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All questions of Microbiology for MCAT Exam
The karyotype of cells formed from continuous cell lines is _____- a)haploid
- b)diploid
- c)aneuploid
- d)haploid and diploid
Correct answer is option 'C'. Can you explain this answer?
The karyotype of cells formed from continuous cell lines is _____
a)
haploid
b)
diploid
c)
aneuploid
d)
haploid and diploid
|
Logan Adams answered |
Understanding Continuous Cell Lines
Continuous cell lines are a vital aspect of biological research, particularly in genetics, cancer research, and drug development. They exhibit unique karyotypic characteristics.
What is Karyotype?
- A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell.
- It reflects the genetic makeup of an organism or cell line.
Characteristics of Continuous Cell Lines
- Continuous cell lines are derived from primary cells that have undergone transformation, usually due to viral infection or genetic manipulation.
- They can proliferate indefinitely under appropriate culture conditions.
Why Are They Aneuploid?
- Continuous cell lines often show aneuploidy, meaning they have an abnormal number of chromosomes.
- This can result from errors during cell division, leading to gain or loss of chromosomes.
Diploid vs. Haploid
- Diploid cells possess two complete sets of chromosomes, while haploid cells have only one.
- Continuous cell lines can originate from diploid cells but typically become aneuploid through various mutations.
Conclusion
- The correct answer to the question is option 'C' (aneuploid) because continuous cell lines frequently exhibit chromosomal abnormalities, deviating from the standard diploid or haploid states.
- Their aneuploid nature is crucial for their adaptability and experimental utility, enabling researchers to study various biological processes and disease mechanisms effectively.
In summary, continuous cell lines are predominantly aneuploid due to their transformative processes, making them essential tools in scientific research.
Continuous cell lines are a vital aspect of biological research, particularly in genetics, cancer research, and drug development. They exhibit unique karyotypic characteristics.
What is Karyotype?
- A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell.
- It reflects the genetic makeup of an organism or cell line.
Characteristics of Continuous Cell Lines
- Continuous cell lines are derived from primary cells that have undergone transformation, usually due to viral infection or genetic manipulation.
- They can proliferate indefinitely under appropriate culture conditions.
Why Are They Aneuploid?
- Continuous cell lines often show aneuploidy, meaning they have an abnormal number of chromosomes.
- This can result from errors during cell division, leading to gain or loss of chromosomes.
Diploid vs. Haploid
- Diploid cells possess two complete sets of chromosomes, while haploid cells have only one.
- Continuous cell lines can originate from diploid cells but typically become aneuploid through various mutations.
Conclusion
- The correct answer to the question is option 'C' (aneuploid) because continuous cell lines frequently exhibit chromosomal abnormalities, deviating from the standard diploid or haploid states.
- Their aneuploid nature is crucial for their adaptability and experimental utility, enabling researchers to study various biological processes and disease mechanisms effectively.
In summary, continuous cell lines are predominantly aneuploid due to their transformative processes, making them essential tools in scientific research.
Cowpea virus belongs to which of the following group of viruses?- a)Comovirus
- b)Dianthovirus
- c)Cucumovirus
- d)Carlavirus
Correct answer is option 'A'. Can you explain this answer?
Cowpea virus belongs to which of the following group of viruses?
a)
Comovirus
b)
Dianthovirus
c)
Cucumovirus
d)
Carlavirus
|
Aurora Ross answered |
Comovirus Group
Cowpea virus belongs to the Comovirus group of viruses. This group is named after the type species, Cowpea mosaic virus, which infects leguminous plants like cowpeas. Here are some key points about the Comovirus group:
Characteristics:
- Comoviruses are non-enveloped, icosahedral viruses with a bipartite genome consisting of two single-stranded RNA molecules.
- They are transmitted by vectors such as aphids and nematodes.
- Comoviruses infect a wide range of plants, causing diseases like mosaic, leaf mottling, and necrosis.
Genus Comovirus:
- The genus Comovirus includes several well-known plant viruses such as Cowpea mosaic virus, Bean pod mottle virus, and Red clover mottle virus.
