mb part 2 Flashcards
(271 cards)
1
Q
While proposing the —- for DNA, Watson and Crick had immediately proposed a scheme
for—- .
A
double helical structure
replication of DNA
2
Q
original statement of watson and crick is:
‘‘It has not escaped our notice that the—– we have postulated immediately suggests a
possible—- for the genetic material’’
(Watson and Crick,— ).
A
specific pairing, copying mechanism
1953
3
Q
The scheme of watson and crick for replication suggested that the two strands would— and act as —- for the synthesis of —- .
A
separate, a template
complementary strands
4
Q
After the completion of
replication, each DNA molecule would have one
— and — strand.
This scheme was termed as — DNA replication
A
parental and one newly synthesised strand.
semiconservative
5
Q
It is now proven that DNA replicates—- , shown first in — and subsequently in—–
A
semiconservatively
Escherichia coli
higher organisms, such as plants and human cells.
6
Q
— Meselson and—- Stahl performed the exp in — :
A
Matthew , Franklin
1958
7
Q
MSE:
(i) They grew E. coli in a medium containing —- as the only nitrogen source for—- .
The result was that — was incorporated into newly synthesised DNA (as well as —-).
A
15NH4Cl (15N is the HEAVY
isotope of nitrogen)
many generations
15N
other nitrogen containing compounds
8
Q
This heavy DNA molecule could be distinguished from the normal DNA by—– IN —-
A
centrifugation in a cesium chloride (CsCl) density gradient
9
Q
15N is not a — isotope, and it can be separated from 14N only based on — .
A
radioactive
densities
10
Q
Then they transferred the cells into a medium with normal— and took samples at —- as
the cells multiplied, and extracted the DNA that remained as —–.
The various samples were separated—- to measure the densities of DNA
A
14NH4Cl
various definite time intervals
double-stranded helices
independently on CsCl gradients
11
Q
Can you recall what centrifugal force is, and think why a molecule with higher mass/density would sediment faster?
A
centrifugal force, angular velocity and mass are inversely proportional to each other. Thus a higher density molecule will sediment faster in centrifugation.
12
Q
Thus, the DNA that was extracted from the culture one
generation after the transfer from 15N to 14N medium [that is
after —- ; E. coli divides in —-] had a hybrid or
—- density. DNA extracted from the culture after
another generation [that is after 40 minutes, II generation] was composed of —- of this hybrid DNA and of ‘light’
DNA.
A
20 minutes, 20 minutes
intermediate
equal amounts
13
Q
Very similar experiments involving use of —- to
detect distribution of newly synthesised DNA in the — was
performed on —- faba (—-) by —– .
The experiments proved that the DNA in CHROMOSOMES also replicate
semiconservatively.
A
radioactive thymidine
chromosomes
Vicia
faba beans
Taylor and colleagues in 1958
14
Q
In living cells, such as —-, the process of replication requires a set of —- (enzymes). The main enzyme is referred to as DNA-dependent
DNA polymerase since it uses a —- to catalyse the
—-.
A
E. coli, catalysts
DNA template
polymerisation of deoxynucleotides
15
Q
DNA-dependent
DNA polymerase enzymes are —- enzymes as they have to catalyse polymerisation of a large number of —-
A
highly efficient
nucleotides in a very short time
16
Q
. E. coli that has only 4.6 ×106 bp (compare
it with human whose diploid content is —), completes the
process of replication within —-; that means the — rate of polymerisation has to be approximately —–
A
6.6 × 10^ 9 bp
18 minutes
average
2000 bp per second.
17
Q
Not only do these polymerases have to be — , but they also have to catalyse the reaction
with —.
Any mistake during replication would result
into —- .
A
fast, high degree of accuracy
mutations
18
Q
Furthermore, — replication is a very expensive process.
A
energetically
19
Q
—- serve dual purposes. In addition to acting as substrates, they provide energy for polymerisation
reaction (the two — in a deoxynucleoside triphosphates
are —-, same as in case of ATP).
A
Deoxyribonucleoside triphosphates
terminal phosphates
high-energy phosphates
20
Q
In addition to DNA-dependent DNA polymerases, many additional enzymes are required to complete the process of replication with —-
A
high degree of accuracy.
21
Q
For — DNA molecules, since the two strands of
DNA cannot be separated in its —- (due to very —-), the replication occur within a —- referred to as replication –
A
long
entire length
high energy requirement
small opening of the DNA helix,
fork
22
Q
The DNA-dependent DNA
polymerases catalyse polymerisation only in one direction, that is —-
This creates some — at the replicating fork.
A
5 prime to 3 prime
additional complications
23
Q
Consequently, on one strand (the template with polarity 3 to 5 prime), the
replication is —, while on the other (the template with polarity 5’ to 3’), it is —.
