Unit 1 Lesson 1 Key Question Biology SBI4U Essay

Testing for the presence of starches in the unknown solution with Lugol’s reagent will be referred to as Test 3

When performing iodine, we are testing for the present of starch. In this case, negative will be seen as yellow-brown indicating no starch and blue-black representing positive (starch present). When performing Sudan test, negative shows that there is no change nor lipids. On the other hand, positive appears to be orange with lipid being present. The last biomolecule we tested for is protein. The Biuret reagent turns blue-green if the outcome is negative and violet for positive (protein present).

The Benedict test, is a test to determine whether a solution has reducing or non-reducing sugars. If the Benedict's test is negative, that means there is not reducing sugars. Next, the Lugol's test is to determine if there is starch in a substance. If the solution is yellow or orange after a Lugol's test, that means it is negative. If the results of a Lugol's test is purple or black, then it is

Proteins are a perfect example. The 3D structure and folding determine the use of the protein, such as the protein becoming an enzyme to fuel cellular respiration. However, before folding can occur, amino acids, which are the monomers of proteins, must be joined together through dehydration synthesis. In order for a protein to be used within an organism’s body, the polypeptide chain must first be built. Dehydration synthesis occurs by reacting the carboxyl group of one amino acid with an amine group in another amino acid. This can be pictured in Figure 1. The OH from the carboxyl group is removed, along with a Hydrogen from the amine functional group. This results in the byproduct of water, which is later used by the cell. The Carbon in the carboxyl group forms a bond with the Nitrogen in the amino group, which is called a peptide bond. The final product of this reaction is an H2O molecule, and the start of a polypeptide chain. The protein that was made through dehydration synthesis can now be used throughout the body for a variety of different processes. The protein made can be used for tissue and cell repair. A large portion of organs and bones are comprised of protein. Other ways that the protein are used is to be made into enzymes that control reactions in the body such as cellular respiration. The creation of a protein strand via dehydration synthesis is not exclusive to

Purpose: The purpose of this lab was to test for sugars, starches, proteins, and lipids.

Hydrolysis of Polysaccharides: (HP) 1.IKI test, Before treatment: make 1% starch and follow the IKI test for starch, water, and glucose by testing three drops of each with one drop IKI’s regent. 2.Benedict’s test before treatment: Add 10 drop of Benedict's regent to three test tubes, each including either glucose, water, or starch. The test tubes are then placed in boiling water and resulting colors are recorded. 3.After treatment for IKI TEST and Benedict’s test: Put 2ml of the 1% starch solution into the 3 test tubes (#2.#3,#4),and then add 5 drops HCl into two tubes (#3,#4). Place tube #2 and #4 into the boiling water and after 10 minutes remove both test tube from heat. Add NaOH, drop by drop to test tubes #3 and #4 to neutralize the pH. Transfer 2 drops of each to the spot plate and repeat the IKI test. Transfer 5 drops of each to the 4 new test tubes and repeat the Benedicts test. For both methods water and glucose were used as a control. These two tests show the presence

DNA is composed by a double helix structure. In this structure we can find a phosphate group, a deoxyribose and a nitrogenous base.

An amino acid is made up of a carbon atom in the centre (known as the  carbon), a carboxyl group, amino group, a hydrogen atom and an R group (figure 1). The R group is the section of the amino acid that determines its chemical properties. In glycine, the R group is hydrogen. Some of the amino acids have R groups that are hydrophobic and some have R groups that are hydrophilic and this often determines how the protein folds into its tertiary structure and also where they can be found within the cell. It is the sequence of these amino acids that determines the type of protein that is made. Amino acids join to form proteins in a process known as protein synthesis where a gene is expressed to produce a polypeptide chain. After the genetic code has been translated from the DNA in the nucleus, the resulting mRNA is transcribed into a polypeptide in the cytoplasm of the cell. The mRNA binds to a ribosome and has 3 base pairs exposed called a codon. The anticodon of a tRNA molecule can then bind to the codon as it has complementary base pairs, and it carries with it an amino acid. The first amino acid in the chain is always methionine. When a second tRNA, carrying a different amino acid arrives and binds, a peptide bond forms between the two amino acids and the resulting product is a dipeptide molecule – two amino acids joined together. This process continues and as more amino acids are joined together by peptide

