Key questions: Biochemistry through proteins ALL ARE DONE
1. Why are biomolecules built from carbon skeletons? DONE
Biomolecules are built from carbon skeletons for two main reasons. One is because Carbon makes four covalent bonds. Carbon needs four valence electrons for it to become stable, or like a nobel gas, so it has four opportunities to make covalent bonds. By having four opputunities for covalent bonds, carbon is very useful and easy to create molecules with. Because it makes four covalent bonds, Carbon is often a connecting point in complex molecules that can branch out in four ways. Carbon is also very abundant in the atmosphere.
2. DONE AS HOMEWORK
3. What are the basic characteristics of
carbohydrates: DONE
Carbohydrates are a category of biomolecules that consist of monosaccharides, disaccharides, and polysaccharides. A carbohydrate can store 4 Calories (food calories, which = kilocalorie which = 1000 calories) per gram of carbohydrate. So the energy in one carbohydrate is enough to heat one gram of water 4000 degrees Celsius. Monosaccharides are a category of carbohydrates that are often described as “simple sugars”, and they all contain amounts of C, H, and O in a 1:2:1 ratio. An example of a monosaccharide is glucose. Disaccharides are formed by joining together two monosaccharides through a process called dehydration synthesis. As two monosaccharides join together, a molecule of water is formed. Dehydration synthesis is sometimes called a “condensation reaction”. The reverse process of this is called hydrolysis or a “decomposition reaction”. It requires one molecule of water to break apart two monosaccharides that are bonded together as a dissacharide. Polysaccharides are hundreds of monosaccharide molecules joined together. Three basic groups of polysaccharides are starch, glycogen, and cellulose. Starch is used to store energy in plants, glycogen is used to store energy in animals, and cellulose is used in plants to build up their cell walls (it is not digestible and is a major component of wood).
lipids: DONE, BUT NOTE THE TWO SENTENCES I ADDED THAT ARE IN ITALICS. THEY TAKE YOUR ANSWER CLOSER TOWARD "CLASSROOM DETAIL" AND HELP EXPLAIN WHY LIPIDS ARE INSOLUBLE AND WHY OILS ARE LIQUID AT ROOM TEMPERATURE.
Lipids, such as fats, oils, and steroids, are water insoluble because they are hydrophobic, meaning they "fear" water. Lipids consist mainly of Carbon and Hydrogen atoms linked together by non-polar covalent bonds, which explains why they do not attract water and are therefore insoluble. For lipids, their energy storage is 9 kcal/g, meaning they can cram more energy into smaller spaces as opposed to carbohydrates and proteins. There are three types of lipids: fats, phospholipids, and steroids. Fats also called triglycerides are made from glycerol and three fatty acids. Not only is fat used for energy storage, but it also provides insulation and cushions the body’s organs. Since hard fats are solid at room temperature, such as steak fat, that means they are saturated or contain no double bonds. Olive oil, on the other hand, would be a liquid fat because it contains double bonds that form kinks, therefore, making it unsaturated. The kinks gives the molecules an overall circular shape, preventing them from being able to line up with each other, keeping them liquid at room temperature. The second type of lipid is the phospholipids. Phospholipids contain a hydrophilic head, which replaces one fatty acid of a triglyceride. This replacement makes one end, the head, hydrophilic and the other part hydrophobic through the process of dehydration synthesis. Phospholipids are important components of cell membranes. The last lipid are steroids. Steroids are recognizable because they have four, fused carbon rings in their carbon skeleton.
