Question:

How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material?

Answer:

1. Hershey and Chase conducted an experiment in which they used bacteriophages (viruses that infect bacteria) to infect bacterial cells.

2. They then used a radioactive isotope, either phosphorus-32 or sulfur-35, to label either the DNA or the protein of the bacteriophage.

3. The infected bacteria were then broken open and the labeled material was separated from the unlabeled material.

4. Hershey and Chase then used a centrifuge to separate the labeled material from the unlabeled material.

5. The centrifuge separated the labeled material from the unlabeled material based on their density.

6. Hershey and Chase then found that the labeled material was located inside the bacterial cells, while the unlabeled material was outside the cells.

7. This showed that the labeled material was the genetic material, which was the DNA, and the unlabeled material was the protein.

Question:

Why is the Human Genome project called a mega project?

Answer:

1. The Human Genome Project is called a mega project because it is a large-scale international scientific research effort focused on understanding the genetic makeup of humans.

2. It is one of the largest and most complex scientific endeavors ever undertaken, involving hundreds of scientists and laboratories around the world.

3. The project has involved the mapping of the entire human genome, which is made up of more than three billion base pairs of DNA.

4. It has also involved the sequencing of the entire human genome, which is the process of determining the exact order of the chemical base pairs that make up the human genome.

5. The data generated from the Human Genome Project has been used to identify genetic markers associated with diseases, which has enabled researchers to develop treatments for a variety of genetic disorders.

6. The project has also helped to advance the field of personalized medicine, which is the use of genetic information to tailor treatments to individual patients.

7. The project has also helped to advance our understanding of evolution and the origins of life, as well as our understanding of the genetic basis of inherited traits.

8. The Human Genome Project has revolutionized the field of genetics and has provided invaluable information to scientists and medical professionals. Therefore, it is considered a mega project due to its immense scope and impact.

Question:

What is DNA fingerprinting? Mention its application.

Answer:

Answer: DNA Fingerprinting is a laboratory technique used to identify the genetic material of an individual or species. It involves the analysis of the unique pattern of DNA fragments that are specific to each individual.

Applications of DNA Fingerprinting:

1. Identifying criminals and solving crimes
2. Establishing paternity and maternity
3. Establishing ancestral relationships
4. Detecting genetic disorders
5. Identifying endangered species
6. Establishing immigration status
7. Determining biological relationships in adoption cases
8. Assisting in forensic investigations

Question:

Briefly describe the following: (a) Transcription (b) Polymorphism (c) Translation (d) Bioinformatics

Answer:

(a) Transcription: Transcription is the process of creating an RNA copy of a gene from the DNA template.

(b) Polymorphism: Polymorphism is a phenomenon in which two or more different forms of a gene can exist in a population.

(c) Translation: Translation is the process of converting the information encoded in an mRNA molecule into a polypeptide chain.

(d) Bioinformatics: Bioinformatics is the field of science that uses computers and algorithms to analyze and interpret biological data. It is an interdisciplinary field that combines computer science, mathematics, and biology to analyze and interpret biological data.

Question:

If a double stranded DNA has 20 percent of cytosine, calculate the percent of adenine in the DNA.

Answer:

1. DNA is composed of four nucleotides: adenine (A), thymine (T), guanine (G), and cytosine (C).

2. Since we know that the DNA has 20% cytosine, that means that 80% of the DNA is composed of the other three nucleotides.

3. Since adenine and thymine always pair together, we can assume that the amount of adenine in the DNA is equal to the amount of thymine.

4. Therefore, the percent of adenine in the DNA is 40%, since 40% of the remaining 80% is composed of A and T.

Question:

Explain (in one or two lines) the function of the following: (a) Promoter (b) tRNA (c) Exons

Answer:

(a) Promoter: A DNA sequence that binds to RNA polymerase and helps initiate transcription.

(b) tRNA: Transfer RNA, a type of RNA molecule that carries amino acids to the ribosome during translation.

(c) Exons: The coding regions of a gene that are spliced together to form the mature mRNA molecule that is translated into a protein.

Question:

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.

Answer:

1. DNA template and DNA synthesised: DNA polymerase
2. DNA template and RNA synthesised: RNA-dependent DNA polymerase
3. RNA template and DNA synthesised: Reverse transcriptase
4. RNA template and RNA synthesised: RNA-dependent RNA polymerase

Question:

Which property of DNA double helix led Watson and Crick to hypothesise semi-conservative mode of DNA replication? Explain.

Answer:

Answer:

The property of DNA double helix that led Watson and Crick to hypothesise semi-conservative mode of DNA replication was its complementary base pairing. This means that the two strands of the double helix are held together by hydrogen bonds between the complementary bases - adenine (A) with thymine (T) and guanine (G) with cytosine (C). This complementary base pairing enabled Watson and Crick to hypothesise that when DNA replicates, each strand of the double helix serves as a template for the new strand, resulting in two identical daughter molecules, each with one original strand and one new strand. This is known as semi-conservative replication.

Question:

Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine.

Answer:

Nitrogenous Bases: Adenine, Thymine, Cytosine, and Uracil

Nucleosides: Cytidine, Guanosine

Question:

If the sequence of the coding strand in a transcription unit is written as follows: 5’-ATGCATGCATGCATGCATGCATGCATGC-3’ Write down the sequence of mRNA.

Answer:

The sequence of mRNA would be: 5’-AUGCAUGCUAGCUAGCUAGCUAGCUAGC-3'

Question:

If the sequence of one strand of DNA is written as follows: 5’-ATGCATGCATGCATGCATGCATGCATGC-3’ Write down the sequence of complementary strand in 5’→ 3’ direction.

Answer:

3’-TACGTACGTACGTACGTACGTACGTACG-5'

Question:

Differentiate between the followings: (a) Repetitive DNA and Satellite DNA (b) mRNA and tRNA (c) Template strand and Coding strand

Answer:

(a) Repetitive DNA: Repetitive DNA is made up of short sequences of nucleotides that are repeated over and over again throughout the genome. It does not code for any proteins. Satellite DNA: Satellite DNA is a type of repetitive DNA that is made up of longer sequences of nucleotides that are repeated in tandem throughout the genome. It does not code for any proteins.

(b) mRNA: mRNA (messenger RNA) is a type of RNA that carries genetic information from DNA to the ribosome, where it is used to construct proteins. tRNA: tRNA (transfer RNA) is a type of RNA that is responsible for transporting amino acids to the ribosome during protein synthesis.

(c) Template strand: The template strand is the strand of DNA that is used as a template for the synthesis of mRNA. Coding strand: The coding strand is the strand of DNA that is complementary to the template strand and is used to determine the sequence of bases in the mRNA.

Question:

In the medium where E. coli was growing, lactose was added, which induced the lac operon. Then, why does lac operon shut down sometime after addition of lactose in the medium?

Answer:

1. The lac operon is a group of genes that are responsible for the metabolism of lactose in E. coli.

2. When lactose is present in the medium, it binds to the lac repressor, which in turn binds to the operon and turns it on, allowing the E. coli to metabolize the lactose.

3. However, when the lactose is used up, the lac repressor is no longer bound and the operon is shut off, preventing the E. coli from continuing to metabolize the lactose.

Question:

List two essential roles of ribosome during translation.

Answer:

1. Ribosomes are the sites of protein synthesis, or translation, in the cell.
2. Ribosomes read the mRNA sequence and assemble the corresponding amino acids into a polypeptide chain.