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Flashcards in Chapter 5 Deck (345):
1

Plant cell walls consist mainly of _____.

cellulose

2

Cellulose is a

polysaccharide that is a major component of the tough walls that enclose plant cells.

3

The characteristic that all lipids have in common is that _____.

none of them dissolves in water.

4

Almost all the covalent bonds in lipids are nonpolar, causing their

solubility in water to be extremely low.

5

Lipids are

hydrophobic substances.

6

Palm oil and coconut oil are more like animal fats than are other plant oils. Because they _____ than other plant oils, they may contribute to cardiovascular disease.

contain fewer double bonds

7

Evidence suggests that a diet high in saturated fats may contribute to

human cardiovascular disease.

8

Some regions of a polypeptide may coil or fold back on themselves. This is called _____, and the coils or folds are held in place by _____.

secondary structure ... covalent bonds

9

Secondary structure is the

localized folding and/or coiling of the primary structure of a polypeptide. It results from hydrogen bonding between atoms of the polypeptide backbone.

10

A dehydration reaction (or condensation reaction) is the process in which _____.

water molecules are produced as a polymer is formed from monomers

11

Monomers are joined together in a

reaction in which two molecules are covalently bonded to each other through the loss of a water molecule; this is called a condensation reaction or, specifically, a dehydration reaction.

12

A hydrophobic amino acid R group (side group) would be found where in a protein?

on the inside of the folded chain, away from water

13

Hydrophobic R groups are

nonpolar. By orienting within the folded chain they associate with other nonpolar R groups or side chains and avoid coming into contact with water.

14

Sucrose is formed when glucose is joined to fructose by a(n) _____.

glycosidic linkage

15

Glycosidic linkages join

simple sugars to form polysaccharides.

16

The flow of genetic information in a cell goes from _____.

DNA to RNA to protein

17

The information in DNA is transcribed into

RNA and then translated into protein.

18

The building blocks or monomers of nucleic acid molecules are called _____.

nucleotides

19

A nucleotide is a

nucleic acid monomer consisting of a nitrogen base, a pentose sugar, and a phosphate group.

20

Nucleotides joined together by covalent bonds are called

phosphodiester linkages and form nucleic acid molecules.

21

The four main categories of large biological molecules present in living systems are _____.

proteins, nucleic acids, polysaccharides, and lipids
(CHECK AND MAKE SURE THIS IS RIGHT??))

22

Which polymers are composed of amino acids?

Proteins

23

Proteins are composed of

amino acids joined together.

24

Which of the following are attached to the central carbon atom in an amino acid?

A carboxyl functional group,
A side chain ("R group")
and An amino functional group

25

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

An oxygen

26

The central carbon atom in an amino acid is bonded to

an amino functional group, a carboxyl functional group, a side chain, and hydrogen.

27

Which part of an amino acid is always acidic?

Carboxyl functional group

28

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.

29

Which monomers make up RNA?

Nucleotides

30

Nucleotide monomers make up

nucleic acids.

31

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

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

32

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.

33

Enzymes in the digestive tract catalyze

hydrolysis reactions.

34

Enzymes in the digestive tract break down food molecules, which is

a process that occurs by hydrolysis.

35

The linking of monomers involves the

removal of water

36

Which molecule is not a carbohydrate?

Lipid

37

A lipid is a

hydrophobic polymer, not a carbohydrate.

38

Some molecules that are carbohydrates are

Glycogen
Cellulose
and
Starch

39

Monosaccharides

can be classified according to the spatial arrangement of their atoms.

40

Peptidoglycan is a

polysaccharide found only in bacteria.

41

Which complex carbohydrate contains only a-1, 4-glycosidic linkages?

Amylose

42

Cellulose's function

structural component of plant cell walls

43

Cellulose is the

main structural component of plant cells walls

44

Which polysaccharide contains a modified monosaccharide?

Peptidoglycan

45

The N-acetylglucosamine and N-acetylmuramic acid units that make up peptidoglycan are composed of

modified glucose monomers.

46

Glycogen is

a polysaccharide found in animals

47

Animals store energy in the form of

glycogen

48

glucose + glucose —> _____ by _____.

maltose + water ... dehydration synthesis

49

Maltose is the disaccharide formed when

two glucose molecules are linked by dehydration synthesis.

