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Biochemistry Year 1 > Part As - 2007-2011 > Flashcards

Part As - 2007-2011 Flashcards

1
Q

Primer annealing in the polymerase chain reaction is determined by

A

Sequence homology

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2
Q

In polymerase chain reaction DNA synthesis occurs in the … direction

A

5’->3’

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3
Q

In agarose gel electrophoresis under standard conditions, DNA migrates towards the … electrode

A

Positive

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4
Q

In agarose gel electrophoresis larger DNA fragments move … than smaller DNA fragments

A

Slower

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5
Q

In a DNA sequencing reaction, dideoxynucleotide triphosphates are added since they do not have a …

A

3’ OH group

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6
Q

DNA replication is

A

Semi-conservative

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7
Q

In … expression of genes is sometimes regulated by chromatin remodelling

A

Eukaryotes

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8
Q

… are activated by covalent linkage to amino acids

A

Transfer RNAs

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9
Q

… undergoes extensive post-transcriptional processing in the form of 5’ capping polyadenylation and splicing

A

Mammalian mRNA

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10
Q

… are coding sequences in gene transcripts

A

Exons

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11
Q

A vitamin whose deficiency is associated with an increased risk of neural tube defects

A

Thiamine

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12
Q

Site of ribosome assembly

A

nucleolus

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13
Q

Site for processing of very long chain fatty acids

A

peroxisome

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14
Q

site for synthesis of proteins destined for export from the cell

A

Rough ER

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15
Q

Site where fatty acids are alpha oxidised

A

mitochondrial matrix

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16
Q

Site for activation of sugars for oxidation

A

cytoplasm

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17
Q

Basic R group

A

Lysine

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18
Q

Sulphur-containing R group

A

Methionine

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19
Q

Aliphatic R group

A

Leucine

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20
Q

Aromatic R group

A

Phenylalanine

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21
Q

Acidic R group

A

Aspartate

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22
Q

Vmax

A

Rate of enzyme reaction at saturating substrate concentration

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23
Q

Km

A

Substrate concentration at half maximal velocity

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24
Q

Allostery

A

Co-operative enzymes

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25
Q

Competitive inhibition

A

Some inhibitors bind to enzyme active site

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26
Q

Kcat

A

Number of molecules of substrate converted to product in unit time

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27
Q

membrane phospholipid example

A

phosphatidyl choline

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28
Q

Precursor of bile salts

A

Cholesterol

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29
Q

Essential fatty acid

A

linoleic acid

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30
Q

Signalling molecule example

A

Cortisol

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31
Q

Storage form of fat

A

Triglyceride (triacyl glycerol)

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32
Q

The covalent bond between two adjacent amino acids in a polypeptide is called a …

A

Peptide bond

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33
Q

The level of structural organisation produced by interaction between two or more polypeptides
is called …

A

Quaternary

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34
Q

Secondary structure in polypeptides includes …

A

Beta-sheet

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35
Q

Disulphide bonds stabilise … structures in proteins

A

Quaternary

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36
Q

Histones are basic proteins that form … structures that associate with DNA to form nucleosomes.

A

Octameric

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37
Q

The presence of a nuclear envelope around the core genetic material defines a eukaryotic cell

A

True

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38
Q

Mitochondria are the powerhouse of the cells and have a small circular DNA genome

A

True

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39
Q

All ribosomes in the cell are associated with the rough endoplasmic reticulum

A

False

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40
Q

Endoplasmic reticulum and the Golgi apparatus play key roles in protein assembly.

A

True

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41
Q

Condensed chromatin is generally associated with gene inactivity.

A

True

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42
Q

Nucleosides lack a phosphate group but have a ribose sugar and nitrogenous base.

A

True

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43
Q

The two DNA strands in the double helix are said to run anti-parallel to each other.

A

True

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44
Q

Some genes may be directly translated into polypeptides without the intermediate RNA step.

