Bio mastering
In the molecule below, how many atoms could make hydrogen bonds with water?
10
How many atoms in the pictured molecule can form hydrogen bonds with water molecules?
5
The following question is based on the 15 molecules illustrated in the figure. Which molecule has both hydrophilic and hydrophobic properties and is found in plasma membranes? 14 1 12 5
5
The type of bonding and the numbers of covalent bonds an atom can form with other atoms is determined by _____. See Concept 2.2 (Page 34) View Available Hint(s) the size of the atom; smaller atoms are chemically more reactive the number of neutrons the number of unpaired electrons in the valence shell the number of protons the nucleus
C
If you want a molecule that is highly polar, look for one that contains: C-S C-H H-N O-N S-H
H-N
Use your knowledge of electronegativity to pick out the most polar bond in the list below. O-N N-H O-C C-H O-H
O-H
Which answer correctly ranks the atoms in terms of decreasing electronegativity (the highest electronegativity first)? C, H, O, N N, O, H, C N, O, C, H O, N, C, H O, N, H, C
ONCH
A hydrophobic amino acid R group (side group) would be found where in a protein? See Concept 5.4 (Page 78) View Available Hint(s) on the inside of the folded chain, away from water forming hydrogen bonds with other R groups forming a peptide bond with the next amino acid in the polypeptide chain only at one end of a protein chain on the outside of the folded chain, in the water
a
All of the following statements help to explain why water molecules form hydrogen bonds except: Water is an electronegative molecule. Attractions form between opposite partial charges. There is a partial positive charge on each hydrogen atom and two partial negative charges on the oxygen atom in a water molecule. The electrons spend more time around the oxygen atom because oxygen is more electronegative than hydrogen.
a
Dr. Haxton says the O-O bond is polar and the C-C bond is nonpolar. A good student would say ... Wrong again, Ralph. Both bonds are nonpolar. No way. C is more electronegative than O. Yes. O attracts electrons more strongly than C. Right! O is electronegative, so O2 is polar. No, both bonds are highly polar.
a
For a protein to be an integral membrane protein, it would have to be _____. amphipathic, with at least one hydrophobic region hydrophobic exposed on only one surface of the membrane hydrophilic
a
Given what you know about the human body, what do you think accounts for the high percentage of oxygen (65.0%)? The human body is made up mainly of water, and there is one oxygen atom in every water molecule. The human body breathes in oxygen constantly, and oxygen in the blood and tissues makes up a large percentage of body mass. The human body is made up mainly of water, and there are two oxygen atoms in every water molecule. The human body breathes in oxygen constantly, and because oxygen is a heavy element, it makes up a large percentage of body mass.
a
How do phospholipids interact with water molecules? The polar heads interact with water; the nonpolar tails do not. Phospholipids do not interact with water because water is polar and lipids are nonpolar. Phospholipids dissolve in water. The polar heads avoid water; the nonpolar tails attract water (because water is polar and opposites attract). Previous Answers
a
Hydrogen bonds ... can form between H and N. are covalent bonds. share electrons between the two bonded atoms. occur within a water molecule. All of the above.
a
Identify the functional groups. Amino and carboxyl are functional groups. DNA and RNA are functional groups. Lipids and proteins are functional groups.
a
There are four levels of protein structure. These figures show primary, secondary, tertiary, and quaternary protein structure. Which level(s) of protein structure may be stabilized by covalent bonds? Primary, tertiary and quaternary levels of protein structure None of the levels of protein structure is stabilized by covalent bonds. Secondary level of protein structure
a
These figures show the four levels of protein structure: primary, secondary, tertiary, and quaternary structure. Which level of protein structure is characteristic of some, but not all, proteins? Quaternary level of protein structure Tertiary level of protein structure Secondary level of protein structure
a
What holds phospholipids together in a bilayer formation? hydrophilic and hydrophobic interactions with water ionic interactions between phospholipid tails interaction of cis-double bonds in tails with polar heads covalent bonds between polar heads
a
What is the difference between covalent bonds and ionic bonds? Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms. Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between charged atoms. Covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms. Covalent bonds involve the transfer of electrons between charged atoms; ionic bonds involve the sharing of electrons between atoms.