50

Which of these is a source of lactose?

milk

51

Lactose is the sugar found in

milk

52

Which of these is a polysaccharide?

cellulose

53

_____ is the most abundant organic compound on Earth.

cellulose

54

Cellulose is a

component of plant cell walls, and is the most abundant organic compound found on earth

55

Lactose, the sugar in milk, is a

disaccharide, because it can be split into two monosaccharides.

56

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

carbohydrate

57

A carbohydrate that yields many monosaccharides when hydrolyzed is a

polysaccharide

58

A monosaccharide cannot be

hydrolyzed any further

59

Which is not a lipid?

RNA

60

RNA is a

nucleic acid.

61

Which of these are lipids?

phospholipid
steroids
cholesterol
wax

62

The fatty acid tails lack

double bonds

63

Phospholipids are composed of

a phosphate group, a glycerol, and fatty acids

64

Which of these is rich in unsaturated fats?

olive oil

65

Olive oil is a

plant oil, and most plant oils are rich in unsaturated fats

66

A function of cholesterol that does not harm health is its role _____.

as a component of animal cell membranes

67

Cholesterol is an important component of

animal cell membranes

68

Defensive proteins are manufactured by the _____ system.

immune

69

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

foreign objects.

70

Proteins are polymers of

amino acids

71

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

peptide

72

The amino acids of a protein are linked by

peptide bonds

73

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

secondary structure

74

The secondary structure of a protein results from _____.

hydrogen bonds.

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

75

Tertiary structure is NOT directly dependent on _____.

peptide bonds

76

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

primary structure

77

Secondary structures describes the

alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain.

78

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

79

Primary structure is

the sequence of amino acids in a protein

80

Quaternary structure is

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

81

The tertiary and quaternary structures of proteins—how they fold into their overall three-dimensional shapes, and how different protein subunits come together to interact—both ultimately depend on the

primary structure, the sequence of amino acids in the proteins. A different sequence of amino acids will lead to different secondary structures and a different shape of the overall protein.

82

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

3'-TAAACG-5'

83

Adenine pairs with

thymine

84

Guanine pairs with

cytosine

85

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

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.

86

The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.

hydrogen bonds

87

Nitrogenous base pairs are joined by

hydrogen bonds

88

A nucleotide is composed of a(n) _____.

phosphate group, a nitrogen-containing base, and a five-carbon sugar

89

Which structure is not a component of a nucleotide?

Sulfhydryl Oxygen group

90

Which structures are components of a nucleotide?

pentose
nitrogen-containing base
phosphate group

91

Nucleotide structure

The nitrogenous base is bonded to the sugar.
The sugar can either be ribose or deoxyribose
The sugar is bonded to the phosphate group.
The phosphate group is bonded to the sugar.

92

Guanine and uracil are examples of

nitrogenous bases.

93

Adenine, thymine, and cytosine are examples of

nitrogenous bases

94

Guanine, Uracil, Adenine, Thymine, and cytosine

examples of nitrogenous bases

95

Which linkage forms the backbone of a nucleic acid?

A sugar-phosphate linkage

96

In DNA's structure

The nucleic acid strands in a DNA molecule are oriented antiparallel to each other.

97

The 5’ end of one strand in a DNA molecule is oriented opposite the 3’ end of the other strand, making the strands

antiparallel.

98

What is the complementary DNA sequence to 5’ ATGCATGTCA 3’?

5’ TGACATGCAT 3’

99

The nucleic acids DNA and RNA are made from chains of

nucleotides

100

Nucleotides consist of three components:

a five-carbon sugar (either ribose or deoxyribose), a nitrogenous base attached to the sugar’s 1'-carbon, and a phosphate group attached to the sugar’s 5'-carbon.

101

Components of Nucleotides (Nucleotide building blocks)

phosphate
ribose
deoxyribose
purine
pyrimidine

102

All of the genetic material in all living organisms is made from these basic building blocks of nucleotides.

nucleotides.

103

Thymine and deoxyribose occur

exclusively in DNA

104

Adenine, guanine, cytosine, and phosphate occur in

both DNA and RNA

105

Uracil and ribose occur

exclusively in RNA

106

DNA is used for

storage of genetic information.

107

The presence of deoxyribose as the sugar in DNA makes the molecule

more stable and less susceptible to hydrolysis.

108

The 2'-oxygen on the ribose found in RNA makes RNA

much more susceptible to breakdown.

109

It is important that mRNA be easily broken down, to ensure that

the correct levels of protein are maintained in the cell.

