Microbiology: Chapter 2 The Molecules of Life
Match the component of an atom with the description. Page 20 Select the right answer. A) Electron B) Proton C) Neutron 1. Positively Charged Particle 2. Negatively Charged Particle 3. Uncharged Particle
A) Electron: Negatively Charged Particle B) Proton: Positively Charged Particle C) Neutron: Uncharged Particle
Which of the following are found in DNA molecules? Page 38-40 Select all that apply. A) Thymine B) Guanine C) Uracil D) Adenine E) Cytosine F) Ribose G) Deoxyribose
A) Thymine B) Guanine D) Adenine E) Cytosine G) Deoxyribose
There are _____________________ different common amino acids from which proteins are constucted. Page 33
20
An oxygen atom has eight electrons, so the number of electrons in the first shell is ____________________ and the number in the outer shell is ___________________. Page 21
2;6
Carbon atoms form the basis for many diverse structures because each atom has _____________________ valence electrons. Page 23
4 Carbon (C) is a particularly important element in biological systems because its bonding properties provide the basis for many diverse structures. A carbon atom has four electrons in its outer shell, so it needs four more to fill it.
Which of the following pairs conform to the base-pairing rules? Page 38-40 Select all that apply. A) A-T B) T-C C) G-C D) A-G
A) A-T C) G-C The two strands of DNA are also complementary and are held together by hydrogen bonds between the nucleobases. The term "complementary" refers to the fact that wherever an A is in one strand, a T is in the other; these opposing A-T bases are held together by two hydrogen bonds. Similarly, wherever Page 40a G is in one strand, a C is in the other. The G-C bases are held together by three hydrogen bonds, a slightly stronger attraction than that of an A-T pair. The double-stranded DNA molecule is generally quite stable because of the numerous hydrogen bonds that occur along its length. Over short segments of DNA, however, it is relatively easy to separate the two strands.The characteristic bonding of A to T and G to C is called base-pairing and is a fundamental characteristic of DNA. Because of the rules of base-pairing, one DNA strand can be used as a template to make the complementary strand.
Triglycerides are composed of Select all that apply. A) Fatty Acids B) Glycerol C) Cholesterol D) Glucose Page 30-32
A) Fatty Acids B) Glycerol
Which of the following are molecules but NOT compounds? Page 22-23 Select all that apply. A) N2 B) O2 C) H2 D) CH4 E) NH3 F) H2O
A) N2 B) O2 C) H2
Match the amino acid with its important characteristic. Page 33 & 36 Match these items correctly. A) Tryptophan B) Cysteine --------------------------- 1. Bulky because of its double-ring structure. 2. Has a sulfur atom that can form a covalent bond with the sulfur atom of another of the same type of amino acid.
A) Tryptophan: Bulky because of its double-ring structure. B) Cysteine: Has a sulfur atom that can form a covalent bond with the sulfur atom of another of the same type of amino acid.
YOUR DOING GREAT!!
ALMOST DONE.
Cell walls of plants, fungi and bacteria are made primarily of ___________________. Page 28 Select the right answer. A) Lipids B) Carbohydrates C) Proteins D) Nucleic Acids
B) Carbohydrates
Which of the following is NOT always composed of repeating subunits? A) Polysaccharides B) Lipids C) Proteins D) Nucleic Acids Page 30
B) Lipids Explanation of why: Unlike other macromolecule, not all lipids are composed of similar subunits.
If a chemical is described as organic, it contains ________________ and _______________________ atoms. Page 23
Carbon; Hydrogen Molecules that contain at least carbon and hydrogen are organic compounds; those that do not are inorganic compounds.
A protein substructure associated with a particular function is called a protein _________________________. Page 37
Domain For example, a certain domain may bind DNA; another may act as a catalyst. Once a known function can be attributed to a specific domain, the role of an unknown protein with that domain cna be inferred.
A protein that has sugar molecules bound to it is called a(n) ______________________, and a protein that has lipid molecules bound it is called a(n) _________________________. Page 33
Glycoprotein; Lipoprotein Glyco: Relating to producing sugar. Lipo: Relating to fat and other lipids.
A protein's ________________ structure refers to the specific sequence of amino acids that makes up the polypeptide chain. Page 35
Primary The sequence and number of amino acids in the polypeptide determine its primary structure, which affects all other levels of protein structure.
