৪৯তম বিসিএস ⎯ প্রাণ রসায়ন [৬০১]

Answer: B) Identify transformed cells
Explanation:
Selection markers differentiate transformed from untransformed cells.

Answer: B) Facilitates DNA entry
Explanation:
Heat shock creates a thermal imbalance, driving DNA into cells.

Answer: C) BAC
Explanation:
Bacterial Artificial Chromosomes (BACs) carry up to 300 kb of DNA.

Answer: B) A carrier DNA molecule
Explanation:
Vectors carry foreign DNA into host cells for replication and expression.

Answer: B) Sticky ends
Explanation:
EcoRI produces staggered cuts creating sticky ends that easily join with complementary sequences.

Explanation:
Primers provide the starting point for DNA polymerase to extend.

Answer: C) Restriction endonucleases
Explanation:
Restriction enzymes cut DNA at specific recognition sequences, typically palindromic, and are essential in genetic engineering.

Answer: Selection of transformed cells
Explanation:
Only cells containing the plasmid grow in antibiotic-containing media.

Explanation:
PCR uses DNA primers, not RNA primers.

Answer: B) DNA sequences
Explanation:
GenBank is a repository of nucleotide sequences.

Answer: D) Unstable replication
Explanation:
Stable replication ensures reliable propagation of inserted DNA.

Answer: B) LacZ gene
Explanation:
Blue-white screening uses disruption of the LacZ gene to identify successful recombinants.

Answer: B) Plasmids and bacteriophage lambda
Explanation:
Cosmids combine features of plasmids and lambda phages for cloning larger fragments.

Answer: B) Several unique restriction sites
Explanation:
MCS allows flexibility in inserting DNA fragments.

Answer: B) RNA
Explanation:
Reverse transcriptase uses RNA as a template to make complementary DNA.

Answer: B) Primer sequence
Explanation:
Annealing temperature depends on the primer melting temperature.

Answer: B) Taq polymerase
Explanation:
Taq polymerase is heat-resistant and derived from Thermus aquaticus.

Answer: B) DNA amplification in real time
Explanation:
It uses fluorescent markers to quantify DNA during amplification.

Answer: B) Amount of amplified product
Explanation:
Each cycle doubles the product, leading to exponential growth.

Answer: B) Extension
Explanation:
At this step, Taq polymerase synthesizes new DNA strands.

Answer: B) Uptake of foreign DNA by a cell
Explanation:
Transformation introduces new genetic material into a host.

Answer: B) Transfection
Explanation:
Transfection refers specifically to eukaryotic cells.

Answer: B) Add methyl groups to protect host DNA
Explanation:
Methylation marks host DNA as self, avoiding cleavage.

Answer: B) Making cell membranes permeable
Explanation:
CaCl₂ increases membrane permeability, aiding DNA uptake.

Answer: B) 3 billion base pairs
Explanation:
The genome consists of 3 billion base pairs of DNA.

Answer: B) 20,000–25,000
Explanation:
Only about 1.5% of human DNA codes for proteins.

Answer: B) Haemophilus influenzae
Explanation:
Its genome was sequenced in 1995.

Answer: B) Only from the mother
Explanation:
Mitochondria are maternally inherited.

Answer: A) Cutting DNA into random fragments
Explanation:
Fragments are later assembled computationally.

Answer: B) Total DNA content of an organism
Explanation:
A genome includes all nuclear and mitochondrial DNA.

Answer: B) Yeast (Saccharomyces cerevisiae)
Explanation:
Yeast was a model organism in genomic studies.

Answer: A) Single Nucleotide Polymorphism
Explanation:
SNPs are single base changes that contribute to genetic diversity.

Answer: C) Proteomics
Explanation:
Proteomics focuses on protein expression and interactions.

Answer: D) All of the above
Explanation:
The HGP has broad benefits across many scientific fields.

Answer: B) Coding regions (exons) only
Explanation:
cDNA libraries contain only expressed genes, not introns.

Answer: B) cDNA
Explanation:
PCR creates millions of copies of a specific DNA sequence.

Answer: C) Screening transformants
Explanation:
Screening identifies which colonies contain the desired insert.

Answer: D) Type IV
Explanation:
There are three major types: Type I, II, and III, with Type II most commonly used in molecular cloning.

Answer: A) Gel electrophoresis
Explanation:
Electrophoresis separates DNA fragments by size to verify successful digestion.

Answer: B) Defend against bacteriophages
Explanation:
Bacteria use restriction enzymes to cut foreign DNA from viruses as a defense mechanism.

Answer: B) Palindromic sequences
Explanation:
Most restriction enzymes recognize palindromic DNA sequences, reading the same in both directions.

Answer: A) Ethidium bromide
Explanation:
Ethidium bromide binds DNA and fluoresces under UV light.

Answer: C) SmaI
Explanation:
SmaI makes straight cuts, producing blunt ends without overhangs.

Answer: B) Plasmid
Explanation:
Plasmids are small, circular DNA molecules ideal for cloning.

Answer: B) Specificity
Explanation:
Nested PCR uses two sets of primers to reduce non-specific amplification.

Explanation: Some bacteria like Bacillus subtilis naturally take up DNA.

Answer: B) Electric pulses
Explanation:
An electric field creates pores in the cell membrane for DNA entry.

Explanation:
Competency allows DNA uptake during transformation.

Answer: C) 42°C
Explanation:
42°C is the standard temperature for heat shock transformation.

Answer: 1990
Explanation: The project officially launched in 1990.