Download MOLECULAR BASIS OF INHERITANCE

CHAPTER 6
MOLECULAR
BASIS OF INHERITANCE
MOLECULAR BASIS OF INHERITANCES
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CONTENTS
THE DNA
THE SEARCH FOR
GENETIC MATERIALS
REPLICATION
TRANSCRIPTION
GENETIC CODE
MOLECULAR BASIS OF INHERITANCES
• TRANSLATION
• REGULATION OF GENE
EXPRESSION
• HUMAN GENOME PROJECT
• DNA FINGER PRINTING
STRUCTURE OF POLY NUCLEOTIDE CHAIN
• A NUCLEOTIDE HAS THREE COMPONENTS
1. A NITROGENOUS BASES
a. PURINES EX- adenine & guanine
b. PYRIMIDINES EX- cytosine & thymine
Uracil
2. PENTOSE SUGAR – deoxyribose &
ribose
3. A PHOSPHATE GROUP
POLY NUCLEOTIDE CHAIN
• N B LINKED TO PENTOSE SUGAR THROUGH NGLYCOSIDIC BOND TO FORM NUCLEOSIDE, WHICH
INTURN LINKED TO PHOSPHATE THROUGH
PHOSPHOESTER LINKAGE TO FORM NUCLEOTIDE
NUCLEOSIDES & NUCLEOTIDES OF DNA
NUCLEOSIDES
• Deoxyadenosine
• Deoxyguanocine
• Deoxycytosine
• Deoxythymidine
NUCLEOTIDES
• Deoxy adenylic acid
or dAMP
• Deoxy guanylic acid
or dGMP
• Deoxy cytidylic acid
or dCMP
• Deoxy thymidiylic
acid or dTMP
STRUCTURE OF DNA
• Two polynucleotide strands
running anti parallel
• Sugar and phosphate
• Complementary base pairing
• Chargaff’s rule of base
equivalence
• Paired through hydrogen bond
• 0.34nm . 3.4 nm 10 bp in each turn
PACKAGING OF DNA HELIX
• IN PROKARYOTES THE NEGETIVE CHARGED DNA
IS HELD WITH POSITIVE CHARGED SOME
PROTEIN TO FORM NUCLEOID
• IN EUKARYOTES THE NEGETIVE CHARGED DNA
IS HELD WITH POSITIVE CHARGED BASIC
PROTEINS CALLED HISTONES.
• THE DNA WRAPPED AROUND AS HISTONE
OCTOMER TO FORM NUCLEOSOME.
PACKAGING OF DNA HELIX
THE SEARCH OF GENETIC MATERIAL
• TRANSFORMING PRINCIPLE BY- FREDERICK
GRIFFITH
• BIOCHEMICAL CHARACTERISATION OF
TRANSFORMING PRINCIPLE
• THE GENETIC MATERIAL IS DNA – HERSHEY &
CHASE (1952)
PROPERTIES OF GENETIC MATERIAL
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IT UNDER GO REPLICATION
CHEMICALLY & STRUCTURALLY STABLE
UNDERGO MUTATION
EXPRESS IT SELF AS CHARACTER
REPLICATION
• COPYING MECHANISM FOR THE GENETIC
MATERIAL
OR
DNA PRODUCE AN EXACT COPY OF ITSELF
CALLED REPLICATION
REPLICATION IS SEMICONSERVATIVE.
STEPS OF REPLICATION
• ACTIVATION OF
NUCLEOTIDE
• UNWINDING
• RNA PRIMER
• ELONGATION
• TERMINATION
TRANSCRIPTION
• THE PROCESS OF COPYING OF GENETIC
INFORMATION FROM ONE STRAND OF DNA
INTO RNA IS CALLED TRANSCRITPION.
