Human Genetics

It is a case of loss of memory and capability of judgement as well as general physical impairment. It is caused by the augmentation of amyloid protein plaques in the brain resulting in the degeneration of neurons.

It results due to the presence of an extra chromosome, No.21. Both the chromosomes of the pair 21 pass into a single egg due to non-disjunction during oogenesis in the mother's ovary. Therefore, the egg contains 24 chromosomes in place of of 23 & the progeny has 47 chromosomes.

This mutation causes no change in the final protein product and can only be identified by sequencing the gene. Most amino acids that make up a protein are encoded by several different codons.

It is an inducible gene whose expression is either reactive to environmental change or dependent on the position in the cell cycle.

Human DNA is 98% identical to chimpanzees. The average amount of genetic difference between any 2 chimpanzees is 4 or 5 times more than the average difference between any 2 humans.

A repressor is a DNA-binding protein that regulates the expression of one or more genes by binding to the operator & blocking the attachment of RNA polymerase to the promoter, thus inhibiting transcription of the genes.

This operon is found in many bacteria, but was first noticed in Escherichia coli. It is regulated so that when tryptophan is present in the environment, it is not used.

This occurs when a segment of chromosome breaches but later rejoins after rotating by 180^o results in inversion. If the centromere is included in the inverted segment, it is known as pericentric but if inversion occurs only in one arm and the centromere is not involved, it is referred as paracentric inversion.

In this position, the centromere is located far away from the centre so that the two arms are highly unequal. The chromosome acquires 'J' shape during anaphase.

It is a DNA sequence present in the promoter area of genes in archaea and eukaryotes. Around 24% of human genes contain a TATA box within the core promoter.

It is a process in which an organism assimilates genetic material from another organism without being the offspring of that organism.

Dolly was the first mammal & a female domestic sheep, which was cloned from an adult somatic cell, through the process of nuclear transfer. Its clonning was done by Ian Wilmut.

It is the process by which an allele may enhance in frequency by worth of being linked to a gene that is positively selected. Proximity on a chromosome may allow genes to be dragged along with a selective sweep experienced by an advantageous gene nearby.

It is a recessive genetic disease. It mainly affects the lungs, the pancreas, the liver, and the intestine.

It is the increase in such properties as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. Plant and animal breeders use heterosis by mating two different pure-bred lines that have certain desirable traits.

This gene regulates the operator gene with the help of a chemical substance known as inducer present in the cytoplasm. It is not certainly present close to the operator gene which it controls.

Endosperm is the tissue formed inside the seeds of flowering plants during the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch. Xenia denotes the effect of pollen on endosperm.

Mendel choose garden Pea as his experimental substrate and collected 36 different varieties, of which he finally chose seven characters, which were distinct and showed clear cut variation. The genes regulating the seven pea characters studied by mendel were located on 4 chromosomes.

It is a genetic syndrome which is the most commonly known single-gene cause of autism & the most frequent inherited cause of intellectual disability.

Neurospora crassa is a red bread mold. It is used as a model organism because it is convenient to grow and has a haploid life cycle that makes genetic analysis easier since recessive traits will come in the progenies.

Wilhelm Johannsen was a Danish botanist, plant physiologist and geneticist. He coined the terms phenotype and genotype.

Patau syndrome is a chromosomal abnormality in which a patient has an additional chromosome 13 due to a nondisjunction of chromosomes during meiosis.

Archibald Garrod is known as 'Father of human genetics' for describing that the inborn errors of metabolism are governed by genes and are inherited in a Mendelian pattern.