Part As - 2007-2011 Flashcards
(250 cards)
1
Q
Primer annealing in the polymerase chain reaction is determined by
A
Sequence homology
2
Q
In polymerase chain reaction DNA synthesis occurs in the … direction
A
5’->3’
3
Q
In agarose gel electrophoresis under standard conditions, DNA migrates towards the … electrode
A
Positive
4
Q
In agarose gel electrophoresis larger DNA fragments move … than smaller DNA fragments
A
Slower
5
Q
In a DNA sequencing reaction, dideoxynucleotide triphosphates are added since they do not have a …
A
3’ OH group
6
Q
DNA replication is
A
Semi-conservative
7
Q
In … expression of genes is sometimes regulated by chromatin remodelling
A
Eukaryotes
8
Q
… are activated by covalent linkage to amino acids
A
Transfer RNAs
9
Q
… undergoes extensive post-transcriptional processing in the form of 5’ capping polyadenylation and splicing
A
Mammalian mRNA
10
Q
… are coding sequences in gene transcripts
A
Exons
11
Q
A vitamin whose deficiency is associated with an increased risk of neural tube defects
A
Thiamine
12
Q
Site of ribosome assembly
A
nucleolus
13
Q
Site for processing of very long chain fatty acids
A
peroxisome
14
Q
site for synthesis of proteins destined for export from the cell
A
Rough ER
15
Q
Site where fatty acids are alpha oxidised
A
mitochondrial matrix
16
Q
Site for activation of sugars for oxidation
A
cytoplasm
17
Q
Basic R group
A
Lysine
18
Q
Sulphur-containing R group
A
Methionine
19
Q
Aliphatic R group
A
Leucine
20
Q
Aromatic R group
A
Phenylalanine
21
Q
Acidic R group
A
Aspartate
22
Q
Vmax
A
Rate of enzyme reaction at saturating substrate concentration
23
Q
Km
A
Substrate concentration at half maximal velocity
24
Q
Allostery
A
Co-operative enzymes
25
Competitive inhibition
Some inhibitors bind to enzyme active site
26
Kcat
Number of molecules of substrate converted to product in unit time
27
membrane phospholipid example
phosphatidyl choline
28
Precursor of bile salts
Cholesterol
29
Essential fatty acid
linoleic acid
30
Signalling molecule example
Cortisol
31
Storage form of fat
Triglyceride (triacyl glycerol)
32
The covalent bond between two adjacent amino acids in a polypeptide is called a ...
Peptide bond
33
The level of structural organisation produced by interaction between two or more polypeptides
is called ...
Quaternary
34
Secondary structure in polypeptides includes ...
Beta-sheet
35
Disulphide bonds stabilise ... structures in proteins
Quaternary
36
Histones are basic proteins that form ... structures that associate with DNA to form nucleosomes.
Octameric
37
The presence of a nuclear envelope around the core genetic material defines a eukaryotic cell
True
38
Mitochondria are the powerhouse of the cells and have a small circular DNA genome
True
39
All ribosomes in the cell are associated with the rough endoplasmic reticulum
False
40
Endoplasmic reticulum and the Golgi apparatus play key roles in protein assembly.
True
41
Condensed chromatin is generally associated with gene inactivity.
True
42
Nucleosides lack a phosphate group but have a ribose sugar and nitrogenous base.
True
43
The two DNA strands in the double helix are said to run anti-parallel to each other.
True
44
Some genes may be directly translated into polypeptides without the intermediate RNA step.
False
45
Genes can be transcribed into RNAs but these RNAs are not necessarily translated into proteins
True
46
Both RNA and DNA form the same double helical structures.
False
47
What is the direction of DNA synthesis catalysed by a DNA-dependent DNA polymerase?
5’->3’
48
What are the enzymes that can cut double-stranded DNA at specific sequences?
Restriction endonucleases
49
What is the direction of DNA migration under standard electrophoretic conditions (pH 8.2)?
Towards cathode
50
What name is given to autonomously-replicating DNA molecules used in standard cloning reactions?
Plasmid vectors
51
What are the enzymes called that can that can join 3’OH and 5’PO ends of existing double stranded DNA molecules?
