1
Q
A
2
Q
Amino acids are the building blocks of which macromolecule?
A
Proteins
3
Q
Which two functional groups are always present in an amino acid?
A
Carboxyl group (–COOH), Amino group (–NH₂)
4
Q
In amino acids, the amino group and carboxyl group are attached to what?
A
The same carbon atom
5
Q
An amino acid with its amino group attached to the alpha (Cα) carbon is called a:
A
Alpha-amino acid
6
Q
An amino acid with its amino group attached to the beta (Cβ) carbon is called a:
A
Beta-amino acid
7
Q
The majority of metabolically important amino acids are classified as:
A
Alpha-amino acids
8
Q
What is the R group of an amino acid?
A
The side chain that distinguishes one amino acid from another
9
Q
Which component of an amino acid determines its unique properties?
A
The side group (R group)
10
Q
Which of the following can an amino acid side group (R group) be?
A
Hydrogen, Unbranched or branched chain, Cyclic structure (ring)
11
Q
A cyclic side group made only of carbon atoms is described as:
A
All-carbon (cyclic)
12
Q
A cyclic side group that contains atoms other than carbon is called:
A
Heterocyclic
13
Q
Which amino acid is given as an example of having a cyclic side group?
A
Tyrosine
14
Q
Which functional groups may be present in amino acid side chains?
A
Sulfhydryl group (–SH), Hydroxyl group (–OH), Additional carboxyl groups, Additional amino groups
15
Q
What effect do side groups have on proteins?
A
They affect the total structure of a protein
16
Q
The structure and behavior of a protein depend on which amino acid components?
A
Side groups (R groups), Carboxyl group, Alpha-amino group
17
Q
Proteins are organic molecules that contain which elements?
A
Carbon, hydrogen, oxygen, and nitrogen (some also contain sulfur)
18
Q
Which group of organic compounds makes up 50% or more of a cell’s dry weight?
A
Proteins
19
Q
Approximately how many different proteins can be found in a single cell?
A
Hundreds
20
Q
Proteins are essential to which of the following?
A
All aspects of cell structure and function
21
Q
Enzymes are best described as proteins that:
A
Speed up biochemical reactions
22
Q
Which type of protein helps move chemicals into and out of cells?
A
Transporter proteins
23
Q
Bacteriocins produced by many bacteria function to:
A
Kill other bacteria
24
Q
Exotoxins produced by some disease-causing microorganisms are best described as:
A
Proteins
25
Which protein function is involved in muscle contraction and cellular movement?
Contractile and movement proteins
26
Proteins that form parts of cell walls, membranes, and cytoplasmic components are classified as:
Structural proteins
27
Hormones in certain organisms are best classified as which type of protein?
Regulatory proteins
28
Antibodies are proteins that function in which system?
Vertebrate immune system
29
Which of the following is NOT a function of proteins?
(Correct answer would be anything not listed: energy storage, genetic material, etc.)
30
Which statement best summarizes protein function?
Proteins perform diverse roles including enzymatic, structural, transport, regulatory, defensive, and movement functions
31
Amino acids are best described as:
The building blocks of proteins
32
All amino acids contain at least one of which functional groups?
A carboxyl group (–COOH) and an amino group (–NH₂)
33
In an alpha-amino acid, the amino group is attached to which carbon?
The first (alpha) carbon (Cα)
34
An amino acid is classified as a beta-amino acid when the amino group is attached to:
The second (beta) carbon (Cβ)
35
The majority of metabolically important amino acids are classified as:
Alpha-amino acids
36
Which component of an amino acid determines its identity and distinguishing properties?
The side chain (R group)
37
The side chain (R group) of an amino acid may be:
A hydrogen atom, a branched or unbranched chain, or a ring structure
38
A cyclic side chain composed only of carbon atoms is best described as:
Cyclic (all carbon)
39
A cyclic side chain containing an atom other than carbon is classified as:
Heterocyclic
40
Tyrosine is best described as an amino acid with which type of side group?
A cyclic side group
41
Which functional group may be present in amino acid side chains?
Sulfhydryl (–SH), hydroxyl (–OH), carboxyl, or amino groups
42
The total structure of a protein is influenced by:
Side chains, the carboxyl group, and the alpha-amino group
43
What distinguishes one amino acid from another?
The R group (side chain)
44
How many different amino acids are commonly found in proteins?
20
45
In a general amino acid structure, which atom is located at the center?