110

Three possible components of a DNA molecule

deoxyribose, phosphate group, thymine

111

DNA and RNA have similar structures:

a pentose sugar with a nitrogenous base and a phosphate group.

112

DNA and RNA differ in the

type of pentose sugar each possesses (DNA has deoxyribose; RNA has ribose) and in one base (DNA has thymine; RNA has uracil).

113

In a DNA sequence, the purine adenine always pairs with the

pyrimidine thymine

114

In a DNA sequence, the purine guanine always pairs with the

pyrimidine cytosine.

115

The base pair adenine-cytosine occurs

very rarely in nature. It only happens during a mutation event. When the DNA is replicated, one of the two daughters will contain a guanine-cytosine base pair in the location of the mutation, and the other daughter will contain an adenine-thymine base pair.

116

What is the function of fimbriae?

They are used to attach the cell to its substrate or to other prokaryotes.

117

Fimbriae are

hair-like projections that aid in attachment. They are also known as attachment pili to distinguish them from the pili used in conjugation.

118

How does the large amount of genetic variation observed in prokaryotes arise?

They have extremely short generation times and large populations.
They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer.

119

The short generation times and large population sizes in most prokaryotic species, coupled with their ability to exchange genes, helps to

increase genetic variability beyond what we would expect in asexually reproducing organisms.

120

Genes for the resistance of antibiotics are usually located _____.

on plasmids

121

Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are _____.

chemoautotrophs

122

chemoautotrophs use

inorganic molecules (in redox reactions) for energy, and carbon dioxide for carbon.

123

Obligate anaerobes are

poisoned by O2.

Some obligate anaerobes live exclusively by fermentation; others extract chemical energy by anaerobic respiration, in which substances other than O2 accept electrons at the "downhill" end of electron transport chains.

124

Bacteria reproduce through

binary fisson.
During binary fission, the DNA in the bacterial chromosome is replicated, and one copy is passed to each daughter cell.
Although plasmids (small, circular DNA molecules separate from the main bacterial chromosome) are not shown in the figure, any plasmids in a bacterial cell are also replicated and passed to each daughter cell during binary fission.
Mutations that arise during DNA replication are one source of genetic variation in bacterial populations.
The rapid reproduction and large sizes of many bacterial populations can yield considerable genetic variation despite a low mutation rate.

125

Gram-positive bacteria

-alcohol rinse does not remove crystal violet.
-have a thick peptidoglycan layer
-appear purple have Gram staining

126

Gram-negative bacteria

-alcohol rinse easily removes crystal violet
-have a thin peptidoglycan layer
-appear pink after Gram staining
-have an outer membrane as part of their cell wall structure

127

Both gram-positive bacteria and gram-negative bacteria

have a plasma membrane

128

Gram staining is a technique for

classifying bacteria based on differences in the structure of their cell walls.

129

_____ are surface appendages that allow a bacterium to stick to a surface.

Pili

130

Pili enable bacterial cells to

stick to a surface

131

What is the function of a bacterium's capsule?

protection

132

Where is a bacterial cell's DNA found?

nucleoid region

133

Bacteria lack a nucleus so

their DNA is found in the nucleoid region.

134

In a bacterium, where are proteins synthesized?

ribosomes

135

Ribosomes are involved in the

manufacture of polypeptides (proteins).

136

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

cell wall

137

The cell wall is a

rigid supporting structure

138

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.

plasma membrane

139

The plasma membrane is

selectively permeable

140

The structure that regulates the passage of material into and out of this bacterial cell is

the plasma membrane

141

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.

transferring of information from DNA to messenger RNA

142

Transcription is the

first of the two main steps of protein synthesis.

143

Pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. Photographic emulsions are prepared at different times during the chase. Where would the black spots appear on an emulsion prepared 3 hours after the pulse?

Exterior of the cell.
Black spots would appear on the exterior of the cell after 3 hours, indicating that the proteins had been secreted from the cell.

144

What path does a protein in the secretory pathway take, starting from its site of synthesis?

Rough ER, Golgi apparatus, secretory vesicles, plasma membrane

145

Proteins are

synthesized in the rough ER, modified in the Golgi apparatus, and carried in secretory vesicles to the plasma membrane, where they are secreted.

146

During a pulse-chase experiment, photographic emulsions were prepared at different times during the chase, and radioactive spots were detected at the following times and locations: 5 minutes: rough ER; 10 minutes: Golgi apparatus; 40 minutes: endosomes; 70 minutes: lysosomes; 140 minutes: lysosomes. Which of the following conclusions can be drawn from these results?

