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How many base pairs are there in every helical turn of Watson-Crick double helix model?- a)32.3
- b)11.6
- c)20
- d)10.4
Correct answer is option 'D'. Can you explain this answer?
How many base pairs are there in every helical turn of Watson-Crick double helix model?
a)
32.3
b)
11.6
c)
20
d)
10.4
|
Orion Classes answered |
Watson-Crick double helix model consists of 10.4 base pairs per helical turn. Since one helical turn formed by 360° and there would be 34.3° twist angle per residue among adjacent base pair.
Which one of the following statement is INCORRECT for Z-DNA?- a)Left-handed DNA
- b)Mostly found in alternating purine-pyrimidine sequences
- c)Only one deep, narrow groove
- d)Anti glycosidic bond conformation
Correct answer is option 'D'. Can you explain this answer?
Which one of the following statement is INCORRECT for Z-DNA?
a)
Left-handed DNA
b)
Mostly found in alternating purine-pyrimidine sequences
c)
Only one deep, narrow groove
d)
Anti glycosidic bond conformation
|
Everly Young answered |
Incorrect Statement for Z-DNA:
Z-DNA is a unique form of DNA with distinct structural features that differentiate it from the more common B-DNA. One of the statements provided is incorrect for Z-DNA:
Anti glycosidic bond conformation:
- The incorrect statement is that Z-DNA has an anti glycosidic bond conformation. In reality, Z-DNA actually has a syn glycosidic bond conformation. This means that the nucleotide bases are oriented in a way that allows for a syn conformation of the glycosidic bond between the sugar and the base.
Other Characteristics of Z-DNA:
- Left-handed DNA: Z-DNA is indeed a left-handed helical form of DNA, which is different from the more common right-handed B-DNA.
- Mostly found in alternating purine-pyrimidine sequences: Z-DNA is typically found in DNA sequences that alternate between purine (adenine and guanine) and pyrimidine (cytosine and thymine) bases.
- Only one deep, narrow groove: Z-DNA has a single deep, narrow major groove and a shallow minor groove, which is different from the major and minor groove combination found in B-DNA.
In conclusion, the incorrect statement about Z-DNA is that it has an anti glycosidic bond conformation, when in fact it has a syn glycosidic bond conformation.
Z-DNA is a unique form of DNA with distinct structural features that differentiate it from the more common B-DNA. One of the statements provided is incorrect for Z-DNA:
Anti glycosidic bond conformation:
- The incorrect statement is that Z-DNA has an anti glycosidic bond conformation. In reality, Z-DNA actually has a syn glycosidic bond conformation. This means that the nucleotide bases are oriented in a way that allows for a syn conformation of the glycosidic bond between the sugar and the base.
Other Characteristics of Z-DNA:
- Left-handed DNA: Z-DNA is indeed a left-handed helical form of DNA, which is different from the more common right-handed B-DNA.
- Mostly found in alternating purine-pyrimidine sequences: Z-DNA is typically found in DNA sequences that alternate between purine (adenine and guanine) and pyrimidine (cytosine and thymine) bases.
- Only one deep, narrow groove: Z-DNA has a single deep, narrow major groove and a shallow minor groove, which is different from the major and minor groove combination found in B-DNA.
In conclusion, the incorrect statement about Z-DNA is that it has an anti glycosidic bond conformation, when in fact it has a syn glycosidic bond conformation.
Which of the following infection causes a change in the properties of the cell?- a)Latent
- b)Abortive
- c)Transforming
- d)Null
Correct answer is option 'C'. Can you explain this answer?
Which of the following infection causes a change in the properties of the cell?
a)
Latent
b)
Abortive
c)
Transforming
d)
Null
|
Alexander Blake answered |
Transforming Infection
Transforming infection causes a change in the properties of the cell.
- Definition: Transforming infections are caused by viruses that have the ability to transform normal cells into cancerous cells.
- Mechanism: These viruses can integrate their genetic material into the host cell's DNA, disrupting normal cellular processes and leading to uncontrolled cell growth.
- Consequences: The transformed cells can acquire properties such as unlimited growth potential, resistance to cell death, and the ability to invade surrounding tissues, characteristics typical of cancer cells.
- Examples: Some well-known viruses that can cause transforming infections include human papillomavirus (HPV) and Epstein-Barr virus (EBV).
Which of the following is not the type of viral infection?- a)Null
- b)Meningitis
- c)Latent
- d)Persistent
Correct answer is option 'B'. Can you explain this answer?