- These viruses are economically important as they can cause significant yield losses in crops.
Cowpea Virus:
- Cowpea virus specifically infects cowpeas and other leguminous plants, leading to symptoms like mosaic patterns on leaves and stunted growth.
- It can be transmitted through seeds as well as by insect vectors.
In conclusion, Cowpea virus belongs to the Comovirus group, a group of plant viruses with bipartite genomes that infect a wide range of plants and are economically significant.
Cowpea virus belongs to the Comovirus group of viruses. This group is named after the type species, Cowpea mosaic virus, which infects leguminous plants like cowpeas. Here are some key points about the Comovirus group:
Characteristics:
- Comoviruses are non-enveloped, icosahedral viruses with a bipartite genome consisting of two single-stranded RNA molecules.
- They are transmitted by vectors such as aphids and nematodes.
- Comoviruses infect a wide range of plants, causing diseases like mosaic, leaf mottling, and necrosis.
Genus Comovirus:
- The genus Comovirus includes several well-known plant viruses such as Cowpea mosaic virus, Bean pod mottle virus, and Red clover mottle virus.
- These viruses are economically important as they can cause significant yield losses in crops.
Cowpea Virus:
- Cowpea virus specifically infects cowpeas and other leguminous plants, leading to symptoms like mosaic patterns on leaves and stunted growth.
- It can be transmitted through seeds as well as by insect vectors.
In conclusion, Cowpea virus belongs to the Comovirus group, a group of plant viruses with bipartite genomes that infect a wide range of plants and are economically significant.
Which of the following viruses possess an envelope?- a)Herpesvirus
- b)Reovirus
- c)Tobacco mosaic virus
- d)Papillomavirus
Correct answer is option 'A'. Can you explain this answer?
Which of the following viruses possess an envelope?
a)
Herpesvirus
b)
Reovirus
c)
Tobacco mosaic virus
d)
Papillomavirus
|
Orion Classes answered |
Herpesvirus possesses an icosahedral symmetry and contains DNA as its genetic material. Its nucleocapsid is surrounded by an envelope.
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
|
Michael Warren answered |
Understanding the Watson-Crick Double Helix
The Watson-Crick model of DNA describes its structure as a double helix, where two strands twist around each other. An important aspect of this structure is the number of base pairs that occur in one complete turn of the helix.
Base Pairs Per Turn
- The correct answer to how many base pairs are present in every helical turn is 10.4.
- This value represents the average number of base pairs that participate in a single complete turn of the helical structure of DNA.
Significance of 10.4 Base Pairs
- The number 10.4 is derived from the helical structure of B-DNA, which is the most common form of DNA found in living organisms.
- Each helical turn spans approximately 34 angstroms (3.4 nanometers) in length, making the compact structure of DNA efficient for storage and replication.
Implications of Base Pair Count
- Understanding the number of base pairs per turn is crucial for various biological processes, including DNA replication and transcription.
- The uniformity of base pairs per turn aids in the stability and predictability of DNA interactions with proteins and enzymes.
Conclusion
- The average of 10.4 base pairs in each helical turn showcases the intricate design of DNA, allowing it to fulfill its roles in genetics and cellular function efficiently. This knowledge is foundational in molecular biology, genetics, and biochemistry studies.
The Watson-Crick model of DNA describes its structure as a double helix, where two strands twist around each other. An important aspect of this structure is the number of base pairs that occur in one complete turn of the helix.
Base Pairs Per Turn
- The correct answer to how many base pairs are present in every helical turn is 10.4.
- This value represents the average number of base pairs that participate in a single complete turn of the helical structure of DNA.
Significance of 10.4 Base Pairs
- The number 10.4 is derived from the helical structure of B-DNA, which is the most common form of DNA found in living organisms.
- Each helical turn spans approximately 34 angstroms (3.4 nanometers) in length, making the compact structure of DNA efficient for storage and replication.
Implications of Base Pair Count
- Understanding the number of base pairs per turn is crucial for various biological processes, including DNA replication and transcription.
- The uniformity of base pairs per turn aids in the stability and predictability of DNA interactions with proteins and enzymes.
