Molecular Basis Of Inheritance Flashcards
1
Q
Statement 1: RNA though it also acts as a genetic material in some viruses, mostly functions as a messenger.
Statement 2: RNA has additional roles as well. It functions as adapter, structural, and in some cases as a catalytic molecule.
A
Both are correct
2
Q
Bacteriophage φ ×174 has……..nucleotides
A
5386
3
Q
Bacteriophage lambda has………. base pairs
A
48502
4
Q
Escherichia coli has………bp
A
4.6 × 10*6
5
Q
Haploid content in human DNA is……….. bp
A
3.3 x 10*9 base pairs
6
Q
………….. is common for both DNA and RNA
A
Cytosine
7
Q
Thymine is also known as…….
A
5-methyl uracil
8
Q
DNA as an acidic substance present in nucleus was first identified by Friedrich Meischer in……….. He named it as………
A
1869
Nuclein
9
Q
In …………. James Watson and Francis Crick, based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin
A
1953
10
Q
Erwin Chargaff that for a double stranded DNA, the ratios between…………. and Thymine and Guanine and…………..are constant and equals one.
A
Adenine
Cytosine
11
Q
The pitch of the helix is……. nm and distance between a bp in a helix is approximately……….nm as there are……… base pairs in one single turn
A
3.4 nm
0.34 nm
10
12
Q
…………….. proposed the Central dogma in molecular biology,
A
Francis Crick
13
Q
Reverse transcription aka Teminism is seen in some viruses name some of them
(4)
A
Rous sarcoma virus
HIV
Tobacco mosaic virus
QB bacteriophage
14
Q
Statement 1: In prokaryotic cells the DNA is scattered throughout the cell
Statement 2: The DNA in nucleoid is organised in small loops held by proteins.
A
Both are incorrect
Though they do not have a defined nucleus, the DNA is not scattered throughout the cell. DNA (being negatively charged) is held with some proteins (that have positive charges) in a region termed as ‘nucleoid’. The DNA in nucleoid is organised in large loops held by proteins.
15
Q
Histones are………. charged proteins rich in two basic amino acids…..&……..
A
Positively
Arginine and Lysine
16
Q
Histones are organised to form a unit of…….molecules called histone…….
A
eight
octamer
17
Q
The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called
A
nucleosome
18
Q
A typical nucleosome contains………. bp of DNA helix
A
200
19
Q
Statement 1: The beads-on-string structure in chromatin is packaged to form chromatin fibers
Statement 2: These are further coiled and condensed at metaphase stage of cell division to form chromosomes
A
Both are correct
20
Q
By year…….. the quest to determine the mechanism for genetic inheritance had reached the molecular level
A
1926
21
Q
In 1928……………… in a series of experiments with Streptococcus pneumoniae (pneumococcus) (bacterium responsible for pneumonia), witnessed a miraculous transformation in the bacteria
A
Frederick Griffith
Bacteria had changed in PHYSICAL form
22
Q
Prior to the work of………/……../…….. (1933-44), the genetic material was thought to be a protein.
A
Oswald Avery
Colin MacLeod
Maclyn McCarty
23
Q
The unequivocal proof that DNA is the genetic material came from the experiments of ………/………. (1952)
A
Alfred Hershey and Martha Chase
24
Q
Radioactive elements used in Hershey Chase experiment
A
Radioactive sulphur in proteins S35
Radioactive phosphorus in DNA P32
25
Molecule that can act as a genetic material must fulfill the following criteria:
4 given in NCERT
(i) It should be able to generate its replica (Replication).
(ii) It should be stable chemically and structurally.
(iii) It should provide the scope for slow changes (mutation) that are required for evolution
(iv) It should be able to express itself in the form of 'Mendelian Characters’.
26
‘‘It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material’’
This was statement of
Watson and Crick, 1953
27
Matthew Meselson and Franklin Stahl performed experiment in year…….. to prove that the DNA replicates ………….
