Chemical Composition of Cells .pdf

Chemical Composition of Cells BIOLOGY LAB COLLEGE OF HEALTH SCIENCES  Cells Organic Water Inorganic Ions...

Chemical Composition of Cells BIOLOGY LAB COLLEGE OF HEALTH SCIENCES  Cells Organic Water Inorganic Ions Molecules Most abundant (70%) Less than 1% of cell mass They are macromolecules inside Involved in different cell function and every living organism which are Universal solvent Metabolism essential for biological processes Play an important role in Cations: 𝑁𝑎 + , 𝐾 + , 𝐶𝑎 +2 , 𝑀𝑔+2 that sustain life like cell chemical reactions Anions: 𝐶𝑙 − , 𝐻𝐶𝑂3−, 𝐻𝑃𝑂4−2 development, growth,,etc. Proteins Carbohydrates Lipids Nucleic Acids  Dehydration and Hydrolysis Dehydration: it’s the reaction were two monomers (small molecules) are joined together to form polymer (larger molecules), releasing a water molecule. It links two monomers by removing a water from two adjacent hydroxyl groups (-OH) Hydrolysis: is the opposite of dehydration, where Polymers are broken down into monomers, in which a bond is broken, or lysed, by addition of a water molecule. Proteins Proteins are polymers of amino acids joined together by peptide bonds. Proteins are polymers of 20 different amino acids. Each amino acid consists of a carbon atom bonded to a carboxyl group (COO-), an amino group (NH3+), a hydrogen atom, and a distinctive side chain. The specific chemical properties of the different amino acid side chains determine the roles of each amino acid in protein structure and function. Amino Acids Amino Acid Dipeptide Proteins They can be divided into 4 classes according to their function: Functional Transport Proteins Proteins Regulatory Structural Proteins Proteins  Functional Proteins Transport Proteins Antibodies are functional protein that combine with disease Hemoglobin, in the red blood cells, transport oxygen causing pathogens as part of body’s immune response. throughout the body. Enzymes, such as amylase, lipase, and pepsin, are also Albumin is another transport protein in the blood that functional proteins that speed up the biological reactions. transport fatty acids.  Regulatory Proteins Structural Proteins Control cellular metabolism like insulin Include keratin, which is found in hair and regulates the amount of glucose in the blood. nails, and myosin, which is found in muscle. Tests to detect proteins – Biuret reagent -Biuret reagent: it is a blue solution made of Copper Sulfate (CuSO4) and Sodium Hydroxide (NaOH) -It is used to test for the presence of protein in the sample. The reagent changes color to purple in the presence of proteins. Tests to detect proteins – Biuret reagent Procedure: Bring 5 Test tubes and label them as follow: Tube1: Water Tube 2: Protein (albumin) 1 2 3 4 5 Tube 3: Unkown1 Tube 4: Unknown 2 Tube 5: Unknown 3 Then add: Protein Water UN 2 1 mL of water to tube 1 UN 3 UN 1 1 mL of Protein Solution (Albumin) to tube 2 1 mL of Unknown 1 to tube 3, Unknown 2 to tube 4, Unknown 3 to tube 5 Tests to detect proteins – Biuret reagent Procedure: Then 5 drops of Biuret reagent to each tube 1 2 3 4 5 Protein Water UN 2 UN 3 UN 1 Tests to detect proteins – Biuret reagent Results Interpretation If Blue color changed into Purple  Presence of Protein   Glucose Carbohydrates The carbohydrates include simple sugars as well as polysaccharides. These simple sugars, such as glucose, are the major nutrients of cells. They are polymers of one sugar unit called monosaccharide. Example of monosaccharides: Glucose, Fructose and Galactose When two monosaccharides join by dehydration, they form Disaccharide, linked together by glycosidic bond. Disaccharides : Maltose: Glucose + Glucose Lactose: Galactose + Glucose Sucrose: Fructose + Glucose  Carbohydrates When chain of glucose units join together, they form  Polysaccharide Polysaccharide examples: Starch, Glycogen, Cellulose. Animals store glucose as glycogen and plants store glucose as starch. The plant cell walls are made of cellulose. Carbohydrates Carbohydrates Tests to detect Starch or Glycogen – Iodine Solution Iodine Solution: it is used to test for starch, it is brown in color. When adding iodine solution to a solution containing starch the color shifts from brown to a deep purple to black. Iodine Test – Procedure: Bring 5 Test tubes and label them as follow: Tube1: Water Tube 2: Starch Tube 3: Unkown1 1 2 3 4 5 Tube 4: Unknown 2 Tube 5: Unknown 3 Then add: 1 mL of water to tube 1 Water Starch 1 mL of Starch solution to tube 2 UN 2 UN 3 UN 1 1 mL of Unknown 1 to tube 3, Unknown 2 to tube 4, Unknown 3 to tube 5 Iodine Test – Procedure: Procedure: Then 2 drops of iodine reagent to each tube 1 2 3 4 5 Water Starch UN 2 UN 3 UN 1 Iodine Test – Results Interpretation: Observe the change on color, if the color changed into deep purple or black, it is positive for Starch  Tests to detect Glucose – Benedict Test Benedict reagent: Benedict reagent, blue in color, is a chemical mixture of sodium carbonate (Na2CO3), sodium citrate and copper(II) sulfate (CuSO4). It is used to test for the presence of glucose in a solution. When Benedict reagent is added to a solution containing glucose, the color change can range from green to orange red after heating the tube in boiling water. The color change depends on the concentration of glucose present in the solution  Benedict Test - procedure Bring 5 Test tubes and label them as follow: Tube1: Water Tube 2: Glucose Tube 3: Unkown1 1 2 3 4 5 Tube 4: Unknown 2 Tube 5: Unknown 3 Then add: 1 mL of water to tube 1 Glucose Water UN 2 UN 3 UN 1 1 mL of Glucose solution to tube 2 1 mL of Unknown 1 to tube 3, Unknown 2 to tube 4, Unknown 3 to tube 5  Benedict– Procedure: Then 5 drops of Benedict reagent to each tube Heat all the 5 tubes in a boiling water bath of 5 to 10 minutes 1 2 3 4 5 Glucose Water UN 2 UN 1 UN 3 Benedict Test - Results Interpretation Chemical Benedict reagent color after heating Water Blue (no Change) Glucose Varies with concentration: Very low Green Low yellow Moderate yellow orange High orange Very high orange red Starch Blue (no change) Benedict Test - Results Interpretation Any Questions?