The final destination of the proteins was the lysosome.

This conclusion can be drawn from the results, since the radioactive spots were last detected at the lysosome, which is not a secretory vesicle.

147

What scientific hypotheses can be tested by a pulse-chase experiment?

Movement of molecules through a cell over time

Pulse–chase experiments allow for the tracking of molecules in a cell over time.

148

Which organelle plays a role in intracellular digestion?

lysosome.

The prefix "lyso-" means decomposition.

149

The pathway of secretory proteins

Proteins that are secreted from a eukaryotic cell must first travel through the endomembrane system. As they are being synthesized, secretory proteins enter the lumen of the endoplasmic reticulum. From the ER, vesicles transport these proteins to the Golgi, where they are sequentially modified and concentrated in a cis-to-trans direction. Secretory vesicles bud from the Golgi and move along cytoskeletal filaments to eventually fuse with the plasma membrane, secreting their protein cargo. Each of these transport steps requires specialized proteins to ensure that the cargo is sent to the proper location and is able to fuse with the target membrane.

150

The cilia and flagella of eukaryotic cells are composed of _____.

microtubules

151

Eukaryotic cilia and flagella are composed of

microtubules.

152

Prokaryotes thrive (live)

almost everywhere, including places too acidic, salty, cold, or hot for most other organisms

153

Most prokaryotes are

microscopic, but what they lack in size they make up for in numbers

154

Prokaryotes are divided into two domains:

Bacteria and archaea

155

Domain Archaea

things live in extreme environments

156

Domain bacteria

things live in regular environments

157

Earth's first organisms were likely

prokaryotes.
been around the longest.

158

Most prokaryotes are

unicellular, although some species form colonies

159

Most prokaryotic cells are much smaller than

eukaryotic cells

160

Prokaryotic cells have a

variety of shapes

161

The three most common shapes of prokaryotic cells are

spheres (cocci)
rods (bacili)
and
spirals (spirilla)

162

An important feature of nearly all prokaryotic cells is their

cell wall
which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment

163

Eukaryote cell walls are made of

cellulose or chitin

164

Bacterial cell walls contain

peptidoglycan, a network of sugar polymers cross-linked by polypeptides

165

Archaea contain

polysaccharides and proteins but lack peptidoglycan

166

scientists use the Gram Stain to

classify bacteria by cell wall composition

167

Gram-positive bacteria have

simpler walls with a large amount of peptidoglycan

168

Gram-negative bacteria have

less peptidoglycan and an outer membrane that can be toxic

169

Gram-positive bacteria

turn purple.
have a cell wall with only a peptidoglycan layer. and the peptidoglycan layer is bigger than gram-negative bacteria.
And then it has a plasma membrane underneath

170

Gram-negative bacteria

turn pink.
have a cell wall that has an outer membrane and a smaller layer of peptidoglycan.
and then a plasma membrane underneath.

171

many antibiotics target

peptidoglycan and damage bacteria cell walls

172

gram-negative bacteria are more likely to be

antibiotic resistant.
not good to get.

173

A polysaccharide or protein layer called a capsule covers

many prokaryotes

174

Some prokaryotes have fimbriae, which

allow them to stick to their substrate or other individuals in a colony.
They are like hairy looking extensions.

175

Pili (or sex pill) are longer than

fimbriae and allow prokaryotes to exchange DNA

176

In a heterogeneous environment, many bacteria exhibit

taxis, the ability to move forward or away from a stimulus

177

Chemotaxis is the

movement toward or away from a chemical stimulus

178

Most motile bacteria propel themselves by

flagella scattered about the surface or concentrated at one or both ends

179

Flagella of bacteria, archaea, and eukaryotes are

composed of different proteins and likely evolved differently

180

Prokaryotic cells usually lack

complex compartmentalization
(They dont have membranes on the inside. no nucleus)

181

Some prokaryotes do have

specialized membranes that perform metabolic functions.
These are usually infoldings of the plasma membrane

182

The prokaryotic genome has less DNA than the

eukaryotic genome

183

Most of the genome consists of a

circular chromosome

184

The chromosome is not surrounded by a membrane; it is located in the

nucleoid region

185

Some species of bacteria also have similar rings of DNA called

plasmids

186

There are some differences between prokaryotes and eukaryotes in

DNA replication, transcription, and translation.
These allow people to use some antibiotics to inhibit bacterial growth without harming themselves.