The alpha carbon (Cα)
46
Most amino acids exist in which of the following configurations?
Two stereoisomers designated D and L
47
D- and L-amino acids are best described as:
Mirror images of each other
48
The D and L configurations of amino acids correspond to which three-dimensional shapes?
Right-handed (D) and left-handed (L)
49
Which statement best describes stereoisomers?
They are mirror images that cannot be superimposed
50
Amino acids found in proteins are always which isomer?
L-isomers
51
Which amino acid is an exception to having stereoisomers?
Glycine
52
Why does glycine not have stereoisomers?
It is the simplest amino acid
53
D-amino acids are most likely to be found in:
Certain bacterial cell walls and antibiotics
54
Which of the following statements about D-amino acids is correct?
They occasionally occur in nature
55
Which isomer of amino acids is incorporated into proteins?
L-isomer
56
The relationship between D- and L-amino acids is most similar to:
Left and right hands
57
Which of the following best defines stereoisomers?
Molecules with the same chemical formula but different three-dimensional arrangements
58
The inability of D- and L-isomers to overlap perfectly is described as:
Not superimposable
59
Which of the following amino acids lacks stereoisomers?
Glycine
60
How many different amino acids occur naturally in proteins?
20
61
A single protein molecule typically contains:
50 to several thousand amino acids
62
The large diversity of proteins is mainly due to:
Different lengths, compositions, and arrangements of amino acids
63
The number of different proteins produced by living cells is best described as:
Practically endless
64
Every living cell produces:
Many different proteins
65
A peptide bond forms between which two atoms?
The carbon atom of the carboxyl (–COOH) group of one amino acid and the nitrogen atom of the amino (–NH₂) group of another
66
The bond that joins amino acids together is called a:
Peptide bond
67
For every peptide bond formed, what molecule is released?
One water molecule
68
Peptide bonds are formed by which process?
Dehydration synthesis
69
A compound consisting of two amino acids joined by a peptide bond is called a:
Dipeptide
70
Adding one amino acid to a dipeptide forms a:
Tripeptide
71
A peptide is best defined as a chain containing how many amino acids?
4 to 9 amino acids
72
A polypeptide contains approximately how many amino acids?
10 to 2000 or more amino acids
73
Long chainlike molecules of amino acids are referred to as:
Peptides or polypeptides
74
Which statement about peptide bond formation is correct?
It involves the release of water
75
The chemical reaction that links amino acids together into proteins is an example of:
Dehydration synthesis
76
Which statement best describes amino acids?
A. They are the building blocks of carbohydrates
B. They are the building blocks of fats
C. They are the building blocks of proteins
D. They are composed only of carbon and hydrogen
C. They are the building blocks of proteins
77
All amino acids contain which of the following?
A. A phosphate group and a hydroxyl group
B. A carboxyl group and an amino group attached to the same carbon
C. Two amino groups
D. A nitrogen ring
B. A carboxyl group and an amino group attached to the same carbon
78
An amino acid is called an alpha-amino acid when the amino group is attached to which carbon?
The alpha carbon
79
The majority of metabolically important amino acids are classified as:
Alpha-amino acids
80
What is the primary feature that distinguishes one amino acid from another?
The side chain (R group)
81
Most amino acids exist in two configurations called:
D and L stereoisomers
81
Which of the following may be part of an amino acid’s R group?
Functional groups such as –SH or –OH
82
Which amino acid configuration is always found in proteins?
L-isomers
83
Why does glycine not have stereoisomers?
It has no asymmetric carbon
84
Which of the following is NOT a function of proteins?
A. Acting as enzymes
B. Transporting molecules
C. Serving as structural components
D. Storing genetic information
D. Storing genetic information
84
Proteins make up approximately what proportion of a cell’s dry weight?
50% or more
85
A peptide bond forms between which two atoms of adjacent amino acids?
Carboxyl carbon and amino nitrogen
85
Enzymes are best described as proteins that:
Speed up biochemical reactions
86
Peptide bonds are formed by which process?
Dehydration synthesis
87
For each peptide bond formed, what is released?
One water molecule
88
A molecule composed of two amino acids joined by a peptide bond is called a:
Dipeptide
89
A polypeptide typically consists of how many amino acids?
10–2000 or more
90
Protein function depends primarily on its ability to:
Bind to specific molecules
91
Which level of protein structure refers to the unique amino acid sequence?
