Functional Biology 1330

Select the statement that is incorrect. Why? Complex sugars are carbohydrates. All carbohydrates have the general formula Cn(H2O)n. Simple sugars are carbohydrates. Simple sugars contain only carbon, oxygen, and hydrogen atoms.

All carbohydrates have the general formula Cn(H2O)n. -This formula only applies to simple sugars, which are equal parts carbon and water. Complex sugars, which do not have this general formula, are also carbohydrates.

What does cholesterol have in common with sex hormones?

All steroids have four linked rings.

Which statement is true of phospholipids? (a) Their synthesis uses fatty acids. (b) Some of their tails have double bonds. (c) They all ionize. All the above. Both (a) and (b).

All the above.

Molecules that are amphipathic must contain _____.

Amphipathic (dual-sympathy) molecules contain both hydrophilic and hydrophobic regions.

A substance that gives up a proton during a chemical reaction, raising the hydrogen ion concentration of water, is most appropriately called _____.

An acid will donate a proton, raising the hydrogen ion concentration and lowering the pH.

Cells of which organisms lack cell walls?

Animal cells do not have a cell wall external to the plasma membrane.

__________ solution: pH > 7

Basic

By convention, biologists write the sequence of amino acids in a polypeptide in which direction?

By convention, biologists write the sequence of amino acids in a polypeptide in which direction?

The _____ functional group can always be found in a carbohydrate molecule.

Carbohydrates are aldehydes or ketones with multiple hydroxyl groups.

What are the components of a nucleotide?

a sugar, a phosphate group and a nitrogenous base In ribonucleotides the sugar is ribose and in deoxyribonucleotides the sugar is deoxyribose.

A "mystery molecule" was isolated in a laboratory and scientists found that the molecule readily crossed artificial membranes. Which of the following molecules can be ruled out as the "mystery molecule?" chloride ion H2O CO2 O2

Charged molecules do not cross membranes on their own because it is energetically unfavorable for them to break their interactions with water and enter the hydrophobic interior of the membrane. Thus, a chloride ion cannot be the mystery molecule that easily crossed membranes.

Why are cholesterol and phospholipids are amphipathic but fats are not?

Cholesterol and phospholipids contain both hydrophilic and hydrophobic regions; fats are primarily hydrophobic.

Covalent bonds are due to the sharing of _____.

Covalent bonds form when electrons are shared between atoms.

What two functional groups are present on every amino acid?

an amino group and a carboxyl group

Which of the following types of glycosidic bonds are more readily broken by hydrolysis?

Due to the strong interactions between strands consisting of beta-1,4-glycosidic linkages, water is excluded and the fibers tend to be insoluble. The absence of water within these fibers makes their hydrolysis more difficult than the hydrolysis of polysaccharides containing alpha linkages. In addition, few organisms have the enzymes to digest beta linkages, while many organisms contain enzymes to digest starch and glycogen, which contain alpha linkages.

Which statement most accurately describes the relative potential energies (P.E.) of the electrons in the following molecules: H2, O2, and H2O? Why? -Electrons in H2 and H2O have relatively high P.E; electrons in O2 have relatively low P.E. - The P.E. of electrons are equivalent in all three molecules. -Electrons in H2 and O2 have relatively low P.E; electrons in H2O have relatively high P.E. - Electrons in H2 and O2 have relatively high P.E; electrons in H2O have relatively low P.E.

Electrons in H2 and O2 have relatively high P.E; electrons in H2O have relatively low P.E. Electrons are held less tightly (farther from a nucleus) in the bonds of H2 and O2 than in the bonds of H2O. This results in higher P.E.

Phospholipids are most important for ... preventing leakage from cells. lubricating cells. storing energy. waterproofing cell walls. stiffening cells.

Every cell depends on phospholipid bilayers to limit leakage of molecules through membranes.

In the reaction that builds a fat,________ groups react with ________ groups.

Fatty acids supply the carboxyl groups; the hydroxyls come from glycerol.

In a natural population of a grass species, the average protein content of seeds would increase over time if seeds with higher protein content survived better and grew into individuals that produced many seeds with high protein content when they matured. Why?

