Biology in Focus Chapter 3 Review

Which of these illustrates the secondary structure of a protein?

Alpha helices and beta pleated sheets are characteristic of a protein's secondary structure.

The green molecules in the diagram ... (a) contain the base uracil. (b) contain the sugar deoxyribose. (c) are made by copying RNA. Both (a) and (c). (a), (b), and (c).

(a) contain the base uracil. All kinds of RNA contain uracil.

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).

(a), (b), and (c). Good choice! 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.

The information in DNA tells a cell how to make ... The information in DNA tells a cell how to make ... (a) proteins. (b) DNA. (c) tRNA. Both (a) and (b). (a), (b), and (c).

(a), (b), and (c). Excellent! The information in DNA tells how to make every nucleic acid and protein that the cell's parent could make.

Which statement is true of the process in the animation below? (a) It's called DNA replication. (b) Cells do it to produce proteins. (c) Its product contains the nitrogenous base thymine. Both (a) and (b). Both (b) and (c).

(b) Cells do it to produce proteins. Correct! All the information stored in DNA is concerned, directly or indirectly, with making proteins. The process you see here is called transcription. Its products help to build proteins.

What do fats, steroids, and waxes have in common? (a) Moderate polarity. (b) Low solubility in water. (c) They occur in membranes. Both (a) and (c). Both (b) and (c).

(b) Low solubility in water Correct! Low water solubility is the trait that defines lipids.

Which statement is true of nucleic acids? Which statement is true of nucleic acids? (a) rRNA positions amino acids along mRNA. (b) mRNA binds amino acids together to make proteins. (c) mRNA is part of the ribosome. (d) DNA carries information for making RNA. Both (b) and (d).

(d) DNA carries information for making RNA. Correct! All RNA is made by copying segments of DNA.

Quaternary Structure

2 or more polypeptide subunits. these units are stabilized by same sort of attractions that stabilize tertiary structures

If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand? 3'-ATTTGC-5' 3'-TUUUCG-5' 3'-TAAACG-5' 3'-GCAAAT-5' 3'-UAAACG-5'

3'-TAAACG-5' Adenine pairs with thymine and guanine pairs with cytosine.

If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain? 25 75 150 50 200

75 100 nucleotide pairs are a total of 200 nucleotides. Because of base pairing, if there are 25 adenine there must also be 25 thymine. This leaves 200-50 = 150 nucleotides to be divided evenly between guanine and cytosine.

Which of the functional groups behaves as a base?

A The electronegativity of nitrogen means that amino groups tend to pick up hydrogen ions.

Which one of these is an amino group?

A This is an amino group, NH2

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 can form between any carbon and nitrogen atom in the two amino acids being joined. 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.

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.

polysaccharide

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

monosaccharide

A monosaccharide cannot be hydrolyzed any further.

What type of bond joins the monomers in a protein's primary structure? hydrogen S - S hydrophobic peptide ionic

A peptide bond joins amino acids together.

carbohydrate

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

Carbohydrates, more commonly known as sugars, are made up of carbon, oxygen, and hydrogen atoms. The smallest unit of a carbohydrate is a monosaccharide. Two monosaccharides make up a disaccharide, and many monosaccharides make up a polysaccharide. Disaccharides and polysaccharides can be hydrolyzed back into the individual monosaccharide units. which statement is false? a.) Complex sugars are carbohydrates. b.) All carbohydrates have the general formula Cn(H2O)n. c.) Simple sugars are carbohydrates. d.) 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.

secondary protein structures

Areas of folding or coiling within a protein; examples include alpha helices and beta pleated sheets, which are stabilized by hydrogen bonding between the hydrogen and carbon and nitrogen bonds.

Which of these is a phosphate group?

B Of the choices, this is the only one that contains phosphorus.

Which of these groups plays a major role in energy transfer?

B Phosphate groups are a component of ATP.

Which of these functional groups is characteristic of a ketone?

C A carbonyl group in the middle of a carbon skeleton characterizes ketones.

Which of these is a carbonyl group?

C This is a carbonyl group.

_____ is the most abundant organic compound on Earth. Glucose Lactose Glycogen Cellulose Starch

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

Which of these functional groups is characteristic of alcohol?

D Hydroxyl groups are characteristic of alcohol.

Which of these is a hydroxyl group?

D This is a hydroxyl group.