Primary
92
The primary structure of a protein is determined by:
Genetic information
93
What are the building blocks of proteins?
Amino acids
94
All amino acids contain at least one ______ group and one ______ group attached to the same carbon atom.
carboxyl; amino
95
An amino acid is classified as an alpha-amino acid when the amino group is attached to:
the alpha carbon
96
The majority of metabolically important amino acids are:
alpha-amino acids
97
What distinguishes one amino acid from another?
The side chain (R group)
98
Which of the following may be found in amino acid side chains (R groups)?
A. Sulfhydryl (–SH) groups
B. Hydroxyl (–OH) groups
C. Additional amino or carboxyl groups
D. All of the above
D. All of the above
99
Amino acids that are mirror images of each other are called:
stereoisomers
100
Which amino acid configuration is found in proteins?
A. D-isomers only
B. L-isomers only
C. Both D and L
D. Neither D nor L
B. L-isomers only
101
Which amino acid does not have stereoisomers?
Glycine
102
D-amino acids are occasionally found in:
bacterial cell walls and antibiotics
103
A peptide bond forms between the ______ of one amino acid and the ______ of another.
A. amino group; amino group
B. carboxyl group; carboxyl group
C. carboxyl carbon; amino nitrogen
D. R group; R group
C. carboxyl carbon; amino nitrogen
104
Formation of a peptide bond releases:
water
105
Peptide bonds are formed by which process?
A. Hydrolysis
B. Oxidation
C. Dehydration synthesis
D. Reduction
C. Dehydration synthesis
106
A molecule consisting of two amino acids joined together is called a:
A. polypeptide
B. dipeptide
C. tripeptide
D. protein
B. dipeptide
107
A polypeptide is defined as a chain containing:
A. 2 amino acids
B. 3 amino acids
C. 4–9 amino acids
D. 10 or more amino acids
D. 10 or more amino acids
108
Proteins make up approximately what percentage of a cell’s dry weight?
50% or more
109
Enzymes are proteins that:
A. store genetic information
B. speed up biochemical reactions
C. transport oxygen
D. form cell walls
B. speed up biochemical reactions
110
Which of the following is not a function of proteins?
A. Transport of molecules
B. Catalyzing reactions
C. Acting as hormones
D. Storing energy long-term
D. Storing energy long-term
111
Protein function depends primarily on its:
three-dimensional shape
112
The primary structure of a protein refers to:
the amino acid sequence
113
Secondary protein structure includes:
alpha helices and pleated sheets
114
Secondary protein structure is stabilized by:
A. ionic bonds
B. disulfide bonds
C. hydrogen bonds
D. covalent bonds between R groups
C. hydrogen bonds
115
Tertiary protein structure is stabilized by interactions between:
amino acid side chains
116
Hydrophobic amino acid side chains are usually found:
at the core of the protein
117
Disulfide bridges form between which amino acid?
A. Glycine
B. Alanine
C. Cysteine
D. Tyrosine
C. Cysteine
118
Quaternary structure refers to:
the interaction between multiple polypeptide chains
119
Quaternary protein structure consists of:
An aggregation of two or more polypeptide chains acting as one unit
120
The individual polypeptide chains that make up a quaternary protein are called:
subunits
121
The bonds holding quaternary structure together are primarily the same as those that maintain:
tertiary structure
122
Which of the following describes possible overall protein shapes?
C. Globular or fibrous
123
Globular proteins are best described as:
B. compact and roughly spherical
124
Fibrous proteins are best described as:
C. threadlike in shape
125
Which of the following is an example of a protein with quaternary structure?
A. Hemoglobin
126
Hemoglobin functions primarily to:
B. transport oxygen in red blood cells
127
Microfilaments and microtubules are examples of proteins that:
C. generate movement and provide mechanical support
128
Microtubules are involved in:
C. movement of eukaryotic organelles and flagella
129
The virus coat is an example of a protein with:
D. quaternary structure
130
DNA polymerase is best described as:
C. an enzyme involved in DNA synthesis
131
Which conditions can cause a protein to lose its characteristic shape?