proteins: DONE
Proteins have an energy storage of 4 Kcal/ g, but are not used for energy storage. They are used for structural roles, such as the building of hair, bone, and muscle, and they also play important metabolic roles. The proteins that generally help with metabolism, which is the sum of all the chemical processes occurring in the body, are enzymes, which control the rate at which these chemical reactions occur. Proteins are polymers of amino acids, meaning that proteins are made up of many different amino acids bonded together by dehydration synthesis and peptide bonds. An amino acid is made with a central carbon atom bonded to an amino group, a carboxyl group, and one of 20 R groups. When two amino acids are bonded together through dehydration synthesis (which is where a water molecule is formed from the H on the amino group, and the hydroxyl from the carboxyl group, and then the water is removed. Then carbon and nitrogen covalently bond together and from a peptide bond.) When THREE or more amino acids are strung together, they are called polypeptides. The shape of a protein determines the function, and the shape is determined by four main aspects of the protein. Some R groups in an amino acid can become ionzied, meaning they have either a positive or negative charge, which means they could be attracted to other ionized R groups, changing the shape of the protein. Also, hydrogen bonds can occur within a protein if two or more atoms are both polar, they will form hydrogen bonds. Also, the R groups can be so large that they alter the shape. The fourth aspect is the formation of cysteine bridges, which is the covalent bonds between sulfur atoms in the r-group called cysteine. These bonds are extremely strong and will not break even with a change in temperature, like hydrogen bonds will.
4. What role does dehydration synthesis and hydrolysis play in the synthesis and breakdown of large biomolecules? DONE
Dehydration Synthesis mainly plays a role in synthesis between large biomolecules through a Dehydration Reaction. Dehydration Reaction links separate monomers to form larger polymers by removing a water molecule, H2O, from those monomers. A hydroxyl group is removed from one monomer and hydrogen is given up from the other monomer, therefore causing a covalent bond between the two monomers. For example, when two carbohydrate monomers, called glucose, want to bond, dehydration reaction removes hydrogen from one monosaccharide and a hydroxyl group from the other monosaccharide in order for them to bond and form a polysaccharide. For example, a dehydration reaction occurs when amino acids join via peptide bonds to form proteins. The OH molecule on a carboxyl group connects to an H on an amino group, which created an H2O molecule. This results in a peptide bond and the reaction loses a water molecule. Hydrolysis mainly plays a role in the breakdown of large biomolecules. Hydrolysis is exactly the opposite of dehydration reaction. Instead of linking two monomers by removing a water molecule, during hydrolysis enzymes help break bonds in polymers by adding a water molecule. When a water molecule is added, a hydroxyl group attaches to one monomer and the remaining hydrogen attaches to the other monomer. For example, if a protein wanted to break its peptide bond and form separate amino acids, hydrolysis would add a hydroxyl group to one amino acid in the protein and hydrogen to the other amino acid in order to remove their bond.
5. What factors determine the shape of proteins? DONE, BUT I ADDED SOME DETAIL (BELOW IN CAPS) NAMING WHICH AMINO ACIDS ARE + AND WHICH ARE -
The shape of proteins, which are made from polymers of amino acids, depends on several factors. First, R Groups are the key factor that differentiates the twenty amino acids from one another. R Groups, consist of one or more carbons with different chemical groups attached. The charges on R Groups determine whether amino acids will attract or repel. Since R Groups have charges (positive, negative, partially positive or negative, or even no charge) they will either be hydrophilic or hydrophobic. These charges then become attracted to one another, if they lie next to each other, causing the R Groups to bend towards each other, or they repel each other causing the R Groups to bend away from each other on a chain called a polypeptide. For example, a positively charged R Group will attract a negatively charged R Group if side by side, therefore, causing a bend in the protein. These attractions and repulsions taking place between R Group is ionic bonding. Ionic bonding occurs when a negatively charged anion is attracted to a positively charged cation. In this case, for ionic bonding to occur, charges must be present on the R Groups. SOME R GROUPS CARRY CARBOXYL GROUPS THAT CAN HAVE A NEGATIVE CHARGE WHEN IONIZED; SOME CARRY AMINO GROUPS THAT CAN BECOME POSITIVE CHARGED WHEN IONIZED. WHETHER OR NOT THEY CARRY A CHARGE DEPENDS ON pH. Since ionic bonding is occurring, the polypeptide chain begins to form into a coiled, twisted shape that creates a protein. Secondly, the size of R Groups is also important because that is what alters the shapes of proteins. For example, if there are bulky R Groups they will bump into each other more easily, allowing the bumps to create bends in the protein. Thirdly, hydrogen bonds form when neighboring molecules contain polar covalent bonds. These hydrogen bonds that are formed are very weak, but help create the protein’s shape. For example, if the temperature increases, hydrogen bonds will break and if there is a temperature decrease, more bonds will form between monomers where they are not supposed to, therefore altering the shape and function. Also, the hydrogen bonds help maintain the tertiary structure of a protein by being evenly spaced between hydrogen’s of the amino groups and the oxygen’s of the carboxyl group, which creates coiling (alpha helices) and folding (pleated sheets) on the polypeptide chain. Lastly, the formation of cysteine bridges occur between Sulfur atoms, which are covalent bonds, in the R Group "cysteine". These are just as powerful as any other bond within the protein, and they help stabilize the protein since hydrogen bonds are weak and are affected by temperature change or pH change.