A
continuous, discontinuous
24
Q
The —- fragments are later joined by the enzyme DNA ligase
A
discontinuously synthesised
25
The DNA polymerases on their own --- the process of replication.
cannot initiate
26
Also the replication does not initiate randomly at any place in DNA. There is a definite region in ---- DNA where the replication originates. Such regions are termed as ---
E. coli
origin of replication
27
It is because of the requirement of the --- that a piece of DNA if needed to be ---- during recombinant DNA procedures, requires a vector.
origin of replication
propagated
28
The --- provide the origin of replication during recombinant dna procedures
vectors
29
Further, not every detail of --- is understood well.
replication
30
In ---- , the replication of
DNA takes place at S-phase of the cell-cycle.
eukaryotes
31
The replication of DNA and cell division cycle should be ----.
highly coordinated
32
A failure in cell division after DNA replication results into --- (a
---).
polyploidy
chromosomal anomaly
33
Def Transcription.
The process of copying genetic information from one strand of the DNA into RNA is termed as
transcription
34
In Transcription also, --- governs the process of transcription, except the --- complements now forms base pair with uracil instead of thymine.
complementarity
adenosine
35
However, unlike in the process of replication, which ---, the --- DNA of an organism gets duplicated, in transcription only a --- of DNA and only --- is copied into RNA.
This necessitates defining the --- that would demarcate the region and the strand of DNA that
would be transcribed
once set in
total
segment, one of the strands
boundaries
36
Both the strands are not copied during transcription because:
1. If both strands act as a---, they would code
for RNA molecule with ----(Remember complementarity
does not mean ----)
and in turn, if they code for proteins, the sequence of --- in the proteins would be different. Hence, one segment of the DNA would be coding for two different proteins, and this would
------.
2. the two RNA molecules if produced simultaneously would be complementary to
each other, hence would form---- RNA.
This would prevent
---- and the exercise of transcription would become a --- one.
template, different sequences
identical
amino acids
complicate the genetic information transfer machinery
a double stranded
RNA from being translated into protein
futile
37
A --- unit in DNA is defined --- by the three regions in
the DNA:
(i) A Promoter
(ii) The Structural ---
(iii) A Terminator
transcription, primarily,
gene
38
There is a convention in defining the two strands of the DNA in the
--- of a transcription unit.
structural gene
39
Since the two strands have --- and the DNA-dependent --- polymerase also catalyse the polymerisation in only one direction, that is, --- the strand that has
the polarity 3'→5' acts as a ----, and is also referred to as ----
opposite polarity
RNA
5'→3',
template
template strand
40
The other strand of dna which has the polarity (5'→3') and the --- (except ----), is displaced during
transcription.
sequence same as RNA
thymine at the place of uracil
41
Strangely, this strand (5' to 3') (which ----) is referred to as coding strand.
does not code for anything
42
All the reference point while defining a
transcription unit is made with ----
coding strand
43
The promoter and terminator flank the --- in a transcription unit.
structural gene
44
The promoter is said to be located towards 5' -end (----) of the structural gene (the reference is made with respect to
the ----).
upstream
polarity of coding strand
45
It is a --- sequence that provides --- for RNA polymerase, and it is the presence of a ---- in a transcription unit that also --- the template and coding strands.
DNA
binding site
promoter
defines
46
By switching promoters position with terminator: -----
the definition of coding and template strands could be reversed
47
The terminator is located towards 3' -end (--- ) of the coding strand and it ---- of the process of transcription
downstream
usually defines the end
48
There are --- sequences that may be present further upstream or downstream to the
---.
additional regulatory
promoter
49
A gene is defined as ---
the FUNCTIONAL unit of inheritance.
50
Though there is no --- that the genes are located on the ---, it is difficult to literally define a gene in terms of ----
ambiguity
DNA
DNA sequence.
51
The DNA sequence coding for ---- or --- molecule also define a gene
tRNA or rRNA
52
However by defining a --- as a segment of DNA coding for a ---, the structural gene in a
transcription unit could be said as monocistronic (mostly in ---) or polycistronic (mostly in ----).
cistron, polypeptide
eukaryotes
bacteria or prokaryotes
53
In eukaryotes, the
monocistronic --- have --- sequences; the genes in eukaryotes are ----
structural genes
interrupted coding
split
54
The coding sequences or ---- are defined as ---.
expressed sequences
Exons
55
Exons are said to be those sequence that appear in ---- RNA.
mature or processed
56
The exons are interrupted by --- .
introns
57
Introns or --- do not appear in mature or
--- RNA.
intervening sequences
processed
58
The ---- further complicates the
definition of a gene in terms of a DNA segment
split-gene arrangement
59
Inheritance of a character is also affected by ---- and ---- sequences of a structural gene.
promoter and regulatory
60
Hence, sometime the regulatory sequences
are --- as regulatory genes, even though these sequences ----
loosely defined
do not code for any RNA or protein.