The R group is a different molecule in different amino acids which can make them neutral, acidic, alkaline, aromatic (has a ring structure) or sulphur-containing. When 2 amino acids are joined together (condensation) the amino group from one and the acid group from another form a bond, producing one molecule of water. The bond formed is called a peptide bond. Primary structure of proteins -----------------------------

In contrast, there is glucose that is considered a “simple sugar or a monosaccharide” due to its structure (Georgia State University). Most foods made of glucose molecules are used as sources of energy for animals as ATP (Georgia State University). Both these sugars are in our diets, yet they are quiet different in chemical structure and physical form. This is why a substance that contains starch, does not always contains glucose (Shorter KR). To test for these two carbohydrates, two different tests were developed: Lugol’s and Benedict’s. Lugol’s indicates whether or not a substance contains starch, and if so, how much (Shorter KR). This is determined based on a color scale (5 different shades), from amber to a bluish black (Shorter KR). The farther down the scale, the more starch the substance contains. Likewise, the Benedict’s solution indicates the amount of starch as the 8-color shades (light blue to dark green) progress (Shorter KR).

 Iodine test is used to detect the presence of starch in a solution. When starch presents, iodine changes its colour from yellow to dark purple. Benedict’s test is used to detect the presence of reducing sugar in a solution. When reducing sugar presents, a brick-red precipitate appears in the solution. Benedict reagent contains copper (II) ions, which is blue in colour can be reduced to copper (I) ions, which is insoluble brick-red precipitate when reducing sugar is present. Carbohydrate B is more complex than carbohydrate A, because salivary amylase or hydrochloric acid is needed at 37˚C and 95˚C respectively to be hydrolyzed into monomers before it gives positive result for Benedict’s test. In conclusion, solution A contains simple sugar and solution B contains starch.

Amino acids are linked together via peptide bonds to form polypeptide chains, which undergo various levels of folding and interaction with other polypeptides to create a functional protein. The N terminus of one amino acid, which is acts as a base, links to the C terminus of another amino acid which is acidic. Proteins vary in complexity and properties, all owing to the collective natures and behaviors of their amino acid constituents.

A peptide bond is formed between the carboxyl acid group (COOH) of one amino acid and the amino group (NH2) of another amino acid by condensation reaction. During the condensation reaction, the oxygen and hydrogen atoms (OH) from the carboxyl group of the first amino acid and the hydrogen atom (H) from the amino group of the second amino acid are lost. This means

The purpose of this lab was to test for macromolecules consisting of starch (carbohydrates), lipids, proteins, and nucleic acids. Testing for the macromolecules occurred by using specific reagents on each macromolecule. If a color change occurred, then the sample would prove to be positive for that macromolecule. For simple sugars, the Benedicts solutions was used as the reagent; for starches, the iodine solution was used as the reagent; for lipids the Sudan III solution was used as the reagent; and for the proteins, the Biurets solution was used as the reagent.

Test ORANGE TEST: Test for acidity: Take 5ml of orange juice in a test tube and dip a pH paper The pH Orange juice in it. If pH is less than 7 the comes out to is acidic. juice is acidic else the juice is be 6. basic. Test for Startch: Take 2 ml of juice in a test tube and add few drops of iodine solution. It turns blue black in colour than the starch is present. Test for Carbohydrates (FEHLING 'S TEST): Take 2 ml of juice and 1 ml No red of fehling solution A & B and coloured Carbohydrates absent. Absence of Orange juice blue black in is acidic. colour. Observation Inference