The ____________________ scale, measured on a logarithmic scale from 0 to 14, is used to indicate the relative acidity of a solution. Page 25-26
pH An important property of aqueous solutions (solutions in which water is the solvent) is their pH, a measure of their acidity. It is measured on a logarithmic scale from 0 to 14 in which lower numbers represent more acidic solutions (figure 2.10)
Most macromolecules are polymers, which are created by forming chemical bonds between subunits called _________________________. Page 27
Monomers Organic molecules are often macromolecules (macro means "large"). Most macromolecules are polymers (poly means "many") formed by joining subunits or monomers (mono means "single"). Different classes of macromolecules are made up of different subunits. The four major classes of organic molecules are carbohydrates, lipids, proteins, and nucleic acids
On organic molecules such as amino acids, the presence of a _______________ ______________ (or R group) is designed by the presence of -R. Page 33 Look at the image on page 33
Side Chain - "R" is the general designation for a chain.
The study of matter is called __________________________. Page 19-20 A) Physics B) Microbiology C) Material Science D) Chemistry
D) Chemistry Matter: Or the "stuff" of which the universe is composed.
_______________________________ are the general class of macromolecules that are very soluble in polar substances like water. Page 30-32
Lipids
Simple sugars, or ______________________, are the basic unit of a carbohydrate, typically having five or six carbon atoms and forming a ring. Page 28
Monosaccharides Monosaccharides, or simple sugars, are the basic unit of a carbohydrate (sacchar means "sugar"). Most common monosaccharides have five or six carbon atoms, typically forming a ring (table 2.6). Each carbon atom of a monosaccharide is numbered using a characteristic scheme, allowing scientists to describe the positions of various functional groups attached to the molecules (figure 2.12).
A change in protein structure that disrupts the function of the protein is called ________________________. Page 37
Denature or Denaturation: Can affect the interactions between amino acids within a protein, causing it to denature or lose its characteristic shape. Factors: High Temperature, Extreme pH, and certain solvents. Can be reversible, but sometimes it is not. Most organisms cannot grow at very high temperatures because their enzymes denature and no longer catalyze chemical reactions. Each enzyme functions best within a specific narrow range of environmental conditions.
A disaccharide is composed of two _________________ joined together by a covalent bond. Page 28-29
Monosaccharides Carbohydrate molecule consisting of two monosaccharide molecules. Disaccharides are composed of two monosaccharides joined together by covalent bonds (see table 2.6). Two common examples are sucrose (table sugar) and lactose (milk sugar). Sucrose, which comes from sugar cane and sugar beets, is composed of the monosaccharides glucose and fructose, whereas lactose consists of glucose and galactose. Another disaccharide, maltose, composed of two glucose molecules, is a breakdown product of starch. To form a disaccharide, two monosaccharides are joined together by a dehydration synthesis reaction between a pair of their hydroxyl groups, with the loss of the equivalent of a water molecule (figure 2.14). The reaction is reversible, so hydrolysis, which adds a water molecule, produces the two original monosaccharides.
The subunits that serve as the building blocks of the nucleic acids DNA and RNA are called _________________________, and these are composed of the pentose sugar, a phosphate group, and a nitrogenous base. Page 37-38
Nucleotides Nucleotides are the subunits of nucleic acids. Each nucleotide consists of a pentose sugar, a phosphate group, and a nucleobase (also called a base or a nitrogenous base). The phosphate Page 38group is attached to the number 5 carbon of the sugar, and the nucleobase is attached to the number 1 carbon (figure 2.25). There are five nucleobases: two are purines, which have a double-ring structure, and three are pyrimidines, which have a single-ring structure (figure 2.26). The purines are adenine (A) and guanine (G); and the pyrimidines are cytosine (C), thymine (T), and uracil (U).
With the exception of hydrogen, most biologically significant atoms are most stable when their outer shell holds _________________ electrons. Page
8 The number of electrons that each shell can hold is limited. Electrons are attracted to the protons in the nucleus, so shells closer to the nucleus are generally filled before electrons occupy other shells. The shell closest to the nucleus holds no more than 2 electrons. These electrons are most highly attracted to the nucleus and have the lowest energy levels in that particular atom. Once that shell is filled, additional electrons occupy the next shell, which holds 8 electrons. Larger atoms have additional shells that hold even more electrons, but most atoms of biological significance follow the "octet rule," meaning they are most stable when their outer shell contains 8 electrons. An important exception is hydrogen, with a single shell; recall that the first shell has a limit of 2 electrons.
