Genetics, Bioethics & Bioinformatics

Genetics, Bioethics & Bioinformatics

The reductive pentose phosphate pathway is also known as (A) Photosynthetic Carbon Oxidation cycle (PCO) (B) Calvin – Be

Reductive pentose phosphate pathway fixes CO2 into carbohydrates using ATP and NADPH in chloroplast stroma, known as Calvin-Benson cycle. Oxidative PCO cycle refers to photorespiration, not reductive fixation. C4 cycle is distinct CO2 concentrating mechanism with PEP carboxylase.

Ref: Buchanan et al., Biochemistry and Molecular Biology of Plants, 2nd Edition, Chapter 12, Photosynthesis, describes reductive pentose phosphate cycle as Calvin-Benson cycle for CO2 fixation distinct from oxidative photosynthetic carbon oxidation and C4 pathways, published by Wiley Blackwell.

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Genetics, Bioethics & Bioinformatics

Match the List I with List II. List I List II (A) Autotroph (I) Macro consumers (B) Phagotrops (II) Micro consumers (C)

Autotrophs synthesize organic matter from inorganic sources acting as primary producers. Phagotrophs ingest particulate food as macroconsumers, saprotrophs absorb dissolved organics as microconsumers or decomposers, heliotrophs are sun-loving plants orienting toward light, clarifying ecological trophic classification.

Ref: Odum and Barrett, Fundamentals of Ecology, 5th Edition, Chapter 3, Trophic Structure and Ecological Classification, defines autotrophs as primary producers, phagotrophs macroconsumers, saprotrophs microconsumers, heliotrophs sun-loving species, published by Brooks Cole Cengage.

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Genetics, Bioethics & Bioinformatics

Which of the following steps in PCR is responsible for separating double-stranded DNA into single strands?

Melting or denaturation step heats reaction to 94-98°C, breaking hydrogen bonds between strands and producing single-stranded templates. Annealing allows primer binding at lower temperature, extension elongates via Taq polymerase. Without melting, primers cannot access complementary sequences.

Ref: Green and Sambrook, Molecular Cloning: A Laboratory Manual, 4th Edition, Chapter 10, PCR, details three steps: high-temperature melting to separate duplex DNA, annealing of primers and elongation by thermostable polymerase, published by Cold Spring Harbor Laboratory Press.

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Genetics, Bioethics & Bioinformatics

What is the main advantage of using Short Tandem Repeats (STRs) over restriction fragment length polymorphism (RFLP) in

STR analysis amplifies short 2-6 base repeats using PCR requiring only nanogram amounts of partially degraded DNA, unlike RFLP needing micrograms of intact high-molecular-weight DNA and Southern blotting. This makes STRs more sensitive, robust and amenable to multiplexing for forensic fingerprinting.

Ref: Butler, Advanced Topics in Forensic DNA Typing: Methodology, 2012, Chapter 5, STR Markers, explains PCR-based STR advantages of low DNA requirement and degradation resistance over RFLP requiring large intact DNA and Southern hybridization, published by Elsevier Academic Press.

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Genetics, Bioethics & Bioinformatics

Which protein is responsible for cleaving double stranded RNA into smaller fragments during RNA interference?

During RNA interference, RNase III enzyme Dicer recognizes and cleaves long double-stranded RNA or pre-miRNA into 21-23 nucleotide siRNA or miRNA duplexes. These fragments are then loaded onto RISC complex where slicer Argonaute degrades target mRNA, silencing gene expression.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 8, RNA and RNA interference, describes Dicer as RNase III endonuclease processing dsRNA into siRNAs for RISC loading and Argonaute-mediated slicing, published by Garland Science.

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Genetics, Bioethics & Bioinformatics

Which non-viral gene delivery method utilizes physical forces to introduce genetic material into cells?

Electroporation applies brief high-voltage pulses creating transient pores in plasma membrane, allowing DNA entry via physical force without viral vectors. Liposomes and poly-L-lysine are chemical carriers, adenoviruses are viral vectors, thus electroporation is categorized as physical non-viral delivery method.