A. Temperature, pH, or salt concentration changes
132
The process by which a protein unravels and loses its shape is called:
C. denaturation
133
As a result of denaturation, a protein:
C. is no longer functional
134
Protein function is lost during denaturation primarily because:
C. the protein’s shape is altered
135
Simple proteins are best defined as proteins that:
C. contain only amino acids
136
Conjugated proteins are best described as:
B. combinations of amino acids with other organic or inorganic components
137
Conjugated proteins are named based on their:
D. non–amino acid component
138
Glycoproteins are conjugated proteins that contain:
C. sugars
139
Nucleoproteins are conjugated proteins that contain:
B. nucleic acids
140
Metalloproteins are conjugated proteins that contain:
D. metal atoms
141
Lipoproteins are conjugated proteins that contain:
B. lipids
142
Phosphoproteins are conjugated proteins that contain:
B. phosphate groups
143
In eukaryotic cells, phosphoproteins are important primarily as:
C. regulators of activity
144
Bacterial synthesis of phosphoproteins may be especially important for the survival of bacteria that:
C. grow inside host cells
145
What two functional groups are present in all amino acids?
B. amino and carboxyl
146
Nucleic acids are best defined as:
Organic compounds that carry genetic information
147
Which of the following are the only two naturally occurring nucleic acids?
DNA and RNA
148
Which scientists discovered that DNA is the substance of which genes are made?
Avery, MacLeod, and McCarty
149
Just as amino acids are the structural units of proteins, the structural units of nucleic acids are:
Nucleotides
150
Each nucleotide is composed of:
A nitrogen-containing base, pentose sugar, and phosphate group
151
Which sugars are found in nucleotides?
Ribose and deoxyribose
152
Which of the following is NOT a nitrogen-containing base found in nucleic acids?
Methionine
153
Which bases are classified as purines?
Adenine and guanine
154
Which bases are pyrimidines?
T, C, and U
155
A nucleotide containing adenine is called a(n):
Adenine nucleotide
156
A nucleoside consists of:
Base + sugar
157
According to Watson and Crick, DNA consists of:
Two strands forming a double helix
158
The structure of DNA is best described as:
A twisted ladder
159
Which statement best describes how DNA and RNA differ?
DNA is double-stranded and contains deoxyribose and thymine; RNA is usually single-stranded and contains ribose and uracil
160
Which sugar is found in DNA but not RNA?
Deoxyribose
161
Which nitrogenous base is present in RNA but not DNA?
Uracil (U)
162
Which statement correctly compares the strand structure of DNA and RNA?
DNA is double-stranded; RNA is usually single-stranded
163
Which of the following roles is correctly associated with RNA?
Carrying genetic information and participating in protein synthesis
164
Which two functional groups are found in all amino acids?
C. Amino group and carboxyl group
165
Which of the following best describes how DNA and RNA differ?
C. DNA contains deoxyribose and thymine; RNA contains ribose and uracil
166
What forms the backbone of the DNA double helix?
B. Alternating sugar and phosphate groups
167
Which nitrogen-containing bases pair together in DNA?
C. A–T and G–C
168
How many hydrogen bonds hold adenine and thymine together?
B. Two
169
If one DNA strand has the sequence ATGC, what is the complementary strand?
C. TACG
170
Which of the following is true of RNA?
C. It contains uracil instead of thymine
171
Which type of RNA carries genetic information from DNA to the ribosome?
C. mRNA
172
Adenosine triphosphate (ATP) is composed of:
B. Adenine, ribose, and three phosphates
173
ATP releases energy when:
C. The terminal phosphate group is hydrolyzed
174
Which molecule provides more energy for a cell, and why?
B. ATP, because it has more phosphate groups
175
How is ATP regenerated from ADP?
B. By adding energy and a phosphate group
176
What are the building blocks of proteins?
Amino acids.
177
How do amino acids form polypeptide chains?
Amino acids bond through peptide bonds, which are formed by dehydration synthesis between the carboxyl group of one amino acid and the amino group of another.
178
What are the four levels of protein structure?
Primary, secondary, tertiary, and quaternary structure.
179
What determines the primary structure of a protein?
The unique sequence of amino acids in the polypeptide chain, which is genetically determined.
180
What types of structures make up secondary protein structure?
Helices and pleated sheets, held together by hydrogen bonds along the polypeptide backbone.
181
What interactions contribute to tertiary protein structure?
Hydrophobic interactions, hydrogen bonds between side groups, ionic bonds between charged side groups, and disulfide bridges between cysteine residues.
182
What is quaternary protein structure?
The association of two or more polypeptide chains (subunits) that function as a single protein.
183
What are the two types of nucleic acids found in cells?
DNA and RNA.
184
What are the building blocks of nucleic acids?
Nucleotides.
185
What three components make up a nucleotide?
