A Study On The Lac Operon

Different types of bonds/interactions in proteins lead to different kinds of structures. Three of the most commonly known chemical bonds in proteins include the hydrogen bond, the covalent bond, and the ionic bond. In hydrogen bonds, hydrogen interacts with oxygen, nitrogen, or fluorine to form either the alpha helix, or the beta sheet, which in turn determines its secondary, tertiary, or quaternary structure. Another type of bonds, the covalent bond, links amino acids together by sharing electrons;

Enzymes are types of proteins that work as a substance to help speed up a chemical reaction (Madar & Windelspecht, 104). There are three factors that help enzyme activity increase in speed. The three factors that speed up the activity of enzymes are concentration, an increase in temperature, and a preferred pH environment. Whether or not the reaction continues to move forward is not up to the enzyme, instead the reaction is dependent on a reaction’s free energy. These enzymatic reactions have reactants referred to as substrates. Enzymes do much more than create substrates; enzymes actually work with the substrate in a reaction (Madar &Windelspecht, 106). For reactions in a cell it is

Lactose is a sugar that can be put into smaller molecules, glucose and galactose. Lactose is when you are not able to digest milk and dairy meaning that the enzyme lactase that breaks down lactose is not functioning properly. ONPG was used as a substitute for lactase because even though it is colorless it helps show enzyme activity by turning yellow. This experiment measured the absorbance ONPG when exposed to lactase within an environment of different salinity’s. The enzyme, lactase, was obtained by crushing a lactaid pill and then was added into four cuvettes. ONPG and salt solution of different concentrations were added and their levels of absorption was measured by a spectrophotometer. The results showed that higher salt concentrations have a lower level of absorption. There were 4 cuvettes and within those cuvettes that solutions within them were being tested and the results showed the more salt solution added with the lactase the lower the absorbance. The less salt solution there was a higher rate of absorbance. The data supported the hypothesis that with increasing NaCl concentration there would be a decrease in enzyme activity.

1. EMG 9 and EMG 26 contain strain _lac-_(I- Z+ Y+) and strain _lac -_ (I+ Z- Y-)respectively.Three genes huddled together on the chromosome are required for two strains of _E.coli_ to utilize lactose.Consisting of three genes, namely, _lacZ_, _lacY_ and _lacA_, the _lac_ operon orderly handles these genes to code specific enzymes necessary for the metabolism of lactose. The genes _lacZ_, _lacY_ and _lacI_ would code for beta-galactosidase, galactosidase permease and _lac_ repressor respectively. Regulation of _lac_ operon is also tight and the operon's negative control is made possible by _lac_ repressor (Hill, 1996). With the presence of _lac_ repressor, _lac_ operon will be deactivated and will

The enzyme that will be used in this experiment is lactase. Lactase is an enzyme that breaks down a sugar found in milk called lactose into glucose and galactose. Lactase is found in the small intestine, and is naturally produced by the body. If someone’s body does not produce the lactase properly, or the lactase itself doesn’t act properly, that person would be considered lactose intolerant. This means your body would not be able to digest milk properly, and you could suffer symptoms such as cramping, diarraea, painful gas, and nausea after having some sort of dairy. If one would was lactose intolerant, but wanted to have some sort of dairy product, they could take a lactase supplement. The lactase in the supplement will break down the lactose

The gene for GFP is regulated by an inducible repressor system, meaning it is turned on by environmental factors. In this case, GFP is expressed when exposed to the sugar arabinose; moreover, the organism will glow only when arabinose is present. Without arabinose, the repressor attaches to the regulator/ operator segment of the gene and acts as a roadblock, preventing RNA polymerase (RNAP) from reading the structural gene and creating a complementary mRNA strand; thus, GFP protein production is prohibited. However, when present, arabinose binds to the repressor, changing its active site, so it can no longer bind to the operon; RNAP can then initiate the transcription of the GFP gene by binding to the promoter segment. Thus, I predict that the E. coli will glow only when pGLO and arabinose are present because arabinose activates the expression of GFP, a gene found in pGLO. Regulation of gene expression is crucial to prevent wasteful overproduction of unneeded proteins and to allow adaptation to new environments (Regulation of

“Enzymes are proteins that have catalytic functions” [1], “that speed up or slow down reactions”[2], “indispensable to maintenance and activity of life”[1]. They are each very specific, and will only work when a particular substrate fits in their active site. An active site is “a region on the surface of an enzyme where the substrate binds, and where the reaction occurs”[2].

Proteins are polymeric chains that are built from monomers called amino acids. All structural and functional properties of proteins derive from the chemical properties of the polypeptide chain. There are four levels of protein structural organization: primary, secondary, tertiary, and quaternary. Primary structure is defined as the linear sequence of amino acids in a polypeptide chain. The secondary structure refers to certain regular geometric figures of the chain. Tertiary structure results from long-range contacts within the chain. The quaternary structure is the organization of protein subunits, or two or more independent polypeptide chains.

The purpose of this lab is to examine the specificity of the lactase enzyme to a specific substrate and how it can denature due to the rise in temperature.

b. Secondary- Hydrogen bonding is involved at the secondary level of protein structure. Hydrogen bonding occurs at regular intervals along the polypeptide backbone. Hydrogen bonding is an intermolecular force much weaker than covalent or ionic bonds that occurs between a hydrogen atom bonding to fluorine, nitrogen or an oxygen atom. c. Tertiary- Tertiary structure is formed between the bonding of the R-groups connected to the polypeptide backbone.

The primary protein structure can be likened to a human chain in which each person is assumed to be an amino acid and their hands viewed as the carboxyl and amino groups. The person on one end of the chain, who has a free left hand, is assumed to be the free carboxyl group. The person on the other end, who has a free right hand, is assumed to be the free amino group. Everyone in this chain has a left hand linked to somebody’s right hand and a right hand linked to somebody else’s left hand forming peptide bonds. The heads and legs just like the side chains and hydrogens, do not take part in the linking.

Two separate variables were hypothesized and tested within the confines of the experiment on their effects on the productivity of lactase enzyme. The measurement of light absorbance levels of different solutions based on both the concentration of o-nitrophenol (ONP) as well as the pH of the solution tested. To begin with, differing concentrations of ONP were tested to find the absorbance levels of ONP. Three different pH values, 5, 6, and 7, in solution, were tested over a period of 8 minutes and their absorbance’s recorded. Both plots of data were then used to find at which concentrations of ONP absorption levels, and thus enzyme activity rates, were at their highest across each of the three pH solutions. Based on the results

Transcription is where DNA is transcribed into RNA which then can be pass to the ribosome’s to act as a template for protein synthesis. Before transcription can begin DNA must unwind and the two halves of the molecule much come apart so exposing the base sequence. This process begins when a region of a two DNA strands is unzipped by enzyme called RNA polymerase attaches to the DNA molecule at the imitation site.

The formation of a protein begins in the genes, which contain the basic building information for all parts of living organisms. There are four DNA nucleotides that make up genes: A, T, C, and G. A codon is any arrangement of three of these nucleotides. Each triplet of nucleotides codes for one amino acid. First transcription will begin in the nucleus where mRNA will transcribe the DNA template. During both transcription and translation, there are three steps. The first step in transcription is initiation where RNA polymerase separates a DNA strand and binds RNA nucleotides to the DNA. RNA nucleotides are the same as DNA ones except that U replaces the T. The second is just the elongation of the mRNA. The third step of transcription is termination. This occurs when RNA polymerase reads a codon region and the mRNA separates from the

material of some viruses. RNA molecules are like DNA. They have a long chain of