A

False

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45
Q

Genes can be transcribed into RNAs but these RNAs are not necessarily translated into proteins

A

True

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46
Q

Both RNA and DNA form the same double helical structures.

A

False

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47
Q

What is the direction of DNA synthesis catalysed by a DNA-dependent DNA polymerase?

A

5’->3’

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48
Q

What are the enzymes that can cut double-stranded DNA at specific sequences?

A

Restriction endonucleases

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49
Q

What is the direction of DNA migration under standard electrophoretic conditions (pH 8.2)?

A

Towards cathode

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50
Q

What name is given to autonomously-replicating DNA molecules used in standard cloning reactions?

A

Plasmid vectors

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51
Q

What are the enzymes called that can that can join 3’OH and 5’PO ends of existing double stranded DNA molecules?

A

Ligases

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52
Q

There are specific sequences in messenger RNAs that interact with ribosomes to help them to initiate translation.

A

True

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53
Q

The carboxy terminus of polypeptides is produced first during protein synthesis

A

False

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54
Q

mRNA codons are read by ribosomes in a 5’ to 3’ direction.

A

True

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55
Q

Chromatin re-modelling, i.e. the modification of histones, provides an important level of regulatory control for transcription in eukaryotes.

A

True

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56
Q

Exons are the non-coding parts of eukaryotic pre-mRNA

A

False

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57
Q

Which macromolecules have been shown to display biological enzymatic activity?

A

Proteins and RNA

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58
Q

Enzyme specificity is achieved by substrate interaction with which feature of the enzyme?

A

The active site

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59
Q

Which name(s) are given to the various theories for how enzyme specificity is achieved?

A

Induced fit or Lock and key

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60
Q

How is enzyme activity normally regulated in a cell?

A

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

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61
Q

What features of allosteric enzymes allow for efficient regulation of enzyme activity?

A

Alternative 3D shapes or Quaternary structure

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62
Q

All amino acid sequence downstream of the mutation is altered

A

Frame shift

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63
Q

No change occurs to the protein coding sequence

A

Silent

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64
Q

The protein produced is shorter than normal.

A

Nonsense

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65
Q

The mutation that affects males

A

X- linked

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66
Q

The mutation results in substitution of one amino acid for another

A

Missense

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67
Q

The definition of a typical triglyceride is

A

glycerol with three fatty acids attached

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68
Q

Allows a substance to move up a concentration gradient

A

Active transport (solute pumping)

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69
Q

Net movement of particles from an area of higher concentration to an area of lower concentration until saturation achieved

A

Simple diffusion

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70
Q

Glucose is moved into cells via this transport process

A

Facilitated diffusion

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71
Q

Movement of water into and out of cells via membrane pores

A

Osmosis

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72
Q

Secretion of Neurotransmitters and hormones occurs in this way

A

Bulk transport - (exocytosis)

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73
Q

Serves as an external cell barrier and acts in transport of substances into or out of a cell

A

PM

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74
Q

Site of lipid and steroid synthesis.

A

Smooth ER

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75
Q

Site where ketone bodies are produced

A

Mitochondrial matrix

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76
Q

Site where gluconeogenesis takes place

A

Cytoplasm

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77
Q

Site of modification and packaging of proteins ready for secretion from the cell

A

Gogli apparatus

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78
Q

Collagen is the most abundant protein in the body

A

True

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79
Q

Structural proteins provide tensile strength to tissue

A

True

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80
Q

Myoglobin has a quaternary structure

A

False

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81
Q

Functional proteins are very stable molecules.

A

False

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82
Q

Collagen is found in bone, tendons, ligaments and cartilages

A

True

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83
Q

Cell stage where two copies of each chromosome exist is referred to as

A

G2

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84
Q

Phase in which separation of sister chromatids occurs

A

M

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85
Q

Phase in which cytokinesis occurs

A

anaphase and telophase

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86
Q

Phase in which cells that are not undergoing cell cycling are referred to as being

A

G0

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87
Q

Phase in which DNA replication takes place

A

S

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88
Q

Translation of messenger RNA by ribosomes polymerises amino acids from the … of the final
protein product.