Conclusion
- The average of 10.4 base pairs in each helical turn showcases the intricate design of DNA, allowing it to fulfill its roles in genetics and cellular function efficiently. This knowledge is foundational in molecular biology, genetics, and biochemistry studies.
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 method is used for the production of vaccines against yellow fever?- a)tissue-culture method
- b)chick-embryo method
- c)through susceptible animals
- d)through appropriate media
Correct answer is option 'B'. Can you explain this answer?
Which of the following method is used for the production of vaccines against yellow fever?
a)
tissue-culture method
b)
chick-embryo method
c)
through susceptible animals
d)
through appropriate media
|
|
Orion Classes answered |
The chick-embryo technique has been used in the production of vaccines against smallpox, yellow fever, influenza, and other diseases and in immunologic tests and other studies whenever large amounts of virus are required.
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
|
|
Orion Classes answered |
Anti glycosidic bond conformation is incorrect as in Z-DNA the sugar and glycosidic bond conformations alternate, anti for C and syn for G while in B form there is only anti glycosidic bond conformation.
How many dsRNA segments are present in the reovirus genome?- a)1
- b)3
- c)50
- d)10
Correct answer is option 'D'. Can you explain this answer?
How many dsRNA segments are present in the reovirus genome?
a)
1
b)
3
c)
50
d)
10
|
Ella Baker answered |
Number of dsRNA segments in reovirus genome:
Reoviruses are double-stranded RNA (dsRNA) viruses that contain segmented genomes. The reovirus genome consists of 10 segments of dsRNA. Each segment encodes for different proteins that are essential for the virus's replication and survival within the host cell.
Importance of segmented genome:
Having a segmented genome provides reoviruses with several advantages. Firstly, it allows for genetic reassortment to occur when two different strains of reovirus infect the same host cell. This reassortment can lead to the generation of novel virus strains with potentially altered pathogenicity or host range.
Genetic diversity and evolution:
The presence of multiple segments also contributes to the genetic diversity of reoviruses. This genetic diversity plays a crucial role in the virus's ability to adapt to changing environmental conditions and host immune responses. It also drives the evolution of reoviruses over time.
Segment-specific functions:
Each dsRNA segment in the reovirus genome encodes for specific viral proteins that are involved in different stages of the viral life cycle, such as attachment, entry, replication, and assembly. The coordinated expression of these proteins is essential for the successful replication and spread of the virus within the host.
In conclusion, the reovirus genome consists of 10 segments of dsRNA, each encoding for different viral proteins. This segmented genome structure provides reoviruses with genetic flexibility, diversity, and the ability to evolve in response to changing environmental pressures.
Reoviruses are double-stranded RNA (dsRNA) viruses that contain segmented genomes. The reovirus genome consists of 10 segments of dsRNA. Each segment encodes for different proteins that are essential for the virus's replication and survival within the host cell.
Importance of segmented genome:
Having a segmented genome provides reoviruses with several advantages. Firstly, it allows for genetic reassortment to occur when two different strains of reovirus infect the same host cell. This reassortment can lead to the generation of novel virus strains with potentially altered pathogenicity or host range.
Genetic diversity and evolution:
The presence of multiple segments also contributes to the genetic diversity of reoviruses. This genetic diversity plays a crucial role in the virus's ability to adapt to changing environmental conditions and host immune responses. It also drives the evolution of reoviruses over time.
Segment-specific functions:
Each dsRNA segment in the reovirus genome encodes for specific viral proteins that are involved in different stages of the viral life cycle, such as attachment, entry, replication, and assembly. The coordinated expression of these proteins is essential for the successful replication and spread of the virus within the host.
In conclusion, the reovirus genome consists of 10 segments of dsRNA, each encoding for different viral proteins. This segmented genome structure provides reoviruses with genetic flexibility, diversity, and the ability to evolve in response to changing environmental pressures.
The cycle which is completed quickly in the infection by a phage is ____- a)Lysogenic
- b)Lytic
- c)Replication
- d)Capsid formation
Correct answer is option 'B'. Can you explain this answer?
