Answer:
Crossing over is a biological occurrence that happens during meiosis when the paired homologs, or chromosomes of the same type, are lined up. Hope this helps :)
Explanation:
Answer:
Primitive Earth where life emerged was subjected to extreme conditions
Explanation:
The origin of life is still an issue of intense debate today, although most researchers believe that life emerged from primitive organisms generated by the synthesis of organic compounds in early Earth. In line with this theory, it has been shown that membrane-forming compounds can be formed in extreme conditions (i.e., UV rays, extreme temperature, etc). It is believed that such conditions recreated in a laboratory were similar to the early Earth about 3,900 million years ago, thereby supporting the idea of the 'primordial soup theory' proposed by John Burdon Sanderson Haldane in 1929.
Answer:
a) There are lots of genes on chromosome 1 could be affected, and the gametes could be imbalanced (missing segments of DNA or whole chromosomes)
b) Roughly 50%
c) No. I would advise that the couple undergo preimplantation genetic diagnosis, so that a zygote carrying the normal copy of chromosome 1 could be selected.
Explanation:
Chromosome 1 is one of the largest and most gene rich chromosomes. An inversion that covers 70% of its length would cover lots of genes.
While an inversion on its own would not seem problematic (as all the genes on the chromosome are still there), when it comes to meiosis, the sister chromatids would not be able to correctly align, and crossing over would further complicate this. It could also lead to unbalanced gametes missing entire parts of the chromosome. Therefore, there are likely numerous genes that will be affected and messed up by the inversion.
This could explain the high incidence of past still births, as if lots of genes are affected, and non-functional, the pregnancy would be rendered non-viable, or highly deleterious causing premature death.
b) There is a 50% chance of a child inheriting the defective copy of chromosome 1 (and 50% of a chance of them inheriting the normal chromosome 1. Therefore, there is likely a 50% chance that future offspring would be affected by defects
c) No. I would advise that the couple undergo preimplantation genetic diagnosis. In this, the couple undergoes in vitro fertilization (IVF). When embryos are produced through IVF, they can then be tested for the presence of the abnormal chromosome. Embryos will only be implanted into the mother if the normal chromosome 1 is present.
