Chapter 2 Microbio

You are administering a 5% dextrose in water solution to your patient to replace lost fluids and provide carbohydrates to the body. How much dextrose was added to 1 liter of water?

50 g/L 5% dextrose is written as a weight/volume ratio. A 1% solution contains 1g of solute per 100mL of solvent. A 5% dextrose solution would contain 5g per 100mL or 50g per 1000mL (50g/L)

Which of the following definitions is correctly matched?

Activation energy- the minimum amount of energy needed to get a reaction started. All reactions require a certain activation energy under physiological conditions and special proteins called ennzymes can decrease that activation energy. Endergonic reactions result in products that contain more energy than the reactants, e.g., the assembly of proteins from amino acids. Equilibrium is a dynamic process in which the total amount of products and reactants no longer changes Exergonic reactions result in products that contain less energy than the reactants, e.g., the breakdown of glucose to release energy for cellular activities.

Which of the following molecules would not change the pH of an unbuffered solution?

NaCl Acids contribute hydrogen ions (H+) to an aqueous solution while bases release hydroxide ions (OH-) in an aqueous solution. The molecule NaCl (sodium chloride) does not contain a hydrogen nor hydroxide ion and therefore would not change the pH of an unbuffered solution. HCl *hydrochloric acid) will dissociate and contribute a hydrogen ion (OH-) to the solution, increasing the pH and making it more alkaline. H2SO4 (hydrogen surface) will dissociate and contribute hydrogen ions (H+) to the solution, decreasing the pH and making it more acidic.

Which of the following is a correct statement about polar substances?

Polar, or hydrophilic, substances readily dissolve in water. Water is a polar substance, and the force of attraction between the polar molecule is greater than the force of attraction between polar and non polar molecules. Like dissolves like, therefore polar solutes dissolve in polar solvents, while non polar solutes are dissolved in non polar solvents. Amphiphathic molecules form micelles when exposed to an aqueous environment. Amphipathic molecules are both hydrophobic and hydrophilic. Micelles form when the hydrophobic portion of the molecule orients away from the aqueous environment, while the hydrophilic portion faces the aqueous environment. The plasma membrane is a bilayer composed of the amphipathic molecules called phospholipids. These molecules assemble in such a way that the hydrophobic portion faces the middle of the bilayer, while the hydrophilic layer makes up the outside of the bilayer. Fats and vitamins like A and D are considered non polar molecules. They are not soluble in water; they are fat soluble and can be easily stored, e.g., in the human body

The building blocks of nucleic acids are

deoxyribonucleotides or ribonucleotides deoxyribonucleotides are the building blocks of DNA. DNA serves as the "blue print" or genetic material of cells and viruses. Amino acids are the building blocks of proteins. Proteins have a variety of functions in biological systems; they serve as building blocks, facilitate chemical reactions, and are used for cell communication and recognition. Simple sugars, such as glucose, are the building blocks of carbohydrates, which are the chief energy source in biological systems. Waxes (one molecule composed of a long-chain alcohol and fatty acid) are the building blocks of lipids, such as mycelia acids found in the cell wall of acid fast organisms.

The organism Mycobacterium tuberculosis makes mycelia acid, which is deposited in the bacterial cell wall and acts as a protective barrier for the cell and increase. bacterial pathogenicity. Mycolic acid would be an example of a(n)

wax The organism Mycobacterium tuberculosis make mycelia acid, which is deposited in the bacterial cell wall. Simple sugars are the building blocks of carbohydrates. Along with proteins, they are found in the bacterial cell wall component peptidoglycan. Steroid molecules are composed of four fused hydrocarbon ring structures. Steroids can be found in eukaryotic cell membranes.

Which of the following is a molecule?

C6H12O6 A molecule is formed when two or more atoms bond together Ca+2 is an ion of calcium. The ion calcium lost 2 electrons, rendering the charge +2 123i is an isotope of iodine 3He2+ is both an isotope and ion of helium.