Which of the following is not the type of viral infection?
a)
Null
b)
Meningitis
c)
Latent
d)
Persistent
|
|
Orion Classes answered |
Meningitis is a type of bacterial infection. The interactions between viral and cells can be classified into acutely cytopathogenic, persistent, null, latent, abortive, transforming infections.
Which form of DNA is described by Watson-Crick model?- a)B-DNA
- b)Z-DNA
- c)A-DNA
- d)Quadraplex DNA
Correct answer is option 'A'. Can you explain this answer?
Which form of DNA is described by Watson-Crick model?
a)
B-DNA
b)
Z-DNA
c)
A-DNA
d)
Quadraplex DNA
|
|
Orion Classes answered |
There are many forms of DNA which are biologically important, out of which Watson-Crick double helix model describes the B form of DNA. The confirmation of DNA would depend on the hydration level, base modification etc.
Apoptosis regulates cell numbers.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
Apoptosis regulates cell numbers.
a)
True
b)
False
|
|
Orion Classes answered |
Apoptosis is the process that regulates cell numbers during development. The unique feature of apoptosis is that the dying cell remains intact and its contents stay within the plasma membrane.
UL37x1 is a protein encoded by __________- a)Cytomegalovirus
- b)HSV
- c)SV40
- d)HIV
Correct answer is option 'A'. Can you explain this answer?
UL37x1 is a protein encoded by __________
a)
Cytomegalovirus
b)
HSV
c)
SV40
d)
HIV
|
|
Orion Classes answered |
UL37x1 is a protein encoded by human cytomegalovirus which is a herpes virus. The protein inhibits the apoptosis of infected cells, which permits the virus to establish a long-lasting infection.
The third strand of triple helix is paired in which scheme?- a)Hoogsteen base pair scheme
- b)Intermolecular base pair scheme
- c)Intramolecular base pair scheme
- d)G-quartet scheme
Correct answer is option 'A'. Can you explain this answer?
The third strand of triple helix is paired in which scheme?
a)
Hoogsteen base pair scheme
b)
Intermolecular base pair scheme
c)
Intramolecular base pair scheme
d)
G-quartet scheme
|
|
Orion Classes answered |
Triple helix formed by three strands polypurine, polypyrimidine and the third strand which lay in the major groove of DNA and makes a hydrogen bond to duplex. The third strand is paired in hoogsteen base pairing scheme where the central strand is purine rich.
In which of the following infection the cells do not have the appropriate receptor for the virus?- a)Null
- b)Transforming
- c)Abortive
- d)Cytopathogenic
Correct answer is option 'A'. Can you explain this answer?
In which of the following infection the cells do not have the appropriate receptor for the virus?
a)
Null
b)
Transforming
c)
Abortive
d)
Cytopathogenic
|
|
Orion Classes answered |
Null infection represents the cells which do not have appropriate receptors for a particular virus, and thus cannot interact with virus particle. The viral genome is artificially introduced into such cells in the laboratory to produce progenies.
The stability and formation of G-quadruplex depends on __________- a)Monovalent cation
- b)Divalent cation
- c)Bivalent cation
- d)Pentavalent ion
Correct answer is option 'A'. Can you explain this answer?
The stability and formation of G-quadruplex depends on __________
a)
Monovalent cation
b)
Divalent cation
c)
Bivalent cation
d)
Pentavalent ion
|
|
Orion Classes answered |
A monovalent cation is responsible for the stability of G-quadruplex as it is present in the center of the tetrad. It can be formed in either DNA or RNA.
Which of the following infection results in the continuous production of viruses?- a)Persistent
- b)Abortive
- c)Null
- d)Transforming
Correct answer is option 'A'. Can you explain this answer?
Which of the following infection results in the continuous production of viruses?
a)
Persistent
b)
Abortive
c)
Null
d)
Transforming
|
|
Orion Classes answered |
Persistent infections are the infections that cause or result in the continuous production of infectious viruses. This is achieved either by the survival of the infected cells or by a situation in which a minority of cells are initially infected and the spread of the virus is limited.
In which of the following infection no infectious progeny is produced?- a)Latent
- b)Abortive
- c)Persistent
- d)Null
Correct answer is option 'A'. Can you explain this answer?
In which of the following infection no infectious progeny is produced?
a)
Latent
b)
Abortive
c)
Persistent
d)
Null
|
|
Orion Classes answered |
The term latent is defined as existing but not exhibited. In terms of the virus-infected cell, it means that the viral genome is present but no infectious progeny is produced. Adeno-associated virus, herpesvirus exhibits latency.
Which infection causes a reduction in the total yield of virus particles?- a)Null
- b)Transforming
- c)Abortive
- d)Cytopathogenic
Correct answer is option 'C'. Can you explain this answer?