a
Which of the following is not attached to the central carbon atom in an amino acid? View Available Hint(s) An oxygen An amino functional group A carboxyl functional group A side chain ("R group")
a
Which of the following statements is true for lipids? Lipids mix poorly with water. Waxes and pigments are not lipids. Lipids are true polymers. Lipids are true polymers and mix poorly with water.
a
Which of these images shows the correct orientation of phospholipids in a biological membrane?
a
You disrupt all hydrogen bonds in a protein. What level of structure will be preserved? primary structure secondary structure tertiary structure quaternary structure
a
1. When an electron absorbs the required amount of light energy, it moves from a lowerelectron shell to a higher electron shell, which is farther from the nucleus. 2. When an electron loses a discrete amount of energy, it moves from a higher electron shell to a lower electron shell, which is closer to the nucleus.
answers
Complete the following vocabulary exercise relating to the level of structure in proteins. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column. View Available Hint(s) ResetHelp 1. Quaternary structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex. 2. Tertiary structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids. 3. Secondary structure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain. 4. Primary structure is the sequence of amino acids in a protein.
answers to the left
When two amino acid monomers are positioned so that the carboxyl group of one is adjacent to the amino group of the other, they can be joined through a dehydration reaction. This reaction forms a(n) peptide bond.
answers to the left
An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function? attaching the plasma membrane to the cytoskeleton cell-cell recognition establishing a diffusion barrier to charged molecules transporting ions against an electrochemical gradient
b
As a researcher in a protein lab, you analyze two different proteins for their shape and the amino acids they contain. Your results show that the two proteins have exactly the same numbers and types of amino acids, but they have different shapes. What is the best explanation for these results? All proteins have the same numbers and types of amino acids. Differences between proteins are all based on shape. Each protein has a unique linear sequence of amino acids. With only 20 amino acid types to work with, many proteins must have the same numbers and types. Proteins from the same functional class (enzymatic, structural, etc.) contain exactly the same amino acids.
b
Based on your knowledge of the polarity of water molecules, the solute molecule depicted is most likely ________. negatively charged positively charged nonpolar without charge
b
Compare the three atom diagrams. Which one shows the electron with the highest potential energy?
b
Electrons are held in an atom by attraction to what particle or location? Attraction to the other electrons in the atom Attraction to the positively charged protons in the nucleus Attraction to the lowest electron shell Attraction to the magnetic neutrons in the nucleus
b
Hydrophobic substances such as vegetable oil are _____. polar substances that repel water molecules nonpolar substances that repel water molecules nonpolar substances that have an attraction for water molecules polar substances that have an affinity for water
b
Some regions of a polypeptide may coil or fold back on themselves. This is called _____, and the coils or folds are held in place by _____. See Concept 5.4 (Page 78) View Available Hint(s) tertiary structure ... hydrogen bonds secondary structure ... hydrogen bonds tertiary structure ... covalent bonds primary structure ... covalent bonds secondary structure ... peptide bonds
b
The complexity and variety of organic molecules is due to _____. the variety of rare elements in organic molecules the chemical versatility of carbon atoms the diverse bonding patterns of nitrogen their interaction with water
b
Which bond or interaction would be difficult to disrupt when compounds are put into water? hydrogen bonds covalent bonds between carbon atoms ionic and hydrogen bonds ionic bonds
b
Which molecule is less soluble in water--a fat or a phospholipid? Why? A phospholipid is less soluble in water because even though it has one end that is hydrophilic, the end that is hydrophobic is larger. A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has. A phospholipid is less soluble in water because it is smaller than a fat molecule. A fat molecule is less soluble in water because it has more carbons and hydrogens than a phospholipid.
b
Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer? cholesterol peripheral membrane proteins integral membrane proteins transmembrane proteins
b
Which polymers are composed of amino acids? View Available Hint(s) Monomers Proteins Carbohydrates Nucleic acids
b
The molecule shown the figure is a ________. fatty acid steroid triacylglycerol phospholipid
b, pic
Which functional group(s) shown below is (are) present in all amino acids?