Which of the following statements about proteins folding are true Page 36 Select all that apply. A) Proteins must be specifically and carefully folded by specialized enzymes present in the cell. B) Most proteins fold spontaneously into the correct shape. C) Multiple functional folding options are generally possible for a given protein. D) Protein chaperones are sometimes needed to help the folding process.
B) Most proteins fold spontaneously into the correct shape. D) Protein chaperones are sometimes needed to help the folding process.
The bond highlighted in red is a(n) ____________________ bond. Page 35 Select the right answer. A) Ionic B) Peptide C) Hydrogen D) Glycosidic E) Phosphodiester Look at the image on Page 35
B) Peptide
Although the term are often used interchangeably, in the purest sense a _____________ is composed of one or more amino acids folded to form a functional unit, and a ______________ is composed of only a single amino acid chain. Page 32-35 Select the right answer. A) Protein; Dipeptide B) Protein; Polypeptide C) Polypeptide; Protein
B) Protein; Polypeptide Protein: One or more amino acids (one or more polypeptides) folded to form a functional group. Polypeptide: Composed of only a single amino acid chain. (A longer sequence of amino acids).
In terms of the placement of their hydrogen atoms attached to the double-bonded carbon atoms, most naturally occurring unsaturated fatty acids are ______________________________________. Page 31
Cis Most naturally occuring unsaturated fatty acids are cis, meaning the hydrogen atoms attached to the double-bonded carbon atoms are the same on the side of the bond.
Considering that polysaccharides often contain only glucose molecules, what accounts for their structural diversity? Page 30 Select all that apply. A) Some have alternating subunits of glucose and amino acids. B) Some are branched. C) The position of the carbon atoms involved in bonding can differ.
B) Some are branched. C) The position of the carbon atoms involved in bonding can differ. Polysaccharides are large complex carbohydrates composed of long chains of monosaccharide subunits or their derivatives (see table 2.6). Polysaccharides often contain only glucose molecules, but nevertheless are structurally diverse. Some molecules are branched. The position of the carbon atoms involved in the bonding can also differ (figure 2.15).
_____________________ covalent bond form between atoms that have the same or similar electronegativity. Page 23 Select the right answer. A) Amphipathic B) BiPolar C) NonPolar D) Ambivalent E) Polar F) Ionic
C) NonPolar A NonPolar Covalent Bond forms when elections shared equally, such as when identical atoms share electrons. The same can occur between atoms , if both have a similar attraction for electrons.
Which of the following terms describes a carbohydrate composed of long chains of monosaccharides bound to each other in one of various patterns? Page 29-30 A) Disaccharide B) Monosaccharides C) Polysaccharides
C) Polysaccharides Polysaccharides are large complex carbohydrates composed of long chains of monosaccharide subunits or their derivatives (see table 2.6). Polysaccharides often contain only glucose molecules, but nevertheless are structurally diverse. Some molecules are branched. The position of the carbon atoms involved in the bonding can also differ (figure 2.15).
The _________________ structure of a protein results from two or more polypeptides joining to create a large, multiunit protein. Page 36 Select the right answer. A) Secondary B) Primary C) Quaternary D) Tertiary
C) Quaternary
Phospholipids have a polar phosphate head that is ________________ ("water-loving") and the non-polar tails that are ______________________ ("water-fearing"). Page 32
Hydrophilic ("Water-loving"); Hydrophobic ("Water-fearing") ______________________________________ Hydrophilic = Polar Phosphate Head Hydrophobic = Non-Polar Tails
In a chemical reaction, the starting components are called ______________, which are changed to _________________ in the course of the reaction. Page 24
Reactants; Products Chemical reactions transfer electrons, a process that often involves making and breaking bonds. The starting components, or reactants, are changes to products in the course of the reaction. Depending on the nature of the reactants and products, chemical reactions can be described as synthesis reactions or decomposition reactions. Synthesis reactions combine multiple reactants to make a complex product; decomposition reactions separate a complex reactant into multiple products: Synthesis Reaction A + B ---------------------------> AB (reactants) (product) Decomposition Reaction AB -----------------------------> A + B (reactant) (products)
Peptides fold to form an overall three-dimensional shape largely based on interactions of R groups on amino acids. This shape is defined as ____________________ structure. Page 35
Tertiary
True or False: Lipoproteins and lipopolysaccharides are compound lipids. Page 32 Select the right answer.