A

amino->carboxy ends

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89
Q

Transcription of a gene by RNA polymerase reads from the …

A

5’->3’ ends

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90
Q

Ribosomes are composed of which macromolecules?

A

Protein and RNA

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91
Q

Chromatin is composed of which macromolecules?

A

Protein, RNA and DNA

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92
Q

Active genes are generally present in

A

Euchromatin

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93
Q

Ribosomal RNA is synthesized in the

A

Nucleolus

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94
Q

The end of a chromosome is referred to as a

A

Telomere

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95
Q

Chromosomes, other than X and Y chromosomes, are referred to as

A

Autosomal

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96
Q

The nuclear envelope is a double lipid membrane structure bridged by multiple … complexes

A

Nuclear pore

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97
Q

DNA size and identity

A

Southern blot

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98
Q

DNA sequence

A

Dideoxynucleotides

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99
Q

RNA size and identity

A

Northern blotting

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100
Q

Protein identity

A

Western blotting

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101
Q

Amplification of a DNA segment

A

PCR

102
Q

Mammalian - A DNA template and RNA primer are required for transcription

A

False

103
Q

Alternative splicing is a process for generating a number of different possible protein products from a single gene

A

True

104
Q

The poly(A) tail sequences of mRNAs are derived by sequential addition of adenine nucleotides to the 5’ end of the mRNA precursor.

A

False

105
Q

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.

A

False

106
Q

The 5’ cap sequence of the mature mRNA is encoded in the gene sequence

A

False

107
Q

Common sequence variants are referred to as

A

Polymorphism

108
Q

Mutagenic insertion or deletion of a single nucleotide in a gene exon causes a

A

Frame shift

109
Q

Most of the mutant genes in the population are in

A

heterozygous individuals

110
Q

Downs syndrome is an example of a

A

Trisomy

111
Q

Turner’s syndrome is an example of

A

Monosomy

112
Q

What type of mutation in DNA is this?
5’ATGACAATACCTCCCGCC -> 5’ATGAGAATACCTCCCGCC

A

Base substitution

113
Q

The co-linear relationship between genes and proteins means that

A

A linear array of triplet nucleotides determines the primary sequence of proteins

114
Q

RNA transcription in E.coli involves which of the following in addition to RNA polymerase

A

Sigma factor

115
Q

The chemical bond between two adjacent ribonucleotides in RNA is called

A

Phosphodiester bond

116
Q

Transfer RNAs are important in protein synthesis because

A

They can bind with both mRNA and amino acids

117
Q

The number of phosphate groups present in a nucleoside

A

0

118
Q

The number of sugar molecules in a nucleotide in DNA

A

1

119
Q

The number of phosphate groups per nucleotide in RNA

A

1

120
Q

The number of hydrogen bonds between adenine and cytosine in DNA

A

0

121
Q

The number of helical turns per ~10 nucleotides in natural B-form DNA

A

1

122
Q

Post-transcriptional modifications in eukaryotic mRNA include

A

5’ 7-methyl guanosine capping

123
Q

In humans, pre-mRNA is transcribed by

A

RNA polymerase II

124
Q

The process of splicing refers to

A

The removal of introns from pre-mRNA

125
Q

If the template DNA strand for transcription has the sequence 5’-GGCTAGACAAATGAC-3’ then the RNA transcript produced would have the following sequence

A

5’- GUCAUUUGUCUAGCC-3’

126
Q

Transcription of a eukaryotic gene requires

A

Recognition of promoter sequences by specific DNA-binding proteins

127
Q

The presence of a … around the core genetic material defines a eukaryotic cell.

