question

The element present in all organic molecules is___.

answer

Carbon

question

The large diversity of shapes of biological molecules is possible because of the extensive presence of ____ in the molecules.

answer

Carbon - With four electrons to share, carbon-based molecules can be multi branching and 3D variable.

question

How many electron pairs does carbon share in order to complete its valence shell.

answer

4

question

Why are hydrocarbons insoluble in water?

answer

The majority of their bonds are non-polar covalent carbon-to-hydrogen linkages.

question

Which of the following is a hydrocarbon?

answer

C3H8 -This is a typical hydrocarbon with single covalent bonds; the number of hydrogen atoms is equal to two times the number of carbon atoms plus 2.

question

Molecules that have the same chemical formula (same numbers of each atom) but different 3D shapes are called_____.

answer

isomers -Isomers of carbon compounds can arise in several different ways.

question

How do isomers differ from one another?

answer

Isomers differ in the arrangement or bonding of atoms. -Isomers may differ in the covalent arrangements of their atoms or the position of double bonds within the molecule and thus have different chemical properties.

question

Which of the following best describes cis-trans isomers?

answer

They differ in their spatial arrangement around inflexible double bonds. -Cis-trans isomers maintain the same covalent partnerships, but the atoms may be arranged differently.

question

Variations in the reactive properties of different organic molecules are most closely associated with_____.

answer

The presence or absence of functional groups. -Functional groups are the most common participants in chemical reactions.

question

Citric acid makes lemons taste sour. Which of the following is a functional group that would cause a molecule such as citric acid to be acidic?

answer

Carboxyl -The carboxyl group can release a hydrogen ion when in solution.

question

Which statement about a methyl functional group is correct?

answer

A methyl group consists of a carbon bonded to three hydrogen atoms. -A methyl group consists of a carbon covalently bonded to three hydrogen atoms.

question

Most organic compounds contain carbon and ____.

answer

Hydrogen -In fact, some argue that carbon dioxide should not be considered an organic molecule because it does not contain hydrogen.

question

Organic chemistry is currently defined as

answer

The study of carbon compounds.

question

Vitalism gave way to mechanism, the view that____.

answer

Physical and chemical laws govern living systems. -Living things are subject to physical and chemical laws. They so not exist outside of them.

question

What are the six most important chemical elements of life?

answer

Carbon, nitrogen, oxygen, hydrogen, phosphate, sulfur. -All of these elements are capable of forming strong covalent bonds, important in building large, complex molecules.

question

Which of the following is an organic molecule?

answer

CH4 -Compounds containing carbon are said to be organic.

question

Which statement helps most to explain why life is based on carbon compounds?

answer

C-C bonds are as strong as C-O bonds. -C is the only element that bonds with its own kind about as strongly as it bonds with other elements. That, plus C's ability to form 4 bonds, makes it possible to build stable, varied biological molecules.

question

L-dopa is used to treat____.

answer

Parkinson's disease -People with Parkinson's disease lack dopamine.

question

What kind of effect does R-dopa have on Parkinson's disease?

answer

None -R-dopa has no effect on Parkinson's disease.

question

Enantiomers are molecules that_____.

answer

Are mirror images.

question

Geometric isomers are molecules that _____.

answer

Differ in the arrangement of their atoms about a double bond.

question

A molecule has one carbon-carbon double bond and four monovalent atoms or group. How many different cis-trans isomers exist for this molecule?

answer

2 -Only 2 cis-trans isomers exist.

question

Identify the functional groups.

answer

Amino and carboxyl are functional groups.

question

Which of the following functional groups increases the solubility of organic compounds in water?

answer

-COH -OH -NH2 -COOH -All of the listed functional groups are hydrophilic and thus increase the solubility of organic molecules in water.

question

Which statement is true of organic molecules?

answer

An organic molecule can have many functional groups. -If the molecule is large, it may have thousands of functional groups.

question

Choose the pair of terms that correctly completes this sentence about functional groups in organic chemistry; Carboxyl is to ______as_______is to base.

answer

Acid...Amino -A carboxyl group has acidic properties because it can donate a proton (hydrogen ion) to a solution. The amino group acts as a base because it can pick up or accept a proton (hydrogen ion) from a solution.

question

Which of the following groups is capable of hydrogen bonding with an oxygen atom or another functional group?

answer

-Hydroxyl group -Carboxyl group -Carbonyl group -Amino group -All of the listed functional groups are polar, and thus capable of hydrogen bonding with the oxygen of another molecule.

question

Covalent bonds hold atoms together because they...

