Microbiology & Clinical Medicine

Microbiology & Clinical Medicine

In the cross AaBBcc x aaBbCc, what is the probability of an offspring that is aaBbcc?

Independent assortment predicts probability product of individual loci. Cross Aa x aa gives 1/2 aa, BB x Bb gives 1/2 Bb, cc x Cc gives 1/2 cc. Multiplying 1/2 × 1/2 × 1/2 equals 1/8 chance of aaBbcc offspring genotype.

Ref: Pierce, Genetics: A Conceptual Approach, 7th Edition, Chapter 3, Mendelian Genetics and Probability, and Griffiths et al., Introduction to Genetic Analysis, explains independent assortment product rule for cross AaBBcc x aaBbCc calculating probability of aaBbcc as 1/8 using monohybrid probabilities,

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Microbiology & Clinical Medicine

Both the alleles express themselves equally in F1 generation, EXCEPT:

Codominance allows simultaneous phenotypic expression of both alleles, as seen in AB blood group, sickle heterozygotes and roan cattle. Antirrhinum majus displays incomplete dominance where heterozygous pink phenotype blends red and white parents, not equal simultaneous expression, representing blending inheritance.

Ref: Pierce, Genetics: A Conceptual Approach, 7th Edition, Chapter 12, Extensions of Mendelian Inheritance, and Snustad and Simmons, Principles of Genetics, 7th Edition, Chapter 3, describe codominance AB blood group roan cattle sickle cell versus incomplete dominance in Antirrhinum majus snapdragon, pub

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Microbiology & Clinical Medicine

The type of inheritance in which many traits of a character are spread across a gradient and the effect of each allele i

Polygenic traits controlled by multiple loci exhibit continuous variation with bell-shaped distribution, each allele contributing additive small effect influenced by environment. Examples include height, skin color, weight. This contrasts codominance showing both alleles simultaneously and monohybrid crosses showing discrete Mendelian ratios.

Ref: Hartl and Jones, Essential Genetics, 6th Edition, Chapter 12, Polygenic Inheritance, and Falconer and Mackay, Introduction to Quantitative Genetics, 4th Edition, Chapter 1, explain polygenic traits continuous variation additive alleles examples height skin color, published by Jones and Bartlett.

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Microbiology & Clinical Medicine

Which one of the following crosses will produce two phenotypes in the next generation?

Test cross mating heterozygous Aa with homozygous recessive aa reveals gametes contributed by heterozygote, producing 1:1 phenotypic ratio with two distinct phenotypes. Selfing pure lines yields uniform progeny, while outcross and incomplete dominance examples do not guarantee two phenotypes predictably.

Ref: Griffiths et al., Introduction to Genetic Analysis, 12th Edition, Chapter 2, Mendelian Principles, and Pierce, Genetics: A Conceptual Approach, 7th Edition, Chapter 3, describe test cross Aa crossed to aa producing two phenotypes 1:1 ratio revealing heterozygote gametes, published by Macmillan.

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Microbiology & Clinical Medicine

“Compensation” refers to which of the following processes in relation to flow cytometry?

Multicolor flow cytometry suffers from spectral spillover where fluorescence of one fluorochrome leaks into neighboring detector. Compensation mathematically subtracts overlapping percentages using single-stained controls, ensuring accurate quantification of each marker expression and proper gating of leukocyte subsets.

Ref: Kuby, Punt, Stranford and Jones, Immunology, 8th Edition, Chapter 5, Flow Cytometry section, and Shapiro, Practical Flow Cytometry, 5th Edition, Chapter 7, explain compensation as correction of fluorescence spillover by subtracting overlapping signals using single-stained controls, published by W.H.

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Microbiology & Clinical Medicine

What does SNP stand for?

Single nucleotide polymorphisms represent single base variations at specific genomic positions present in more than one percent population, serving as markers for genome-wide association studies, linkage mapping, pharmacogenomics and ancestry analysis. They differ from indels, CNVs and monomorphic mutations.

Ref: Griffiths, Wessler, Carroll and Doebley, Introduction to Genetic Analysis, 12th Edition, Chapter 1, Genetic Variation, and Hartl and Jones, Genetics, 9th Edition, define SNP as single nucleotide polymorphism single base change at locus as common variation marker, published by W.H. Freeman.

