Gametogenesis, the production of sperm and eggs, involves the process of meiosis. During meiosis, two nuclear divisions separate the paired chromosomes in the nucleus and then separate the chromatids that were made during an earlier stage of the cell's life cycle.
Answer:
Explanation: The first Australopithecus fossil was found in a lime quarry at Tuang, it was found by Raymond Dart in November 1924.
Answer:
Explanation:
Meiosis is a form of cell division that occurs in the sex cells of organisms. It ensures the reduction of a diploid cell to an haploid cell to allow for the formation of a diploid zygote after fertilization (contribution of both parents haploid sex cells to give a diploid zygote). Thus, this process is very essential and important.
The reduction is accomplished by 2 divisions after the duplication of chromosomes
- first division: separation of homologous pairs of chromosomes (this reduces the total in half)
- second division: separation of sister chromatids of a chromosome.
The rearrangement in meiosis occurs by crossing over/genetic recombination.
This is the exchange of genetic material between homologous pairs of chromosome bringing about a rearrangement and genetic variation
An example of a chromosomal abnormality that arises as a result of defects in this process is the Down Syndrome which is caused by a nondisjunction of the chromosomes 21 pair in a sex cell.
This condition produces offsprings that have some characteristic facial features, short stature etc
Answer:
interspersed, transposon-derived repeats, simple sequence repeats.
Explanation:
In the human genome, not only the protein coding genes are present, in fact these genes make up just a very little portion of the human genome about 1.5-2% of the entire human genome. Repeats make up about 48% of the human genome which is the largest and the rest include, conserved non coding sequences (43.5%), heterochromatin regions etc.
Some of the repetitive elements includes LINEs, SINEs, DNA fossils tranposoon, Retrovirus like elements. all these are transposable elements which are mobile DNA sequences that can migrate to different regions/areas of the genome.
Microsatellites (simple sequence repeats) are tracts of repetitive DNA in which certain DNA motifs are repeated normally 5-50 times.