A nitrogen-containing base, a pentose (five-carbon) sugar, and a phosphate group.
186
What sugars are found in DNA and RNA nucleotides?
DNA contains deoxyribose; RNA contains ribose.
187
What nitrogen-containing bases are found in nucleic acids?
Adenine (A), thymine (T), cytosine (C), guanine (G), and uracil (U).
188
Which bases are purines and which are pyrimidines?
Adenine and guanine are purines; thymine, cytosine, and uracil are pyrimidines.
189
Which nucleic acid is the master molecule of the cell?
DNA.
190
How do DNA and RNA differ?
DNA is double-stranded, contains deoxyribose, and uses thymine; RNA is usually single-stranded, contains ribose, and uses uracil instead of thymine.
191
What does ATP stand for?
Adenosine triphosphate.
192
What is the structure of ATP?
ATP consists of adenine, ribose, and three phosphate groups.
193
Why is ATP considered a high-energy molecule?
Because a large amount of usable energy is released when the third phosphate group is removed, forming ADP and inorganic phosphate.
194
What is the primary function of ATP in cells?
ATP stores and supplies energy for cellular reactions that require energy.
195
Which molecule provides more energy for a cell, ATP or ADP, and why?
ATP, because it contains an additional phosphate group whose removal releases a large amount of energy.
196
What are the four nitrogenous bases found in DNA?
Adenine (A), thymine (T), cytosine (C), and guanine (G).
197
What is a DNA nucleotide composed of?
A deoxyribose sugar, a phosphate group, and a nitrogen-containing base.
198
What type of sugar is found in DNA?
Deoxyribose.
199
Where is the phosphate group attached on a DNA nucleotide?
To the 5′ carbon of the deoxyribose sugar.
200
Where is the nitrogen-containing base attached on a DNA nucleotide?
To the 1′ carbon of the deoxyribose sugar.
201
What forms the backbone of a DNA strand?
Alternating deoxyribose sugars and phosphate groups.
202
What forms the “rungs” of the DNA ladder?
Paired nitrogen-containing bases.
203
How do the two DNA strands run relative to each other?
They are antiparallel (one runs 5′ → 3′, the other 3′ → 5′).
204
Which bases pair together in DNA?
Adenine pairs with thymine; guanine pairs with cytosine.
205
What type of bonds hold complementary base pairs together?
Hydrogen bonds.
206
How many hydrogen bonds form between adenine and thymine?
Two hydrogen bonds.
207
How many hydrogen bonds form between guanine and cytosine?
Three hydrogen bonds.
208
Why is base pairing described as complementary?
Because each base pairs only with its specific partner (A–T and G–C).
209
What overall shape does DNA form?
A double helix.
210
Why is DNA described as “ladder-like”?
The sugar-phosphate backbone forms the sides, and base pairs form the rungs.
211
What connects one nucleotide to the next within the same DNA strand?
Covalent bonds between the sugar of one nucleotide and the phosphate of the next.
212
What structural feature allows the sequence of one DNA strand to determine the other?
Complementary base pairing.
213
Which components repeat throughout the DNA molecule?
Sugar-phosphate units forming the backbone and repeating base pairs.
214
What three components make up an RNA nucleotide?
A phosphate group, a ribose sugar, and a nitrogen-containing base.
215
What sugar is found in RNA?
Ribose.
216
Which nitrogenous base is shown in Figure 2.17?
Uracil (U).
217
Which base is present in RNA but not in DNA?
Uracil (U).
218
Where is the phosphate group attached on the RNA nucleotide?
To the ribose sugar.
219
What distinguishes ribose from deoxyribose in structure?
Ribose has one more oxygen atom than deoxyribose.
220
How are DNA and RNA similar in structure (based on Figure 2.17)?
Both are made of nucleotides consisting of a sugar, phosphate group, and nitrogen-containing base.
221
What type of backbone do both DNA and RNA have?
A sugar–phosphate backbone.
222
How many strands does DNA usually have?
DNA is double-stranded.
223
How many strands does RNA usually have?
RNA is usually single-stranded.
224
What sugar is found in DNA?
Deoxyribose.
225
Which nitrogen-containing bases are found in DNA?
Adenine (A), thymine (T), cytosine (C), and guanine (G).
226
Which nitrogen-containing bases are found in RNA?
Adenine (A), uracil (U), cytosine (C), and guanine (G).
227
Which base is unique to DNA?
Thymine (T).