Seeds with higher protein content become more common in the population because this characteristic is heritable and increases survival. (This is an example of differential reproductive success, which is the basis of evolution by natural selection)

How many bonds is carbon able to form? What is it called?

Since carbon atoms are tetravalent (able to form four bonds), atoms may branch off a carbon atom in as many as four places. The ability of a carbon atom to form four different bonds allows carbon to form many different sizes and types of molecules. Carbon atoms may form chains, rings, or combinations of chains and rings. The tetravalence of carbon makes it particularly well-suited to forming the backbone of a huge diversity of organic molecules.

Lipids are insoluble in water because_____.

Since lipids contain nonpolar C-C and C-H bonds, there are no partial charges on the atoms and nothing for water to be attracted to. Thus, lipids are hydrophobic.

Which kinds of bonds are present in a single water molecule?

Since oxygen is very electronegative compared to hydrogen, the electrons spend more of their time near the oxygen. This unequal sharing of electrons creates a polar covalent bond.

Carbohydrates that function as structural molecules withstand pulling and pushing forces well. Which structural feature is most directly responsible?

Structural polysaccharides exist as sets of long, parallel strands that are linked to one another. These structural features result in tough fibers.

Which functional group is least polar?

Sulfhydryl The electronegativity of sulfur (S) is only slightly higher than that of hydrogen (H).

structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids.

Tertiary

What type of bond joins the monomers in a protein's primary structure?

The amino acids of a protein are linked by peptide bonds.

What is specific heat?

The amount of energy required to raise 1 gram of a substance by 1 degree C; a measure of the capacity of a substance to absorb energy

Which part of an amino acid is always acidic?

The carboxyl group (COOH) contains two oxygen atoms that tend to pull electrons away from the hydrogen atom, so this group tends to lose a proton and is acidic.

Which of the following is not attached to the central carbon atom in an amino acid? An amino functional group A carboxyl functional group A side chain ("R group") An oxygen

The central carbon atom in an amino acid is bonded to an amino functional group, a carboxyl functional group, a side chain, and hydrogen.

What do DNA, proteins, and fats have in common? What do DNA, proteins, and fats have in common? They contain nitrogen. They contain phosphorus. They are polar. They contain carbonyl groups. They are polymers.

The contain carbonyl groups

The first law of thermodynamics states that _____.

The first law of thermodynamics states that energy is conserved—it cannot be created or destroyed, only transferred and transformed.

The bond that joins two monosaccharides into a disaccharide is a(n) _____? Via __________ __________?

The glycosidic bond is a covalent bond that joins two sugars together via a condensation reaction.

To find the best source of phospholipids, look at ...

The great majority of a cell's phospholipids occur in membranes.

Which fact is most important in causing phospholipids to behave as they do in water? Hydrogen is more electronegative than oxygen. Hydrocarbons attract one another. Water molecules make hydrogen bonds. Phosphate groups can bind together. Nonpolar groups repel water.

The hydrogen bonds in water exclude the nonpolar tails of phospholipids, forcing the molecules into a bilayer.

Defensive proteins are manufactured by the _____ system.

The immune system is involved in protecting the body against invasion by foreign objects.

The presence of many C-C and C-H bonds causes fats to be ...

The many C-C and C-H bonds make fats nonpolar and insoluble in water. They can also be oxidized, releasing much energy.

What is the molar concentration of [H3O+] in a cola that has a pH of 3.120?

The molar concentration of [H3O+] in a cola with a pH of 3.120 can be calculated this way: [H3O+]=10^−pH [H3O+]=10^−3.120 [H3O+]=7.59×10−4M

If water were a linear (not bent) molecule, electrostatic interactions between water molecules would be much weaker. Why?

The partial negative charge on oxygen would stick out less and be less able to participate in hydrogen bonding. In a linear water molecule, the partial positive charges of the two hydrogen atoms would be on either side of the oxygen atom.

Which statement expresses a real difference between DNA and RNA? Which statement expresses a real difference between DNA and RNA? (a) DNA can make a double helix; RNA cannot. (b) DNA is much longer than RNA. (c) DNA has more kinds of bases than RNA. Both (a) and (b). (a), (b), and (c).

