DNA Replication

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Questions and Answers

What is the polarity of the template strand on which replication is continuous?

It has no polarity

3' à5' (correct)

5' à3'

It depends on the type of DNA

What is the role of DNA ligase in the process of DNA replication?

To initiate the process of replication

To unwind the double helix

To join the discontinuously synthesised fragments (correct)

To provide the origin of replication

What is the reason for the requirement of a vector in recombinant DNA procedures?

Because of the requirement of the origin of replication (correct)

Because of the need for DNA polymerase

Because of the need for DNA ligase

Because of the need for RNA synthesis

In which phase of the cell-cycle does the replication of DNA take place in eukaryotes?

S-phase Signup and view all the answers

What is the consequence of a failure in cell division after DNA replication?

Polyploidy Signup and view all the answers

What is the base that pairs with adenine in the process of transcription?

Uracil Signup and view all the answers

What is the process of copying genetic information from one strand of DNA into RNA?

Transcription Signup and view all the answers

What is the principle that governs the process of transcription?

The principle of complementarity Signup and view all the answers

What is the purpose of deoxyribonucleoside triphosphates in DNA replication?

To provide energy for polymerisation reaction and act as substrates Signup and view all the answers

What is the average rate of polymerisation in E. coli?

2000 bp per second Signup and view all the answers

What is the consequence of a mistake during DNA replication?

Genetic mutation Signup and view all the answers

Why do DNA-dependent DNA polymerases need to be fast and accurate?

To prevent mutations and ensure genetic fidelity Signup and view all the answers

What is the region where DNA replication occurs called?

Replication fork Signup and view all the answers

What is the main enzyme responsible for catalysing DNA replication?

DNA-dependent DNA polymerase Signup and view all the answers

What is the purpose of the experiment involving radioactive thymidine?

To detect distribution of newly synthesised DNA in chromosomes Signup and view all the answers

Why is it not possible to separate the two strands of DNA in its entire length during replication?

Due to very high energy requirement Signup and view all the answers

Which RNA polymerase is responsible for transcribing precursor of mRNA?

RNA polymerase II Signup and view all the answers

What is the process called where the introns are removed and exons are joined in a defined order?

Splicing Signup and view all the answers

What is added to the 5'-end of hnRNA during capping?

Methyl guanosine triphosphate Signup and view all the answers

Which of the following is NOT a function of RNA polymerase III?

Transcription of mRNA Signup and view all the answers

What is the significance of the presence of introns in the genome?

They represent an ancient feature of the genome Signup and view all the answers

What is the main challenge in understanding the process of translation?

Lack of complementarity between nucleotides and amino acids Signup and view all the answers

What is the outcome of the process of splicing and additional processing of hnRNA?

Formation of mRNA Signup and view all the answers

What is the function of RNA polymerase I?

Transcription of rRNA Signup and view all the answers

In the lac operon, the regulation of gene expression is primarily in response to the amount of which molecule?

Lactose Signup and view all the answers

What is the primary function of transcription regulation in bacteria?

To tightly regulate gene expression Signup and view all the answers

What is the name of the process by which the sequence of one DNA strand is used to synthesize a complementary RNA molecule?

Transcription Signup and view all the answers

What is the term for the process by which the sequence of a mRNA molecule is used to synthesize a protein?

Translation Signup and view all the answers

What is the name of the technique used to find out variations in individuals of a population at the DNA level?

DNA Fingerprinting Signup and view all the answers

What is the consequence of the Human Genome Project?

The opening up of new areas and avenues in biology Signup and view all the answers

What is the term for the mode of DNA replication proposed by Watson and Crick?

Semi-conservative Signup and view all the answers

What is the reason why transcription and translation are tightly regulated?

They are energetically expensive Signup and view all the answers

What is the primary difference between replication and transcription in terms of DNA involvement?

In replication, the entire DNA is duplicated, whereas in transcription, only a segment of DNA is copied. Signup and view all the answers

Why does the cell not copy both strands of DNA during transcription?

Because both strands would code for different RNA molecules, leading to different proteins. Signup and view all the answers

What is the consequence of both RNA molecules being produced simultaneously during transcription?

They would form a double-stranded RNA, preventing translation. Signup and view all the answers

What is the role of the promoter in a transcription unit?

To initiate transcription by binding RNA polymerase. Signup and view all the answers

What is the significance of the 5' →3' polarity in DNA-dependent RNA polymerase catalysis?

It determines the direction of RNA polymerization. Signup and view all the answers

Why is the strand with 3' →5' polarity referred to as the template strand?

Because it is the strand that is copied during transcription. Signup and view all the answers

What is the consequence of having a double-stranded RNA?

It would prevent translation from occurring. Signup and view all the answers

What is the primary function of transcription?

To copy a segment of DNA into RNA. Signup and view all the answers

Study Notes

Replication

DNA-dependent DNA polymerases catalyse polymerisation in one direction, 5' →3', creating complications at the replicating fork.
On one strand (template with polarity 3' →5'), replication is continuous, while on the other strand (template with polarity 5' →3'), it is discontinuous.
Discontinuously synthesised fragments are joined by the enzyme DNA ligase.
DNA polymerases cannot initiate replication on their own, requiring a specific origin of replication.
In E. coli, replication originates from a specific region in the DNA, which is termed the origin of replication.

Vectors and Replication

A piece of DNA requires a vector to be propagated during recombinant DNA procedures, which provides the origin of replication.
Not every detail of replication is understood well, especially in eukaryotes, where DNA replication occurs during the S-phase of the cell cycle.

Transcription

Transcription is the process of copying genetic information from one strand of DNA into RNA.
The principle of complementarity governs transcription, except that adenine now forms a base pair with uracil instead of thymine.
RNA polymerase I transcribes rRNAs, RNA polymerase III transcribes tRNAs, 5srRNA, and snRNAs, and RNA polymerase II transcribes the precursor of mRNA.
Primary transcripts contain both exons and introns and are non-functional, requiring processing through splicing, capping, and tailing to form mature mRNA.

Genetic Code

The process of translation requires the transfer of genetic information from a polymer of nucleotides to synthesise a polymer of amino acids.
No complementarity exists between nucleotides and amino acids, making translation a complex process.
The genetic code is used to translate mRNA into a sequence of amino acids.

Regulation of Gene Expression

Regulation of transcription is the primary step for regulation of gene expression.
In bacteria, multiple genes are arranged together and regulated in units called operons, which are regulated by the amount of substrate in the medium.
Human genome project aimed to sequence every base in the human genome, yielding new information and opening up new areas of research.

DNA Fingerprinting

DNA fingerprinting is a technique to find out variations in individuals of a population at the DNA level.
It works on the principle of polymorphism in DNA sequences and has immense applications in forensic science, genetic biodiversity, and evolutionary biology.

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Description

This quiz covers the process of DNA replication, including the role of DNA polymerases, replicating fork, and the origin of replication.