Biology HW 9
Organize the terms below into a table.
(left to right) carbohydrates- monosaccharides, polysaccharides, glyosidic linkage lipids- fatty acid, triacylglycerol, ester linkages proteins- amino acids, polypeptides, peptide bonds nucleic acids- nucleotides, polynucleotides, phosphodiester linakge
Complete the complementary strand of DNA, using the same symbols for phosphates (circles), sugars (pentagons), and bases. Mark the 5' and 3' direction of the strands.
(top to down) original strand- 5,3 middle- CAGA Complementary strand- 3,5
Complete the following vocabulary exercise relating to the level of structure in proteins. B.
1. 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. 2. Primary structure is the sequence of amino acids in a protein. 3. 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. 4. Quaternary structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex. B. https://docs.google.com/document/d/1J4FFxKA1uD1B9drV2W-Aq-qTvm-xgsoDtg93KAb-1EQ/edit
If a DNA sample were composed of 20% guanine, what would be the percentage of cytosine?
20
If a DNA sample were composed of 15% adenine, what would be the percentage of guanine?
35
How many peptide bonds are present in a polypeptide that contains 45 amino acids?
44
If one strand of a DNA molecule has the sequence of bases 5'-ATTGCA-3', the other complementary strand would have the sequence
5'-TGCAAT-3'.
A double-stranded DNA molecule contains a total of 120 base pairs. This DNA molecule could be composed of
50 adenine, 70 guanine, 70 cytosine, and 50 thymine molecules.
Which bond in the figure is closest to the amino-terminus of the molecule?
A
A. If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand? b. If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain? c. The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases. d. A nucleotide is composed of a(n) _____.
A. 3'-TAAACG-5' b.75 c. hydrogen bonds d. phosphate group, a nitrogen-containing base, and a five-carbon sugar
Which molecule shown in the figure can form a covalent bond between side chains (R groups) in a polypeptide?
B
At which bond in the figure would water need to be added to achieve hydrolysis of the dipeptide resulting in production of its component amino acids?
C
Which bond in the figure is a peptide bond?
C
Which statement about steroids is true?
Cholesterol is a precursor of other steroids.
The flow of genetic information in a cell goes from __________.
DNA to RNA to protein
Which of the following statements is true regarding cellulose?
It is a primary structural component of plant cell walls.
Which of the following statements regarding the molecule illustrated in the figure is true? https://session.masteringbiology.com/problemAsset/2967391/2/3.2_27.gif
It is a saturated fatty acid.
Which of the following statements regarding the chemical reaction illustrated in the figure is true?
It results in a peptide bond.
Which of the following statements regarding the molecule illustrated in the figure is true? https://session.masteringbiology.com/problemAsset/2967392/3/3.2_28.gif
Molecules of this type are usually liquid at room temperature.
How will brief heating (to 95°C) affect macromolecular structures in aqueous solution?
Proteins will unfold (denature).
The side chain (R group) of the amino acid serine is −−CH2 −−OH. The side chain of the amino acid leucine is −−CH2 −−CH−−(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution?
Serine would be on the exterior, and leucine would be in the interior of the globular protein.
What structural difference accounts for the functional differences between starch and cellulose?
Starch and cellulose differ in the glycosidic linkages between their glucose monomers.
DNase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNase?
The bonds between deoxyribose phosphate groups would be broken.
Why are hydrocarbons insoluble in water?
The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
Why are the vertebrate sex hormones estrogen and testosterone considered to be lipids?
Their carbon skeletons are composed of primarily C
Which of the following statements is true of both starch and cellulose?
They are both polymers of glucose.
Which of the following statements concerning saturated fats is true?
They are generally solid at room temperature.
Which of the following statements regarding lipids is true?
They are insoluble in water.
A nucleotide is composed of
a nitrogenous base, a phosphate group, and a pentose sugar.
Which of the following molecules is not a polymer synthesized from several simple monomers?
a steroid
a. How many amino acids differ between the monkey and the human sequences? b. How many amino acids differ between the gibbon and the human sequences? C. What percent of monkey β-globin amino acids are identical to the human sequence? (This is called the percent identity between the monkey and human β-globin sequences.) D. What percent of gibbon β-globin amino acids are identical to the human sequence? (This is called the percent identity between the gibbon and human β-globin sequences.) E. Based on the β-globin alignment, identify the best hypothesis about how humans are related to monkeys and gibbons. F. What other evidence could you use to analyze evolutionary relatedness among gibbons, monkeys, and humans?
a. 8 b. 2 c. 94.5 D. 98.6 E. Gibbons are more closely related to humans than monkeys are because the gibbon β-globin sequence is a closer match with the human sequence. F. the amino acid sequences of other proteins from gibbons, monkeys, and humans
a. Select the statement that is incorrect. b. Complete the following sentences about carbohydrates.
a. All carbohydrates have the general formula b. 1. A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a carbohydrate . 2. Lactose, the sugar in milk, is a disaccharide, because it can be split into two monosaccharides. 3. A carbohydrate that yields many monosaccharides when hydrolyzed is a polysaccharide . 4. A monosaccharide cannot be hydrolyzed any further.
a. How many fatty acids are in a phospholipid? b. What functional feature(s) does the phosphate group contribute to the structure of a phospholipid? c. What holds phospholipids together in a bilayer formation? d. Which molecule is less soluble in water--a fat or a phospholipid? Why? e. Which of these images shows the correct orientation of phospholipids in a biological membrane?