Which of the following is an organic molecule?

CH4 CH4 is the simplest organic molecule. Organic molecules contain carbon and hydrogen. Inorganic molecules may contain carbon, but will lack the associated hydrogen. H2O (water), NaCl (sodium chloride or table salt), and CO2 (carbon dioxide) are all inorganic molecules.

Which of the following would not be a building block of a nucleotide?

Glucose molecule A glucose molecule contains six carbons (C6H12O6); nucleic acids contain five carbon sugars. Each nucleotide has three common components: (1) a five-carbon sugar (deoxyribose in DNA or ribose in RNA), (2), one to three phosphate groups, and (3) one nitrogenous base: adenine, guanine, cytosine, thymine (present in DNA), or uracil (present only in RNA).

Which of the following statements about hydrogen bonds is incorrect?

Hydrogen bonds are a covalent electrostatic attraction between two or more molecules Hydrogen bonds are not technically "bonds", but are formed by noncovalent electrostatic attractions between two or more molecules. Technically, they are not bonds; they are truly electrostatic interactions between dipoles. Hydrogen bonds can exist between two or more individual molecule. Water contains an abundance of hydrogen bonds.

Chlorine (Cl-) is most likely to form a(n) ______________ bond with ____________

Ionic; Na+ An ionic bond is the electrostatic force of attraction that exists between oppositely charged ions, (cations bearing a positive charge and anions bearing a negative charge). Therefore, chloride (Cl-) ions would most likely form an ionic bond with Na+ ions. The hydroxide ion OH- and the chloride ion Cl- have the same negative charge and would repel. Hydrogen "bonds" are formed by non covalent attractions between two or more molecules. Even though both Cl- and H+ have opposite charges, hydrogen bonds would not form due to the absence of dipoles. Hydrogen and chlorine would share their electrons equally, resulting in a covalent. bond. A chloride (Cl-) ion would form an ionic bond with sodium (Na+) ions. Elements joined by covalent bonds do not lose electrons (as indicated by the charge of each ion); they equally share electrons.

The picture shows the amino acid tryptophan. The highlighted group in green is also known as the

R group The group highlighted in green is also known as the R-group. These groups vary between the different amino acids and confer varying characteristics (acidic, basic, size, etc.) to each amino acid and, consequently, proteins. An amine group (NH2) is one of the three basic components of an amino acids: amine group, a carboxyl group, and an R-group that varies between different amino acids. A carboxyl group is formed in a variety of organic acids, such as amino acids withe the formula is R-COOH. Adenine is a nitrogenous base found as part of a nucleotide. Other nitrogenous bases are thymine, guanine, cytosine, and uracil.

Which of the following functional groups is matched with its correct name?

R-OH: hydroxyl group Functional groups are molecules with shared chemical properties. They often participate in chemical reactions, and the presence of certain ones of these groups can be used to predict chemical properties of a molecule. When describing a generic functional group, you will see the group attached to an "R", which is the "rest of the molecule." R-OH denotes an alcohol or hydroxyl group. R-COOH is the formula for a carboxyl functional group. This functional group is found in a variety of organic acids, such as amino acids and fatty acids. R-CH3 is the formula for a methyl functional group. This functional group is common in many organic molecules, especially in hydrocarbon chains. R-NH2 is the formula for an amine group. This functional group is found in many organic molecules, including amino acids and the nitrogen bases of nucleotides.

You are interested in the alpha helices present in a novel protein. In order to study them, you must consider the __________ structure of a protein more closely

Secondary Alpha-helices and beta-pleated sheets are secondary protein structures. There are four levels of protein stricture: primary, secondary, tertiary, and quaternary. The primary structure represents amino acids linked together by peptide bonds; the secondary structure represents the alpha-helices and beta-pleated sheets; there tertiary structure represents the three-dimensional, globular structure; and the quaternary structure represents the interaction between two or more polypeptide chains.