Practice: For each set of terms, write a sentence or two to show a relationship between them.
Example: shoestring, broken leg, hospital
correct: I was in the hospital because I broke my leg after tripping over my shoestring.
incorrect: I ate a shoestring because my broken leg was in the hospital.
1. electron; energy level; ion DONE
— Electrons are the negatively charged part in an atom that orbit around the nucleus. The farther the electron is from the nucleus, the higher energy level it has. If an element has 6 outer shell electrons, it will need two more to become stable. Thus, an ion forms from an atom or molecule gaining or losing one of these electrons TO FILL ITS OUTER energy levels.
(NOTE: YOU HAD "THROUGH SWITCHING" WHERE I WROTE "TO FILL ITS OUTER". NOT SURE WHAT YOU MEANT BY THROUGH SWITCHING. UNDERSTAND OK? COME SEE ME IF YOU DON'T.
2. covalent bond; electron pair; energy level DONE
—A covalent bond is a bond between two nonmetals that share an electron pair. The reason the nonmetals covalently bond is so that they can obtain eight electrons in the outer energy level, making the atoms stable like the noble gases.
3. electronegativity; positive; hydrogen DONE
— Hydrogen bonds form between two molecules that contain polar covalent bonds, implying that the electronegativity is >.4 and <2.0, when the partial positive charge on H atoms become attracted to the partial negative charges on O's and N's in the nearby molecules.
4. polar covalent bond; water; glucose DONE, I ADDED "HYDROGEN" AND "OXYGEN" TO PROVIDE THE NECESSARY DETAIL TO EXPLAIN THE HYDROGEN BONDING THAT'S TAKING PLACE
polar solutes such as glucose (C6H12O6) will dissolve in polar solvents such as water (H2O) because the partially positively charged HYDROGEN atom of the solute molecule is attracted to the partially negatively charged OXYGEN atom of the solvent molecule, and the partially negatively charged OXYGEN atom of the solute molecule is attracted to the partially positively charged HYDROGEN atom of the solvent molecule. The partial positive and negative charges were created by polar-covalent bonds, or unequal sharing of electrons.
5. dehydration synthesis, monomer, polymer DONE
—Monomers string together to form polymers using dehydration synthesis. Dehydration syntheses is when one monomer gives up a hydroxyl group (OH) and the other gives up a hydrogen atom (H) and they form a water molecule. When more than two monomers are joined, a polymer is formed. An example of this is when glucose molecules (monomers) bond together to form starch, glycogen, or cellulose (polymers).
6. hydrolysis, disaccharide, monosaccharide DONE
—Disaccharides are carbohydrates formed from two monosaccharides. When this disaccharide undergoes hydrolysis, the reaction requires one molecule of water. This water molecule added splits up the disaccharide into two separate molecules, otherwise known as monosaccharides. Monosaccharides are the simplest forms of carbohydrates.
7. shape of a protein, positive, negative DONE
—The shapes of proteins are determined IN PART by the positive and negative charges of the “R” groups which differ from protein to protein. If a positively charged R group and a negatively R charged group are next to each other in a polypeptide chain, FOR EXAMPLE, the forces will attract each other and form a kink in the chain.
