ANSC 313 Lecture Notes - Lecture 1: Chromosome Abnormality, Microchromosome, Cytogenetics
BMSC 313!
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inheritance patterns!
single gene!•
chromosomal!•
multifactorial!•
teratogenic!•
!
cytogenetics - the study of chromosomes!
why?!
multiple malformations ( have these because of chromosomal problems)!•
fertility problems ( have these because of chromosomal problems)!•
phylogeny/ evolution!•
sexing birds ( replaced mostly by DNA sexing)!•
!
Karyotype!
arranged by size (descending order)!•
numbered!◦
sex chromosomes last!•
XY- male mammal!◦
ZW- female bird!◦
grouped by centromere placement ( part of the chromosome that attaches to the spinal fiber in •
cell division)!
short arm up (p for "petite")!•
other arm is labeled as q!◦
!
sexing birds - now done with DNA typically!
many micro-chromosomes - can not identify the pairs of these or really count them!•
6-9 pairs of macro chromosomes!•
including the sex chromosomes!◦
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nomenclature!
- first total number of chromosomes (always even number) , sex chromosomes!
examples: !
#78, XX (normal bitch)!
#65,XY, +15 #(abnormal colt fetus, had an extra chromosome)!
total number!1.
sex!2.
anything abnormal!3.
!
basically the number of chromosomes does not have anything to do with evolution!
!
origin of chromosome anomalies!
many chromosomal anomalies arise "de novo" ( new for the first time ) during meiosis of one of •
the parents!
other arise through mismatching of homologues during meiosis!•
!
chromosomes divide by:!
mitosis!
#DNA replicates!◦