1958
Semi conservatively
28
Matthew Meselson and Franklin Stahl used radioactive N15 isotope in their experiments
False
It was just a heavy isotope and not any radioactive isotope
29
Similar experiments involving use of radioactive……. to detect distribution of newly synthesised DNA in the chromosomes was performed on………. (faba beans) by Taylor and colleagues in 1958
thymidine
Vicia faba
30
E. coli that has only 4.6×106 bp completes the process of replication within……..minutes
18
31
The average rate of polymerisation in E.coli has to be approximately………..bp per second
2000
32
Assertion: For long DNA molecules replication occurs in small opening of helix
Reason: In such long molecules two strands of DNA cannot be separated in its entire length due to very high energy requirement
33
The DNA-dependent DNA polymerases catalyse polymerisation only in one direction, that is………
5' to 3'.
34
Why both the strands are not copied during transcription
First, if both strands act as a template, they would code for RNA molecule with different sequences and if they code for proteins, the sequence of amino acids in the proteins would be different. Hence, one segment of the DNA would be coding for two different proteins
Second, the two RNA molecules if produced simultaneously would be complementary to each other, hence would form a double stranded RNA. This would prevent RNA from being translated
35
The RNA polymerase is only capable of catalysing the process of…….
elongation
36
The RNA polymerase I transcribes
The RNA polymerase II transcribes
RNA polymerase III transcribes.
rRNAs (28S, 18S, and 5.8S)
precursor of mRNA, the heterogeneous nuclear RNA (hnRNA).
tRNA, 5srRNA, and snRNAs (small nuclear RNAs)
37
In capping an unusual nucleotide…………. is added to the………. end of hnRNA.
methyl guanosine triphosphate
5'-end
38
In tailing, adenylate residues are added at 3'-end in a template………….manner
200-300
independent
39
The presence of……….. is reminiscent of antiquity, and the process of splicing represents the dominance of………..-world.
introns
RNA
40
It was………….. a physicist, who argued that since there are only 4 bases and if they have to code for 20 amino acids, the code should constitute a combination of bases.
George Gamow
41
The chemical method developed by………………was instrumental in synthesising RNA molecules with defined combinations of bases (homopolymers and copolymers)
Har Gobind Khorana
42
……………… cell-free system for protein synthesis finally helped the code to be deciphered
Marshall Nirenberg’s
43
……………….. (polynucleotide phosphorylase) was also helpful in polymerising RNA with defined sequences in a template independent manner (enzymatic synthesis of RNA)
Severo Ochoa enzyme
44
Statement 1: 61 codons code for amino acids and 3 codons do not code for any
Statement 2: Codon is read in mRNA in a contiguous fashion. There are no punctuations.
Both are correct
45
Statement 1: One specific codon codes for one specific amino acid, this is known as degeneracy
Statement 2: Some amino acids can be coded by more than one codons this is known as unambiguous nature of codon
Both are incorrect vice versa is true
46
The code is nearly universal like from bacteria to human UUU would code for Phenylalanine
But there are some exceptions to this
Paramecium (Protozoa)
Termination codons UAA UGA code for Glutamate in
Mitochondria
AGG AGA generally coding for arginine works as stop codons in mitochondria
UGA a stop codon codes for tryptophan in mitochondria
AUA generally coding Isoleucine codes for methionine in mitochondria
47
…./…../…….. are stop terminator codons.
UAA, UAG, UGA
48
NCERT question intext
-AUG UUU UUC UUC UUU UUU UUC-
Give order of amino acids formed
Met-Phe-Phe-Phe-Phe-Phe-Phe
49
The protein synthesising machinery has evolved around……..
RNA
50
……… being more stable is preferred for storage of genetic information. For the transmission of genetic information…….. is better.
DNA
RNA
51
Sense strand in transcriptional unit is
Coding strand or structural gene ie which doesn’t code for protein
52
Assertion: It was clear to Francis Crick that there has to be a mechanism to read the code and also to link it to the amino acids
Reason:The amino acids have no structural specialities to read the code uniquely
53
The tRNA, then called…………… was known before the genetic code was postulated
sRNA (soluble RNA)
54
Statement 1: tRNA has an anticodon loop that has bases complementary to the code, and it also has an amino acid acceptor end to which it binds to amino acids
Statement 2: tRNAs are specific for each amino acid
Both are correct
55
There are no tRNAs for stop codons
True
56
The secondary structure of tRNA has been depicted that looks like a…………….. In actual structure, the tRNA is a compact molecule which looks like………
clover-leaf
inverted L
57
Assertion: In the first phase itself amino acids are activated in the presence of ATP and linked to their cognate tRNA–a process commonly called as charging of tRNA or aminoacylation of tRNA
Reason: The amino acids are joined by a bond which is known as a peptide bond. Formation of a peptide bond requires energy
58
The ribosome consists of………. and about…….. different proteins
structural RNAs
80
59
When the……… subunit of ribosome encounters an mRNA, the process of translation of the mRNA to protein begins
small
60
The ribosome also acts as a catalyst (23S rRNA in bacteria is the enzyme- ribozyme) for the formation of peptide bond
True
61
Statement 1: An mRNA also has some additional sequences that are not translated and are referred as untranslated regions (UTR)
Statement 2: The UTRs are present at both 5'-end (before start codon) and at 3'-end (after stop codon). They are required for efficient translation process.