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Microbiology & Clinical Medicine

What is PHRED score in a Next generation sequencing data?

PHRED quality score logarithmically quantifies base-calling error probability, defined as Q = -10 log10 P, incorporated in FASTQ files from sequencers. Higher scores indicate greater accuracy, enabling trimming and filtering of low-quality reads before alignment, variant calling and coverage analysis.

Ref: Ewing and Green, PHRED: Base-calling Quality Scores 1998 Genome Research, and Pevsner, Bioinformatics and Functional Genomics, 3rd Edition, Chapter 9, Next Generation Sequencing, explains PHRED score Q equals minus ten log error probability as read quality score in FASTQ, published by Wiley-Blackwel

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Microbiology & Clinical Medicine

The material used as a bioplastic is:

Polyhydroxybutyrate, synthesized by Ralstonia eutropha and other bacteria as carbon storage granules under nutrient limitation, is biodegradable polyester used as bioplastic. Polystyrene and polypropylene are petroleum-derived non-biodegradable polymers, while dextran is a polysaccharide not suitable for thermoplastic manufacturing.

Ref: Madigan, Bender, Buckley, Sattley and Stahl, Brock Biology of Microorganisms, 16th Edition, Chapter 14, Industrial Microbiology, and Prescott's Microbiology, 11th Edition, Chapter 41, describes polyhydroxybutyrate PHB bioplastic granules produced by Ralstonia eutropha as biodegradable polyester, pub

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Microbiology & Clinical Medicine

To study the living cells without staining, which of the following microscopes can be used?

Phase contrast microscope converts small phase shifts induced by transparent living cells into amplitude brightness differences using annular diaphragm and phase plate, enabling visualization of organelles without fixation. Electron microscopes require vacuum and fixation, killing cells, while fluorescence typically needs stains.

Ref: Lodish, Berk, Kaiser, Krieger, Bretscher, Ploegh, Amon and Martin, Molecular Cell Biology, 9th Edition, Chapter 9, Microscopy Techniques, describes phase contrast microscope invented by Zernike allowing unstained living cells observation via phase to amplitude conversion, published by W.H. Freeman.

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Microbiology & Clinical Medicine

Fluorescence recovery after photobleaching (FRAP) is a technique to study:

FRAP bleaches fluorophore-tagged membrane proteins or lipids with intense laser, then monitors fluorescence recovery driven by lateral diffusion within fluid mosaic bilayer. Mobile fraction and diffusion coefficient quantify membrane fluidity, protein mobility, lipid raft dynamics, essential for receptor signaling studies.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 10, Membrane Dynamics section, describes fluorescence recovery after photobleaching FRAP to study lateral diffusion of membrane proteins and lipids measuring fluidity mobile fraction, published by Garland Science.

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Microbiology & Clinical Medicine

Pericentric inversion is a type of chromosome mutation in which:

Chromosomal inversions result from two breaks and reversal; pericentric includes centromere producing altered arm ratio, paracentric excludes centromere within single arm. Both can suppress recombination, cause loop formation in meiosis, potentially leading to unbalanced gametes and recurrent miscarriages.

Ref: Gardner, Simmons and Snustad, Principles of Genetics, 8th Edition, Chapter 14, Chromosome Aberrations, explains pericentric inversion including centromere versus paracentric excluding centromere, loop formation, recombination suppression and unbalanced gametes, published by Wiley.

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Microbiology & Clinical Medicine

Which one of the following is used to study the structural details of biological tissues using freeze-fracture technique

Freeze-fracture splits lipid bilayers along hydrophobic core, and replicas shadowed with platinum are examined by transmission electron microscopy to reveal membrane protein particles and intramembranous details. Scanning electron microscopy shows surface topography, not internal bilayer organization, making TEM the appropriate method.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 10, Membrane Structure and Techniques, and Lodish et al., Molecular Cell Biology, 9th Edition, Chapter 9, discuss freeze-fracture electron microscopy using transmission electron microscopy to visualize membrane proteins, published b

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