The cycle which is completed quickly in the infection by a phage is ____
a)
Lysogenic
b)
Lytic
c)
Replication
d)
Capsid formation
|
|
Orion Classes answered |
With some phage types the entire infection cycle is completed very quickly, possibly in less than 20 minutes. This type of rapid infection is called a lytic cycle, as a release of the new phage particles is associated with lysis of the bacterial cell.
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 infection cycle is characterized by retention of the phage DNA molecule in the host bacterium for many thousands of cell division?- a)Lysogenic cycle
- b)Lytic cycle
- c)Integrative Phase
- d)Protein synthesis
Correct answer is option 'A'. Can you explain this answer?
Which infection cycle is characterized by retention of the phage DNA molecule in the host bacterium for many thousands of cell division?
a)
Lysogenic cycle
b)
Lytic cycle
c)
Integrative Phase
d)
Protein synthesis
|
|
Orion Classes answered |
With many lysogenic phages the phage DNA is inserted into the bacterial genome in a manner similar to episomal insertion. The integrated form of the phage DNA is called the prophage and bacterium is referred to as a lysogen.
Rous sarcoma virus consists of RNA as its genetic material.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
Rous sarcoma virus consists of RNA as its genetic material.
a)
True
b)
False
|
|
Orion Classes answered |
Rous sarcoma virus belongs to Retroviridae family, has a virion size of 100-120. It possesses icosahedral symmetry and consists of RNA as its genetic material.
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.
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.
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.
Which of the following viruses have a complex symmetry?- a)Alphavirus
- b)Mobillivirus
- c)Orthopoxvirus
- d)Parvovirus
Correct answer is option 'C'. Can you explain this answer?
Which of the following viruses have a complex symmetry?
a)
Alphavirus
b)
Mobillivirus
c)
Orthopoxvirus
d)
Parvovirus
|
|
Orion Classes answered |
Orthopoxvirus posseses a complex symmetry and is surrounded by a coat. It consists of DNA as its nucleic acid.
Approximate size of lambda phage is ____- a)23 kb
- b)100 kb
- c)49 kb
- d)12 kb
Correct answer is option 'C'. Can you explain this answer?
Approximate size of lambda phage is ____
a)
23 kb
b)
100 kb
c)
49 kb
d)
12 kb
|
|
Orion Classes answered |
Lambda phage is extensively used as a cloning vector. The lambda DNA molecule is 49 kb in size and has been intensively studied by the techniques of gene mapping and DNA sequencing.
The family of Rhabdoviridae possesses dsRNA.- a)True
- b)False
Correct answer is option 'B'. Can you explain this answer?
The family of Rhabdoviridae possesses dsRNA.
a)
True
b)
False
|
|
Orion Classes answered |
The family of Rhabdoviridae consists of ssRNA and they are enveloped. An example is vesicular stomatitis.
Which of the following is not true for a bacteriophage?- a)A very simple structure
- b)Consist either DNA or RNA
- c)Bacteriophages are viruses
- d)Complex structure that infects bacteria
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not true for a bacteriophage?
a)
A very simple structure
b)
Consist either DNA or RNA
c)
Bacteriophages are viruses
d)
Complex structure that infects bacteria
|
|
Orion Classes answered |
Bacteriophages are viruses that specifically infect bacteria but these are very simple structures consisting merely of a DNA/RNA molecule surrounded by a protective coat.
Which of the following statements is not true in the context of infection by an M13 phage?- a)Lytic phage
- b)Lysogenic phage
- c)New phage particles are continually synthesized
- d)The DNA is not integrated in host genome
Correct answer is option 'A'. Can you explain this answer?
Which of the following statements is not true in the context of infection by an M13 phage?
a)
Lytic phage
b)
Lysogenic phage
c)
New phage particles are continually synthesized
d)
The DNA is not integrated in host genome
|
|
Orion Classes answered |
M13 is a lysogenic phage that follows a different infection cycle when M13 infects a bacterium, new phage particles are assembled and released continually from the cell. There is no integration of phage DNA into the bacterial chromosome and lysis of the cell also never occurs.