True Other compound lipids will also be discussed in chapter 3. These include the lipoproteins (covalent associations of proteins and lipids) and lipopolysaccharides (molecules of lipid linked with polysaccharides through covalent bonds). a
___________________________ fatty acids have carbon chains with at least one double bond. Page 31
Unsaturated Explanation of why: Unsaturated fatty acids contain one or more double bonds between carbon atoms. _____________________________________________________________________________________________ Why not saturated fatty acids? **Saturated Fatty Acids: No double bonds**
When manufacturers hydrogenate oils, the product is solid at room temperature because ______________________ fatty acids are converted to _______________________ ones. Page 31-32
Unsaturated; Saturated **Explanation:** 1. Unsaturated: Tend to be liquid at room temperature. / Prevent tight packing w/ kinks in long tails Fats that contain one or more unsaturated fatty acids tend to be liquid at room temperature because these fatty acids have kinks in their long tails that prevent tight packing. 2. Saturated: Tend to be solids at room temperature. / Pack tightly togetherd due to straight, long tails Fats that contain only saturated fatty acids are typically room temperature because the straight, long tails of the fatty acids can pack tightly together.
A change in the nucleotide sequence of DNA can result in a change in the __________________________. Page 37-38 Select all that apply. A) Amino Acid sequence of a Protein. B) Folding of a Polypeptide. C) Monosaccharide sequence of a Polysaccharide.
A) Amino Acid sequence of a Protein. B) Folding of a Polypeptide. DNA, which stands for deoxyribonucleic acid, is the storage form of a cell's genetic information; the cell uses that information to make proteins. The sequence (order) of nucleotides in a cell's DNA codes for the primary structure of every protein that the cell produces. Because proteins can act as enzymes that catalyze the chemical reactions that occur in a cell, DNA determines all of the structural and functional properties of the cell. A change in the DNA sequence that results in changing even a single amino acid in a polypeptide can have a significant impact on the subsequent folding of the chain, much as changing a single letter can change the meaning of a word. For lunch, would you rather eat rice or lice?
Methane has the chemical formula CH4 and hydrogen gas has the chemical formula H2. Based on this information, you can say that methane is a _________________ whereas hydrogen is not. Page 22 Select the right answer. A) Compound B) Molecule C) Ion
A) Compound Compound- Atoms of an molecule that have different elements. Ex. NaCl (Salt such as NaCl are called ionic compounds).
The sharing of pairs of electrons between atoms creates a(n) ___________________ bond. Page 22 Select the right answer. A) Covalent B) Atomic C) Ionic D) Hydrogen
A) Covalent Atoms do not always fill their valence shells by gaining or losing electrons. They may instead share pairs of valence electrons, forming covalent bonds. For example, a hydrogen atom (H) has 1 electron and requires 1 additional electron to fill its valence shell. If two H atoms each share their single electrons, both atoms gain stability. The single covalent bond between the two atoms is indicated by a dash, as H—H. Some atoms share more than one pair of electrons with each other, forming a double or triple covalent bond, indicated by a corresponding number of lines between the atoms. For example, an oxygen atom needs 2 electrons to fill its outer shell. If two oxygen atoms share 2 electrons with each other, then a double covalent bond is formed, represented as O=O. Two or more atoms joined together by covalent bonds form a molecule. A molecule is represented by a molecular formula that indicates how many atoms of each type are present. For example, a hydrogen molecule is represented by the formula H2. If atoms that make up a molecule are different elements, the term compound may be used. (Salts such as NaCl are called ionic compounds.) As an example, water is a compound that contains two hydrogen atoms and one oxygen atom; it is represented by the formula H2O. The molecular mass of a molecule is based on the mass numbers of the component atoms. The molecular mass of most water molecules is 1 + 1 + 16, or 18.