Ref: Klug et al., Concepts of Genetics, 12th Edition, Chapter 19, Gene Therapy, and Lodish et al., Molecular Cell Biology 8th Edition, describe electroporation as physical transfection using electric fields versus liposomal chemical and adenoviral biological vectors, published by Pearson and W.H. Freeman.

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Genetics, Bioethics & Bioinformatics

What happens to transferrin when iron is bound to it and it interacts with its receptor?

Iron-bound holotransferrin undergoes conformational change exposing receptor binding sites, allowing high-affinity interaction with transferrin receptor 1 on cell surface. Complex internalizes via receptor-mediated endocytosis, iron releases in acidic endosome, apotransferrin recycles, avoiding lysosomal degradation.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 13, Intracellular Vesicular Traffic, describes transferrin conformational change upon iron binding enabling TfR binding and clathrin-mediated endocytosis with iron release in endosomes, published by Garland Science.

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Genetics, Bioethics & Bioinformatics

The computational approaches to predict the three-dimensional structures of proteins are : (A) Homology modeling (B) X-r

Protein structure prediction computationally includes homology modeling using known templates, threading fitting sequence onto fold library, and ab initio modeling based on physicochemical principles. X-ray crystallography and NMR are experimental determination methods, not computational, requiring crystals or magnetic resonance data.

Ref: David W. Mount, Bioinformatics: Sequence and Genome Analysis, 2nd Edition, Chapter 10, Protein Structure Prediction, discusses homology modeling, threading and ab initio as computational methods versus X-ray and NMR as experimental structure determination techniques, published by Cold Spring Harbor.

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Genetics, Bioethics & Bioinformatics

Which one of the following is not a primary database?

Primary databases archive original experimental sequences with minimal annotation, such as GenBank, EMBL and DDBJ forming INSDC collaboration. SWISS-PROT is curated secondary protein database with high-quality annotation, manual curation and functional information derived from primary entries and literature.

Ref: Baxevanis and Ouellette, Bioinformatics: A Practical Guide, 3rd Edition, Chapter 2, Biological Databases, classifies GenBank, EMBL and DDBJ as primary nucleotide repositories and SWISS-PROT/UniProt as curated secondary protein database, published by Wiley.

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Genetics, Bioethics & Bioinformatics

________ variant of BLAST, compares a DNA query sequence to the protein database.

BLASTX translates DNA query in six frames and searches against protein database, useful for identifying coding potential of uncharacterized genomic sequences. BLASTP protein-protein, BLASTN DNA-DNA, TBLASTN protein query against translated DNA database, distinguishing variant applications.

Ref: Altschul et al., Journal of Molecular Biology 1990 and NCBI BLAST Help Manual, and Mount, Bioinformatics 2nd Edition, Chapter 3, describes BLASTX as six-frame translation of nucleotide query to search protein databases for homology detection, published by CSHL Press.

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Genetics, Bioethics & Bioinformatics

Select the correct primer pair of forward and reverse primer sequence that amplify full length of sequence given below :

Forward primer must match 5' end of coding strand to amplify forward direction, while reverse primer must be reverse complement of 3' end to anneal opposite strand. Option B provides forward identical to 5' sequence and reverse reverse-complementary to 3' sequence, enabling full-length amplification.

Ref: Green and Sambrook, Molecular Cloning: A Laboratory Manual, 4th Edition, Chapter 10, Polymerase Chain Reaction, explains primer design principles requiring forward identical to target and reverse complement to downstream sequence for exponential amplification, published by Cold Spring Harbor.

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Genetics, Bioethics & Bioinformatics

Match the List I with List II. List I List II (A) Taq DNA polymerase (I) used to make cDNA (B) MMLV Reverse Transcriptas

Taq polymerase thermostable enzyme drives PCR amplification. MMLV reverse transcriptase synthesizes cDNA from mRNA templates. RNA polymerase II transcribes mRNA and lncRNA in eukaryotes. T4 polynucleotide kinase transfers phosphate to 5' ends of DNA oligos for labeling or ligation.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 8, Analyzing Cells and Molecules, and Green and Sambrook, Molecular Cloning, 4th Edition, detail functions of Taq polymerase, MMLV RT, RNA Pol II and T4 polynucleotide kinase, published by Garland and CSHLP.

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