IMED1002 Lecture Notes - Lecture 32: Telomere, Centromere, Chromosome
12 Jul 2018
School
Department
Course
Professor
Lecture 32
CHROMOSOME CHANGES: STRUCTURE
1. DEFINE THE FOUR BASIC TYPES OF CHROMOSOMAL
REARRANGEMENTS, INCLUDING CHANGES TO CHROMOSOMES AND
DESCRIBE THEIR POSSIBLE EFFECTS
CHROMOSOME STRUCTURE CHANGES
• Following meiosis, only get survival of cell if chromosomes have one centromere and
two telomeres
• Lack of centromere= acentric, nowhere for spindle to attach, so DNA lost
• Two centromeres= dicentric, typically not incorporated into progeny cell
• Loss of telomeres impacts DNA stability and replication
Chromosome Mutations
Document Summary
Chromosome changes: structure: define the four basic types of chromosomal. Chromosome structure changes: mutatio(cid:374)s that cha(cid:374)ge the structure of a(cid:374) i(cid:374)dividual"s chro(cid:373)oso(cid:373)es, rearrangements 2 types: Deletion= loss of chromosome segment (can be small or large) Inversion= orientation within chromosome reversed (180 degree flip, change in orientation) Inversion and translocations require cleavage> need to chop out a segment to move the location. Proteins that break dna break the phosphodiester bonds and move the dna segments. Deletions: multigenic deletions= several or many genes lost, if have multigenic on boht homologous then not viable. Often multigenic deletion on one chromosome also not viable. Gene dosage effect (or expression of deleterious recessive allele) Can have a line to indicate loss. Need same dosage of genes to be maintained. Multigenic in both homologs=lost completely those gene copies form the dna> causes zygote to be nullisomic> not viable. Phenotypic consequences depend on which genes located in deleted region.