Which of these groups is characteristic of thiols?

E Thiols are characterized by the presence of a sulfhydryl group

Which of functional groups listed below behaves as an acid?

F By donating hydrogen ions, carboxyl groups act as an acid.

Which of these is a carboxyl group?

F This is a carboxyl group

tertiary structure

Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges. 3d structure due to noncovalent interactions between amino acid R groups (subunit interaction) (factors: H-bonds, ionic bonds, hydrophobic effect [R groups push away from water center], disulfide bonds, van der waals) -acidic and basic R groups ionize, and these positvely or negatively charged groups may form ionic bonds. -polar forces allso contribute to tertiary structure (hydrophilic =polar = may form hydrogen bond with one another or stays outside and forms hydrogen bonds with the water surrounding molecules) (hydrophobic=nonpolar =cluster on the inside of the protein away from water ) - make covalent bonds with sulfur atoms in certain R groups.

disaccharide

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

What kind of effect does R-dopa have on Parkinson's disease? a.) It alleviates the symptoms. b.) At first it makes the symptoms worse but over the long term it alleviates the symptoms. c.) At first it alleviates the symptoms but over the long term it makes the symptoms worse. d.) None. e.) It makes the symptoms of Parkinson's disease worse.

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

Which monomers make up RNA? Nucleotides Simple sugars Amino acids Polymers

Nucleotides Nucleotide monomers make up nucleic acids.

L-dopa is used to treat _____. muscle sprains Alzheimer's disease Parkinson's disease laryngitis Marfan's syndrome

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

Which of these is a phospholipid?

Phospholipids are composed of a phosphate group, a glycerol, and fatty acids.

Which polymers are composed of amino acids? Carbohydrates Nucleic acids Monomers Proteins

Proteins Proteins are composed of amino acids joined together.

These molecules are _____. thiols enantiomers geometric isomers structural isomers R-dopa and L-dopa

enantiomers These molecules are mirror images.

Which of these is NOT a lipid? steroids phospholipid RNA cholesterol wax

RNA RNA is a nucleic acid

Which part of an amino acid is always acidic? Carboxyl functional group Side chain ("R group") Amino functional group None of the above

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.

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? The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected. There would be no effect as long as the protein had quaternary structure, because primary structure does not affect that level. The hydrophilic amino acid could not form the proper peptide bond in its new location, so both the shape and function of the protein would be affected. The shape of the protein would not be affected if only one amino acid in the primary structure is changed.

The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected. In the formation of tertiary structure, a polypeptide folds so that amino acids with hydrophobic R groups often cluster in the center of the protein. Because the new amino acid has a hydrophilic R group, it would not be part of those interactions. Thus, this mutation would affect the overall shape of the protein.

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. ? Which of the following statements is an accurate description of proteins? The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene. The 20 amino acids found in proteins differ in the composition of their R groups, which may be either polar or charged. Secondary structures, which include the alpha helix or beta pleated sheet, are held together by interactions between R groups. Tertiary structure is the overall shape of a polypeptide, which may be stabilized by hydrophobic interactions, hydrogen bonds, ionic bonds, and peptide bonds. Quaternary structure is only found in proteins that have four identical polypeptide subunits.

The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene. The order of DNA nucleotides in a gene provides the code for the specific order of amino acids in the primary structure of a protein

Which statement is true of polymers? They are often made by a hydrolysis process. Their synthesis generally consumes water. They are always made of monomers. They are always made by condensation reactions. None of the above.

They are always made of monomers. Correct! A polymer is a chain of monomers.

Enantiomers are molecules that _____. a.) contain a carboxyl group b.) are isomers that differ in the covalent partnerships between their atoms c.) are mirror images d.) differ in the arrangement of their molecules about a double bond e.) contain an -OH group

This is the definition of enantiomers.

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

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

Dr. Haxton told one of his students, "To move in the bloodstream, fats need the help of phospholipids." What would a good student say? Yes. Nonpolar molecules aren't compatible with water. Not so. Fats are small enough to travel easily without help. Right. Fats are too polar to travel alone in water. You have it backwards. Fats help phospholipids to travel. Sorry, Dr. Haxton! Help comes from cholesterol, not phospholipids.

Yes. Nonpolar molecules aren't compatible with water. Good choice! Water rejects nonpolar molecules such as fats, so fats travel inside particles that are coated with polar parts of phospholipids and proteins.

