Biology Ch 3

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

They contain carbonyl groups.

In the reaction that builds a fat,________ groups react with ________ groups. hydroxyl; carboxyl carboxyl; amino phosphate; amino hydroxyl; phosphate sulfhydryl; carboxyl

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

What hormone is believed to help muscles absorb amino acids? testosterone glucagon thyroid-stimulating hormone insulin

insulin

To find the best source of phospholipids, look at ... cell walls. membranes. nasal mucus. storage droplets. surfaces of leaves.

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

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

milk

The organic molecule called DNA is an example of ....

DNA is a nucleic acid, a polymer made of nucleotide monomers.

A food company hydrogenated a barrel of fat. The treatment ... (a) made the fat less fluid. (b) made the fat less saturated. (c) lengthened the fat tails. (d) put more bends (kinks) in the fat tails. Both (a) and (d).

(a) made the fat less fluid. Hydrogenation removes double bonds, so the tails can straighten. Do you know why that makes the fats less fluid?

DNA and mRNA differ with respect to ... (c) how many kinds of nucleotides are used to make the polymer. Both (a) and (b). (d) the ability to make a double helix. (b) the kinds of purines they contain. (a) the kind of sugar they contain.

(a) the kind of sugar they contain. RNA uses ribose; DNA uses deoxyribose. The polymer names reflect this difference: RNA is short for Ribonucleic acid; DNA is short for deoxyribonucleic acid.

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.

In a membrane, the________of the phospholipids in one monolayer face the________of the phospholipids in the other monolayer. (a) heads; heads (b) heads; tails (c) tails; tails Sometimes (a), sometimes (c). None of these; a membrane is a monolayer.

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

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. All RNA is made by copying segments of DNA.

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

3'-TAAACG-5'

Many people believe you should consume carbohydrates and proteins in what ratio following a long workout? 1:1 2:1 3:1 4:1

4:1

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

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 lipid is most amphipathic? Wax Phospholipid Fat Triglyceride Cholesterol

A phospholipid has a strongly polar (charged) head and two nonpolar tails.

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

A polymer is a chain of monomers.

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. Every phospholipid has all these traits.

Glycogen is _____.

Animals store energy in the form of glycogen.

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.

Both (b) and (c). Tail lengths of 16 to 22 are common. There may be from 0 to 6 double bonds.

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

Cellulose is a carbohydrate composed of many monomers

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

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

Which statement helps to explain how DNA stores hereditary information? DNA contains 20 kinds of amino acids. DNA is a self-replicating type of protein. DNA binds a master copy of each kind of protein. DNA contains four kinds of nitrogenous bases. DNA is made from thousands of kinds of monomers.

DNA contains four kinds of nitrogenous bases.

What do phosphoglycerides and fats have in common? A strongly polar group. A tendency to form bilayers. A role in membrane structure. Ester linkages. Three fatty acid tails.

Ester linkages. Like fats, phosphoglycerides are made by coupling fatty acids to glycerol by means of ester linkages.

DNA has the appearance of a _____. single strand letter U double helix triple helix circle

Eukaryotic DNA is organized as a double helix.

What happens to the shape and function of a protein if one of the amino acids is replaced with a different type of amino acid? The protein will unravel and become entirely nonfunctional. It depends on the role of the amino acid that is altered. One amino acid might be replaced with no measurable effect on the protein's function; replacing another might cause a total loss of function. The protein will remain unchanged; several amino acids would have to be altered to have any effect on protein function. The protein's fourth-level structure will be damaged.

It depends on the role of the amino acid that is altered. One amino acid might be replaced with no measurable effect on the protein's function; replacing another might cause a total loss of function.

Which statement is true of the molecule shown here? - It's made by breaking down starch, during beer production. -Inability to digest it causes some adults to be unable to tolerate milk. -It's called maltose. -It's a polysaccharide. -It differs from sucrose in that an O atom links the sugars.

It's lactose, or milk sugar. Nearly all children can digest it, but many adults lose the enzyme needed to separate the sugars.

glucose + glucose —> _____ by _____.