61
In ---, there are three major types of RNAs: ---, ---, ----.
bacteria
mRNA (messenger RNA),
tRNA (transfer RNA), and rRNA (ribosomal RNA)
62
--- RNAs are needed to synthesise a protein in a cell.
All three
63
The mRNA provides the ---, tRNA brings --- and reads the ----, and rRNAs play --- and --- role during ----.
template
aminoacids, genetic code
structural and catalytic
translation
64
There is --- DNA- dependent RNA polymerase that catalyses transcription of all types
of RNA in ---.
single, bacteria
65
RNA polymerase binds to --- and initiates
transcription (----)
It uses nucleoside triphosphates as --- and polymerises in a --- fashion following the rule of ----.
promoter
Initiation
substrate
template depended
complementarity
66
RNA polymerase somehow also facilitates opening of the ---- and -----.
helix and continues elongation
67
Only a short stretch of RNA remains ----.
bound to the enzyme (RNA pol)
68
Once the polymerases reaches the terminator region, the --- falls off, so also the ----.
This results in termination of ---
nascent RNA, RNA polymerase
transcription
69
An intriguing question is that how is the RNA polymerases able
to catalyse all the three steps, which are ---, --- and ---.
initiation, elongation and
termination
70
The RNA polymerase is ONLY capable of catalysing the process of ----.
elongation
71
RNA pol associates --- with initiation-factor ----
and termination-factor ---to initiate and terminate the transcription,
respectively.
Association with these factors alter the --- of the RNA polymerase to either initiate or terminate
transiently
(σ), (ρ)
specificity
72
In bacteria, since the --- does not require any processing to become
active, and also since transcription and translation take place in the --- (there is no separation of --- in bacteria), many times the translation can begin ---
mRNA
same compartment
cytosol and nucleus
much before the mRNA is fully transcribed.
73
Consequently, the transcription and translation can be --- in bacteria.
coupled
74
In eukaryotes, there are two additional complexities –
(i) There are --- RNA polymerases in the --- (in addition to the RNA polymerase found in the ---).
AT LEAST three
nucleus
organelles
75
There is a clear cut --- of RNA polymerase in eukaryotes.
division of labour
76
The RNA polymerase -- transcribes rRNAs
(---)
I- 28S, 18S, and 5.8S
77
RNA polymerase III is responsible for transcription of ----,--- and ----.
tRNA, 5srRNA, and snRNAs (small nuclear
RNAs)
78
The RNA polymerase II transcribes ----, the ----
precursor of mRNA-
heterogeneous nuclear RNA (hnRNA).
79
The second complexity in eukaryotic transcription is that the ---- contain both
the exons and the introns and are ---
primary transcripts
non-functional
80
Hence, Primary transcript is subjected to a process called -- where the --- are removed and exons ---.
splicing, introns
are joined in a defined order
81
--- undergoes
additional processing called as capping and tailing.
hnRNA
82
In capping an --- (--) is added to the --- end of ---
unusual nucleotide (methyl guanosine triphosphate)
5'-end of hnRNA.
83
In tailing, ---- (---) are
added at --- end in a template --- manner.
adenylate residues (200-300)
3'-end
independent
84
It is the fully processed --, now called mRNA, that is transported out of the
nucleus for ---
hnRNA
translation
85
The ---- of such complexities in eukaryotic transcription is now beginning to be
understood.
significance
86
The --- represent probably an ancient
feature of the genome.
split-gene arrangements
87
The presence of introns is ----, and the process of splicing represents the ----.
reminiscent of antiquity
dominance of RNA-world
88
In recent times, the understanding of ---- and ---- in the living system have assumed more importance.
RNA and RNA-dependent processes
89
During replication and transcription a --- was copied to form another ---. Hence, these processes are easy to conceptualise
on the basis of ---.
nucleic acid, nucleic acid
complementarity
90
The process of translation requires transfer of genetic information from a ---- to synthesise ----.
polymer of nucleotides to synthesise a polymer of amino acids
91
Neither does any complementarity exist between --- and ---, nor could any be drawn theoretically.
nucleotides and amino acids
92
There existed ---, though, to support the notion that change in --- (--) were responsible for change in amino acids in proteins.
ample evidences
nucleic acids (genetic material)
93
This led to the proposition of a --- that could direct the sequence of amino acids during synthesis of ---.
genetic code
proteins
94
If determining the --- of genetic material and the
structure of DNA was very exciting, the proposition and --- were most ---.
biochemical nature
deciphering of
genetic code
challenging
95
In a very true sense, Proposition of genetic code required
involvement of scientists from several disciplines – ----,----,----,----.
physicists, organic
chemists, biochemists and geneticists
96
It was ---, a ---,
who argued that since there are only 4 bases and if they have to code for 20 amino acids, the code should constitute a ----.