Ligases
52
There are specific sequences in messenger RNAs that interact with ribosomes to help them to initiate translation.
True
53
The carboxy terminus of polypeptides is produced first during protein synthesis
False
54
mRNA codons are read by ribosomes in a 5’ to 3’ direction.
True
55
Chromatin re-modelling, i.e. the modification of histones, provides an important level of regulatory control for transcription in eukaryotes.
True
56
Exons are the non-coding parts of eukaryotic pre-mRNA
False
57
Which macromolecules have been shown to display biological enzymatic activity?
Proteins and RNA
58
Enzyme specificity is achieved by substrate interaction with which feature of the enzyme?
The active site
59
Which name(s) are given to the various theories for how enzyme specificity is achieved?
Induced fit or Lock and key
60
How is enzyme activity normally regulated in a cell?
The enzyme is covalently modified so that its 3D shape is altered or the levels of molecules of similar shape to the substrate are altered
61
What features of allosteric enzymes allow for efficient regulation of enzyme activity?
Alternative 3D shapes or Quaternary structure
62
All amino acid sequence downstream of the mutation is altered
Frame shift
63
No change occurs to the protein coding sequence
Silent
64
The protein produced is shorter than normal.
Nonsense
65
The mutation that affects males
X- linked
66
The mutation results in substitution of one amino acid for another
Missense
67
The definition of a typical triglyceride is
glycerol with three fatty acids attached
68
Allows a substance to move up a concentration gradient
Active transport (solute pumping)
69
Net movement of particles from an area of higher concentration to an area of lower concentration until saturation achieved
Simple diffusion
70
Glucose is moved into cells via this transport process
Facilitated diffusion
71
Movement of water into and out of cells via membrane pores
Osmosis
72
Secretion of Neurotransmitters and hormones occurs in this way
Bulk transport - (exocytosis)
73
Serves as an external cell barrier and acts in transport of substances into or out of a cell
PM
74
Site of lipid and steroid synthesis.
Smooth ER
75
Site where ketone bodies are produced
Mitochondrial matrix
76
Site where gluconeogenesis takes place
Cytoplasm
77
Site of modification and packaging of proteins ready for secretion from the cell
Gogli apparatus
78
Collagen is the most abundant protein in the body
True
79
Structural proteins provide tensile strength to tissue
True
80
Myoglobin has a quaternary structure
False
81
Functional proteins are very stable molecules.
False
82
Collagen is found in bone, tendons, ligaments and cartilages
True
83
Cell stage where two copies of each chromosome exist is referred to as
G2
84
Phase in which separation of sister chromatids occurs
M
85
Phase in which cytokinesis occurs
anaphase and telophase
86
Phase in which cells that are not undergoing cell cycling are referred to as being
G0
87
Phase in which DNA replication takes place
S
88
Translation of messenger RNA by ribosomes polymerises amino acids from the ... of the final
protein product.
amino->carboxy ends
89
Transcription of a gene by RNA polymerase reads from the ...
5'->3' ends
90
Ribosomes are composed of which macromolecules?
Protein and RNA
91
Chromatin is composed of which macromolecules?
Protein, RNA and DNA
92
Active genes are generally present in
Euchromatin
93
Ribosomal RNA is synthesized in the
Nucleolus
94
The end of a chromosome is referred to as a
Telomere
95
Chromosomes, other than X and Y chromosomes, are referred to as
Autosomal
96
The nuclear envelope is a double lipid membrane structure bridged by multiple ... complexes
Nuclear pore
97
DNA size and identity
Southern blot
98
DNA sequence
Dideoxynucleotides
99
RNA size and identity
Northern blotting
100
Protein identity
Western blotting
101
Amplification of a DNA segment
PCR
102
Mammalian - A DNA template and RNA primer are required for transcription
False
103
Alternative splicing is a process for generating a number of different possible protein products from a single gene
True
104
The poly(A) tail sequences of mRNAs are derived by sequential addition of adenine nucleotides to the 5' end of the mRNA precursor.
False
105
Spicing of introns is dependent on highly conserved GU and AG dinucleotides at the 3' splice donor and 5' splice acceptor ends of the introns respectively.