A membrane is a continous bilayer formed by _________________________ that are oriented with the polar heads toward the outside and the nonpolar tails toward the inner part of the membrane. Page 32 Select the right answer. A) Triglycerides B) Phospholipids C) Fatty Acids D) Polysaccharides E) Sterols
B) Phospholipids
RNA differs from DNA in which two of the following ways? Page 40 Select all that apply. A) RNA has guanine instead of cytosine. B) RNA has the sugar ribose instead of deoxyribose. C) RNA has adenine instead of thymine. D) RNA has uracil instead of thymine. E) RNA has the sugar xylose instead of mannose.
B) RNA has the sugar ribose instead of deoxyribose. D) RNA has uracil instead of thymine.
Alpha-helices and beta-pleated sheets are secondary structures of proteins; they are held together by ________________ bonds between the carboxyl and amino groups of amino acids. Page 35 Select the right answer. A) Ionic B) Hydrogen C) Covalent D) Peptide
B) Hydrogen
Match the type of reaction. Page 27 Select the right answer. A) Dehydration Synthesis B) Hydrolysis 1. Breaks the covalent bond between two subunits and adds the equivalent of one molecule of water. 2. Joins one subunit and removes the equivalent of one molecule of water.
A) Dehydration Synthesis: Joins one subunit and removes the equivalent of one molecule of water. B) Hydrolysis: Breaks the covalent bond between two subunits and adds the equivalent of one molecule of water. -lysis: to break Cells synthesize macromolecules by covalently joining subunits together by dehydration synthesis, a chemical reaction that removes the equivalent of one molecule of water: a hydroxyl group (—OH) from one subunit and a hydrogen atom (—H) from an adjacent subunit (figure 2.11). The reverse type of reaction, called hydrolysis, breaks down a macromolecule into its subunits; the equivalent of H2O is added when a covalent bond between two subunits is broken. Specific enzymes catalyze both types of chemical reactions.
In NaCl (a salt), a sodium cation and a chloride anion are bonded together by a(n) __________________ bond. Page 22 A) Ionic B) Single C) Double D) Hydrogen E) Covalent
A) Ionic Ionic bonds form between cations and anions because of the attraction between positive and negative charges (see figure 2.4). The resulting product is called a salt. A common type of salt, sodium chloride (table salt), is composed of Na+ (sodium cations) and Cl- (chloride anions) and forms a solid crystal. The structure is highly ordered because the electrical attraction between positive and negative charges brings the ions together, but the like charges repel one another and are positioned as far apart as possible. Crystals continue to grow as new ions are added. Salts such as sodium chloride dissolve in water and are called electrolytes, meaning that they conduct electricity. Cation: Those that lose an electron become positively charged. Anion: Atoms that gain an electron become negatively charged. Ion: An atom that gains or loses an electron is no longer neutral --- it is an ion.
Match the chemical symbol with the description. Page 22 Select the right answer. A) Na^+ B) Cl^- 1. Cation 2. Anion
A) Na^+ = Cation B) Cl^- = Anion
___________________________ amino acids are characterized by side chains that lack polar bonds. Page 33 Select the right answer. A) Nonpolar B) Polar
A) Nonpolar Nonpolar amino acids are characterized by side chains that lack polar bonds; an example is the methyl group (--CH3) of alanine.
Compounds that contain at least carbon and hydrogen are ________________. Page 23 Select the right answer. A) Organic Compounds B) Carbohydrates C) Inorganic Compounds D) Lipids
A) Organic Compounds
To which group do these three amino acids belong? Page 34 Select the right answer. A) Polar (Hydrophilic/Uncharged) B) Charged (Hydrophilic/Polar) C) Nonpolar Look at the images on page 34
A) Polar (Hydrophilic/Uncharged)
Match the chemical structure. Page 38 Select the right answer. A) Purine B) Pyrimidine 1. Cytosine (C), Thymine (T), and Uracil (U) 2. Adenine (A) and Guanine (G)
A) Purine: Adenine (A) and Guanine (G) B) Pyrimidine: Cytosine (C), Thymine (T), and Uracil (U)
Match the disaccharide with its characteristics. Page 28 Select the right answer. A) Sucrose B) Lactose C) Maltose 1. Breakdown product of starch. 2. Table sugar from sugar cane and beets. 3. Sugar naturally present in milk.