George Gamow
physicist
combination of bases
97
George gamow suggested that in order to code for all the 20 amino acids, the code should be made up of ---.
This was a very ---proposition, because
a permutation combination of 4^3
(4 × 4 × 4) would generate -----;
generating ----.
three nucleotides
bold
64 codons, many more codons than required
98
Providing proof that the ----- was a ,more daunting task
code was triplet
99
The ---- method developed by ---- was instrumental in synthesising RNA molecules with defined combinations of bases (--- and ----).
chemical
Har Gobind Khorana
homopolymers and copolymers
100
---- and ----, --- system for protein synthesis finally helped the code to be deciphered.
Marshall Nirenberg’s cell-free
101
---- enzyme (---) was also helpful in polymerising RNA with defined sequences in a template independent manner (----).
Severo Ochoa
polynucleotide phosphorylase
enzymatic synthesis of RNA
102
(i) The codon is ----.
--- codons code for amino acids and ---codons do
not code for any amino acids, hence they function as ----
triplet
61, 3- stop codons.
103
(ii) Some --- are coded by ----, hence the code is ----.
amino acids
more than one codon
degenerate
104
(iii) The codon is read in ---in a --- fashion. There are
no punctuations.
mRNA , contiguous
105
(iv) The code is --- : for example, from bacteria to human UUU would code for ----
NEARLY universal
Phenylalanine (phe).
106
Some exceptions to this
rule of universality of code have been found in --- codons, and in some ---.
mitochondrial, protozoans
107
(v) --- has dual functions. It codes for --- , and it
also act as --- codon.
AUG
Methionine (met), initiator
108
(vi) UAA, UAG, UGA are ---- codons
stop terminator
109
The relationships between ---- are best understood by mutation
studies.
genes and DNA
110
Effects of ---- and ---- in a segment of DNA are easy to comprehend. It may result in loss or gain of a gene and so a ---.
large deletions and rearrangements, function
111
A classical example of
--- is a change of single --- in the gene for -- chain that results in the change of amino acid residue ---- to ----
It results into a diseased condition called as ---.
point mutation
base pair
beta globin
glutamate to valine.
sickle cell anemia
112
Insertion or deletion of --- changes the reading frame from ----
However, such mutations are referred to as ----- insertion or ---- mutation
one or two bases
the point of
insertion or deletion.
frameshift insertion or deletion mutations
113
Insertion or deletion of
---- insert or delete in one or multiple codon hence
one or multiple ---, and reading frame remains unaltered from
that point onwards
three or its multiple bases
amino acids
114
From the very beginning of the proposition of code, it was clear to --- that there has to be a mechanism to read the --- and also to link it
to the ---, because amino acids have no---- .
Francis Crick
code , amino acids
structural specialities to
read the code uniquely
115
Francis crick postulated the presence of an ---molecule that would on one hand --- and on other hand would --- .
adapter
read the code , would bind to specific amino acids
116
The tRNA, then called sRNA (--- RNA), was known --- code was postulated. However, its role as an adapter molecule was assigned much later.
soluble, before the genetic
117
tRNA has an
--- loop that has bases
complementary to
the code, and it also
has an --- end to
which it binds to
amino acids.
anticodon
amino acid acceptor
118
tRNAs are specific
for each amino acid
T/F
true
119
For initiation, there is
another specific tRNA that is referred to as ----.
initiator tRNA
120
There are --- tRNAs for stop codons.
no
121
The --- structure of tRNA looks like a clover-leaf.
secondary
122
In actual structure, the
tRNA is a --- molecule which looks like -----
compact, inverted L
123
Translation refers to the process of ----
polymerisation of amino acids to form a polypeptide
124
The--- and --- of amino acids are defined by the sequence of bases in the ---.
order and sequence
mRNA
125
The amino acids are
joined by a bond which is known as a ----.
peptide bond
126
Formation of a
peptide bond requires ---.
energy
127
If two such --- tRNAs
are brought close enough, the formation of peptide bond between them would be----
charged
favoured energetically
128
Therefore, in the first phase itself amino
acids are activated in the presence of --- and linked to their ----, a process commonly called as --- or ---- to be more specific.