(b) DNA is much longer than RNA. RNA is made by copying short segments of DNA

_________ solution: pH < 7

Acidic

A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a __________________ .

carbohydrate

Carbohydrates, more commonly known as sugars, are made up of __________, ____________, and __________ atoms.

carbon, oxygen, and hydrogen

During protein synthesis, the peptide bond between amino acids is formed by the process of _____.

condensation/ dehydration During peptide bond formation, a water molecule is formed.

As pH ____________, acidity ____________.

decreases; increases

Lactose, the sugar in milk, is a __________, because it can be split into two monosaccharides.

disaccharide

In eukaryotic cells DNA has the appearance of a _____.

double helix

Meaning of tetravalent

having a valence of four

As pH _____________, acidity _____________.

increases; decreases

What causes mad cow disease and other such spongiform encephalopathies?

misfolded proteins known as prions

Triglycerides vary with respect to the number of ... (a) hydrocarbon tails. (b) C atoms in the tails. (c) double bonds in the tails. Both (b) and (c). All of the above.

tail lengths of 16 to 22 are common. There may be from 0 to 6 double bonds.

In a membrane, the________of the phospholipids in one monolayer face the________of the phospholipids in the other monolayer.

tails; tails Water on both sides of the membrane excludes the tails, forcing them into the interior where they face one another.

What is an active site?

the position in an enzyme where substrates bind

What is the difference between linking glucose molecules with α-1,4-glycosidic linkages versus β-1,4-glycosidic linkages? 1.)The linkages have different orientation of the glucose monomers. 2.)In β-1,4-glycosidic linkages the glucose monomers are linked in the same orientation. 3.)In α-1,4-glycosidic linkages every other glucose flipped in orientation. 4.)In α-1,4-glycosidic linkages the glucose monomers are linked in the same orientation. 5.)In β-1,4-glycosidic linkages every other glucose flipped in orientation. 6.)The linkages are located on opposite sides of the plane of the glucose rings.

1, 4 , 5 ,6

How many different primary sequences can be generated by randomly assembling amino acids into peptides that are five residues long?

20^5=3,200,000 Given 20 major amino acids, there are 20 possibilities at each position resulting in 20×20×20×20×20=20^5 different primary sequences.

What is the mass number of an ion with 105 electrons, 157 neutrons, and a +1 charge?

263

By convention, nucleotide sequences are always written from the _____.

5' end to the 3' end

DNA molecules with a high percentage of guanine (G) and cytosine (C) are particularly stable. Why?

A G-C base pair has three hydrogen bonds, while an A-T base pair has two.

Which statement best explains the energy transformation that occurs when methane burns (CH4 + 2 O2 → CO2 + 2 H2O)? -An increase in entropy from reactants to products is released as heat. - A decrease in potential energy from reactants to products is released as heat. -The absorption of heat results in an increase in potential energy from reactants to products. -A decrease in entropy from reactants to products is released as heat.

A decrease in potential energy from reactants to products is released as heat. The potential energies of the electrons in CO2 and H2O are lower than those of the electrons in CH4 and O2, resulting in the release of heat in this exothermic reaction.

Which of the following statements about the formation of polypeptides from amino acids is true? -The reaction occurs through the addition of a water molecule to the amino acids. -A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. -Polypeptides form by condensation or hydrolysis reactions. -A bond can form between any carbon and nitrogen atom in the two amino acids being joined.

A hydroxyl group is removed from the carboxyl group of one amino acid and hydrogen is removed from the amino group of the other amino acid, allowing a bond to form between the two groups.

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.

Secondary

Water exhibits several different properties due to its ability to ___________, including adhesion, cohesion, and surface tension.