A

Nuclear envelope

128
Q

The … in eukaryotic cells has its own small circular DNA genome

A

Mitochondrion

129
Q

Ribosomes in eukaryotic cells may be associated with the

A

Endoplasmic reticulum

130
Q

The endoplasmic reticulum and … play key roles in assembly and modification of cell surface and secreted proteins

A

Golgi apparatus

131
Q

The … is a site for degradation of macromolecules and recycling of their components

A

Lysosome

132
Q

A compound that reduces the VMAX but not the KM of an enzyme displays

A

Non-competitive inhibition

133
Q

This type of inhibition may be overcome by increasing substrate concentration

A

Competitive inhibition

134
Q

The differences in reaction rate versus substrate concentration exhibited by phosphofructokinase-1 in the presence or absence of ATP is an example of

A

Allostery

135
Q

Protein kinase A influences the activity of glycogen synthase by

A

Covalent modification

136
Q

Stabilisation of the reaction intermediate subsequent to formation of the enzyme-substrate complex refers to

A

Transition state

137
Q

The organelle that generates most ATP to drive cellular reactions requiring an input of free energy

A

mitochondrion

138
Q

The organelle that contains digestive enzymes that degrade macro-molecules and particles taken in from outside the cell by endocytosis

A

lysosome

139
Q

The organelle that contains enzymes used in various oxidative processing reactions

A

peroxisome

140
Q

The organelle that is involved in processing and packaging of proteins and lipids from the endoplasmic reticulum for secretion

A

Golgi apparatus

141
Q

Site of initial glycosylation of secreted proteins

A

rough endoplasmic reticulum

142
Q

During DNA replication, the incoming bases are in the form of

A

deoxynucleotide triphosphates

143
Q

Of the following enzymes, all are needed for DNA replication except

A

reverse transcriptase

144
Q

The replicative DNA polymerase

A

makes errors which it corrects by its 3´,5´- exonuclease activity

145
Q

In humans, transcription of DNA into RNA is performed by

A

RNA polymerases

146
Q

For translation of mRNA into a protein product, tRNA molecules react with

A

specific aminoacyl-AMPs

147
Q

If Angelman syndrome is caused by inheritance of both copies of one chromosome from one parent it is said to be

A

Uniparental Disomy

148
Q

A mutation in which the AAG codon (lysine) is change to ACG (threonine) is an example of

A

Missense mutation

149
Q

Which of the following amino acids has a net negative charge at pH 7.0?

A

glutamic acid

150
Q

Which of the following amino acids has a net positive charge at pH 7.0?

A

Lysine

151
Q

Which of the following amino acids can form disulphide bonds

A

Cystine

152
Q

Which of the following amino acids forms hydrophobic interactions with other non-polar amino acids?

A

Isoleucine

153
Q

Which of the following amino acids is both ketogenic and glucogenic?

A

Tyrosine

154
Q

In prokaryotes … are coupled

A

RNA transcription/Protein translation

155
Q

In eukaryotes … are coupled

A

RNA transcription/ RNA splicing

156
Q

Retroviruses copy RNA into double-stranded DNA using

A

Reverse transcription/DNA replication

157
Q

Eukaryotic pre-mRNA undergoes

A

Splicing/5´capping

158
Q

Translation in eukaryotic cells is

A

Cytoplasmic

159
Q

In the polymerase chain reaction, the primer annealing temperature is determined primarily by
the GC pair content.

A

True

160
Q

In a DNA sequencing reaction, dideoxynucleotide triphosphates are employed since they do not have a 3´ OH group

A

True

161
Q

In agarose gel electrophoresis larger DNA fragments move faster than smaller DNA fragments.

A

False

162
Q

The Michaelis constant (KM) reflects the affinity of an enzyme for its substrate

A

True

163
Q

The acid-base properties of an active site influence the rate of chemical catalysis

A

True

164
Q

Enzymes devoid of bound substrate are known as apo-enzymes

A

False

165
Q

Which of the following DOES NOT result from a single nucleotide addition to a gene?

