme was in the production of recombinant DNA in the early 1970s. Scientists used the restriction enzyme EcoRI to cut DNA at specific sequences, allowing them to splice together DNA fragments from different sources. This innovation enabled the development of genetically modified organisms and the production of insulin and other therapeutic proteins. The ability to manipulate DNA in this way revolutionized molecular biology and biotechnology.
The binding together of an enzyme and a substrate forms a what?
enzyme-substrate complex