Form hydrogen bonds. -An example of adhesion is the hydrogen bonding between water and another type of molecule, such as the molecules composing the side of a water glass or beaker. -Cohesion, on the other hand, is the attraction between like molecules. Water forms drops on a table because the water molecules are more strongly attracted to each other through hydrogen bonding than they are to the molecules composing the table's surface. Both adhesion and cohesion enable plants to transport water from the roots to the leaves against the force of gravity. -Surface tension is the resistance of the surface of a liquid to stretching or breaking. Water's surface tension results from the hydrogen bonds formed between the water molecules at the surface and between those surface molecules and the ones below. Water's high surface tension is evident when certain insects are able to walk on the water's surface.

Anton van Leeuwenhoek made an important contribution to the development of the cell theory.

He invented more powerful microscopes and was the first to describe the diversity of cells

The secondary structure of proteins results because of _____ bonding between atoms in the protein's backbone.

Hydrogen bonds are responsible for producing the alpha-helix and beta-sheet secondary structures.

What holds the strands of the DNA double helix together?

Hydrogen bonds between purines (A & G) and pyrimidines (C & T).

Which feature is shared by all monosaccharides?

In their linear forms, they all contain a carboxyl and several hydroxyl functional groups. Note that in aqueous solution monosaccharides tend to exist in cyclic (cycle, circle, rings), not linear, forms.

Atoms of a specific element always have a constant number of _____.

It is the number of protons that define each element.

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. To treat this disease, physicians exclude the monosaccharide galactose from the diet. Which of the following would you also predict to be excluded from the diet? mannose starch lactose maltose

Latose is a glucose covalently linked to a Galactose

How would the properties of the octane molecule be affected by adding hydroxyl groups? It would allow the molecule to form disulfide bonds. It would make the molecule inorganic. It would make the molecule more soluble in water. It would make the molecule less soluble in water

Molecules containing polar hydroxyl (OH) groups will form hydrogen bonds and tend to be soluble in water.

Why a relatively small difference in the location of a carbonyl or hydroxyl group can lead to dramatic changes in the properties and function of a monosaccharide?

Monosaccharides function by interacting in precise ways with other molecules based on their shapes, so changing the spatial arrangement (shape) of functional groups can dramatically alter function.

___________ solution: pH = 7

Neutral

When double-stranded DNA is heated to 95°C, the bonds between complementary base pairs break to produce single-stranded DNA. Considering this observation, is the strand separation step required for replication of the double helix spontaneous? Why or why not?

No. A continuous input of energy is required. Chemical reactions are spontaneous if they can proceed on their own, without any continuous external influence such as added energy (in this case heat).

Which of the following classes of macromolecules always contains a carbohydrate portion? Why? water lipids nucleic acids proteins

Nucleic acids contain a sugar-phosphate backbone. Ribose is the pentose sugar found in RNA while deoxyribose is the pentose sugar found in DNA.

Which monomers make up RNA?

Nucleotides

How do fats differ from proteins, nucleic acids and polysaccharides?

Only fats do not form from the polymerization of monomers. Lipids interact through hydrophobic interactions. The other macromolecules form via the polymerization of monomers: amino acids for proteins, nucleotides for nucleic acids and monosaccharides for polysaccharides.

A sugar that has the chemical formula C5H10O5 would be characterized as a(n) _____. -hexose -pentose -oligosaccharide -triose

Pentose is the general term for a five carbon sugar such as ribose.

Tertiary structure is NOT directly dependent on _____. bonds between sulfur atoms peptide bonds ionic bonds hydrophobic interactions hydrogen bonds

Peptide bonds link together the amino acids of a protein's primary structure.

Which of the following polysaccharides contains peptide bonds? Why? peptidoglycan glycogen starch chitin

Peptidoglycan is a structural polysaccharide found in bacterial cell walls. The sugars are modified with amino acids that can form peptide bonds to covalently link adjacent strands

Polymers that contain sugars ... (a) may store hereditary information. (b) may store energy. (c) may protect cells. Both (b) and (c). (a), (b), and (c).

Polymers that contain sugars do all the named functions and more. For example, they also lubricate the path of roots through soil and they glue plant cells together.

_____________ structure is the sequence of amino acids in a protein.

Primary

Which characteristics make proteins the most versatile macromolecules in cells in terms of functional capabilities?

Proteins have diverse structures, diverse chemical properties, and flexible shapes.