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

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

Nitrogenous base pairs are joined by hydrogen bonds.

You can tell this molecule is NOT a phospholipid because it contains ... (a) a glycerol backbone. (b) nitrogen. (c) ester linkages. Both (a) and (c). None of the above. It looks like a phospholipid to me!

None of the above. It looks like a phospholipid to me!

Which biological activity does NOT directly involve proteins? Sensing light. Changing the shape of a cell. Defending cells against viruses. Breaking food polymers into smaller molecules. None of the above; proteins are involved in all of them.

None of the above; proteins are involved in all of them. Proteins have all the listed functions and many more.

Which of these is rich in unsaturated fats?

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

Which of these is a phospholipid?

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

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

RNA is a nucleic acid

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

Saturated fat. The fatty acid tails lack double bonds.

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

The information in DNA tells how to make every nucleic acid and protein that the cell's parent could make.

The presence of many C-C and C-H bonds causes fats to be ... (a) rich in energy. (b) insoluble in water. (c) low in energy. Both (a) and (b). Both (b) and (c).

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

In fat synthesis,________and fatty acids combine to make fats plus________.

Water is a by-product of the reaction that makes ester links between glycerol and fatty acids.

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

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

Which statement is true of sucrose? (a) It's a disaccharide. (b) It contains glucose. (c) It's table sugar. Both (a) and (c). (a), (b), and (c).

We use sucrose as our table sugar because plants make plenty of it. They use it as their main circulating fuel, and sugar beets and sugar cane store a lot of it. It's a disaccharide made of glucose and fructose.

The primary structure of a protein is like the arrangement of beads on a string. In this analogy, the beads are _____. amino acids nucleosides nucleotide bases codons

amino acids

What are the constituent parts of proteins? amino acids phosphate groups sugars lipids

amino acids

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. You have it backwards. Fats help phospholipids to travel. Sorry, Dr. Haxton! Help comes from cholesterol, not phospholipids. Not so. Fats are small enough to travel easily without help. Right. Fats are too polar to travel alone in water.

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

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

as a component of animal cell membranes (Cholesterol is an important component of animal cell membranes)

Large proteins, like DNA polymerase and hemoglobin, are often composed of several polypeptides that are linked together. The _____ level of protein structure describes how the polypeptides are joined to create a larger complex. first second third fourth

fourth

The highlighted part of this molecule is derived from ... The highlighted part of the molecule has the structure CH2CHCH2 with oxygen atoms attached to each carbon. The whole molecule contains the highlighted part and three different fatty acid residue. fatty acid. guaiacol. glycerol. cholesterol. aniline.

glycerol. The other parts of the molecule are derived from fatty acids.

What is the primary fuel source for muscles? proteins fats glycogen cellulose

glycogen

RNA nucleotides contain __________ than DNA nucleotides. more oxygen less oxygen different purines less phosphorus None of the above.

more oxygen RNA uses the sugar ribose, which has one more oxygen atom than the sugar used in DNA (deoxyribose).

DNA is composed of building blocks called _____. nucleic acids Gs nucleotides adenines amino acids

nucleotides DNA is a composed of nucleotide units.

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

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

It is difficult for molecules to pass through the phospholipid bilayer because ...

polar molecules attract one another. Polar molecules have trouble escaping from the water to enter a membrane, and nonpolar molecules have trouble moving from the membrane into water. Thus, neither kind of molecule moves easily through membranes.

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

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

Your body contains thousands of different types of proteins, each with a specific function. A protein's function is largely determined by its _____. shape electrical charge size elemental composition

shape

The most unsaturated fats have ... the highest ratio of H to C. the fewest double bonds. the longest hydrocarbon tails. the most double bonds. the shortest hydrocarbon tails.

the most double bonds. Every double bond is a place where hydrogen could be added.

A protein's alpha helices and beta sheets fold together to create an overall shape at the _____ level of protein structure. first second third fourth

third