False
106
The 5' cap sequence of the mature mRNA is encoded in the gene sequence
False
107
Common sequence variants are referred to as
Polymorphism
108
Mutagenic insertion or deletion of a single nucleotide in a gene exon causes a
Frame shift
109
Most of the mutant genes in the population are in
heterozygous individuals
110
Downs syndrome is an example of a
Trisomy
111
Turner's syndrome is an example of
Monosomy
112
What type of mutation in DNA is this?
5'ATGACAATACCTCCCGCC -> 5'ATGAGAATACCTCCCGCC
Base substitution
113
The co-linear relationship between genes and proteins means that
A linear array of triplet nucleotides determines the primary sequence of proteins
114
RNA transcription in E.coli involves which of the following in addition to RNA polymerase
Sigma factor
115
The chemical bond between two adjacent ribonucleotides in RNA is called
Phosphodiester bond
116
Transfer RNAs are important in protein synthesis because
They can bind with both mRNA and amino acids
117
The number of phosphate groups present in a nucleoside
0
118
The number of sugar molecules in a nucleotide in DNA
1
119
The number of phosphate groups per nucleotide in RNA
1
120
The number of hydrogen bonds between adenine and cytosine in DNA
0
121
The number of helical turns per ~10 nucleotides in natural B-form DNA
1
122
Post-transcriptional modifications in eukaryotic mRNA include
5' 7-methyl guanosine capping
123
In humans, pre-mRNA is transcribed by
RNA polymerase II
124
The process of splicing refers to
The removal of introns from pre-mRNA
125
If the template DNA strand for transcription has the sequence 5'-GGCTAGACAAATGAC-3' then the RNA transcript produced would have the following sequence
5'- GUCAUUUGUCUAGCC-3'
126
Transcription of a eukaryotic gene requires
Recognition of promoter sequences by specific DNA-binding proteins
127
The presence of a ... around the core genetic material defines a eukaryotic cell.
Nuclear envelope
128
The ... in eukaryotic cells has its own small circular DNA genome
Mitochondrion
129
Ribosomes in eukaryotic cells may be associated with the
Endoplasmic reticulum
130
The endoplasmic reticulum and ... play key roles in assembly and modification of cell surface and secreted proteins
Golgi apparatus
131
The ... is a site for degradation of macromolecules and recycling of their components
Lysosome
132
A compound that reduces the VMAX but not the KM of an enzyme displays
Non-competitive inhibition
133
This type of inhibition may be overcome by increasing substrate concentration
Competitive inhibition
134
The differences in reaction rate versus substrate concentration exhibited by phosphofructokinase-1 in the presence or absence of ATP is an example of
Allostery
135
Protein kinase A influences the activity of glycogen synthase by
Covalent modification
136
Stabilisation of the reaction intermediate subsequent to formation of the enzyme-substrate complex refers to
Transition state
137
The organelle that generates most ATP to drive cellular reactions requiring an input of free energy
mitochondrion
138
The organelle that contains digestive enzymes that degrade macro-molecules and particles taken in from outside the cell by endocytosis
lysosome
139
The organelle that contains enzymes used in various oxidative processing reactions
peroxisome
140
The organelle that is involved in processing and packaging of proteins and lipids from the endoplasmic reticulum for secretion
Golgi apparatus
141
Site of initial glycosylation of secreted proteins
rough endoplasmic reticulum
142
During DNA replication, the incoming bases are in the form of
deoxynucleotide triphosphates
143
Of the following enzymes, all are needed for DNA replication except
reverse transcriptase
144
The replicative DNA polymerase
makes errors which it corrects by its 3´,5´- exonuclease activity
145
In humans, transcription of DNA into RNA is performed by
RNA polymerases
146
For translation of mRNA into a protein product, tRNA molecules react with
specific aminoacyl-AMPs
147
If Angelman syndrome is caused by inheritance of both copies of one chromosome from one parent it is said to be
Uniparental Disomy
148
A mutation in which the AAG codon (lysine) is change to ACG (threonine) is an example of
Missense mutation
149
Which of the following amino acids has a net negative charge at pH 7.0?
glutamic acid
150
Which of the following amino acids has a net positive charge at pH 7.0?