A) Sucrose: Table sugar from sugar cane and beets. B) Lactose: Sugar naturally present in milk. C) Maltose: Breakdown product of starch. Disaccharides are composed of two monosaccharides joined together by covalent bonds (see table 2.6). Two common examples are sucrose (table sugar) and lactose (milk sugar). Sucrose, which comes from sugar cane and sugar beets, is composed of the monosaccharides glucose and fructose, whereas lactose consists of glucose and galactose. Another disaccharide, maltose, composed of two glucose molecules, is a breakdown product of starch. To form a disaccharide, two monosaccharides are joined together by a dehydration synthesis reaction between a pair of their hydroxyl groups, with the loss of the equivalent of a water molecule (figure 2.14). The reaction is reversible, so hydrolysis, which adds a water molecule, produces the two original monosaccharides.
At room temperature, the two strands of double-stranded DNA are held together by many ___________ bonds, which easily break at high temperatures. Page 24 Select the right answer. A) Hydrogen B) Ionic C) Covalent
Although a single hydrogen bond is weak, a large number of them can hold molecules or parts of molecules together firmly. Consider the hook-and-loop fasteners of Velcro. A single hook-and-loop attachment does not provide much strength, but many such attachments result in a stronger connection. Likewise, the two strands of a double-stranded DNA molecule are held together by many hydrogen bonds along the length of the molecule, forming a very stable interaction. However, the two strands will quickly come apart if enough energy is applied, usually in the form of heat approaching temperatures of 100 degrees Celsius.
The property of an atom that most contributes to its chemical reactivity is the number of ______________________. Page 21 Select all that apply. A) Neutrons in its Nucleus B) Electrons in its Outermost Shell C) Valence Electrons D) Protons in its Nucleus E) Electrons in its Innermost Shell
B) Electrons in its Outermost Shell C) Valence Electrons Electrons largely determine the chemical reactivity of an atom. The electrons in an atom's outer shell, called valence electrons, are the most important that regard. Atoms with the maximum number of electrons in the outer shell are very stable. Atoms with an unfilled outer shell tend to react with other atoms that have been unfilled outer shells. A depiction called a Lewis structure highlights the number of valence electrons is illustrated as a dot next to the chemical symbol.
Triglycerides are composed of a single molecule of ___________________ bound to three ______________________. Page 30 Select the right answer. A) Glycerol; Starch Chains B) Glycerol; Fatty Acids C) Glycerol; Polysaccharides D) Glucose; Fatty Acids
B) Glycerol; Fatty Acids
_______________________ is the energy currency of the cell. Page 40 Select the right answer. A) Cytosine Triphosphate B) Guanosine Diphosphate C) Adenosine Monophosphate D) Adenosine Triphosphate E) Guanosine Triphosphate
D) Adenosine Triphosphate Another biologically important molecule is built using the nucleobase adenine. Adenine plus ribose produces the nucleoside called adenosine. When three phosphate groups are added to adenosine, it produces the molecule called adenosine triphosphate, or ATP, the main energy currency of cells (figure 2.29). To understand the concept of "energy currency," consider the currency of the United States—the dollar. You can sell a valuable item for cash, thereby converting the value of the item into dollars. You can then spend the cash, converting the dollars into another item of value. Cells do something similar. They use energy available in sunlight or in chemical compounds like sugars to make ATP, and then they "spend" the ATP to drive chemical reactions in the cell.
Molecules such as oils and waxes that do not dissolve in water are ________________________ molecules. Page 25 Select the right answer. A) Hydrophilic B) Hydrolytic C) Hydrostatic D) Hydrophobic
D) Hydrophobic Substances with charges can dissolve in water; they are hydrophilic, meaning "water-loving." Non-polar molecules are hydrophobic, meaning "water-fearing," and they do not dissolve in water. They can, however, be organized by the presence of water. For example, when oil drops are added to water, they simply float to the top and then often merge. This phenomenon occurs because oil molecules are pushed together as the water molecules form hydrogen bonds among themselves.
The shape of proteins resulting from two or more polypeptide chains held together is ______________________. Page 36 A) Secondary Structure B) Primary Structure C) Tertiary Structure D) Quaternary Structure
D) Quaternary Structure --------------------------------------------------- Explanation of why: Primary Structure- Recall that primary structure is the sequence and number of amino acids.