A

A shorter RNA transcript

166
Q

Non-transmissable mutations in DNA occur in

A

Somatic cells

167
Q

Enzymes used to cut specific sequences in DNA molecules

A

Restriction endonucleases

168
Q

Enzymes used to join DNA

A

Ligases

169
Q

One type of cloning vector

A

Plasmid

170
Q

The method of introducing DNA into a bacterial cloning host

A

Transformation

171
Q

A selectable genetic marker

A

Ampicillin resistance gene

172
Q

Fragile X Syndrome is caused by

A

Triplet Repeat Expansion

173
Q

Females are mosaics expressing either the maternal or paternal X-chromosome in different cells

A

True

174
Q

Apart from trisomy 21 there no other trisomies found in live-born children

A

False

175
Q

Part of the Y-chromosome genome is homologous with part of the X-chromosome

A

True

176
Q

The backbone of DNA is composed of

A

pentose sugar and phosphate

177
Q

The maximum number of hydrogen bonds that a 12 nucleotide sequence can form with its complementary sequence

A

36

178
Q

The nitrogenous base in a nucleotide is attached to the sugar via a covalent

A

C-N bond

179
Q

Movement of water, nutrients, and gases through the capillary wall

A

Filtration

180
Q

During facilitated diffusion, the molecule to be transported across the membrane binds to a

A

Carrier protein

181
Q

Organisation of a peptide chain into alpha-helices and beta-sheets

A

Secondary Structure

182
Q

A type of post-translational modification that occurs in cytoplasm

A

Phosphorylation

183
Q

Used in the formation of alpha-helices

A

Hydrogen bond

184
Q

Residues involved in protein phosphorylation

A

Serine, tyrosine and threonine

185
Q

A force which is of particular importance in the core of globular proteins

A

Hydrophobic interactions

186
Q

Obtaining an mRNA sequence

A

Reverse transcriptase

187
Q

Obtaining DNA size and identity

A

Southern blot

188
Q

Obtaining protein size and identity

A

Western blot

189
Q

Obtaining amplification of a DNA segment

A

Oligonucleotide primers

190
Q

Obtaining subcloning of a DNA fragment

A

Vector

191
Q

The process of splicing refers to what?

A

Removal of introns from pre-mRNA

192
Q

In humans pre-mRNA is transcribed by which of the above?

A

RNAP II

193
Q

At what stage of mitosis are the chromosomes aligned along the centre of the dividing cell?

A

Metaphase

194
Q

Which mutation is most likely to lead to protein truncation?

A

Nonsense mutation

195
Q

Which of the above diseases is not due to a triplet repeat expansion?

A

Duchenne muscular dystrophy

196
Q

What is the pattern of inheritance associated with achondroplasia (short limb dwarfism)?

A

Autosomal dominant

197
Q

Which of the above statements is NOT true of mitochondrial DNA?

A

Encodes the majority of mitochondrial proteins

198
Q

Which compartment is responsible for the biosynthesis of membranes?

A

Smooth ER

199
Q

In which compartment does the initial processing of very long chain fatty acids occur?

A

Peroxisome

200
Q

Which compartment is responsible for the degradation and reutilisation of a wide range of macromolecules?

A

Lysosome

201
Q

Name an amino acidthat is non polar and hydrophobic?

A

Valine

202
Q

Which of these amino acids is polar, uncharged at physiological pH?

A

Serine

203
Q

Which of these amino acids is polar, charged at physiological pH?

A

Lysine

204
Q

Which of the following bonds, forces, or interactions are NOT responsible for stabilising 2°, 3° or 4° protein structures?

A

Weak nuclear forces

205
Q

Which of the above statements is true of α helices?

A

Proline disrupts alpha helices

206
Q

Which of the above statements is NOT true of enzymes?

A

alter the equilibrium of a reaction

207
Q

What does a competitive inhibitor do?

A

increases the Km of the enzyme

208
Q

What does a non competitive inhibitor do?

A

binds the enzyme at a site other than the active site

209
Q

A feature of allosteric enzymes that allows for efficient regulation of enzyme activity

A

Cooperativity between subunits

210
Q

An enzyme may catalyse a reaction by a number of mechanisms, which of the statements is NOT true?