Lysine
151
Which of the following amino acids can form disulphide bonds
Cystine
152
Which of the following amino acids forms hydrophobic interactions with other non-polar amino acids?
Isoleucine
153
Which of the following amino acids is both ketogenic and glucogenic?
Tyrosine
154
In prokaryotes ... are coupled
RNA transcription/Protein translation
155
In eukaryotes ... are coupled
RNA transcription/ RNA splicing
156
Retroviruses copy RNA into double-stranded DNA using
Reverse transcription/DNA replication
157
Eukaryotic pre-mRNA undergoes
Splicing/5´capping
158
Translation in eukaryotic cells is
Cytoplasmic
159
In the polymerase chain reaction, the primer annealing temperature is determined primarily by
the GC pair content.
True
160
In a DNA sequencing reaction, dideoxynucleotide triphosphates are employed since they do not have a 3´ OH group
True
161
In agarose gel electrophoresis larger DNA fragments move faster than smaller DNA fragments.
False
162
The Michaelis constant (KM) reflects the affinity of an enzyme for its substrate
True
163
The acid-base properties of an active site influence the rate of chemical catalysis
True
164
Enzymes devoid of bound substrate are known as apo-enzymes
False
165
Which of the following DOES NOT result from a single nucleotide addition to a gene?
A shorter RNA transcript
166
Non-transmissable mutations in DNA occur in
Somatic cells
167
Enzymes used to cut specific sequences in DNA molecules
Restriction endonucleases
168
Enzymes used to join DNA
Ligases
169
One type of cloning vector
Plasmid
170
The method of introducing DNA into a bacterial cloning host
Transformation
171
A selectable genetic marker
Ampicillin resistance gene
172
Fragile X Syndrome is caused by
Triplet Repeat Expansion
173
Females are mosaics expressing either the maternal or paternal X-chromosome in different cells
True
174
Apart from trisomy 21 there no other trisomies found in live-born children
False
175
Part of the Y-chromosome genome is homologous with part of the X-chromosome
True
176
The backbone of DNA is composed of
pentose sugar and phosphate
177
The maximum number of hydrogen bonds that a 12 nucleotide sequence can form with its complementary sequence
36
178
The nitrogenous base in a nucleotide is attached to the sugar via a covalent
C-N bond
179
Movement of water, nutrients, and gases through the capillary wall
Filtration
180
During facilitated diffusion, the molecule to be transported across the membrane binds to a
Carrier protein
181
Organisation of a peptide chain into alpha-helices and beta-sheets
Secondary Structure
182
A type of post-translational modification that occurs in cytoplasm
Phosphorylation
183
Used in the formation of alpha-helices
Hydrogen bond
184
Residues involved in protein phosphorylation
Serine, tyrosine and threonine
185
A force which is of particular importance in the core of globular proteins
Hydrophobic interactions
186
Obtaining an mRNA sequence
Reverse transcriptase
187
Obtaining DNA size and identity
Southern blot
188
Obtaining protein size and identity
Western blot
189
Obtaining amplification of a DNA segment
Oligonucleotide primers
190
Obtaining subcloning of a DNA fragment
Vector
191
The process of splicing refers to what?
Removal of introns from pre-mRNA
192
In humans pre-mRNA is transcribed by which of the above?
RNAP II
193
At what stage of mitosis are the chromosomes aligned along the centre of the dividing cell?
Metaphase
194
Which mutation is most likely to lead to protein truncation?
Nonsense mutation
195
Which of the above diseases is not due to a triplet repeat expansion?
Duchenne muscular dystrophy
196
What is the pattern of inheritance associated with achondroplasia (short limb dwarfism)?
Autosomal dominant
197
Which of the above statements is NOT true of mitochondrial DNA?
Encodes the majority of mitochondrial proteins
198
Which compartment is responsible for the biosynthesis of membranes?
Smooth ER
199
In which compartment does the initial processing of very long chain fatty acids occur?
Peroxisome
200
Which compartment is responsible for the degradation and reutilisation of a wide range of macromolecules?