answer

-Fill shells without giving atoms much charge. -Bring electrons closer to protons. -Electron-sharing brings electrons closer to nuclei and it fills shells without giving the atoms much charge. Both factors stabilize the bond.

question

In molecules, C,H,O and N atoms usually make _,_,_, and _, bonds respectively.

answer

4,1,2,3

question

An atom's atomic number is 7. Its valence is most likely..

answer

3 -The neutral atom has 7 electrons. Two electrons fill the first shell, and 5 go into the second (valence) shell. The atom needs 3 more electrons to fill the valence shell.

question

By making two covalent bonds, an O atom (with 8 protons) fills its valence shell. Why does the atom's charge stay close to zero?

answer

Shared electrons aren't always near oxygen. -Oxygen keeps 6 electrons to itself. The 4 shared electrons migrate between O and the other atoms, thus contributing 4 half-charges to oxygen. This gives oxygen about 8 units of negative charge, balancing the atom's 8 protons.

question

In a double covalent bond, a carbon atom shares..

answer

Electrons in two orbitals. - A double bond involves two orbitals, each with a shared pair of electrons.

question

Two C atoms form a double bond. Each C is bound to two H atoms. Which statement is true?

answer

All the atoms lie in a plane. -The double bond limits all the atoms to a plane.

question

Partial charges occur when..

answer

Atoms share electrons unequally. -Each kind of atom has a different attraction for electrons. Thus, atoms of different kinds share electrons unequally. That gives one atom a partial negative charge; the other atom a partial positive charge.

question

To fill the valence shell, an electrically neutral, unbonded atom with atomic number 8 must add...

answer

2 electrons - The neutral atom has 8 electrons. Two electrons fill the first shell, and 6 go into the second (valence) shell. Two more electrons would fill the valence shell.

question

Which answer helps to explain why carbon atoms tend to make 4 covalent bonds?

answer

The valence shell needs 8 electrons. -Without help, C can only hold 4 electrons in the valence shell. To fill the shell, 4 more electrons must be shared, making 4 covalent bonds.

question

An electrically neutral molecule has the formula C3H4O2N. If the carbon atoms form the usual number of bonds, how many covalent bonds will each hydrogen atom have with other atoms in the molecule?

answer

1

question

A(n)____refers to two or more atoms held together by covalent bonds.

answer

Molecule -Two or more atoms held together by covalent bonds.

question

Which of the following individuals is most likely to be a chimera?

answer

A woman who has had children.

question

You are a geneticist interested in studying the mutation that leads to "mosaic animals." Which of the following types of cells should you study?

answer

Skin

question

Which of the following diseases is the result of mosaicism in specific cells?

answer

Pancreatic cancer

question

You are a doctor studying genetic mistakes in fibroblasts. What type of tissue do you specialize in?

answer

Connective

question

Which of the following is true?

answer

Multiple DNA samples from the same individual may not always match

question

Ammonia reacts with water as shown below. Which statement best explains why ammonia is considered to be a base?

answer

Bases are compounds that remove H+ from solutions. - In becoming NH4+, ammonia takes on H+. Removing H+ from a solution is the hallmark of a base.

question

Which of the following can be considered bases?

answer

Na2CO3, KOH - Both sodium carbonate and potassium hydroxide are bases.

question

Compounds that release OH+ are bases because...

answer

OH- combines with H+ and removes it from solution. -This behavior of OH- earns the title of "base" for compounds that release OH-.

question

To determine whether a base is weak or strong,...

answer

Look for undissociated molecules of base. -Strong bases dissociate completely in solution, weak bases don't.

question

Which of the following can be considered strong bases?

answer

NaOH -This is the only base that dissociates completely in water.

question

Water readily sticks to many other substances, a property called____.

answer

Adhesion

question

Water striders are common insects that can skip across the surface of ponds and streams. This lifestyle is enabled by water's ____.

answer

Cohesion and resulting surface tension.

question

Which best describes how charges are distributed on a water molecule?

answer

The oxygen end is negative relative to the end with the 2 hydrogen atoms.

question

Relative to other substances, water tends to resist changes in temperature. Why?

answer

Water is highly cohesive. Its molecules tend to resist increases in their motion. When water is heated, some of the energy is used to disturb the hydrogen bonds between neighboring molecules.

question

Water is sometimes called the "universal solvent". Is that accurate?

answer

For the most part. Water readily dissolves most substances, but nor hydrophobic ones.

question

What feature of large biological molecules explains their great diversity?