• TRANSCRIPTION UNIT
TRANSCRIPTION
CHARACTERS OF GENETIC CODE
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Triplet in nature
Universal
Non-overlapping
Degenerate
Comma less
Non-ambiguous or specific
Initiator codon
Non-sense or terminator
codons
tRNA
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RNA TRANSFER THE AMINOACIDS
FROM AMINOACID POOL IN TO
THE SITE OF PROTEIN SYNTHES IS
CALLED tRNA
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TRANSLATION --The process of
polymerisation of amino acids to form
polypeptide
REGULATION OF GENE EXPRESSION
• GENE EXPRESSION RESULTS IN THE FORMATION
OF POLYPEPTIDES.
GENE REGULATED AT
1. TRANSCRIPTIONAL LEVEL
2. PROCESSING OR SPLICING LEVEL
3. TRANSLATIONAL LEVEL
REGULATION OF GENE EXPRESSION
LAC OPERON CONCEPT (GENE REGULATION)
HUMAN GENOME PROJECT
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GOALS OF HGP
METHODOLOGIES
SEQUENCING
SALIENT FEATURES OF HUMAN GENOME
APPLICATION & FUTURE CHALLENGES
DNA FINGER PRINTING
Technique of sequence of DNA to Identify of
individual at DNA level.
CET CORNER
The bond present between nucleoside
and phosphate is
a. Phosphoester bond
b. Phosphodiester bond
c. Hydrogen bond
d. Ester
Transfer message for synthesis of polypeptides
during translation, the sequence is
a. DNA, t RNA , r RNA,
& amino acids
b. DNA, t RNA , & m RNA
c. DNA, t RNA ,amino acids, r RNA,
& m RNA
d. DNA, m RNA ,t RNA & amino acids
A portion of DNA molecule is found to
contain 200 Adenine and 200 Thymine
nucleotides. The total number of base pairs
in this DNA fragment is
a.
b.
c.
d.
1040
200
400
520
a.
b.
c.
d.
The Ribose sugar is differ from deoxy
ribose sugar is
Additional -OH group at 2 position
Additional -OH group at 3 position
Deletion -OH group at 2 position
Deletion -OH group at 3position
Name the basic amino acids residue are
rich in Histones
a. Lysines & glutamines
b. Lysines & arginines
c. Lysines & valines
d. Lysines & histamines
The region of chromatin are loosely packed
& less stained & are referred as
a. Euchromatin
b. Heterochromatin
c. Nucleosome
d. Chromosome
Which of the following experiment on streptococcus
pneumonia has proved conclusively that DNA is the
genetic material by Avery et. al.,
a. DNA from S strain + R-strain alive + DNase
b. DNA from S strain + Heat killed R-strain + DNase
c. DNA from S strain + R-strain alive + RNase
d. Denaturized DNA from S strain + R-strain +
protease
The average of polymerization of
nucleotides by DNA polymerase III during
replication has to be approximately
a. 2000bp / second
b. 2000 bp/ min
c. 5000bp/ second
d. 5000bp/min
A failure in cell division after DNA
replication results
a. Aneuploidy
b. Trisomy
c. Polyploidy
d. Monosimics
The transcription unit in DNA consists of
a.
b.
c.
d.
A promoter, non coding , initiators
A promoter, the structural gene & terminator
A promoter, the structural gene & RNA
A promoter, RNA & terminator
Match the RNAs listed in column I with their Function
given in column II: choose the answer which gives the
correct combination of alphabets of two columns
Column I
A RNA pol I
B RNA pol II
C RNA pol III
D DNA ligase
p
q
r
s
Column II
Joining
Model of t-RNA
Transcribes rRNA
Transcription of tRNA
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t Precursor of mRNA
a. A= r; B = t;
b. A = r ; B=q ;
c. A = r; B = s;
d. A = t ; B= s;
C = s; D = p.
C = p: D = t
C = p; D = t.
C=p; D =q
A classical example of point mutation
is change of single base pair in the
gene
a.