ATP , cognate tRNA
charging of tRNA or
aminoacylation of tRNA
129
The presence of a ---would enhance the --- of peptide bond formation.
catalyst, rate
130
The ---- responsible for
synthesising proteins is the ribosome.
cellular factory
131
The ribosome consists of --- and about ---.
structural RNAs and 80 different proteins
132
In a ribosome's --- state, it exists as two subunits; a large subunit and a small
subunit.
inactive
133
When the --- encounters an --- , the process of
translation of the mRNA to protein begins.
small subunit of ribosome
mRNA
134
There are -- sites in the ---, for subsequent amino acids to bind to and thus, be --- for the formation of a peptide bond
2, large subunit
close enough
to each other
135
The ribosome also acts as a --- (---- in --- is the enzyme- ribozyme) for the formation of peptide bond.
catalyst
23S rRNA in bacteria
136
A translational unit in mRNA is the sequence of RNA that is flanked
by the --- and codes for a ---.
start codon (AUG) and the stop codon
polypeptide
137
Transcriptional unit in present on --- while translation unit is present on -----
DNA, mRNA
138
An mRNA also has some --- that are not translated
and are referred as ----
additional sequences
untranslated regions (UTR).
139
The UTRs are present
at both ---- and ----.
5' -end (before start codon)
at 3' -end (after stop codon)
140
---- are required for efficient translation process.
UTR's
141
For initiation, the --- binds to the mRNA at the start codon (AUG) that is recognised only by the ---
ribosome
initiator tRNA.
142
The ribosome proceeds to the ---- phase of protein synthesis.
elongation
143
During --- stage, complexes composed of an ---, sequentially bind to the appropriate --- in mRNA by forming complementary base pairs with the --- .
elongation
amino acid linked to tRNA
codon in mRNA
tRNA anticodon
144
The --- moves from codon to codon along the mRNA.
ribosome
145
Amino acids are added one by one, translated into --- sequences dictated by --- and represented by ---.
Polypeptide
DNA , mRNA
146
At the end of translation, a --- binds to the stop codon, terminating translation and releasing the ---- from ----
release factor
complete polypeptide from the ribosome.
147
--- refers to a very broad term that may occur at various levels.
Regulation of gene expression
148
Considering that gene expression results in the formation of a --- , it can be regulated at several levels.
polypeptide
149
In ---, the
regulation could be exerted at
(i) transcriptional level (formation of ---),
(ii) processing level (regulation of ---),
(iii) transport of ----
(iv) ---- level.
primary transcript
splicing
mRNA from nucleus to the cytoplasm,
translational
150
The ---- in a cell are expressed to perform a particular --- or a
set of functions.
genes, function
151
For example, if an enzyme called --- is synthesised by -- , it is used to catalyse the --- of a disaccharide, lactose into galactose and glucose;
the bacteria use them
as a ---
Hence, if the bacteria --- around them to be utilised for energy source, they would no longer require the synthesis of the enzyme.
beta-galactosidase , E. coli
hydrolysis
source of energy.
do not have lactose
152
Therefore, in simple terms, it is the --- , --- or ---conditions that regulate the expression of genes.
metabolic
physiological
environmental
153
The --- and --- of embryo
into adult organisms are also a result of the --- of
expression of several sets of ---.
development and differentiation
coordinated regulation, genes
154
In prokaryotes, control of the rate of ---- is the
predominant site for control of gene expression.
transcriptional initiation
155
In a transcription unit,
the activity of RNA polymerase at a given --- is in turn regulated
by interaction with ----, which affect its ability to ---.
promoter
accessory proteins
recognise start sites
156
These regulatory proteins can act -----
both positively (activators)
and negatively (repressors).
157
The ---- regions of
PROKARYOTIC DNA is in many cases regulated by the interaction of proteins
with sequences termed ---.
accessibility of promoter
operators
158
The operator region is adjacent to the --- in most operons and in most cases the sequences of
the operator bind a ---protein.
promoter elements
repressor
159
Each operon has its specific --- and ----.
operator and repressor
160
For example, lac operator is present only in the --- and it interacts specifically with lac repressor only.
lac operon
161
The --- of the lac operon was also a result of a close association
between a ---- and ----
elucidation
Geneticist, Francois Jacob and a Biochemist, Jacque Monod.
162
Jacob and Monad were the first to elucidate a ---- system.
transcriptionally regulated
163
In lac operon
(here lac refers to ---), a ---- is regulated by a
----.