The organic molecule called DNA is an example of .... a monomer. a polymer made of nucleotides. a protein. a polymer made of nucleotes. a polymer made of amino acids.

a polymer made of nucleotides. Good choice! DNA is a nucleic acid, a polymer made of nucleotide monomers.

Glycogen is _____. a polysaccharide found in plant cell walls a transport protein that carries oxygen a polysaccharide found in animals the form in which plants store sugars a source of saturated fat

a polysaccharide found in animals Animals store energy in the form of glycogen

Proteins are polymers of _____. hydrocarbons glycerol amino acids CH2O units nucleotides

amino acids: proteins are polymers of amino acids

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

A function of cholesterol that does not harm health is its role _____. All of cholesterol's effects cause the body harm. as the primary female sex hormone as a component of animal cell membranes in calcium and phosphate metabolism the most abundant male sex hormone

as a component of animal cell membrane Cholesterol is an important component of animal cell membranes.

Which of these is a polysaccharide? lactose cellulose glucose sucrose galactose

cellulose Cellulose is a carbohydrate composed of many monomers

Geometric isomers are molecules that _____. a.) differ in their molecular formulas b.) are isomers in which one of the molecules contains an amino group and the other contains a phosphate group c.) are mirror images differ in the arrangement of their atoms about a double bond d.) are isomers that differ in the covalent partnerships between their atoms

differ in the arrangement of their atoms about a double bond This is the definition of geometric isomers.

These molecules are _____. thiols structural isomers ATP and ADP geometric isomers enantiomers

geometric isomers These molecules differ in how their atoms are arranged about a double bond.

The secondary structure of a protein results from _____. hydrophobic interactions ionic bonds hydrogen bonds peptide bonds bonds between sulfur atoms

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

The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases. hydrophilic interactions ionic bonds hydrogen bonds S—S bonds covalent bonds

hydrogen bonds Nitrogenous base pairs are joined by hydrogen bonds.

Defensive proteins are manufactured by the _____ system. immune nervous digestive integumentary cardiovascular

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

primary structure proteins have

is a chain of polypeptides, consisting of amino acids linked together by peptide bonds. primary structure determines the shape of the protein, which deterimes its function.

glucose + glucose —> _____ by _____. maltose + water ... dehydration synthesis starch + water ... dehydration synthesis cellulose + water ... hydrolysis sucrose + water ... dehydration synthesis lactose + water ... hydrolysis

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

Which of these is a source of lactose? sugar cane sugar beets starch potatoes milk

milk Lactose is the sugar found in milk.

This pair of molecules are _____. enantiomers identical not isomers structural isomers geometric isomers

not isomers These molecules have different molecular formulas.

Which of these is rich in unsaturated fats? lard a fat that is solid at room temperature olive oil butter beef fat

olive oil Olive oil is a plant oil, and most plant oils are rich in unsaturated fats.

Which of these does NOT contain a structural protein? muscles tendons ovalbumin spider silk ligaments

ovalbumin Ovalbumin is a storage protein.

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

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

A nucleotide is composed of a(n) _____. phosphate group, a nitrogen-containing base, and a five-carbon sugar amino group, a nitrogen-containing base, and a five-carbon sugar glycerol, a nitrogen-containing base, and a five-carbon sugar sulfhydryl group, a nitrogen-containing base, and a five-carbon sugar phosphate group, a nitrogen-containing base, and a hydrocarbon

phosphate group, a nitrogen-containing base, and a five-carbon sugar These are the components of a nucleotide

Identify the level(s) of protein structure present in this molecule. Select all that apply. primary secondary tertiary quaternary

primary+ secondary+tertiary+quaternary This protein illustrates all four levels of protein structure. primary: the order of amino acids in the polypeptide chain secondary: localized regions of alpha helices and beta pleated sheets tertiary: the overall three-dimensional shape of a polypeptide, stabilized by interactions between R groups quaternary: the association of more than one polypeptide subunit into a functional protein.

This figure is an example of a(n) _____. protein saturated fat nucleic acid steroid unsaturated fat

saturated fat The fatty acid tails lack double bonds.

These molecules are _____. thiols enantiomers structural isomers amines geometric isomers

structural isomers The two molecules differ in the covalent bond relationships among their atoms.