187

DNA is a big circularish piece in a part which is called the

nucleoid region

188

Prokaryotes reproduce quickly by

binary fission and can divide every 1-3 hours.

they reproduce really fast

189

Key features of prokaryotic reproduction

they are small
they reproduce by binary fission
they have short generation times

190

Prokaryotes have short generation times which means

it doesn't take a lot of time to mature as bacteria

191

Many prokaryotes form metabolically inactive

endospores, which can remain viable in harsh conditions for centuries

192

Prokaryotes short generation time allows them to

evolve quickly.
For example, adaptive evolution in a bacterial colony was documented in a lab over 8 years.

193

Prokaryotes are not "primitive" (simple) but are

highly evolved.
They are good at what they do.

194

Prokaryotes have

considerable genetic variation.

195

Three factors that contribute to Prokaryote's genetic diversity

Rapid reproduction
Mutation
Genetic recombination

196

Prokaryotes reproduce by

binary fission, and offspring cells are generally identical

197

Mutation rates during binary fission are

low, but because of rapid reproduction, mutations can accumulate rapidly in a population

198

High diversity from mutations allows for

rapid evolution

199

Genetic recombination

the combining of DNA from two sources, contributes to diversity.

genetic recombination- mixing DNA from different types of bacteria?

200

Prokaryotic DNA from different individuals can be brought together by

transformation
transduction
conjugation

201

Movement of genes among individuals from different species is called

horizontal gene transfer

202

Transformation is when

floating around bacterial cells pick up other DNA and pick it up

203

A prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment in a process called

transformation

204

Transduction is

the movement of genes between bacteria by bacteriophages (viruses that infect bacteria)

205

transduction is when

it takes bacterial DNA and puts it into another DNA with the help of a virus that moves it from one to another.

Transduction-virus picking up DNA and moving it

206

Conjugation is

the process where genetic material is transferred between prokaryotic cells

207

In bacteria,

the DNA transfer is one way

208

A donor cell attaches to a recipient by a

pilus, pulls it closer, and transfer DNA

209

A piece of DNA called the

F Factor is required for the production of pili

210

F Factor

plasmid

211

R plasmids

carry genes for antibiotic resistance.

pieces of DNA that tell you how to resist antibiotics

212

Antibiotics kill sensitive bacteria, but

not bacteria with specific R plasmids

213

through natural selection,

the fraction of bacteria with genes for resistance increases in a population exposed to antibiotics.
Antibiotic-resistant strains are becoming more common.

214

Prokaryotes can be categorized by how they obtain energy and carbon

phototrophs
chemotrophs
autotrophs
heterotrophs

215

Phototrophs

obtain energy from light

216

Chemotrophs

obtain energy from chemicals

217

Autotrophs

require CO2 as a carbon source

218

Heterotrophs

require an organic nutrient to make organic compounds

219

Energy and carbon sources are combined to give four major modes of nutrition

photoautotrophy
chemoautotrophy
photoheterotrophy
chemoheterotrophy

220

We are

chemoheterotrophs.
We get energy from chemicals and require an organic nutrient to make organic compounds?

221

Prokaryotic metabolism varies with respect to

O2

222

Obligate aerobes

require O2 for cellular respiration.
have to have it to live

223

Obligate anaerobes

are poisoned by O2 and use fermentation or anaerobic respiration.
Can't live with oxygen.

224

Facultative anaerobes

can survive with or without O2.
Doesn't matter if they have oxygen or not.

Ex. yeast.

225

Nitrogen is essential for the

production of amino acids and nucleic acids.

226

Prokaryotes have to get

nitrogen

227

Prokaryotes can metabolize nitrogen in

a variety of ways

228

In nitrogen fixation,

some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)

229

Cooperation between prokaryotes allows them to use environmental resources they could not use as

individual cells

230

Bacteria cooperate (work)

together

231

In the cyanobacterium Anabaena,

photosynthetic cells and nitrogen-fixing cells called heterocysts (or heterocysts) exchange metabolic products.

232

In some prokaryotic species

metabolic cooperation occurs in surface-coating colonies called biofilms.

biofilms are like the nasty stuff you get/feel on your teeth.

233

Bacteria that ________ tend to have abundant internal membranes.

are photosynthetic

234

Cyanobacteria have

thylakoid membranes, much like those in chloroplasts, that function in photosynthesis

235

Bacterial cells, but not eukaryotic cells, possess

a nucleoid with a circular chromosome

236

The bacterial chromosome is

one double-stranded DNA molecule in the form of a ring, and is not contained within a nuclear envelope

237

What is a difference between bacteria and archaea?