228
Which base is unique to RNA?
Uracil (U).
229
What is the primary function of DNA?
Determines all hereditary traits.
230
What is the primary function of RNA?
Protein synthesis.
231
In addition to protein synthesis, what other function of RNA is listed?
RNA can carry the genetic code of some viruses.
232
How do DNA and RNA differ in strand structure according to Table 2.6?
DNA is double-stranded; RNA is single-stranded.
233
What is the backbone of DNA?
A sugar–phosphate backbone.
234
What is the backbone of RNA?
A sugar–phosphate backbone.
235
How many strands does DNA have?
DNA is double-stranded in cells and most DNA viruses; it forms a double helix. It is single-stranded in some viruses (parvoviruses).
236
How many strands does RNA have?
RNA is single-stranded in cells and most RNA viruses; it is double-stranded in some viruses (reoviruses).
237
What sugar is found in DNA?
Deoxyribose.
238
What nitrogen-containing bases are found in DNA?
Cytosine (C), guanine (G), adenine (A), and thymine (T).
239
What sugar is found in RNA?
Ribose.
240
What nitrogen-containing bases are found in RNA?
Cytosine (C), guanine (G), adenine (A), and uracil (U).
241
What is the function of DNA?
Determines all hereditary traits.
242
What is the function of RNA?
Protein synthesis; genetic code of some viruses.
243
What does ATP stand for?
Adenosine triphosphate.
244
What is the main function of ATP in cells?
ATP is the principal energy-carrying molecule of all cells and provides energy for chemical reactions that require energy.
245
What are the three main components of ATP?
Adenine, ribose, and three phosphate groups.
246
What is adenosine?
Adenosine is composed of adenine and ribose.
247
What type of sugar is found in ATP?
Ribose.
248
How many phosphate groups does ATP contain?
Three phosphate groups.
249
How are the high-energy phosphate bonds shown in the figure?
They are indicated by wavy lines.
250
What happens when ATP breaks down into ADP and inorganic phosphate?
A large amount of chemical energy is released for use in other chemical reactions.
251
What molecule is formed when ATP loses one phosphate group?
Adenosine diphosphate (ADP).
252
Why is ATP considered a high-energy molecule?
Because it releases a large amount of usable energy when the third phosphate group is hydrolyzed.
253
How is ATP similar to a nucleotide in RNA?
ATP contains adenine, ribose, and phosphate groups, which are the components of an RNA nucleotide.
254
How is ATP similar to a nucleotide in DNA?
ATP contains adenine and phosphate groups, like a DNA nucleotide, but it contains ribose instead of deoxyribose.
255
What happens when the amino acids glycine and alanine combine?
They combine to form a dipeptide.
256
What is the newly formed bond between glycine and alanine called?
A peptide bond.
257
Between which two atoms is a peptide bond formed in Figure 2.14?
Between the carbon atom of glycine and the nitrogen atom of alanine.
258
What type of reaction forms a peptide bond?
Dehydration synthesis.
259
What molecule is released during peptide bond formation?
Water (H₂O).
260
What is glycylalanine?
A dipeptide formed from glycine and alanine.
261
How are amino acids related to proteins (based on Figure 2.14)?
Amino acids join together by peptide bonds to form peptides, which make up proteins.
262
What is primary protein structure?
The amino acid sequence.
263
What types of structures make up secondary protein structure?
Helix and pleated sheet.
264
What defines tertiary protein structure?
The overall three-dimensional folding of a polypeptide chain.
265
What is quaternary protein structure?
The relationship between several polypeptide chains that make up a protein.
266
What does Figure 2.15 show as an example of quaternary structure?
A hypothetical protein composed of two polypeptide chains.
267
What property of a protein enables it to carry out specific functions?
Its three-dimensional structure (shape).
268
What type of bonds stabilize secondary protein structure in the figure?
Hydrogen bonds.
269
How are polypeptide chains related to proteins (based on Figure 2.15)?
Proteins are made of one or more polypeptide chains arranged into specific structures.
270
What are proteins?
Organic molecules that contain C, H, O, N, and S.
271
What role do proteins play in cells?
They are essential in cell structure and function.
272
What are enzymes?
Proteins that speed chemical reactions.
273
What is denaturation?
The disruption of the secondary, tertiary, and quaternary structures of proteins.
274
Which levels of protein structure are affected by denaturation?
Secondary, tertiary, and quaternary structures.
275
What do proteins consist of?