answer

The many ways that monomers of each class of biological molecule can be combined into polymers. -Biological molecules belong to four main classes, and are constructed from only 40-50 common monomers (and a few rare ones) made of only a few of the 92 naturally occurring elements. The diversity of biological molecules is due to differences in the arrangements of the monomers in each molecule.

question

Select the statement that is incorrect.

answer

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.

question

Complete the following sentences about carbohydrates. -A carbohydrate that yields many monosaccharides when hydrolyzed is a _____. -A _____cannot be hydrolyzed any further. -Lactose, the sugar in milk, is a ____, because it can be split into two monosaccharides. -A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a ____.

answer

-Polysaccharide -Monosaccharide -Disaccharide -Carbohydrate

question

Glycogen is _____.

answer

A polysaccharide found in animals. - Animal store energy in the form of glycogen.

question

Glucose+glucose--->______by_______.

answer

Maltose+water...Dehydration synthesis. -Maltose is the disaccharide formed when two glucose molecules are linked by dehydration synthesis.

question

Which of these is a source of lactose?

answer

Milk -Lactose is the sugar found in milk.

question

Which of these is a polysaccharide?

answer

Cellulose -Cellulose is a carbohydrate composed of many monomers.

question

______ is the most abundant organic compound on Earth.

answer

Cellulose -Cellulose, a component of plant cell walls, is the most abundant organic compound found on earth.

question

Humans can digest starch but not cellulose because

answer

Humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the ß glycosidic linkages of cellulose.

question

Classify these amino acids as ,acidic, basic, neutral polar, or neutral nonpolar.

answer

Acidic- Basic-Arginine Neutral polar- Glutamine Neutral nonpolar- Alanine

question

Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar.

answer

Acidic- Basic- Lysine Neutral polar- Serine Neutral nonpolar- Phenylalanine

question

Classify these amino acids as acidic, basic, neutral polar, or neutral nonpolar. Drag each item to the appropriate bin.

answer

Acidic- Glutamic Acid Basic- Neutral polar- Theonine Neutral nonpolar- Trytophan

question

Proteins are polymers of _____.

answer

Amino acids -Proteins are polymers of amino acids

question

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

answer

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

question

The secondary structure of a protein results from____.

answer

Hydrogen bonds -Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges.

question

Tertiary structure is NOT directly dependent on_____.

answer

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

question

Complete the following vocabulary exercise relating to the level of structure in protein. 1.______ 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.______Structure is the sequence of amino acids in a protein. 3._____Structure is achieved when a protein folds into a compact, 3D shape stabilized by interactions between side-chain R groups of amino acids. 4.______Structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex.

answer

1. Secondary 2. Primary 3.Tertiary 4.Quaternary

question

Which polymers are composed of amino acids?

answer

Proteins -Proteins are composed of amino acids joined together.

question

Which of the following is not attached to the central carbon atom in an amino acid?

answer

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.

question

Which part of an amino acid is always acidic?

answer

Carboxyl functional group -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.

question

Which monomers make up RNA?

answer

Nucleotides -Nucleotide monomers make up nucleic acids.

question

Which of the following statements about the formation of polypeptide from amino acids is true?

answer

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. -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.

question

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

answer

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

question

Which of the following statements concerning saturated fats is not true?

answer

They have multiple double bonds in the carbon chains of their fatty acids.

question

Why are human sex hormones considered to be lipids?

answer

They are not soluble in water.

question

What does cholesterol have in common with sex hormones?

answer

Four linked rings -All steroids have four linked rings.

question

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

answer

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

question

The sex hormones estradiol and testosterone belong to which class of molecules?

answer

Lipids -Steroids, such as estradiol and testosterone, are lipids based on their insolubility in water. THe molecules are characterized by a carbon skeleton consisting of four fused rings of carbon atoms.

question

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?

answer

Cholesterol is the precursor for many important molecules such as sex hormones. - Cholesterol is the basis for many steroid molecules, including sex hormones.

question

Can you complete these sentences about lipids? 1. Lipids are diverse compounds that are grouped together because they are ____. 2. A fat molecule is composed of two types of smaller molecules: ______ and fatty acids. 3. A fatty acid consists of a _____ and a long hydrocarbon chain. 4. _______ have one or more double bonds in their hydrocarbon chains and are usually found in vegetable oils. 5. The hydrocarbon chains of ______ are not kinked, and thus pack closely together, making animal fats solid at room temperature. 6. _______ are a major component of cell membranes. They form a bilayer with their hydrophobic tails mingling together and their hydrophilic heads facing the watery environment on both sides of the membrane. 7. ______ are lipids with a structure consisting of four fused rings. Many sex hormones are made from this type of lipid.