Down’s syndrome
b. Sickle cell anemia
c. Turner’s syndrome
d. Alkeptanueria
The management & analysis of the
biological information stored in data
base called
a. Bio formatics
b. Bio computers
c. Bio systematic
d. Bioinformatics
Which RNA is present in minimum
amount in a cell ?
a. t RNA
b. m RNA
c. r RNA
d. both a & c
The process which involves removal of introns
and joining of exons of m RNA is called
a)
Ligation
b) Cleaving
c) Splicing
d) modification
In DNA double helix model, how far is
each base pair from the next base pair.
a. 0.34 nm
b. 34nm
c. 3.4 nm
d. 0.0034 nm
The elongation of the leading strand
during DNA synthesis
a. Progresses away from the replication
fork
b. Occurs in the 3¹→5¹ direction
c. Does not require a template strand
d. Depends on the action of DNA
polymerase
DNA molecule has uniform diameter
due to
a. Double stranded nature
b. Presence of phosphate
c. Specific base pairing between purine
and pyrimidine
d. Specific base pairing between purine
and purine
The genetic material must fulfil the following criteria
a. It should able produce its replica
b. It should be structurally and chemically stable
c. It should not changes that leads to evolution
d. It express itself in the form of Mendelian
characters.
1. Only A, B and C.
2. Only A and B
3. Only C &D.
4. Only A, B and D
Identify correct label for alphabets shown in the
diagram of transcription of bacteria
a. A- Sigma factor, B- RNA polymerase,
C- DNA and D- Rho factor.
b. A-RNA polymerase, B- Sigma factor,
C- DNA and D- Rho factor
c. A- RNA polymerase, B-Sigma factor,
C- RNA and D- Rho factor.
d. A- Rho factor, B- RNA polymerase,
C- RNA and D- sigma factor.
Q. If sequence of nitrogen bases on coding strand
of transcription unit is 5’-TACGTACGTA-3’, identify
the sequence of nitrogen bases on corresponding
mRNA produced by it
a.
b.
c.
d.
3’UACGUACGUA-5’
3’-AUGCAUGCAU-5’
5’-UACGUACGUA-3’
5’-AUGCAUGCAU-3’
Removal of RNA polymerase III from
nucleoplasm will affect the synthesis of
1. t-RNA
2. m-RNA
3. r-RNA
4. hn-RNA
DNA sequence is ATG. What would be
the sequence of bases in
corresponding anticodon of t-RNA
1. ATG
2. AUG
3. UAC
4. TAC
Teminism need following enzyme
1. RNA dependent RNA polymerase
2. DNA dependent RNA polymerase
3. DNA dependent DNA polymerase
4. RNA dependent DNA polymerase
Gene regulation is exerted at following
level or levels
a. During transcription
b. During processing or splicing
c. During the transport of m-RNA
d. At translational level
1. Only A, B and D.
2. 2. Only A, C and D
3. Only A and D
4. All these
What would happen if in a gene coding a polypeptide
of 50 amino acids, 20th codon (UAC) is mutated to
‘UAG’
a. A polypeptide of 19 amino acids will be
formed.
b. Two polypeptides of 19 and 30 amino acids
will be formed.
c. A polypeptide of 49 amino acids will be
formed.
d. A polypeptide of 20 amino acids will be
formed
In the following diagram of t-RNA, identify correct
labels with alphabets and choose the correct answer
a. A- amino acid arm, B- DHU arm,
C- anticodon arm, D- Variable arm,
b. A- amino acid arm, B- anticodon arm,
C- Variable arm and D – DHU arm.
c. A- amino acid arm, C- anticodon arm,
D- Pseudo Uridine arm E –Variable arm.