Subunits called amino acids.
276
What group is labeled on the left side of the generalized amino acid?
Amino group.
277
What group is labeled on the right side of the generalized amino acid?
Carboxyl group.
278
What is the side group of an amino acid labeled as?
R (side group).
279
What amino acid is shown in panel (b)?
Tyrosine.
280
What type of side group does tyrosine have?
Cyclic side group.
281
What three main components are shown in both amino acid diagrams?
Amino group, carboxyl group, and side group.
282
What are proteins made of?
Subunits called amino acids.
283
What four components make up a generalized amino acid?
Amino group
Carboxyl group
Side group (R)
Central carbon (C)
284
What does the amino group of an amino acid consist of?
A nitrogen atom bonded to hydrogen atoms (–NH₂).
285
What does the carboxyl group of an amino acid consist of?
A carbon atom double-bonded to oxygen and bonded to a hydroxyl group (–COOH).
286
What is the side group of an amino acid and how is it represented?
The side group is represented by R.
287
What part of an amino acid differs between different amino acids?
The side group (R).
288
What amino acid is shown as an example on the slide?
Tyrosine.
289
What type of side group does tyrosine have?
A cyclic side group.
290
What groups are attached to the central carbon of an amino acid?
Amino group
Carboxyl group
Hydrogen
Side group (R)
291
How are peptide bonds between amino acids formed?
By dehydration synthesis.
292
What two amino acids are shown combining in the diagram?
Glycine and alanine.
293
What type of molecule is formed when glycine and alanine combine?
A dipeptide.
294
What is the name of the dipeptide formed from glycine and alanine?
Glycylalanine.
295
What bond forms between amino acids during dehydration synthesis?
A peptide bond.
296
What molecule is released during peptide bond formation?
Water (H₂O).
297
What process is shown removing water during peptide bond formation?
Dehydration synthesis.
298
What does the diagram show as the result of peptide bond formation?
Two amino acids joined into a dipeptide and water released.
299
What type of bond links amino acids together in proteins?
Peptide bonds.
300
What do nucleic acids consist of?
Nucleotides.
301
What are nucleotides composed of?
A pentose sugar
A phosphate group
A nitrogen-containing base
302
What type of nitrogen-containing bases are found in nucleotides?
Purine or pyrimidine bases.
303
How many kinds of nucleic acids are there?
Two kinds.
304
What are the two kinds of nucleic acids?
DNA (Deoxyribonucleic acid)
RNA (Ribonucleic acid)
305
What does DNA stand for?
Deoxyribonucleic acid.
306
What does RNA stand for?
Ribonucleic acid.
307
What type of molecule is DNA?
DNA is a double-stranded molecule that stores genetic information in all cells.
308
What are adenine, thymine, cytosine, and guanine?
They are nitrogenous bases (nucleobases).
309
What does a DNA nucleotide consist of?
A nitrogen-containing base, a pentose sugar, and a phosphate group.
310
What sugar is found in DNA?
Deoxyribose sugar.
311
How are individual DNA nucleotides connected within a strand?
Alternating sugar and phosphate groups form the backbone.
312
What forms the backbone of the DNA double helix?
Repeating sugar-phosphate combinations.
313
What forms the “rungs” of the DNA ladder?
Nitrogen-containing base pairs.
314
Which bases pair together in DNA?
Adenine pairs with thymine; guanine pairs with cytosine.
315
What type of bonds hold complementary base pairs together?
Hydrogen bonds.
316
How are the two DNA strands oriented relative to each other?
They are antiparallel.
317
What does antiparallel mean in terms of the sugar-phosphate backbone?
The backbone of one strand is upside down relative to the other strand.
318
How are carbon atoms in sugars identified?
By adding a marker, such as 5′ (five-prime).
319
What does the 5′ designation distinguish?
It distinguishes sugar carbon atoms from carbon atoms in nitrogenous bases.
320
What overall shape does DNA have?
A double helix.
321
How is the double-helical structure of DNA described?
A ladder-like form with base pairs as rungs and a sugar-phosphate backbone.
322
What does ATP stand for?
Adenosine triphosphate.
323
What components make up ATP?
Ribose, adenine, and three phosphate groups.
324
What is adenosine composed of?
Adenine and ribose.
325
How many phosphate groups does ATP contain?
Three phosphate groups.
326
How are the phosphate groups represented on the slide?
As three “P” units attached to adenosine.
Microbiology
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