A

Increase activation energy barrier of reaction

211
Q

Which of these statements is NOT true of collagen?

A

2° structure comprises supercoiled alpha helices

212
Q

Which of these statements is TRUE of collagen?

A

Polypeptide chains held together by interchain H bonds

213
Q

Organisation of peptide chain into beta sheets

A

Secondary structure

214
Q

Fully assembled and functional haemoglobin

A

Quaternary structure

215
Q

Which of these histones is NOT present in the nucleosomal histone octamer?

A

H1

216
Q

A necessary component of the polymerase chain reaction

A

Oligonucleotide primers

217
Q

An enzyme needed to complete the synthesis of the trailing strand during DNA replication

A

DNA ligase

218
Q

Nucleotide derivatives which are used in the Sanger (chain termination) method for DNA sequencing

A

Dideoxynucleotide triphosphate

219
Q

Site of action of peptide hormones such as insulin and glucagon

A

Plasma membrane

220
Q

Site of lipid and steroid synthesis

A

Smooth endoplasmic reticulum

221
Q

Site where ketone bodies are synthesised

A

Mitochondrial matrix

222
Q

Site where the pentose phosphate pathway takes place

A

Cytoplasm

223
Q

Site of modification and packaging of proteins ready for secretion from the cell

A

Golgi apparatus

224
Q

The backbone of DNA is composed of

A

pentose sugar and phosphate

225
Q

The number of hydrogen bonds that the nucleotide sequence ACGT can form with its complementary sequence

A

10

226
Q

The number of helical turns in 60 base pairs of natural B-form DNA

A

6

227
Q

The combined rate constant relating the formation and dissociation of the enzyme-substrate complex in an enzyme catalysed reaction

A

Km

228
Q

Enzymes increase the rate of reactions by reducing the

A

Ea

229
Q

Size and identity of a DNA molecule with

A

Southern blot

230
Q

Size of an RNA molecule with

A

Agarose gel electrophoresis

231
Q

Used for cloning of a cDNA molecule

A

Plasmid vector

232
Q

Used for cleavage of a DNA molecule at a specific sequence

A

Restriction enzyme

233
Q

Used for amplification of a specific DNA segment

A

PCR

234
Q

A mutation where the mutant phenotype is only present in homozygotes

A

Recessive

235
Q

Site for processing of primary gene transcripts into mature mRNAs

A

nucleus

236
Q

Km

A

A combined rate constant relating to the formation and dissociation of the enzyme-substrate complex

237
Q

Allostery

A

A property which depends on co-operativity between protein subunits

238
Q

Kcat

A

Number of molecules of substrate converted to product in unit time

239
Q

Competitive inhibition

A

Binding of an inhibitor to the enzyme active site

240
Q

One step in the processing of pre-mRNAs is

A

polyadenylation

241
Q

Chromatin is composed of

A

Protein and DNA

242
Q

During translation of messenger RNA by ribosomes, amino acids are added sequentially starting from the … end of the final protein product.

A

Amino terminal

243
Q

Proof-reading by DNA polymerases requires … enzyme activity

A

3’ to 5’ exonuclease

244
Q

One form of protein secondary structure is the

A

Beta sheet

245
Q

The greatest number of interactions between amino acids in folded proteins comprises

A

Van der Waals forces

246
Q

A covalent bond contributing to the tertiary structure of extra-cellular proteins is

A

Disulphide bond

247
Q

In the DNA molecule, the two strands

A

Are anti-parallel

248
Q

The structure of double-stranded DNA provides an efficient framework for replication, because

A

Each strand is a complementary copy of the other

249
Q

Which of the following enzymes is involved in the process of DNA replication in vivo?

A

Helicase

250
Q

DNA strands are anti-parallel. This means that

A

DNA strands run in opposite directions

Biochemistry Year 1 (2 decks)

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