_____________ structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex.

Quaternary

Which statement most accurately describes how the carbohydrates you ate today are functioning in your body right now? They are storing and replicating hereditary information. They are catalyzing a variety of chemical reactions. They are storing chemical energy, indicating cell identity, and serving as the primary structural components of plasma membranes. They are storing chemical energy, indicating cell identity, and serving as raw material for synthesizing other molecules.

They are storing chemical energy, indicating cell identity, and serving as raw material for synthesizing other molecules. Carbohydrates also provide fibrous structural materials.

Pasteur's results showed that When growth medium is not contaminated by pre-existing cells, the growth medium remains sterile.. and disproved what theory?

This finding disproved the theory of spontaneous generation.

Which functional group contains nitrogen?

This group is found in amino acids, for example.

What is the process that Darwin described as "descent with modification?"

This is evolutionary change. The characteristics of a species may change from generation to generation.

In a DNA double helix, what kind of chemical bonds form between the complementary nitrogenous bases?

Three hydrogen bonds form between GC base pairs and two hydrogen bonds form between AT base pairs.

True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.

True; Enzymes in the digestive tract break down food molecules, which is a process that occurs by hydrolysis.

How could two four-sugar oligosaccharides be structurally different even if both consist of two glucose monomers and two galactose monomers?

Types of structural differences that could occur: The sequence of monomers along the chain or the location and geometry of glycosidic linkages could vary (or both).

What's the correct orders amino acids Asp, Tyr, and Val from most hydrophobic (on the left) to most hydrophilic (on the right)?

Val, Tyr, Asp Val (nonpolar) is most hydrophobic and Asp (charged) is most hydrophilic. Tyr (polar, uncharged) is intermediate in character.

The hydrogen bonds among water molecules endow water with which property? -Water is a good solvent for nonpolar molecules. -Water has a high specific heat. -Solid water (ice) is denser than liquid water. -Water has low cohesion.

Water has a high specific heat. (amount of energy required to raise temperature It takes a lot of energy to raise the temperature of water. Temperature measures the movement of molecules and energy must first go into breaking the hydrogen bonds before the energy can allow increased movement. >>>Water's high specific heat has some important consequences for life on Earth. For example, coastal areas generally have milder climates than inland areas due to the oceans' high specific heat. Oceans are able to absorb a large amount of heat during the daytime and summer, keeping air temperatures relatively cool. At night and during the winter, the oceans cool gradually, releasing heat and warming the air. Water's high specific heat also stabilizes ocean temperatures, resulting in a favorable environment for marine life.

What is the pH of an aqueous solution with the hydronium ion concentration [H3O+] = 2 x 10-14 M ? Basic or acidic?

With a pH of 13.7, this is a strongly basic solution.

Proteins that interact with DNA often interact with the phosphates that are part of this molecule. Which of the following types of amino acids would you predict to be present in the DNA binding sites of these proteins? nonpolar amino acids acidic amino acids uncharged polar amino acids basic amino acids

basic amino acids

In fat synthesis,________ and fatty acids combine to make fats plus________. Why?

glycerol; water Water is a by-product of the reaction that makes ester links between glycerol and fatty acids (dehydration/condensation reaction)

A ________________ cannot be hydrolyzed any further.

monosaccharide

DNA is composed of building blocks called _____

nucleotides

The condensation reaction that forms nucleic acid polymers occurs between a _____ group on one nucleotide and a _____ group on a second nucleotide.

phosphate, hydroxyl A phosphate group on the 5' carbon of the sugar forms a phosphodiester bond with a hydroxyl on the 3' carbon of a second sugar, forming a sugar-phosphate backbone.

A carbohydrate that yields many monosaccharides when hydrolyzed is a ___________________ .

polysaccharide .

What type of energy is stored in the chemical bonds of a molecule?

potential energy

The alpha-helix is a component of __________ protein structure.

secondary

For good health, you don't want your body to run the LDL part of this diagram faster than the HDL part because ... LDL cholesterol is ... HDL cholesterol is ...

stored; destroyed If LDL exceeds HDL, your body is probably storing excess cholesterol, which may clog the arteries and cause heart disease.