answer

1. Hydrophobic 2. Glycerol 3.Carboxyl group 4. Unsaturated fatty acids 5. Saturated fatty acids 6. Phospholipids 7. Steroids

question

How many amino acids differ between the monkey and the human sequences?

answer

8

question

How many amino acids differ between the gibbon and the human sequences?

answer

2

question

What percentage of monkey ß- globin amino acids are identical to the human sequence?

answer

94.5%

question

What percentage of gibbon ß- globin amino acids are identical to the human sequence?

answer

98.6%

question

Based on the ß- globin alignment, identify the best hypothesis about how humans are related to monkeys and gibbons.

answer

Gibbons are more closely related to humans than monkeys because the gibbon ß- globin sequence is a closer match with the human sequence.

question

What other evidence could you use to analyze evolutionary relatedness among gibbons, monkeys, and humans?

answer

The amino acid sequences of other proteins from gibbons, monkeys, and humans.

question

What do the three main forces that stabilize protein tertiary structure have in common?

answer

They involve the side chains. - The side chains are always involved. That's one distinction between secondary and tertiary structure.

question

Among the forces that stabilize protein tertiary structure, hydrogen bonds are especially important because they are...

answer

More numerous than the other forces. - Hydrogen bonds are weak individually, but they are much more numerous than the other forces.

question

Which fact results from the presence of both polar and non-polar side chains in a protein.

answer

Water has a strong effect on tertiary structure. - United by hydrogen bonds, water forms a cage that binds to the polar side chains while rejecting the nonpolar side chains. THis keeps the protein folded with the polar side chains at the surface and nonpolar side chains in the interior.

question

The sequence of polar and nonpolar side chains has a strong effect on a protein's folding mainly because...

answer

Water attracts polar but not nonpolar groups. - The great majority of proteins reside in water. Because of the attractions, the protein folds with its polar groups on the surface and its nonpolar groups in the interior. THat makes the folding dependent on the locations of polar and nonpolar groups.

question

The graph shows how the rate of action by a certain protein responds to temperature. The decrease between 43*C and 60*C probably results from...

answer

Breaking hydrogen bonds. -It doesn't take much to disrupt the weak hydrogen bonds that keep the protein folded in its functional shape.

question

When a protein has been unfolded enough to lose its function, the protein has been...

answer

Denatured

question

The amino acid lysine has an amino group in its side chain. In a protein, a scientist replaced every lysine with serine (side chain-CH2OH). THe alteration made the protein's folding...

answer

Less sensitive to pH. - Changes in pH affect the ionization of amino groups much more than -CH2OH groups.

question

Which factor is most important in determining a protein's optimum pH?

answer

The locations of side-chain carboxyl groups. - The effect of pH depends on the number and locations of ionizationable side chains, including those with carboxyl groups. pH affects their ionization, which determines the balance of attractions and repulsions between side chains.

question

Why don't cells rely more on disulfide bridges to stabilize the folding of proteins?

answer

They make the protein rigid. Many proteins change their shape as they work. - There may be additional reasons for the low number of disulfide bridges, but one reason is the need for changes in shape. Disulfide bridges make the folding rigid.

question

To make a disulfide bridge, its necessary to...

answer

Remove two H atoms. -The two cysteines start with -SH groups, they end up linked as -S-S.

question

A certain protein is not very sensitive to pH. It may have many side chains with ____ groups.

answer

-CH2OH -These groups don't ionize readily, so their effects on folding don't change much when the pH is altered.

question

The helical foldings of proteins are stabilized mainly by bonds between...

answer

CO and NH. - Hydrogen bonds between these groups keep the helix coiled.

question

Which of the following is true of pleated sheet foldings within a polypeptide?

answer

They depend in regular occurrence of CO and NH. - Occurring at regular intervals along the backbone, these groups stabilize the sheet by forming many hydrogen bonds between neighboring segments of the polypeptide.

question

What will probably be the effect on a protein if you replace the amino acid proline with the amino acid glycine (side chain -H) at several points?

answer

The altered protein will have longer helices than before. -Helical segments come to an end when they meet a proline residue, because proline grips the backbone in two places. Remove proline, and the helix can continue.

question

The helical foldings in proteins...

answer

Are kept folded by hydrogen bonds. -The hydrogen bonds form between c=O and N-H groups of the backbone.

question

The helical foldings of proteins are stabilized by bonds between...

answer

CO and NH -Hydrogen bonds between these groups keep the helix coiled.

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