b,c
What functional feature(s) does the phosphate group contribute to the structure of a phospholipid? Select all that apply. nonpolar group that avoids water place to attach another small charged molecule place where bonds can form between adjoining phospholipids negative charge to interact with water place to attach fatty acids
b,d
A carbon atom is most likely to form what kind of bond(s) with other atoms? ionic ionic bonds, covalent bonds, and hydrogen bonds covalent hydrogen
c
An ionic bond is formed when _____. See Concept 2.3 (Page 37) View Available Hint(s) both atoms are electrically neutral both atoms are equally attractive to electrons one atom transfers an electron to another atom atoms are subjected to radioactive isotopes both atoms are nonpolar
c
Hydrophobic substances like salad oil are nonpolar molecules that have an affinity for water because they contain many hydrogens that can form hydrogen bonds with water. polar molecules that have an affinity for water because they contain many hydrogens that can form hydrogen bonds with water. nonpolar molecules that repel water molecules. polar molecules that repel water molecules.
c
If an atom has a charge of +1, which of the following must be true? It has one more electron than it does protons. It has the same number of protons as electrons. It has one more proton than it does electrons. It has two more protons than neutrons.
c
In what way do the membranes of a eukaryotic cell vary? Only certain membranes of the cell are selectively permeable. Some membranes have hydrophobic surfaces exposed to the cytoplasm, while others have hydrophilic surfaces facing the cytoplasm. Certain proteins are unique to each membrane. Phospholipids are found only in certain membranes.
c
Many of water's emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____. See Concept 3.2 (Page 45) View Available Hint(s) are extremely large are in constant motion are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively tend to repel each other are very small
c
Most organic compounds contain carbon and _____. See Concept 4.1 (Page 57) View Available Hint(s) sulfur nitrogen hydrogen oxygen phosphate
c
The characteristic that all lipids have in common is that _____. See Concept 5.3 (Page 72) View Available Hint(s) they do not have a high energy content they are all made of fatty acids and glycerol none of them dissolves in water they are all acidic when mixed with water they all contain nitrogen
c
The partial negative charge in a molecule of water occurs because _____. one of the hydrogen atoms donates an electron to the oxygen atom the oxygen atom donates an electron to each of the hydrogen atoms the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms
c
The simplified diagram of rhodopsin shows the protein embedded in the phospholipid bilayer of the membrane. Portions of the protein extend into the intracellular and extracellular spaces. Which characteristics best describe the side chains in the part of the protein in contact with the phospholipid tails of the membrane? Polar; hydrophilic Charged - basic; hydrophilic Non-polar; hydrophobic Charged - acidic; hydrophilic
c
What happens when two atoms form a chemical bond? A chemical bond forms when two atoms transfer or share protons to achieve a stable nucleus. Two atoms fuse together to form a chemical bond. A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.
c
Which of the following bonds can form between atoms of equal electronegativity? Hydrogen bonds can form between atoms of equal electronegativity. Ionic bonds can form between atoms of equal electronegativity. Van der Waals interactions can form between atoms of equal electronegativity.
c
Which of the following is true of carbon? It is highly electronegative. It can form a maximum of three covalent bonds with other elements. It can form both polar and nonpolar bonds. It forms only polar molecules.
c
Which of the following molecules is polar? C3H7OH C2H5COOH C2H5COOH is polar, but C3H7OH is not polar. Neither C2H5COOH or C3H7OH is polar. C3H7OH and C2H5COOH are both polar molecules. C2H5COOH is not polar, but C3H7OH is polar.
c
Which part of an amino acid is always acidic? View Available Hint(s) Side chain ("R group") Amino functional group Carboxyl functional group None of the above
c
Which parts of the amino acids X and Y are involved in the formation of a peptide bond? (N-terminus) XY (C-terminus) amino group of X and carboxyl group of Y carboxyl group of X and side chain of Y carboxyl group of X and amino group of Y side chains of both X and Y
c
Which statement about a methyl functional group is correct? A methyl group may be negatively charged. A methyl group is polar. A methyl group consists of a carbon bonded to three hydrogen atoms.
c
Which atom in the pictured molecule will have the strongest partial positive charge?
c the c thats in C--O
A carbon atom and a hydrogen atom form what type of bond in a molecule? See Concept 2.3 (Page 36) View Available Hint(s) ionic bond hydrogen bond polar covalent bond nonpolar covalent bond Van der Waals interaction
d
A polar covalent bond between two atoms results from the presence of two ions close to each other. whether the bond is single or not. the shape of the molecule that has the bond. two atoms that do not have similar electronegativities.