Bacteria and Archaea have different chemicals in their cell membranes and cell walls.

238

Bacteria have

peptidoglycan in their cell walls

239

Archaea never have

peptidoglycan

240

Plasmids

often contain antibiotic resistance.
are transferred from one bacterium to another by conjugation.
allow bacteria to survive adverse conditions.
replicate independently of the main chromosome.

241

Plasmids may also direct the

metabolism of rarely encountered nutrients

242

An F+ bacterial cell

acts as a donor during conjugation.
The F+ designation indicates that the bacterial cell has the genes necessary to initiate conjugation and transfer DNA to the receptor cell.

243

Photoautotrophs use

light as an energy source and CO2 as a carbon source

244

Gram-negative bacteria have less peptidoglycan than gram-positive cells, and their cell walls are

more complex structurally.

245

Gram-negative bacteria do not contain as much

peptidoglycan. They have an additional outer membrane with lipopolysaccharides

246

Portions of the genomes of certain prokaryotic species are very similar to portions of the genomes of distantly related prokaryotes. The process that most likely accounts for this genetic similarity is

horizontal gene transfer.

247

prokaryotes are adept at obtaining DNA from other sources, including other species of prokaryotes, through the processes of

conjugation, transformation, and transduction.

248

Bacteria that use light for their energy source and CO2 for their carbon source are called

photoautotrophs.

Photoautotrophs are photosynthetic organisms that harness light energy to drive the synthesis of organic compounds from carbon dioxide.

249

Scientists hypothesize that the O157:H7 strain of E. Coli is so different from the K-12 strain because of

horizontal gene transfer over many years, most likely through the action of bacteriophages.

Many of these imported genes are associated with the pathogenic bacterium's invasion of the host.

250

The desulfovibrio bacterium breaks down organic matter (which it must have) and uses sulfate (not oxygen) as an electron acceptor. As a result, it produces hydrogen sulfide (H2S), accounting for the "rotten egg" smell of swamp muck. Oxygen is a deadly poison to Desulfovirbrio. We would call Desulfovirbrio an

obligately anaerobic chemoheterotroph.

Obligate anaerobes are poisoned by oxygen.
Chemoheterotrophs must consume organic molecules for both energy and carbon.

251

Why is salt a good preservative to use for foods such as pork and fish?

Prokaryotic cells living in the food will shrink from their cell walls, impacting their ability to reproduce.

252

A gram-negative cell wall consists of

a thin layer of peptidoglycan surrounded by an outer membrane containing lipipolysaccharides

253

Which of the following involves metabolic cooperation among prokaryotic cells?

biofilms

254

In an experiment, a microbiologist put equal numbers of each of the following organisms into a flask of sterile broth, consisting mostly of sugar and a few amino acids. She then placed the flask in the dark. Which of the organisms would be most likely to survive?

chemoheterotrophic bacteria.
these organisms do not require light and use organic compounds for both energy and carbon

255

Which statement about prokaryotes is true?

prokaryotes are widely used for bioremediation.
prokaryotes have been used in sewage treatment for decades, and they are being used to clean up oil spills and radioactive waste.

256

prokaryotes are completely indispensable to which chemical cycle?

nitrogen.

257

Nitrogen-fixing bacteria are

the only organisms that can fix atmospheric nitrogen into compounds that other organisms can use to build cellular components.

258

Which of the following is true about R Plasmids?

R plasmids can carry genes that confer resistance to many antibiotics,
and they can be transferred via conjugation

259

How is it possible that as many as 9 million mutations can arise each day in the E. coli inhabiting one human?

the mathematics of large population size and rapid reproduction rate combine to produce many mutations without a particularly high mutation rate.

260

SImply by rapid multiplication and a very large population with a normal mutation rate,

enormous numbers of mutations can arise in a single day. Even if many of the mutations are lethal, they will hardly make a dent in the population.

261

Bacterial flagella have a very complex structure composed of 42 distinct proteins. What is the most likely explanation for the evolution of these complex structures?

exaptation.
proteins that were already part of the bacterial body were modified through natural selection to take on new functions as the bacterial flagella.

262

Which statement about transformation is true?

it can be facilitated by cell-surface proteins that recognize compatible DNA.

for some bacteria, transformation is a very important source of genetic material, and they have evolved mechanisms to make the process efficient.