Such arrangement is very common in --- and is referred to as operon
lactose
polycistronic structural gene
common promoter and regulatory genes
bacteria
164
To name few such examples, lac operon, ---- operon, ---, ---, etc
trp, ara, val, his
165
The lac operon consists of -- regulatory gene (the --- gene – here the term i does not refer to ---, rather it is derived from the word ----) and --- structural genes (z, y, and a).
one- i
inducer, inhibitor
three - z,y,a
166
The i gene codes for the ---- of the lac operon.
repressor
167
The --- codes for beta-galactosidase (---), which is primarily responsible for the -----, lactose
into its monomeric units, ---- and ----
z genes, β-gal
hydrolysis of the disaccharide
galactose and glucose
168
The y gene codes for
----, which increases ---- to β-galactosides.
permease
permeability of the cell
169
The a gene encodes a ---.
transacetylase
170
Hence, all the three gene --- in lac operon are required for ---.
products
metabolism of lactose
171
In most other operons
as well, the genes present in the operon are needed together to function
in the ---- metabolic pathway
same or related
172
Lactose is the --- for the enzyme beta-galactosidase
substrate
173
--- regulates switching on and off of the operon. Hence, it is termed as ---.
Lactose
inducer
174
In the absence of a ---- such as glucose, if lactose is provided in the --- medium of the bacteria, the lactose is transported
into the cells through the action of ---
(Remember, a ---- of lac operon has to be present in the cell ---,
otherwise --- cannot enter the cells).
The lactose then induces the ---- in the following manner.
preferred carbon source
growth
permease
very low level of expression, all the time, lactose
operon
175
The repressor of the operon is synthesised (----) from the i gene.
all-the-time – constitutively
176
The ---- binds to the operator region of the
operon and prevents --- the operon.
repressor protein
RNA polymerase from transcribing
177
In the presence of an inducer, such as --- or ----, the repressor is --- by interaction with the inducer. This allows RNA polymerase access to the --- and transcription proceeds
lactose or allolactose
inactivated
PROMOTER
178
Essentially, regulation of lac operon can also be visualised as regulation
of ----
enzyme synthesis by its substrate.
179
Remember, --- or --- cannot act as inducers for lac operon.
glucose or galactose
180
Lac operon would be expressed till the time the bac is in in the presence of lactose
True/False
True
181
Regulation of lac operon by repressor is referred to as ----.
negative regulation
182
Lac operon is under control of --- regulation as well
+ve
183
it is the sequence of bases in DNA that determines the --- of a given organism.
genetic information
184
---- of an organism or an individual lies in the DNA
sequences.
Genetic make-up
185
If two individuals differ, then their DNA sequences should also be ----.
different, at least at some places
186
These assumptions led to the quest of finding out the complete DNA sequence of ---.
human genome
187
With the establishment of ---- techniques where it was possible to
--- and ---- any piece of DNA and availability of simple and fast techniques for determining DNA sequences, a very ambitious project of
--- human genome was launched in the year ---
genetic engineering
isolate, clone
sequencing
1990.
188
Human Genome Project (HGP) was called a --- project.
mega
189
Human genome is said to have approximately 3 x 109 bp, and if the
cost of sequencing required is --- per bp (the ----), the total estimated cost of the project would be approximately
----
US $ 3- estimated cost in the beginning
9 billion US dollars
190
Further, if the obtained sequences were to be stored in --- in books, and if each page of the book contained ----
letters and each book contained --- pages, then --- such books would
be required to store the information of DNA sequence from a ---.
typed form
1000, 1000,
3300
single human cell
191
The enormous amount of --- expected to be generated also
necessitated the use of ----devices for ----, --- and----
data
high speed computational
data storage, retrieval and analysis
192
HGP was closely associated with the rapid dev of a new area in biology called
Bioinformatics
193
Some of the important goals of HGP were as follows:
(i) Identify all the approximately --- genes in human DNA;
20,000-25,000
194
HGP aims
(ii) Determine the sequences of the ---- that
make up human DNA;
3 billion chemical base pairs
195
HGP aims:
(iiii) Store this information in ---- ;
databases
196
HGP aims:
(iv) Improve tools for ---
data analysis;
197
HGP aims:
(v) ---related technologies to other sectors, such as ----;
transfer, industries
198
HGP aims:
(vi) Address the ---, --- and ---- issues(ELSI) that may arise from the project
ethical, legal, and social issues
199
The Human Genome Project was a ---- year project coordinated by
the --- and ---.
13-year
U.S. Department of Energy and the National Institute of Health
200
During the --- years of the HGP, the --- became a major partner; additional contributions came from --- and others.
early
Welcome Trust (U.K.)
Japan, France, Germany,
China
201
The HG project was completed in ---.
2003
202
Knowledge about
the effects of ---- among individuals can lead to revolutionary
new ways to ---, --- and --- the thousands of disorders that affect human beings.
DNA variations
diagnose, treat and someday prevent
203
Besides providing clues to
understanding human biology, learning about ---
DNA sequences can lead to an understanding of their --- that can be applied toward solving challenges in -----, ----, ---- and ----
non-human organisms
natural capabilities
health care, agriculture,
energy production, environmental remediation.