Which infection causes a reduction in the total yield of virus particles?
a)
Null
b)
Transforming
c)
Abortive
d)
Cytopathogenic
|
|
Orion Classes answered |
Abortive infection causes a reduction in the total yield of virus particles (sometimes to zero). The quality of the progeny, if produced, maybe deficient as the cells do not replicate that virus with equal efficiency.
Name the nitrogenous base which is found in abundance in G-quadruplex?- a)Adenine
- b)Guanine
- c)Cytosine
- d)Thymine
Correct answer is option 'B'. Can you explain this answer?
Name the nitrogenous base which is found in abundance in G-quadruplex?
a)
Adenine
b)
Guanine
c)
Cytosine
d)
Thymine
|
|
Orion Classes answered |
When nucleic acid sequences are rich in guanine and can form four-stranded structure, it will term as G-quadruplex. It is a square arrangement of guanine, stabilized by hoogsteen hydrogen bonding.
Which of the following virus promotes cell death by apoptosis?- a)Vaccinia virus
- b)Myxoma virus
- c)HSV
- d)Rubella virus
Correct answer is option 'D'. Can you explain this answer?
Which of the following virus promotes cell death by apoptosis?
a)
Vaccinia virus
b)
Myxoma virus
c)
HSV
d)
Rubella virus
|
|
Orion Classes answered |
Rubella virus, which belongs to the family Togaviridae, expresses proteins that promote the cell death by apoptosis. Vaccinia virus, myxoma virus, herpes simplex virus, etc. are the viruses that inhibit the cell death by apoptosis.
Which of this factor is not responsible for thermal denaturation of DNA?- a)PH
- b)Temperature
- c)Ionic strength
- d)Humidity
Correct answer is option 'D'. Can you explain this answer?
Which of this factor is not responsible for thermal denaturation of DNA?
a)
PH
b)
Temperature
c)
Ionic strength
d)
Humidity
|
|
Orion Classes answered |
When DNA duplex is laid open to the specific conditions like temperature, pH, or ionic strength it will interrupt the hydrogen bond between strands and they are no longer held together. After denaturation, the strand separates as individual coils and the double helix is denatured.
What is the term given to the supercoiling of circular DNA?- a)Twist number
- b)Linking number
- c)Writhe number
- d)Cross-linking
Correct answer is option 'B'. Can you explain this answer?
What is the term given to the supercoiling of circular DNA?
a)
Twist number
b)
Linking number
c)
Writhe number
d)
Cross-linking
|
|
Orion Classes answered |
Linking number defines the no. of times one strand crosses other in closed circular DNA. It is the sum of twist number (total number of helical turn) and writhe number (supercoiling in the helix).
Lk = Tw + Wr.
Lk = Tw + Wr.
Which of the following infection is also called as lytic infection?- a)Null
- b)Cytopathogenic
- c)Latent
- d)Abortive
Correct answer is option 'B'. Can you explain this answer?
Which of the following infection is also called as lytic infection?
a)
Null
b)
Cytopathogenic
c)
Latent
d)
Abortive
|
|
Orion Classes answered |
Cytopathogenic infections are also called lytic infections as the cell dies due to lysis. But lytic is not the accurate term, as in some infection cells die without being lysed, that is, by apoptosis or programmed cell death.
Which of them is used to introduce negative supercoiling in DNA?- a)Type 1 topoisomerase
- b)Ethidium bromide
- c)Gyrase/ type 2 topoisomerase
- d)SYBR gold
Correct answer is option 'C'. Can you explain this answer?
Which of them is used to introduce negative supercoiling in DNA?
a)
Type 1 topoisomerase
b)
Ethidium bromide
c)
Gyrase/ type 2 topoisomerase
d)
SYBR gold
|
|
Orion Classes answered |
Type 1 topoisomerase break only one strand of DNA while gyrase works on both the strands, it breaks and reseal both DNA strands and introduce negative supercoils. Ethidium bromide and SYBR gold are used to stain DNA molecules.
Who described the structure of DNA double helix?- a)Peter Mitchell
- b)Andre Jagendorf
- c)Ernest Uribe
- d)Watson and Crick
Correct answer is option 'D'. Can you explain this answer?
Who described the structure of DNA double helix?
a)
Peter Mitchell
b)
Andre Jagendorf
c)
Ernest Uribe
d)
Watson and Crick
|
|
Orion Classes answered |
DNA double helix was first described in 1953 by Watson and Crick using X-ray diffraction. DNA fibers were obtained by Franklin and Wilkins. Watson, Crick, and Wilkins were awarded a noble prize in 1962.
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