Cell Cycle and Chromosomes

A chromosome is a single piece of coiled DNA containing many genes. Chromosomes are found in the nucleus of eukaryotic cells. Nucleotides are the building blocks of DNA, chloroplasts are plant organelles, and monochrome relates to color.

Genophore (also called genophore or bacterial chromosome) is the DNA-containing structure in bacteria and archaea. It is the prokaryotic equivalent of a chromosome, making 'Chromosome' the correct answer.

Normal human somatic cells contain 46 chromosomes (23 pairs - one set inherited from each parent). Gametes (sperm and egg cells) contain 23 chromosomes each. 44 chromosomes would indicate a chromosomal abnormality like Turner syndrome, while 48 chromosomes is not a normal human karyotype.

Down syndrome (Trisomy 21) is caused by an extra 21st chromosome, resulting in 47 chromosomes instead of the normal 46. Cretinism is from thyroid deficiency, hydrocephaly involves cerebrospinal fluid accumulation, and microcephaly is an abnormally small head - none involve chromosomal count changes.

The rod-shaped structures in nucleus, which are visible at the time of cell division, are known as chromosomes.

It is centromere, which initiates and regulates the process of cell division.

An example of monosomy is Turner Syndrome where the individual is born with only one sex chromosome, an X.

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 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.

This type of sex determination takes place in insects and mammals including human beings. Here, the females have two identical homologous sex chromosomes designated as XX and the males have two dissimilar sex chromosomes designated as X and Y. 

Allele is a pair of contrasting characters. 

In classical genetics, in a sexually reproducing diploid organism (typically Eukaryota), the genome is a full set of chromosomes.

A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell.

Human chromosome 2 is now known to be a result of an end-to-end fusion of two ancestral ape chromosomes. It is the second largest human chromosome.