d. A- anticodon arm, B- DHU arm, C- anticodon arm,
D- Pseudo Uridine arm
Which of the statement is true
• DHU loop recognize ribosome &
T psi C loop is synthetase site
• DHU loop is synthetase site &
T psi C loop recognize ribosome
• DHU loop both synthetase & ribosome
• T psi C loop recognize both ribosome &
synthetase
DNA replication occurs during which
phase of cell cycle
a. G1 phase
b. S- phase
c. G2 phase
d. mitosis
Non genetic RNA is
a. Only one type
b. Two types
c. Three types
d. Four types
The enzymes repair & fills the correct
nucleotide during DNA replication is
a. DNA polymerase I
b. DNA polymerase II
c. DNA polymerase III
d. Helicase
In a double strand DNA contains ten
turns, the length of DNA strand is
a. 100 nucleotides
b. 3.4 nm
c. 34 nm
d. 340.4 nm
The replication of DNA is
a. Conservative &
bidirectional
b. Semi Conservative &
bidirectional
c. Semi Conservative &
unidirectional
d. Conservative & unidirectinal
Radioactive DNA was allowed to replicate in
non radioactive medium for three generation.
What % of radioactive DNA at the end of third
generation.
a. 100 %
b. 75 %
c. 50 %
d. 25 %
Which group of codons are in
same group
a. UAA, UAG, UGG
b. UAA, UCC, UGA
c. UAA, UCC, GGC
d. UAA, UAG, UGA.
A gene contains 999 nucleotides (including
initiator codon & terminator codon). How many
amino acids would be there in polypeptide chain
a. 333
b. 332
c. 331
d. 999
The 3¹ end of the eukaryotic mRNA has
a. Cap of GPP
b. Poly A tail
c. Non coding region
d. coding region
The number of t RNA is equivalent to
a. The number of mRNA
b. The number of Nucleotides
c. Number of protein
d. Types of amino acids
Which of these are true?
a. The mRNA of prokaryotes is monocistronic
b. The same DNA strand is used for synthesis of all
RNAs
c. The RNAs synthesized on the two strands of DNA
are not the same
d. RNAs are modified after their transcription
1) a and c
2) b and d 3) a and b 4) c and d
The r RNA of E.coli ribosomes has been
found to catalyze peptidyl transferase
reaction is
a) 16 s r RNA
b) 23 s r RNA
c) 5 s r RNA
d) 28 s r RNA
Which of the character is not
applicable to t RNA?
a.
b.
c.
d.
It is the smallest of the RNAs
It acts as an adaptor for amino acid
It has a clover leaf like structure
It bears NODOC
Which one of the following statements
about genetic code is true?
a. In between the codons there are
punctuations
b. Single amino acid is often coded by more
than one triplet codon
c. The base of one codon is shared by
succeeding codon
d. Single triplet codon codes for only one amino
acids
Which of the following are not involved in
the formation of aminoacyl t RNA
1. ATP
2. Initiation factors
3. Aminoacyl t- RNA synthetase
4. GTP molecules
a)1 and 2
b) 2 and 4
c) 2 and 3 d) 4 only
The strand that is used for transcription
a) Sense strand
b) Both sense and antisense
c) Antisense strand
d) Primer
During initiation of protein synthesis,
The methionine t RNA occupies
a. P site and then shift to A site
b. E site and then shift to P site
c. P site and then leaves after depositing amino
acid
d. A site and then leaves after depositing
amino acid
The anticodon of a particular t RNA
molecule is
a. The part of t RNA that binds to a specific
amino acid
b. Complementary to the corresponding triplet
in DNA
c. Complementary to the corresponding m RNA
codon
d. The part of t RNA that binds to ribosome subunit
a.
b.
c.
d.
In the lac-Operon model, lactose molecules
function as
Repressors which bind with the operator gene
Inducers which bind with the operator gene
Co repressors bind with the repressor protein
Inducers which bind with the repressor protein
Which of these is correct
a. One gene can produce several different poly
peptides
b. Normally several genes code for one
Polypeptide
c. One gene codes for one polypeptide
d. Either (a) or (b)
The nitrogen base found in RNA but
not in DNA is
a) Guanine
b) Adenine
c) Uracil
d) Thymine
The central dogma of molecular
biology is
a.
b.
c.
d.
DNA → m-RNA → protein
m RNA → DNA → protein
Polypeptide → DNA → Protein
Protein → m-RNA → t-RNA
In prokaryotes, all genes are together
transcribed into a single m-RNA such
m-RNA called
a) Polycistronic
b) Dicistronic
c) Monocistronic
d) Non-Cistronic
Which of the following enzyme activates the
amino acid during protein synthesis
a.
b.
c.
d.