Some antifungal medications interfere with the synthesis of erogosterol. This chemicall is a sterol (similar to cholestrol) that provides rigidity to fungal cell membranes. It belongs to which group of biological molecules? Page 32 Select the right answer. A) Phospholipid B) Simple Sugar C) Fatty Acid D) Steroid E) Amino Acid
D) Steroid
The electron-rich oxygen atom of one water molecule is attracted to the electron-poor hydrogen atom adjacent water molecule. This attraction between molecules is called a _________________ bond. 23-24
Hydrogen Hydrogen bonds are weak bonds formed when a hydrogen atom in a polar molecule is attracted to an electronegative atom in the same or another polar molecule. Compounds that contain electronegative atoms, such as oxygen (O) or nitrogen (N), are common in biological systems, creating the possibility for many hydrogen bonds. Figure 2.7 Hydrogen Bond Formation: Hydrogen bonds form between water molecule because the electron-rich oxygen atom attracts electron-poor hydrogen atoms.
_______________________ is the storage form of a cell's genetic information. Page 38-40
DNA DNA, which stands for deoxyribonucleic acid, is the storage form of a cell's genetic information; the cell uses that information to make proteins. The sequence (order) of nucleotides in a cell's DNA codes for the primary structure of every protein that the cell produces. Because proteins can act as enzymes that catalyze the chemical reactions that occur in a cell, DNA determines all of the structural and functional properties of the cell. A change in the DNA sequence that results in changing even a single amino acid in a polypeptide can have a significant impact on the subsequent folding of the chain, much as changing a single letter can change the meaning of a word. The pentose sugar in the nucleotides of DNA is deoxyribose (which is why these nucleotides are called deoxyribonucleotides); the nucleobases are A, T, C, and G. The DNA of a typical cell is a double-stranded helical structure. Each strand is composed of a chain of deoxyribonucleotides, creating a series of alternating sugar and phosphate units that together are called the sugar-phosphate backbone (figure 2.27). A single DNA strand will always have a phosphate group (—PO4) at one end and a hydroxyl group (—OH) at the other. These ends are referred to as the 5′ end (pronounced "5 prime end") and the 3′ end ("3 prime end"), reflecting the positions at which the functional groups are attached to the carbon atoms of deoxyribose. During DNA synthesis, the chain is elongated by adding more nucleotides to the hydroxyl group at the 3′ end.
Proteins are polyers made up of subunits called _____________. Page 32 Select the right answer. A) Fatty Acids B) Simple Sugars C) Nucleic Acids D) Nucleotides E) Amino Acids
E) Amino Acids
Proteins play an important role in all of the following EXCEPT __________________. Page 33 Select the right answer. A) Enzyme Catalysis B) Signal Reception C) Regulation D) Motility E) Genetic Code F) Transport G) Support
E) Genetic Code Explanation of why: DNA is the genetic code of the cell.
_____________________ encode genetic information. Page 37 Select the right answer. A) Polysaccharides B) Fatty Acids C) Disaccharides D) Amino Acids E) Nucleic Acids
E) Nucleic Acids Nucleic Acids carry genetic information. Cells decipher the encoded information and use it to link amino acids subunits in the proper order to make the various proteins.
Matter is categorized into _____________________, which are substances that have unique chemical properties and cannot be broken down by ordinary chemical means. Of the 92 naturally occurring examples, living organisms primarily consist of only six. Page 20
Elements Matter is categorized into elements, substances that have unique chemical properties and cannot be broken down by ordinary chemical means. Of the 92 naturally occurring examples, living organisms primarily consist of only six (table 2.1). As a way to remember theses, think of the acronym CHONPS: carbon (the chemical symbol is C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), and sulfur (S). Other elements are also important in living systems, including some referred to as trace elements, reflecting the fact that they are found in very small quantities. The symbol of an element may represent more than one letter of the name, as with Ca, which represents calcium. Not all chemical symbols are derived from English, as seen with the symbol Na, which stands for natrium in Latin, but which we know as sodium.
Which of the following is a group of lipids that have a structure that consists of four connected rings? Page 32 Select the right answer. A) Waxes B) Phospholipids C) Lipoproteins E) Triglycerides F) Steroids G) Glycoproteins
F) Steroids Their chemical structure is quite different from the structures of fats and phospholipids, but they are classified as lipids because they too are relatively insoluble in water.
True or False: A single protein can have only one domain. Page 37 Select the right answer.
False Large proteins sometimes have many domains and several different functions, whereas a small protein may have only one. Single Protein: Many domains with may be one function or it can be several.