263

genetic variation in bacterial populations cannot result from

meiosis.

264

genetic variations in bacterial populations can result from

mutation
transformation
conjugation
and
transduction

265

the bacteria that cause tetanus can be killed only by prolonged heating at temperatures considerably above boiling. this suggests that these bacteria

produce endospores.
endospores are extremely heat resistant.

266

biofilms are an example of

metabolic cooperation among prokaryotic species.

267

Bacteria in biofilms send signals to each other, produce structures to channel nutrients in and wastes out, and

produce proteins that help the cells adhere to the substrate and to each other.

268

in the absence of meiosis and sexual reproduction, what general process allows genetic recombination among prokaryotes?

horizontal gene transfer

269

horizontal gene transfer by wat of transformation, transduction, and conjugation allows

bacteria to share genetic material and recombine it.

270

The peptide bond is

a covalent bond joining amino acids together to form a polypeptide.
It is a specific type of covalent bond joining two amino acids.

271

The lipids that form the main structural component of cell membranes are

phospholipids

272

Phospholipids have a

hydrophilic head and two hydrophobic tails. This permits the phospholipids to be arranged in a bilayer, or double layer, which forms a boundary between the cell and its external environment.

273

a glucose molecule is to starch as

a nucleotide is to a nucleic acid.

274

Nucleotides are the monomers that make

nucleic acid polymers, just as glucose is the monosaccharide (monomer) from which starch (polymer) is constructed

275

Carbohydrates can function in which of the following ways?

structural support and energy storage.

276

Carbohydrates function as both

storage molecules (starch, glycogen) and as structural support molecules (Cellulose)

277

In what polysaccharide form do plants store glucose to be available later as an energy source?

Starch.

278

Starch is a glucose storage polymer in

plants.

279

The molecular formula for glucose is C6H12O6. what would be the molecular formular for a polymer made by linking ten glucose molecules together by dehydration reactions?

C60H102O51

280

The fatty acid tails of a phospholipid are hydrophobic because they

have no charges to which water molecules can adhere.

281

Phospholipid tails, which consists of nonpolar hydrocarbon chains, are

hydrophobic

282

One characteristic shared by sucrose, lactose, and maltose is that

they are all disaccharides.

283

A disaccharide consists of

two monosaccharides joined together by a glycosidic linkage

284

Which of the following is a polymer?

cellulose, a plant cell wall component.

285

The polysaccharide cellulose is a

major component of plant cell walls.
It is a polymer composed of many glucose monomers joined together by glycosidic linkages.

286

A polysaccharide that is used for storing energy in human muscle and liver cells is

glycogen.

287

Humans and other vertebrates store glucose as a

polysaccharide called glycogen in their liver and muscles

288

When a protein is denatured, why does it lose its functionality?

denaturation breaks the weak bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function.

289

Denaturation disrupts

secondary, tertiary, and quaternary protein structure, causing the protein to lose its form, and thus its function

290

Lipids differ from other large biological molecules in that they

are not truly polymers.

291

Lipids are not all made of the same type of

monomer. Their association as a group (fats, phospholipids, and steroids) is related to their solubility behavior.

292

Which of the following are pyrimidines found in the nucleic acid DNA?

thymine and cytosine

293

The polysaccharide that you are most likely to have eaten recently is

starch.

294

Starch is a

storage polysaccharide found especially in certain plant tissues

295

What is the process by which monomers are linked together to form polymers?

dehydration or condensation reactions

296

When monomers are linked together to form a more complex polymer,

a water molecule is removed by dehydration (condensation) reactions

297

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture

DNA.

298

the backbone of a nucleic acid consists of

alternating sugar and phosphate groups.

299

What do Alzheimer's, Parkinson's, and mad cow disease have in common?

all have been associated with the buildup of misfolded proteins in cells.

These diseases and others have been associated with a buildup of misfolded versions of various proteins within cells.

300

Which of the following is true regarding complementary base pairing in DNA and RNA molecules?

Although the base pairing between two strands of DNA in a DNA molecule can be thousands to millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of nucleotides in the same molecule or between two RNA molecules

301

Complementary base pairing provides an

accurate way to synthesize a new DNA molecule from an existing one, and gives RNA molecules particular three-dimensional shapes necessary for their function.

302

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the a form. Which of the following could amylase break down?

glycogen, stach, and amylopectin

303

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by

ester linkages.