d
About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter? carbon, sodium, hydrogen, nitrogen oxygen, hydrogen, calcium, nitrogen carbon, oxygen, phosphorus, hydrogen carbon, hydrogen, nitrogen, oxygen
d
Cooking oil and gasoline (a hydrocarbon) have no affinity for water because they _____. are highly reduced molecules have hydrophobic and hydrophilic regions do not have a nonpolar region do not have a polar or charged region
d
Electronegativity is the number of electrons in the outermost electron shell. the negative charge surrounding the nucleus of an atom. the repulsion of electrons in one atom for electrons in another atom. the attraction of an atom for the electrons in a covalent bond.
d
How is a single covalent bond formed? Two atoms share one electron. Two atoms share two pairs of electrons. One atom loses a pair of electrons to the other. Two atoms share two electrons.
d
Nitrogen (N) is more electronegative than hydrogen (H). Which of the following is a correct statement about the atoms in ammonia (NH3)? The nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge. Ammonia has an overall negative charge. Ammonia has an overall positive charge. Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.
d
The four main categories of large biological molecules present in living systems are _____. See Concept 5.1 (Page 67) View Available Hint(s) proteins, DNA, RNA, and steroids monosaccharides, lipids, polysaccharides, and proteins nucleic acids, carbohydrates, monosaccharides, and proteins proteins, nucleic acids, carbohydrates, and lipids RNA, DNA, proteins, and carbohydrates
d
What component of amino acid structure varies among different amino acids? the long carbon-hydrogen tails of the molecule the glycerol molecule that forms the backbone of the amino acid the presence of a central C atom the components of the R group
d
Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? Dehydration reactions eliminate water from membranes; hydrolysis reactions add water to membranes. Hydrolysis reactions create polymers and dehydration reactions create monomers. Dehydration reactions and hydrolysis reactions assemble polymers from monomers. Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart.
d
Which of the following is a hydrocarbon? See Concept 4.2 (Page 59) View Available Hint(s) C6H12O6 H2CO3 CCl2F2 C3H8 CO2
d
Which of the following statements about the formation of polypeptides from amino acids is true? View Available Hint(s) A bond can form between any carbon and nitrogen atom in the two amino acids being joined. The reaction occurs through the addition of a water molecule to the amino acids. Polypeptides form by condensation or hydrolysis reactions. A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.
d
Which of the following statements is true about proteins? Denaturation is always irreversible Denaturation leads to bond disruption, and the molecule turns into liquid Final folded structure can reveal the steps of protein folding Some proteins form a complete 3-D structure only when they interact with their targets
d
Which of the following statements is true regarding potential energy? Potential energy is the energy matter could have if it were in a different location or structure. Water acquires potential energy as it runs downhill. Matter has a natural tendency to acquire more potential energy until a maximum is reached. Potential energy is the energy possessed by matter due to its location or structure.
d
Which of the following types of molecules lack hydrophilic domains? peripheral membrane proteins integral membrane proteins transmembrane proteins cholesterol
d
You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. What is the significance of this finding? Cysteine causes bends, or angles, to occur in the tertiary structure of proteins. It will be important to include cysteine in the diet of the mice. Cysteine residues are required for the formation of α-helices and β-pleated sheets. Cysteine residues are involved in disulfide bridges that help form tertiary structure.
d
Polar attractions are ... (a) forces between atoms with partial charges. (b) weaker than covalent bonds. (c) important because they are numerous. (a) and (b) are true. (c) is false. (a), (b), and (c) are correct.
e
Proteins perform a variety of functions in living organisms. The protein lysozyme (shown in the figure) is found in tears and saliva where it prevents infection by catalyzing the destruction of specific molecules on the surface of many kinds of bacteria. To which functional class of proteins does lysozyme belong? Transport protein Storage protein Hormonal protein Structural protein Enzymatic protein
e
Identify Structure A.
glycoprotein
Which of the following molecules act as building blocks (monomers) of polypeptides?
idk its d
Identify Structure D.
phospholipid bilayer of membrane
Proteins are polymers--long chains of many similar building blocks linked by covalent bonds. There are 20 building blocks, or monomers, that are used to build proteins. These monomers share a common structure. Drag the labels to the appropriate blanks on the diagram.
pic
Sort the images according to the level of structure in the proteins shown. Sort the items into the appropriate bin.
see pic
What is the function of Structure E?
stabilization of the phospholipids
True or false? Enzymes in the digestive tract catalyze hydrolysis reactions. View Available Hint(s) True False
true
How many fatty acids are in a phospholipid?
two