Both are correct
62
At the end, a……… factor binds to the stop codon, terminating translation and releasing the complete polypeptide from the ribosome.
release
63
Regulation of gene expression refers to a very broad term that may occur at various levels
(i) transcriptional level (formation of primary transcript),
(ii) processing level (regulation of splicing),
(iii) transport of mRNA from nucleus to the cytoplasm,
(iv) translational level.
64
It is the…./…/….conditions that regulate the expression of genes.
metabolic
physiological
environmental
65
The development and differentiation of embryo into adult organisms are also a result of the coordinated regulation of expression of several sets of genes.
True
66
The accessibility of promoter regions of prokaryotic DNA is in many cases regulated by the interaction of proteins with sequences termed……….
operators
67
The elucidation of the lac operon was by……../…….
geneticist Francois Jacob
a biochemist, Jacque Monod
68
Statement 1: In lac operon (here lac refers to lactose), a polycistronic structural gene is regulated by a common promoter and regulatory genes.
Statement 2: Such arrangement is very common in bacteria and is referred to as operon
Both are correct
69
The lac operon consists of one regulatory gene (igene) and three structural genes (z, y, and a)
True
the i gene – here the term i does not refer to inducer, rather it is derived from the word inhibitor
70
The i gene codes for the repressor of the lac operon.
The z gene codes for beta-galactosidase (β-gal)
Both are true
71
The ‘y’ gene and ‘a’gene code for what respectively
The y gene codes for permease, which increases permeability of the cell to β-galactosides.
The a gene encodes a transacetylase
72
Statement 1: The repressor protein binds to the operator region of the operon and prevents RNA polymerase from transcribing the operon.
Statement 2: In the presence of an inducer, such as lactose or allolactose, the repressor is inactivated by interaction with the inducer
Both are correct
73
Remember, glucose or galactose cannot act as inducers for lac operon
True
74
Statement 1: Regulation of lac operon by repressor is referred to as negative regulation
Statement 2: Lac operon is never under control of positive regulation
I is correct and II is incorrect
Lac operon is under control of positive regulation as well, but it is beyond the scope of discussion
75
Assertion:A very ambitious project of sequencing human genome was launched in the year 1990.
Reason: With the establishment of genetic engineering techniques it was possible to isolate and clone any piece of DNA and availability of simple and fast techniques for determining DNA sequences
Both are correct
76
The cost of sequencing required is………. per bp (the estimated cost in the beginning), the total estimated cost of the project would be approximately……….
US $ 3
9 billion US dollars
77
What if the obtained sequences were to be stored in typed form in books
3300 books > each 1000 pages > 1000 letters each page
78
HGP was closely associated with the rapid development of a new area in biology called……….
Bioinformatics
79
Some of the important goals of HGP were as follows:
(i) Identify all the approximately 20,000-25,000 genes in human DNA;
(ii) Determine the sequences of the 3 billion chemical base pairs that make up human DNA;
(iiii) Store this information in databases;
(iv) Improve tools for data analysis;
(v) Transfer related technologies to other sectors, such as industries;
(vi) Address the ethical, legal, and social issues (ELSI) that may arise from the project.
80
The Human Genome Project was a……… year project coordinated by the U.S. Department of Energy and the National Institute of Health
13-year
81
During the early years of the HGP, the…………… became a major partner; additional contributions came from Japan, France, Germany, China and others.
Wellcome Trust (U.K.)