204
Many non-human model
organisms, such as -----, --- and ---- (a free living
non-pathogenic nematode), --- (the fruit fly), plants (-----), etc., have also been sequenced.
bac yeast
caenorhabditis elegans
Drosophila
rice and Arabidopsis
205
Methodologies for HGP: The methods involved --- major approaches.
two
206
One approach focused on identifying all the --- that are expressed as
---- (referred to as---).
genes
RNA
Expressed Sequence Tags (ESTs)
207
The other took
the --- approach of simply sequencing the -----, and later assigning
different regions in the sequence with ---- (a term referred to as ---).
blind
whole set of genome that
contained all the coding and non-coding sequence
functions
Sequence Annotation
208
For sequencing, the total DNA from a cell is
---- and converted into ---- of relatively smaller sizes
(recall DNA is a very long ---, and there are ---- in sequencing very long pieces of DNA) and --- in suitable host using ------
isolated
random fragments
polymer
technical limitations
cloned- specialised vectors
209
The cloning resulted into ---- of each piece of DNA fragment so that it subsequently could be ----.
amplification
sequenced with ease
210
The commonly used hosts were --- and ---- and the vectors were
called as --- and ----
bacteria and yeast,
BAC (bacterial artificial chromosomes), and YAC (yeast artificial
chromosomes).
211
The fragments were sequenced using ---- that
worked on the principle of a method developed by ----
automated DNA sequencers
Frederick Sanger.
212
Sanger is also credited for developing a method for ----
determination of amino acid sequences in proteins
213
These sequences of dna were then arranged based on ---- regions
present in them.
some overlapping
214
This required generation of ---- for sequencing.
overlapping fragments
215
--- of these overlapping sequences was humanly not possible. Therefore, specialised ---- were
developed
Alignment
computer based programs
216
These sequences were subsequently --- and were assigned to each -----.
annotated
chromosome
217
The sequence of
chromosome 1 was completed only
in ---- (this was the last of the --- human chromosomes –----– to be sequenced).
May 2006
24-
22 autosomes and X and Y
218
Another challenging task was assigning the --- and --- on the genome. This was generated using information on ---- of ----- sites, and some repetitive DNA sequences known as ---- (one of the applications of polymorphism in repetitive DNA sequences shall be explained in next
section of DNA fingerprinting).
genetic and physical maps
polymorphism
restriction endonuclease recognition
microsatellites
219
The human genome contains ----- bp.
3164.7 million
220
The average gene consists of --- ---, but sizes vary greatly, with the largest known human gene being --- at --- bases.
3000 bases
dystrophin at 2.4 million
221
The --- is estimated at 30,000–much lower
than previous estimates of ---- to ----.
total number of genes
80,000 to 1,40,000 genes
222
---- (99.9 per cent) --- are exactly the same in all people.
Almost all
nucleotide bases
223
The functions are unknown for over --- per cent of the -----
50 , discovered
genes.
224
Less than 2 per cent of the ---- codes for ----.
genome
proteins
225
---- make up very large portion of the human genome.
Repeated sequences
226
Repetitive sequences are stretches of DNA sequences that are
repeated many times, sometimes ---- to ----.
hundred to thousand times
227
Repetitive dna seqs are thought to have ---- functions, but they shed light on -----, ----, -----
no direct coding
chromosome structure, dynamics and evolution.
228
Chromosome --- has most genes (----), and the Y has the fewest (----).
1
2968
231
229
Scientists have identified about ---- locations where --- DNA differences (----’) occur in humans.
1.4 million locations
singlebase
SNPs – single nucleotide polymorphism,
pronounced as ‘snips
230
Snips information promises to revolutionise the processes of finding ----- and tracing human history.
chromosomal locations for disease-associated sequences
231
Deriving meaningful knowledge from the ---- will define research through the coming decades leading to our understanding of
--- .
This enormous task will require the --- and --- of ---- of scientists from varied disciplines in both
the public and private sectors worldwide.
DNA sequences
biological systems
expertise and
creativity
tens of thousands
232
One of the greatest impacts of having the HG sequence may well be enabling a --- approach to ---.
radically new
biological research
233
In the past, researchers studied --- or --- at a time. With --- sequences and new ---- , we can approach questions systematically and on a much broader scale
one or a few genes
whole-genome
high-throughput
technologies
234
They can study all the genes in a genome, for example, all the ---- in a particular ---- --- or ----, or how tens of thousands of genes and --- work together in interconnected networks
to ---- of life.
transcripts
tissue or organ or tumor
proteins
orchestrate the chemistry
235
Assuming human genome as 3 × 109 bp, ----
sequences would there be differences.
