RT Book, Section
A1 Hogge, W. Allen
A1 Rajkovic, Aleksandar
SR Print(0)
ID 1115992832
T1 Organization and Structure of Human Chromosomes
T2 Practical Genetics for the Ob-Gyn
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 9780071797214
LK obgyn.mhmedical.com/content.aspx?aid=1115992832
RD 2024/04/23
AB The  human  genome  is  comprised  of  nuclear  DNA  sequences,  tightly  packed  into  distinct  subunits  called  chromosomes  and  hundreds  to  thousands  of  circular  DNA  molecules  within  the  mitochondrion.  DNA  sequences  that  encode  for  proteins  account  for  few  percent  of  the  total  genome,  and  the  rest  of  the  genome  is  involved  in  coding  for  various  RNA  molecules  that  do  not  code  for  protein  (noncoding  RNA)  as  well  as  regulatory  function.  DNA  packed  into  chromosomes  is  coated  with  histone  and  nonhistone  proteins,  and  these  proteins  play  an  important  role  in  the  regulation  of  gene  expression.  There  are  a  total  of  22  autosomal  chromosomes  (1–22)  and  the  sex-determining  X  and  Y  chromosomes  (Figure  2-1).  The  gametes,  eggs  and  sperm,  each  contain  a  haploid  set  of  23  different  chromosomes  that  upon  fertilization  gives  rise  to  the  diploid  set,  46  chromosomes.  In  a  normal  diploid  human  cell,  23  chromosome  pairs  are  present:  22  pairs  of  autosomes  and  two  sex  chromosomes—XX  in  females  and  XY  in  males.  In  each  individual,  each  member  of  a  pair  is  derived  from  either  the  father  or  the  mother.