NCERT Class 11 Biotechnology Seventh Chapter Basic processes Solution
NCERT Class 11 Biotechnology Chapter 7 Solution: Dear students Here in this post we are posted Seventh Chapter Basic processes full exercise questions & answer by our arts teacher. This Solution is helpful for CBSE English medium students. Download this 7th Chapter Biotechnology solution & prepare your homework.
Q1. What is the importance of gene expression? What are the steps involved in it?
Ans- The biological information which is carried by DNA segment for the expression of a trait is called as gene. The gene expression is the way in which the genetic information in the form of linear sequence of nucleotides is converted into the linear sequence of amino acids in a polynucleotide chain. Gene expression is important for the information to transfer or to convert it from nucleotides to amino acid. The mechanism is gene expression is same in every organism from bacteria to human, it is basic. There are two steps involved in it:
Step 1:- Transcription- In this transcription the genetic information is transferred from DNA to mRNA.
Step 2:- Translation- In this translation the information is transferred from mRNA to the polypeptide chain. This unidirectional flow of genetic information is also called as central dogma.
Q2. Describe the processes of gene expression in the prokaryotes by giving example of lac operon.
Ans- The first mechanism of regulation of gene expression was studied in bacteria. In prokaryotes the organisation of functionally arranged genes is different from that of eukaryotes. In bacteria the genes is are clustered and often transcribed together into a single mRNA molecule which have related functions. The kac operon is a example of prokaryotes.
The lac operon is an inducible operon which consist of lactose, is a beta galactosidase which is available in the E.coli in the colon when a person drinks milk. The bacteria uses it as a source of energy and as carbon source. The lac operon consists of three structural genes which are lacZ , lacY and lacA genes. These genes encode three different proteins. The lacZ gene encodes beta galactosidase which break down the lactose into glucose and galactose. The lacY gene encodes beta galactoside permease and lacA gene encodes beta galactoside transacetylase. There is a regulator gene called lacI gene which is located upstream to the promoter of lac operon, it is transcribed into small mRNA and then translated into repressor protein which is known as regulator protein. In E.coli cells when lactose is absent the repressor protein encoded by lacI gene is active an bind to lac operator. This will block the binding of RNA polymerase and transcription of structural genes is prevented. The repressor is binding as long as with operator there are no proteins made. The lac operon is an inducible operon as it induces the proteins in presence of lactose.
Q3. What would be the effect of loss of all proteins from a cell on DNA replication?
Ans- DNA replication in eukaryotes and prokaryotes includes some enzymes and proteins which are DNA polymerases, primase, helicase, topoisomerase, single strand binding proteins and DNA ligase. These proteins help in the process of replication i.e. it helps to separate the strands of DNA and each and every protein plays an important role in the replication. When these proteins are lost on cell then the DNA replication can’t be done. The lagging strands and leading strands can’t be separated. The effect of lost of proteins results in the strands of DNA. Replication don’t occur and the mechanism can’t be completed.
In case you are missed :- NCERT Solution for Basic Principles of Inheritance
Q5. Differentiate between the following:-
- Leading strand and lagging strand-
Leading strand |
Lagging strand |
The new strand which is synthesised continuously in 5’→3 is called as leading strand. |
The strands which are synthesized discontinuously with Okazaki fragment is called as lagging strand. |
This strand has only one RNA primer at 5’ end. |
This strand have multiple RNA primers. |
- Transcription and translation-
Transcription |
Translation |
The process by which the genetic information is transferred from DNA to mRNA is called as transcription. |
The process by which the genetic information is transferred from mRNA to the polypeptide chain is called as translation. |
In transcription all type of cellular RNAs are synthesized such as mRNA, tRNA and rRNA. |
In this in the form of codon the mRNA carries information for sequence of amino acid. |
Reverse transcription is one of process in transcription. |
There is synthesis of polypeptide chain in translation. |
Transcription in many ways is similar to process of replication. |
The process involves the charging of tRNA |
- Transition and transversion mutation-
Transition mutation |
Transversion mutation |
Transition mutation is a substitution mutation. |
Transversion mutation is also a substitution mutation. |
There is replacement of same nucleotides. |
In this mutation there is replacement of different nucleotides. |
The purine is replaced by another purine base and pyrimidine can be replaced by pyrimidine base is called as transition mutation. |
The purine base is replaced by pyrimidine base or pyrimidine is replaced by purine base is called as transversion mutation.
|
- Codon and anticodon-
Codon |
Anticodon |
Codon is a genetic code which is triplet. |
Anti codon is the codon which do not code amino acid. |
It has 64 codons which codes amino acids. |
There are 3 codons which do not code amino acids. |
Q6. Which of the following types of radiations are least likely to be harmful?
(d) Alpha rays.
Q7. In which of the following DNA repair mechanism is apyrimidinic or apurunic site is formed?
(a) Excision repair.
In case you are missed :- NCERT Solution for Cellular processes