For the cultivation of viruses the fertile chicken eggs should be incubated for how many day(s)?- a)1
- b)2-4
- c)5-12
- d)2-7
Correct answer is option 'C'. Can you explain this answer?
For the cultivation of viruses the fertile chicken eggs should be incubated for how many day(s)?
a)
1
b)
2-4
c)
5-12
d)
2-7
|
|
Orion Classes answered |
For the cultivation of viruses by embryonated chicken eggs, the fertile chicken eggs should be incubated for 5 to 12 days and then they can be inoculated through the shell aseptically.
What is the capsid (protective coat) of the bacteriophage made up of?- a)DNA
- b)RNA
- c)Protein
- d)Organic acids
Correct answer is option 'C'. Can you explain this answer?
What is the capsid (protective coat) of the bacteriophage made up of?
a)
DNA
b)
RNA
c)
Protein
d)
Organic acids
|
|
Orion Classes answered |
The protective coat or capsid is made up of protein molecules which surround the nucleic acid molecule carrying a number of genes including several for the replication of phage.
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.
Which of the following is an example of head-and-tail bacteriophage?- a)M13
- b)Lambda phage
- c)Pbr322
- d)M16
Correct answer is option 'B'. Can you explain this answer?
Which of the following is an example of head-and-tail bacteriophage?
a)
M13
b)
Lambda phage
c)
Pbr322
d)
M16
|
|
Orion Classes answered |
Enterobacteria phage (Lambda phage) infects the bacterial species E.Coli. It consists of an icosahedral head, measuring 50-60 nanometers in diameter and a flexible tail that is around 150 nanometers in length.
What are sticky ends?- a)Ends of M13 vector
- b)12 nucleotide stretch in lambda phage
- c)The replicated product phage DNA
- d)Ends on two sides of origin
Correct answer is option 'B'. Can you explain this answer?
What are sticky ends?
a)
Ends of M13 vector
b)
12 nucleotide stretch in lambda phage
c)
The replicated product phage DNA
d)
Ends on two sides of origin
|
|
Orion Classes answered |
At either end of the lambda DNA molecule is a short 12 nucleotide stretch in which the DNA is single stranded. The two single strands are complementary and base pair with each other to form a circular completely double stranded molecule.
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 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.
Which is a reason of instability of phage DNA molecule in the host cell in a lytic cycle?- a)The huge size of phage DNA
- b)Inability of replicative enzymes
- c)Immediate synthesis of capsid
- d)Lytic cycle inefficiency
Correct answer is option 'C'. Can you explain this answer?
Which is a reason of instability of phage DNA molecule in the host cell in a lytic cycle?
a)
The huge size of phage DNA
b)
Inability of replicative enzymes
c)
Immediate synthesis of capsid
d)
Lytic cycle inefficiency
|
|
Orion Classes answered |
The characteristic feature of a lytic infection cycle is that phage DNA replication is immediately followed by synthesis of capsid proteins and the phage DNA molecule is never maintained in a stable condition in the host cell.
The replication of phage DNA molecule is associated with which step in the infection cycle of a bacteriophage?- a)First step
- b)Second step
- c)Third step
- d)Preparation stage
Correct answer is option 'B'. Can you explain this answer?
The replication of phage DNA molecule is associated with which step in the infection cycle of a bacteriophage?
a)
First step
b)
Second step
c)
Third step
d)
Preparation stage
|
|
Orion Classes answered |
The general pattern of infection, which is the same for all the phages is a three step process. The first step is the attachment of phage to the surface of bacterium and subsequent injection of its DNA into the cell, second step is replication of the injected DNA.
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.
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.
Enterovirus belongs to which of the following family of viruses?- a)Tymovirus
- b)Picornaviridae
- c)Reoviridae
- d)Closterovirus
Correct answer is option 'B'. Can you explain this answer?
Enterovirus belongs to which of the following family of viruses?
a)
Tymovirus
b)
Picornaviridae
c)
Reoviridae
d)
Closterovirus
|
|
Orion Classes answered |
Enterovirus belongs to the family Picornaviridae and it has a virion size of 28 nm.
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.
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.
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.
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.
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Biology and Biochemistry for MCAT
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