Lac operon is a segment of DNA that is made up of three adjacent structural genes, namely, an operator gene, a promoter gene, and a regulator gene. It works in a coordinated manner to metabolize lactose into glucose and galactose. In lac operon, lactose acts as an inducer. It binds to the repressorRead more
Lac operon is a segment of DNA that is made up of three adjacent structural genes, namely, an operator gene, a promoter gene, and a regulator gene. It works in a coordinated manner to metabolize lactose into glucose and galactose. In lac operon, lactose acts as an inducer. It binds to the repressor and inactivates it. Once the lactose binds to the repressor, RNA polymerase binds to the promoter region. Hence, three structural genes express their product and respective enzymes are produced. These enzymes act on lactose so that lactose is metabolized into glucose and galactose.
After sometime, when the level of inducer decreases as it is completely metabolized by enzymes, it causes synthesis of the repressor from regulator gene. The repressor binds to the operator gene and prevents RNA polymerase from transcribing the operon. Hence, the transcription is stopped. This type of regulation is known as negative regulation.
The important functions of ribosome during translation are as follows. 1. Ribosome acts as the site where protein synthesis takes place from individual amino acids. It is made up of two subunits. The smaller subunit comes in contact with mRNA and forms a protein synthesizing complex whereas the largRead more
The important functions of ribosome during translation are as follows.
1. Ribosome acts as the site where protein synthesis takes place from individual amino acids. It is made up of two subunits. The smaller subunit comes in contact with mRNA and forms a protein synthesizing complex whereas the larger subunit acts as an amino acid binding site.
2. Ribosome acts as a catalyst for forming peptide bond. For example, 23s r-RNA in bacteria acts as a ribozyme.
(a) Repetitive DNA and satellite DNA:- Repetitive DNA:-Repetitive DNA are DNA sequences that contain small segments, which are repeated many times. Satellite DNA:-Satellite DNA are DNA sequences that contain highly repetitive DNA. (b) mRNA and tRNA:- mRNA:- 1. mRNA or messenger RNA acts as a templatRead more
(a) Repetitive DNA and satellite DNA:-
Repetitive DNA:-Repetitive DNA are DNA sequences that contain small segments, which are repeated many times.
Satellite DNA:-Satellite DNA are DNA sequences that contain highly repetitive DNA.
(b) mRNA and tRNA:-
mRNA:-
1. mRNA or messenger RNA acts as a template for the process of transcription.
2. It is a linear molecule.
tRNA:-
1. tRNA or transfer RNA acts as an adaptor molecule that carries a specific amino acid to mRNA for the synthesis of polypeptide.
2. It has clover leaf shape.
(c) Template strand and coding strand:-
Template strand:-
1. Template strand of DNA acts as a template for the synthesis of mRNA during transcription.
2. It runs from 3’ to 5’.
Coding strand:-
1. Coding strand is a sequence of DNA that has the same base sequence as that of mRNA (except thymine that is replaced by uracil in DNA).
2. It runs from 5’to 3’.
Hershey and Chase worked with bacteriophage and E.coli to prove that DNA is the genetic material. They used different radioactive isotopes to label DNA and protein coat of the bacteriophage. They grew some bacteriophages on a medium containing radioactive phosphorus (³²P) to identify DNA and some onRead more
Hershey and Chase worked with bacteriophage and E.coli to prove that DNA is the genetic material. They used different radioactive isotopes to label DNA and protein coat of the bacteriophage.
They grew some bacteriophages on a medium containing radioactive phosphorus (³²P) to identify DNA and some on a medium containing radioactive sulphur (³⁵S) to identify protein. Then, these radioactive labelled phages were allowed to infect E.coli bacteria. After infecting, the protein coat of the bacteriophage was separated from the bacterial cell by blending and then subjected to the process of centrifugation. Since the protein coat was lighter, it was found in the supernatant while the infected bacteria got settled at the bottom of the centrifuge tube. Hence, it was proved that DNA is the genetic material as it was transferred from virus to bacteria.
There are two different types of nucleic acid polymerases. 1. DNA-dependent DNA polymerases 2. DNA-dependent RNA polymerases The DNA-dependent DNA polymerases use a DNA template for synthesizing a new strand of DNA, whereas DNA-dependent RNA polymerases use a DNA template strand for synthesizing RNARead more
There are two different types of nucleic acid polymerases.
1. DNA-dependent DNA polymerases
2. DNA-dependent RNA polymerases
The DNA-dependent DNA polymerases use a DNA template for synthesizing a new strand of DNA, whereas DNA-dependent RNA polymerases use a DNA template strand for synthesizing RNA.
In the medium where E. coli was growing, lactose was added, which induced the lac operon. Then, why does lac operon shut down some time after addition of lactose in the medium?