Peptidyl synthetase
DNA polymerase
RNA polymerase
Aminoacyl synthetase
Which gene in Lac- Operon of E.coli forms
the repressor protein
a) Operator gene
b) Regulator gene
c) Promoter gene
d) Structural gene
The genes are switched on in response to
presence of inducer are known as
a. Inducible gene
b. Housekeeping gene
c. Operator gene
d. Promoter gene
Read the following statements and choose the
correct answer
Statement A: DNA finger printing fails to
differentiate identical twins
Statement B: They are with same VNTR’s
1. Both statement A & B are correct and B is correct
reason for A
2. Both statement A & B are correct and B is not
correct reason for A
3. Only Statement A is correct and B is wrong
4. Only statement B is correct and A is wrong.
In transformation experiment, R-strain is
converted in to S-strain by formation of
a). Cell wall
b. Plasma membrane
c. Capsule
d. All of these
In t-RNA the amino acid binds at
a.
b.
c.
d.
CCA
CUA
CGA
ACA
3¹
3¹
3¹
3¹
Select the correct answer /answers from thefollowing
A. Ligases: - Joins segments of DNA together
B. DNA Polymerase: - cuts DNA
C. Helicase: - Breaks the hydrogen bonds between
complementary pairs during replication
D. Gyrase: - Joins weak hydrogen bonds
1. A, B, C and D, are correct 2. A and B are correct,
3. A and C are correct,
4. A, B, C are correct
In lac-Operon lac – Z gene produce
a. Beta –galactosidase
b.permease
c. trans acetylase
d.. Repressor protein
Part of DNA which contains repetitive
sequences are called
a. Satellite DNA
b. Junk DNA
c. Repetitive DNA
d. Chromosome
Meselson and Stahl proved semi-conservative
replication of DNA by experimenting with
a. E.coli and heavy isotopes of nitrogen
b. E.coli and isotopes of Carbon
c. E.coli and radioactive phosphorous
d. E.coli and radioactive sulphur
Process used for amplification of DNA for
finger printing
a. Polymerase chain reaction
b. southern blotting
c. polymorphism
d. polyploidy
Hershey & Chase worked with viruses, that
are called
a. Plasmids
b. Bacteriophages
c. Prions
d. viroids
In the genetic code dictionary, number
of sensible codons are
a.
b.
c.
d.
20
61
64
03
Breaking of hydrogen bond between
complementary nitrogenous bases called
a. Melting
b. Salting
c. Aneling
d. Tilting
The gene which are constantly express
themselves in a cells known as
a. Inducible gene
b. Housekeeping gene
c. Operator gene
d. Promoter gene
Name the enzymes did not affect during
biochemical transformation principle
a. DN ases & RN ases
b. Proteases & RN ases
c. DN ases & proteases
d. DN ases & ligases
Which of the statement is not true
a. DNA contains AGTC
b. m- RNA carries the message of DNA
c. DNA synthesizes RNA
d. RNA is double stranded
Which of the following group
contains purins
a. Guanine cytosine
b. Uracil cytosine
c. Adenine guanine
d. Thymine adenine
Organisms having either DNA or
RNA as genetic material
a) Nostoc
b) Bacteria
c) viruses
d) Eukaryotes
In protein synthesis, the first initiator
codon codes for
a) Phenyl Alanine
b) Lysine
c) Methionine
d) Glycine
One gene and one enzyme hypothesis was
postulated by
a.
b.
c.
d.
Beadle and Tatum
R. Franklin
Hershey and Chase
Chargaff
DNA and RNA are similar in having
a.
b.
c.
d.
Similar nucleotides
Similar pyrimidines
Similar purines
Similar sugars
Which is not true for genetic code?
a.
b.
c.
d.
It is universal
It is degenerate
It is overlapping
It is unambiguous
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