Presentation on theme: "C-Notes: Chromosomal Abnormalities (Errors of Meiosis) Stnd: 2c 2/14/2014 Objective: SWBAT explain the problems with meiotic spindles not separating properly."— Presentation transcript:
C-Notes: Chromosomal Abnormalities (Errors of Meiosis) Stnd: 2c 2/14/2014 Objective: SWBAT explain the problems with meiotic spindles not separating properly during Meiosis, which causes abnormalities in offspring.
How can genetic material be changed? Incorrect number of chromosomes 1.Non-Disjunction (Chromosomal Aberration) – Problems with meiotic spindle causes the homologous chromosomes NOT to separate properly during Meiosis I – Or sister chromatids fail to separate during Meiosis II – Leading to TOO MANY or TOO FEW chromosomes in one daughter cell. either an extra or missing chromosome causing Aneuploidy (wrong # of chromosome. Ex: XXX) Found in Chromosomes # 8,12,13,14,15,18, & 21) 2.Breakage of Chromosomes – Deletion – Duplication – Inversion – translocation
Changes in chromosome structure deletion – loss of a chromosomal segment duplication – repeat a segment inversion – reverses a segment translocation – move segment from one chromosome to another error of replication error of crossing over
How do changes in the genetic material (alteration of chromosome s) of an organism lead to changes in the traits of that organism? This leads to gametes with irregular numbers of chromosomes.
How does these alteration of chromosomes effect an organism? Baby has wrong number of chromosomes “SOMY” means Mutations – Involve individual extra/missing chromosomes – Usually result in early miscarriage
Why is the extra # 21 chromosome more tolerated by organisms ? (Down Syndrome) Because it does NOT result in miscarriage 3 copies of Chromosome 21 –Characteristic of facial appearance and other varying effects –Varying levels of retardation –Frequently correlates with age of mothers.
Down syndrome & age of mother Mother’s age Incidence of Down Syndrome Under 30<1 in 1000 301 in 900 351 in 400 361 in 300 371 in 230 381 in 180 391 in 135 401 in 105 421 in 60 441 in 35 461 in 20 481 in 16 491 in 12 Rate of miscarriage due to amniocentesis: 1970s data 0.5%, or 1 in 200 pregnancies 2006 data <0.1%, or 1 in 1600 pregnancies
What are the Sex Chromosome s abnormalities ? Human development (body cells/ Autosomes) (chromosome #1-22) are more tolerant of wrong numbers than Sex Chromosome (pair #23/ X & Y) But abnormalities in Sex Chromosomes produces a variety of distinct syndromes in humans – XXY = Klinefelter’s syndrome male – XXX = Trisomy X female – XYY = Jacob’s syndrome male – XO = Turner syndrome female
What is Turner’s Syndrome: Monosomy X? XO Females Phenotypically female (short stature, swelling, broad chest, webbed neck, los set ears, etc) Sterile (cant have kids) Associated with heart defects
What is Klinefelter’s syndrome? XXY Male – one in every 2000 live births – have male sex organs, but are sterile – feminine characteristics some breast development lack of facial hair – tall – normal intelligence
What is Jacob’s syndrome? XYY Males – 1 in 1000 live male births – extra Y chromosome – slightly taller than average – more active – normal intelligence, slight learning disabilities – delayed emotional immaturity – normal sexual development
What is Trisomy X? XXX Females – 1 in every 2000 live births – produces healthy females Why? Barr bodies – all but one X chromosome is inactivated