HMB265H1 Lecture Notes - Lecture 19: Mitosis, Sister Chromatids, Centromere

• School: UTSG
• Department: Human Biology
• Course: HMB265H1
• Professor: Maria Papaconstantinou

Document Summary

These giant chromosomes that are found in the savlivary glands cells embryo drosphilia, they replicate so much up to 10 times without undergoing mitosis, without having cell division. The sister chromatids are never separated from eachother. This gives rise to structures that can be seen under a light microscope. We can also use in situ hybridization to find the position of specific genes on the chromosome to see if they have been deleted. Intragenic deletions are usually breaks in double staanded dna from things like xrays. Even in heterozygotes, the deletions result in major effects on the phenotype because of gene imbalance. They are usually lethal in the homozogoys condition. Deletion loops can be seen under light microscopes like in the polytene chromosome. The portion of the (cid:272)hro(cid:373)oso(cid:373)e that does(cid:374)"t ha(cid:448)e the (cid:271)i(cid:374)di(cid:374)g pair for(cid:373)s a loop. A deleted region can unmask recessive alleles on the other homologue.