82
The project was completed in
2003
83
Non human model organisms sequenced are
bacteria
yeast
Caenorhabditis elegans (a free living non-pathogenic nematode)
Drosophila (the fruit fly)
plants (rice and Arabidopsis)
84
Caenorhabditis elegans is
a free living non-pathogenic nematode
85
One approach focused on identifying all the genes that are expressed as RNA ie termed as
Expressed Sequence Tags (ESTs)
86
A blind approach of simply sequencing the whole set of genome that contained all the coding and non-coding sequence, and later assigning different regions in the sequence with functions a term referred to as
Sequence Annotation
87
The commonly used hosts were bacteria and yeast, and the vectors were called as
BAC (bacterial artificial chromosomes)
YAC (yeast artificial chromosomes
88
The sequence of chromosome 1 was completed only in May 2006
True
89
Another challenging task was assigning the
genetic and physical maps on the genome
90
The human genome contains….. million bp.
3164.7
91
The average gene consists of………. bases, but sizes vary greatly, with the largest known human gene being……………. gene at 2.4 million bases.
3000
dystrophin
92
The total number of genes is estimated at……… much lower than previous estimates of 80,000 to 1,40,000 genes
30,000
93
Almost all (99.9 per cent) nucleotide bases are exactly the same in all people.
True
94
The functions are unknown for over……. per cent of the discovered genes.
50
95
Less than……. per cent of the genome codes for proteins.
2
96
………….. make up very large portion of the human genome.
Repeated sequences
97
Statement 1: Repetitive sequences are stretches of DNA sequences that are repeated many times, sometimes hundred to thousand times.
Statement 2: They are thought to have no direct coding functions, but they shed light on chromosome structure, dynamics and evolution
Both are correct
98
Chromosome 1 has most genes=
Y has the fewest=
2968
231
99
Statement 1: Scientists have identified about 1.4 million locations where single-base DNA differences (SNPs – single nucleotide polymorphism, pronounced as ‘snips’) occur in humans.
Statement 2: This information promises to revolutionise the processes of finding chromosomal locations for disease-associated sequences and tracing human history.
Both are correct
100
Assertion: DNA fingerprinting is a very quick way to compare the DNA sequences of any two individuals.
Reason: DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called as repetitive DNA, because in these sequences, a small stretch of DNA is repeated many times.
Both are correct
101
Assertion: These repetitive DNA are separated from bulk genomic DNA as different peaks during density gradient centrifugation.
Reason: The bulk DNA forms a major peak and the other small peaks are referred to as satellite DNA
Both are correct
102
Depending on……../……./…….the satellite DNA is classified into many categories, such as micro-satellites, mini-satellites
base composition (A : T rich or G:C rich)
length of segment
number of repetitive units
103
Assertion: DNA fingerprinting is the basis of paternity testing, in case of disputes.
Reason: The polymorphisms are inheritable from parents to children,
Both are correct
104
The polymorphism in DNA sequence is the basis of
genetic mapping of human genome
DNA fingerprinting
105
Allelic sequence variation has traditionally been described as a DNA polymorphism if more than one variant (allele) at a locus occurs in human population with a frequency greater than……..
0.01
106
The technique of DNA Fingerprinting was initially developed by……………. He used a satellite DNA as probe that shows very high degree of polymorphism
Alec Jeffreys
107
The satellite DNA that shows very high degree of polymorphism is known as
Variable Number of Tandem Repeats (VNTR)
108
The technique involved………using radiolabelled VNTR as a probe
Southern blot hybridisation
109
DNA fingerprinting involves 6 steps
(i) isolation of DNA,
(ii) digestion of DNA by restriction endonucleases,
(iii) separation of DNA fragments by electrophoresis,
(iv) transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon,
(v) hybridisation using labelled VNTR probe, and
(vi) detection of hybridised DNA fragments by autoradiography
110
The VNTR belongs to a class of satellite DNA referred to as
mini-satellite.
111
Statement 1: A small DNA sequence is arranged tandemly in many copy numbers.
Statement 2: The copy number varies from chromosome to chromosome in an individual.
Both are correct
112
VNTR varies in size from
0.1 to 20 kb
113
The VNTR differs from individual to individual in a population except in the case of monozygotic (identical) twins
True
114
The sensitivity of the technique has been increased by use of
polymerase chain reaction