Lysosome
201
Name an amino acidthat is non polar and hydrophobic?
Valine
202
Which of these amino acids is polar, uncharged at physiological pH?
Serine
203
Which of these amino acids is polar, charged at physiological pH?
Lysine
204
Which of the following bonds, forces, or interactions are NOT responsible for stabilising 2°, 3° or 4° protein structures?
Weak nuclear forces
205
Which of the above statements is true of α helices?
Proline disrupts alpha helices
206
Which of the above statements is NOT true of enzymes?
alter the equilibrium of a reaction
207
What does a competitive inhibitor do?
increases the Km of the enzyme
208
What does a non competitive inhibitor do?
binds the enzyme at a site other than the active site
209
A feature of allosteric enzymes that allows for efficient regulation of enzyme activity
Cooperativity between subunits
210
An enzyme may catalyse a reaction by a number of mechanisms, which of the statements is NOT true?
Increase activation energy barrier of reaction
211
Which of these statements is NOT true of collagen?
2° structure comprises supercoiled alpha helices
212
Which of these statements is TRUE of collagen?
Polypeptide chains held together by interchain H bonds
213
Organisation of peptide chain into beta sheets
Secondary structure
214
Fully assembled and functional haemoglobin
Quaternary structure
215
Which of these histones is NOT present in the nucleosomal histone octamer?
H1
216
A necessary component of the polymerase chain reaction
Oligonucleotide primers
217
An enzyme needed to complete the synthesis of the trailing strand during DNA replication
DNA ligase
218
Nucleotide derivatives which are used in the Sanger (chain termination) method for DNA sequencing
Dideoxynucleotide triphosphate
219
Site of action of peptide hormones such as insulin and glucagon
Plasma membrane
220
Site of lipid and steroid synthesis
Smooth endoplasmic reticulum
221
Site where ketone bodies are synthesised
Mitochondrial matrix
222
Site where the pentose phosphate pathway takes place
Cytoplasm
223
Site of modification and packaging of proteins ready for secretion from the cell
Golgi apparatus
224
The backbone of DNA is composed of
pentose sugar and phosphate
225
The number of hydrogen bonds that the nucleotide sequence ACGT can form with its complementary sequence
10
226
The number of helical turns in 60 base pairs of natural B-form DNA
6
227
The combined rate constant relating the formation and dissociation of the enzyme-substrate complex in an enzyme catalysed reaction
Km
228
Enzymes increase the rate of reactions by reducing the
Ea
229
Size and identity of a DNA molecule with
Southern blot
230
Size of an RNA molecule with
Agarose gel electrophoresis
231
Used for cloning of a cDNA molecule
Plasmid vector
232
Used for cleavage of a DNA molecule at a specific sequence
Restriction enzyme
233
Used for amplification of a specific DNA segment
PCR
234
A mutation where the mutant phenotype is only present in homozygotes
Recessive
235
Site for processing of primary gene transcripts into mature mRNAs
nucleus
236
Km
A combined rate constant relating to the formation and dissociation of the enzyme-substrate complex
237
Allostery
A property which depends on co-operativity between protein subunits
238
Kcat
Number of molecules of substrate converted to product in unit time
239
Competitive inhibition
Binding of an inhibitor to the enzyme active site
240
One step in the processing of pre-mRNAs is
polyadenylation
241
Chromatin is composed of
Protein and DNA
242
During translation of messenger RNA by ribosomes, amino acids are added sequentially starting from the ... end of the final protein product.
Amino terminal
243
Proof-reading by DNA polymerases requires ... enzyme activity
3' to 5' exonuclease
244
One form of protein secondary structure is the
Beta sheet
245
The greatest number of interactions between amino acids in folded proteins comprises
Van der Waals forces
246
A covalent bond contributing to the tertiary structure of extra-cellular proteins is
Disulphide bond
247
In the DNA molecule, the two strands
Are anti-parallel
248
The structure of double-stranded DNA provides an efficient framework for replication, because
Each strand is a complementary copy of the other
249
Which of the following enzymes is involved in the process of DNA replication in vivo?
Helicase
250
DNA strands are anti-parallel. This means that
DNA strands run in opposite directions