304

In making a fat, each of the three fatty acid molecules is bonded to a glycerol by an

ester linkage type of covalent bond

305

Which of the following lists ranks these molecules in the correct oder by size? from largest to smallest.

protein, sucrose, glucose, water

306

which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form?

chaperonins

307

Chaperonins shield proteins from

"bad influences" (interactions with other molecules in the cytoplasm) while they are folding into their functional forms

308

A polypeptide is a

chain of amino acids that have been linked together by dehydration reactions

309

What is the term for compounds that do not mix with water?

hydrophobic

310

Hydrophobic compounds are those that are

insoluble in water

311

which of the following components of a tossed salad will pass through the human digestive tract and be digested the least?

cellulose (in the lettuce)

312

Cellulose contains

glycosidic linkages that cannot be broken by human digestive enzymes

313

Omega-3 fatty acids are

polyunsaturated fats that contain three or more cis double bonds and are found in vegetable oils, some nuts, and in fatty fish. Considered essential fatty acids, they are required for normal growth in children and studies suggest that they provide protection against cardiovascular disease in adults.

314

On the basis of the principle of complementary base pairing, you would expect the percentage of adenine to be equal to the percentage of

thymine

315

Which of the following carbohydrate molecules has the lowest molecular weight?

glucose

316

glucose is a

monosaccharide

317

Which of the following describes differences between DNA and RNA?

RNA molecules consist of a single polynucleotide chain, whereas DNA molecules consist of two polynucleotide chains organized into a double helix.
They contain different sugars.
One of their nitrogenous bases is different.

318

the alpha helix and beta pleated sheet represent which level of protein structure?

secondary structure

319

Both the alpha helix and the beta pleated sheet are localized regions of

polypeptides held in a given structure by hydrogen bonds

320

Protein molecules are polymers (chains) of

amino acid molecules

321

Polymers of amino acids are called

polypeptides

322

A protein consists of

one or more polypeptides folded into specific conformations

323

Which of the following statements concerning unsaturated fats is true?

they have double bonds in the carbon chains of their fatty acids

324

Amylase is an enzyme that breaks down starch. Why can't the same enzyme break down cellulose?

the monosaccharide monomers in cellulose are bonded together differently than in starch.

325

The glucose monomers in cellulose are bonded in a

beta glycosidic linkage, whereas those in starch have an alpha glycosidic linkage. the enzyme amylase is specific for the alpha glycosidic linkage.

326

The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules?

lipids.

327

Steroids, such as estrogen, progesterone, 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.

328

What is a distinguishing feature of most naturally occurring fats?

nearly all naturally occurring unsaturated fats have cis double bonds

329

Naturally occurring unsaturated fats found in plants and fish are distinguished by the

presence of one or more cis double bonds in their hydrocarbon chains

330

A nucleotide is made of which of the following chemical components?

a nitrogenous base, a phosphate group, and a pentose sugar

331

Each nucleotide consists of three parts:

an organic molecule, called a nitrogenous base
a 5 carbon sugar, called a pentose
and a phosphate group that serves in the phosphodiester covalent bond that forms a bridge between adjacent nucleotides

332

In a hydrolysis reaction, a polymer is broke up into its constituent monomers, and in this process water is

consumer.

333

the meaning of "hydrolysis" is

"to break with water"

334

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein?

denaturing the protein
a change in salt concentrations of pH
mixing in a chemical that removes hydrogen bonds
heating the protein

335

Which of the following molecules is a monosaccharide?

C6H12O6

336

Monosaccharides have molecules formulas that are multiples of

CH2O

337

If a small droplet of triaclyglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have

a charged end and a noncharged end.

338

The hydrocarbon tails of phospholipids are

hydrophobic and are excluded from water. The negatively charged phosphate group and its attachments form a hydrophilic head that is attracted to water.

339

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the a (alpha) form. Which of the following could amylase break down?

glycogen, starch, and amylopectin

340

Which of the following statements concerning unsaturated fats is true?

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

341

Which of the following categories includes all of the others in the list?
a. monosaccharide
b. disaccharide
c. starch
d. carbohydrate
e. polysaccharide

d. carbohydrate

342

The structural level of a protein least affected by a disruption in hydrogen bonding is the

primary level

343

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?

The phosphodiester linkages of the polynucleotide back bone would be broken

344

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration synthesis?

C60H102O51

345

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

5'-ATGC-3' with 5'-GCAT-3'