a. How many fatty acids are in a phospholipid? b. negative charge to interact with water, place to attach another small charged molecule Submit c. hydrophilic and hydrophobic interactions with water Submit d. 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. Submit e. https://session.masteringbiology.com/problemAsset/2412321/8/5_11_MQ_A.jpg
a. Which of these is NOT a lipid? b. This figure is an example of a(n) _____. c. Which of these is a phospholipid? d. Which of these is rich in unsaturated fats? e. A function of cholesterol that does not harm health is its role _____.
a. RNA b. saturated fat c. https://session.masteringbiology.com/problemAsset/1100498/8/0509a5.jpg d. olive oil e. as a component of animal cell membranes
a. Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. b. Identify the level(s) of protein structure present in this molecule. c. What could happen if a mutation in a gene caused a hydrophobic amino acid in a polypeptide to be replaced by a hydrophilic amino acid?
a. The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene. b. primary secondary tertiary quaternary c. The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected. Submit
a. Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar. b. Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar. c. Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar.
a. acidic- none, basic- agrinine, neutral polar- asparagine, glutamine, neutral nonpolar- alanine b. acidic- none, basic- lysine, neutral polar- lysine, neutral nonpolar- proline, phenylalanine, methionine c. acidic- glutamic acid, basic- none, neutral polar- threonine, tyrosine, neutral polar- valine, tryptophan
a. Pair up the nucleotide bases with their complementary partners. b.Write the complementary sequence for the following DNA sequence, in order from 3' to 5': c. Rank the following base pairs according to their stability.
a. https://docs.google.com/document/d/1J4FFxKA1uD1B9drV2W-Aq-qTvm-xgsoDtg93KAb-1EQ/edit# b. GCTATAACTCGATTCGAA c. https://docs.google.com/document/d/1J4FFxKA1uD1B9drV2W-Aq-qTvm-xgsoDtg93KAb-1EQ/edit#
a. Arrow A is indicating a(n) _____ protein. b. Arrow D is indicating a _____ protein. c. Which of these does NOT contain a structural protein? d. Defensive proteins are manufactured by the _____ system.
a. structural b. receptor c. ovalbumin d. immune
Normal hemoglobin is a tetramer, consisting of two molecules of ββ-globin and two molecules of αα-globin. In sickle-cell disease, because of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits
altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.
Which of the following is a correct monomer/polymer pairing?
amino acid/polypeptide
Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
as a disaccharide
Which of the following categories includes all others in the list?
carbohydrate
Which two functional groups are always found in amino acids?
carboxyl and amino
Plant cell walls consist mainly of _____.
cellulose
A disulfide bridge is an example of which type of bond?
covalent bond between R groups
What structural feature makes the 20 common amino acids different from one another?
different side chains (R groups) attached to an αα carbon
Which of the following functional groups may be used to form polymers via dehydration reactions?
either hydroxyl or carboxyl groups
A molecule with the formula C18H36O2 is most likely a
fatty acid.
A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog. These data suggest that the new organism is more closely related to
frogs than to humans.
If two of the molecules shown in the figure are linked together, carbon-1 of one molecule to carbon-4 of the other, the bond that is formed would be found in which of the following polymers?
glycogen
Which of the following polymers lacks nitrogen?
glycogen
Sucrose is formed when glucose is joined to fructose by a(n) __________.
glycosidic linkage
Sort these nucleotide building blocks by their name or classification. C. Identify three possible components of a DNA nucleotide.
https://docs.google.com/document/d/1J4FFxKA1uD1B9drV2W-Aq-qTvm-xgsoDtg93KAb-1EQ/edit# C. deoxyribose, phosphate group, thymine
Which of the following chemical equations describes a dehydration reaction?
monosaccharide + monosaccharide = disaccharide + H2O
The sequence 5'-GAACUT-3' may be found in which of the following?
neither DNA nor RNA
The characteristic that all lipids have in common is that __________.
none of them dissolves readily in water
The building blocks, or monomers, of nucleic acid molecules are called __________.
nucleotides
A hydrophobic amino acid R group (side group) would be found where in a properly folded protein?
on the inside of the folded chain, away from water molecules
Which of the following large biological molecules will self-assemble into a bilayer when mixed with water?
phospholipids
Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthesized from four nucleotides.Which class of biological polymer has the greatest functional variety?
proteins
What is the structure shown in the figure?
steroid molecule
Which of the following is the smallest carbohydrate?
sucrose
Polysaccharides, triacylglycerols, and proteins are similar in that they are
synthesized from subunits by dehydration reactions.
Which of the following is an example of a hydrolysis reaction?
the reaction of a fat, forming glycerol and fatty acids with the consumption of water
Which of the following is an example of a dehydration reaction?
the reaction of two monosaccharides, forming a disaccharide with the release of water
The biochemical reaction that joins two amino acids to form a dipeptide is accompanied by
the release of a water molecule.
Lactase is an enzyme composed of a single polypeptide that hydrolyzes the disaccharide lactose to produce monosaccharides. The optimal pH for lactase activity is 6. Transfer of lactase to pH 5 results in a substantial decrease in enzyme activity, likely due to the disruption of
the secondary and tertiary structures of the enzyme.