3 × 106 base pairs
236
It is these differences
in sequence of DNA which make every individual unique in their ----.
phenotypic appearance
237
If one aims to find out genetic differences
between two individuals or among individuals of a population, ---- every time would be a daunting and expensive task.
sequencing the DNA
238
DNA fingerprinting is a very quick way to ---- of any two individuals
compare the DNA sequences
239
DNA fingerprinting involves ---- in some specific regions in DNA sequence called as ---, because in these
sequences, a -----
identifying differences
repetitive DNA
small stretch of DNA is repeated many times.
240
These repetitive DNA are separated from ---- as different --- during
bulk genomic DNA
peaks
density gradient centrifugation.
241
The --- forms a major peak and the --- are referred to as satellite DNA
bulk DNA
other small peaks
242
Depending on -----, ---- and ---- the satellite DNA is classified into many categories, such as ----, ---- etc.
base composition (A : T rich or G:C rich),
length of segment,
number of repetitive units,
micro-satellites, mini-satellites
243
---- normally do not code for any ---, but they form a large portion of human
genome.
Satellite dna seqs
proteins
244
Satellite dna sequence show high degree of ---and form the basis of ---.
polymorphism
DNA fingerprinting
245
Since DNA from every tissue (such as
---- (6), from an individual
show the ----, they become very useful
identification tool in ---applications.
blood, hair-follicle, skin, bone, saliva, sperm etc
same degree of polymorphism
forensic
246
Further, as the ---
are inheritable from parents to children, DNA fingerprinting is the basis
of ----, in case of disputes.
polymorphisms
paternity testing
247
As polymorphism in DNA sequence is the basis of --- of human genome as well as of DNA fingerprinting, it is essential that we
understand what DNA polymorphism means in simple terms.
genetic mapping
248
Polymorphism (----) arises due to
variation at genetic level
mutations
249
New mutations may arise in an individual either in --- or ---- (cells that generate gametes in ---
organisms).
somatic cells or in
the germ cells
sexually reproducing
250
If a --- mutation does not seriously impair individual’s ability to ---- who can transmit the mutation, it can spread to the ---- of population (through sexual reproduction).
germ cell
have offspring
other members
251
---- variation has traditionally been described as a DNA polymorphism if more than ---- at a locus occurs in human population with a --- greater than
Allelic sequence
one variant (allele)
frequency
0.01
252
In simple terms, if an ----
is observed in a population at ---, it is referred to as DNA
polymorphism.
inheritable mutation
high frequency
253
The probability of such variation to be observed in ---- would be higher as mutations in these sequences may not have any immediate effect/impact in an individual’s
noncoding DNA sequence
reproductive ability.
254
These mutations in non coding seqs keep on ----, and form one of the basis of ----
accumulating generation
after generation
variability/ polymorphism.
255
There is a variety of different types of polymorphisms ranging from ---- change to ---- changes.
single nucleotide
very large scale
256
For --- and ----, such polymorphisms play very important role
evolution and
speciation
257
The technique of DNA Fingerprinting was initially developed by ----.
Alec Jeffreys
258
He used a satellite DNA as ---- that shows very high degree of polymorphism. It was called as ----
probe
Variable Number of Tandem Repeats
(VNTR).
259
The technique, as used earlier, involved ---- using --- as a probe.
Southern blot hybridisation
radiolabelled VNTR
260
It included
(i) ---- of DNA,
(ii) digestion of DNA by ---
(iii) separation of DNA fragments by ---,
(iv) ---- of separated DNA fragments to ----, such as --- or ----,
(v) --- using labelled VNTR probe
(vi) detection of hybridised DNA fragments by ---.
1. isolation
2. restriction endonucleases,
3. electrophoresis
4. transferring (blotting)
synthetic membranes
nitrocellulose or nylon
hybridisation
autoradiography
261
The VNTR belongs to a class of satellite DNA referred to as ----
mini-satellite.
262
A small DNA sequence is arranged ---- in many --- numbers.
tandemly
copy numbers
263
The copy number varies from --- to ---- in an individual.
chromosome to chromosome
264
The ---- show very high degree of polymorphism.
numbers of repeat
265
As a result the size of VNTR varies in size from ----
0.1 to 20 kb.
266
Consequently,
after hybridisation with VNTR probe, the --- gives many bands of ---.
These bands give a ---- for an individual
DNA. It differs from individual to individual in a population
except in the case of ---
autoradiogram
bands of differing sizes
characteristic pattern
monozygotic (identical) twins
267
The sensitivity of the DNA fingerprinting
technique has been increased by use of
----
polymerase chain reaction (PCR)
268
Consequently, DNA from a ---- is enough to perform DNA fingerprinting analysis.
single cell
269
In addition to application in ----, DNA fingerprinting has much wider application, such as in determining ---- and ----.
forensic science
population and genetic diversities
270
Currently, many different --- are used to generate DNA fingerprints.
probes
271