Lac operon is a segment of DNA that is made up of three adjacent structural genes, namely, an operator gene, a promoter gene, and a regulator gene. It works in a coordinated manner to metabolize lactose into glucose and galactose. In lac operon, lactose acts as an inducer. It binds to the repressorRead more
Lac operon is a segment of DNA that is made up of three adjacent structural genes, namely, an operator gene, a promoter gene, and a regulator gene. It works in a coordinated manner to metabolize lactose into glucose and galactose. In lac operon, lactose acts as an inducer. It binds to the repressor and inactivates it. Once the lactose binds to the repressor, RNA polymerase binds to the promoter region. Hence, three structural genes express their product and respective enzymes are produced. These enzymes act on lactose so that lactose is metabolized into glucose and galactose.
After sometime, when the level of inducer decreases as it is completely metabolized by enzymes, it causes synthesis of the repressor from regulator gene. The repressor binds to the operator gene and prevents RNA polymerase from transcribing the operon. Hence, the transcription is stopped. This type of regulation is known as negative regulation.
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List two essential roles of ribosome during translation.
The important functions of ribosome during translation are as follows. 1. Ribosome acts as the site where protein synthesis takes place from individual amino acids. It is made up of two subunits. The smaller subunit comes in contact with mRNA and forms a protein synthesizing complex whereas the largRead more
The important functions of ribosome during translation are as follows.
1. Ribosome acts as the site where protein synthesis takes place from individual amino acids. It is made up of two subunits. The smaller subunit comes in contact with mRNA and forms a protein synthesizing complex whereas the larger subunit acts as an amino acid binding site.
2. Ribosome acts as a catalyst for forming peptide bond. For example, 23s r-RNA in bacteria acts as a ribozyme.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-6/
Differentiate between the followings: (a) Repetitive DNA and Satellite DNA (b) mRNA and tRNA (c) Template strand and Coding strand
(a) Repetitive DNA and satellite DNA:- Repetitive DNA:-Repetitive DNA are DNA sequences that contain small segments, which are repeated many times. Satellite DNA:-Satellite DNA are DNA sequences that contain highly repetitive DNA. (b) mRNA and tRNA:- mRNA:- 1. mRNA or messenger RNA acts as a templatRead more
(a) Repetitive DNA and satellite DNA:-
Repetitive DNA:-Repetitive DNA are DNA sequences that contain small segments, which are repeated many times.
Satellite DNA:-Satellite DNA are DNA sequences that contain highly repetitive DNA.
(b) mRNA and tRNA:-
mRNA:-
1. mRNA or messenger RNA acts as a template for the process of transcription.
2. It is a linear molecule.
tRNA:-
1. tRNA or transfer RNA acts as an adaptor molecule that carries a specific amino acid to mRNA for the synthesis of polypeptide.
2. It has clover leaf shape.
(c) Template strand and coding strand:-
Template strand:-
1. Template strand of DNA acts as a template for the synthesis of mRNA during transcription.
2. It runs from 3’ to 5’.
Coding strand:-
1. Coding strand is a sequence of DNA that has the same base sequence as that of mRNA (except thymine that is replaced by uracil in DNA).
2. It runs from 5’to 3’.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-6/
How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material?
Hershey and Chase worked with bacteriophage and E.coli to prove that DNA is the genetic material. They used different radioactive isotopes to label DNA and protein coat of the bacteriophage. They grew some bacteriophages on a medium containing radioactive phosphorus (³²P) to identify DNA and some onRead more
Hershey and Chase worked with bacteriophage and E.coli to prove that DNA is the genetic material. They used different radioactive isotopes to label DNA and protein coat of the bacteriophage.
They grew some bacteriophages on a medium containing radioactive phosphorus (³²P) to identify DNA and some on a medium containing radioactive sulphur (³⁵S) to identify protein. Then, these radioactive labelled phages were allowed to infect E.coli bacteria. After infecting, the protein coat of the bacteriophage was separated from the bacterial cell by blending and then subjected to the process of centrifugation. Since the protein coat was lighter, it was found in the supernatant while the infected bacteria got settled at the bottom of the centrifuge tube. Hence, it was proved that DNA is the genetic material as it was transferred from virus to bacteria.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-6/
Depending upon the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesised from it (DNA or RNA), list the types of nucleic acid polymerases.
There are two different types of nucleic acid polymerases. 1. DNA-dependent DNA polymerases 2. DNA-dependent RNA polymerases The DNA-dependent DNA polymerases use a DNA template for synthesizing a new strand of DNA, whereas DNA-dependent RNA polymerases use a DNA template strand for synthesizing RNARead more
There are two different types of nucleic acid polymerases.
1. DNA-dependent DNA polymerases
2. DNA-dependent RNA polymerases
The DNA-dependent DNA polymerases use a DNA template for synthesizing a new strand of DNA, whereas DNA-dependent RNA polymerases use a DNA template strand for synthesizing RNA.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-6/