chromosomal mutations & their effects
Post on 25-Feb-2016
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Chromosomal Mutations & their
effects
Karyotype• A picture of the chromosomes of an
individual or a species, including number, form, and size of the chromosomes.
• Often used to diagnosis chromosomal abnormalities.
Chromosomes
• Humans have 23 pairs– 22 pairs are autosomes– 1 pair are sex chromosomes
•(women = XX, men = XY)• Chromosomes have a centromere that
holds the chromatids (two parts of the chromosome) together.
• The top ½ of the chromosome is called the “p” arm and the bottom ½ is “q”
Nondisjunction Disorder
• Nondisjunction is the failure of chromosome pairs to separate during meiosis (making of gametes – sex cells)
• it can cause some gametes to gain an extra chromosome and others to lose one
• Monosomy = A chromosome having no homologue (matching chromosome)
• Trisomy =The condition of having three copies of a given chromosome in each somatic (body) cell rather than the normal number of two.
Normal Male Karyotype
Normal Female Karyotype
Turners Syndrome
1 in 5,000 births
45 chromosomesX only #23 MonosomyNondisjunction
Turners Syndrome96-98% do not survive to birthNo menstruationNo breast developmentNo hipsBroad shoulders and neck
Cri-Du-Chat Syndrome
1 in 216,000 births
46 chromosomesXY or XX
#5 Deletion of upper arm of chromosome
Cri-Du-Chat SyndromeMoon-shaped faceHeart diseaseMentally retardedMalformed larynxNormal lifespan
Aniridia-Wilms Tumor Syndrome
1 in 50,000,000 births
46 chromosomesXY or XX
#11 Deletion of upper arm
Aniridia-Wilms Tumor Syndrome
Mentally retardedGrowth retardedBlindnessTumors on kidneysShort lifespan
Thirteen Q Deletion Syndrome
1 in 500,000 births
46 chromosomesXY or XX
#13 Deletion of lower arm
Thirteen Q Deletion Syndrome
Mentally retarded Deformed faceNo thumbs Heart diseaseShort lifespan
Prader-Willi Syndrome
1 in 5,000,000 births
46 chromosomesXY=97% XX=3%
#15 Deletion of lower arm
Prader-Willi SyndromeSmall bird-like headMentally retardedRespiratory problemsObesityShort lifespan
Eighteen Q Deletion Syndrome
1 in 10,000,000 births
46 chromosomesXY or XX
#18 Deletion of lower arm
Eighteen Q Deletion Syndrome
Mentally retardedHeart diseaseAbnormal hands and feetLarge eyesLarge earsNormal lifespan
Cat-Eye Syndrome1 in 1,000,000 births
46 chromosomesXY or XX
#22 Deletion of bottom arm
Cat-Eye SyndromeFused fingers and toesMentally retardedSmall jawHeart problemsNormal lifespan
Four-Ring Syndrome
1 in 10,000,000 births
46 chromosomesXY or XX
#4 Inversion
Four-Ring Syndrome
Cleft palateClub feetTestes don’t descendShort lifespan
Down Syndrome
1 in 31,000 births
46 chromosomesXY=97%
XX=3%
#14/21 Translocation
1 in 1,250 births
47 chromosomesXY or XX
#21 Trisomy Nondisjunction
Down Syndrome Trisomy
Down Syndrome
Short, broad hands Stubby fingersRough skinImpotency in malesMentally retardedSmall round faceProtruding tongueShort lifespan
Patau’s Trisomy Syndrome
1 in 14,000 births
47 chromosomesXY or XX
#13 Trisomy Nondisjunction
Patau’s Trisomy Syndrome
Small headSmall or missing eyesHeart defectsExtra fingersAbnormal genitaliaMentally retardedCleft palateMost die a few weeks after birth
Edward’s Trisomy Syndrome
1 in 4,400 births
47 chromosomesXX=80%
XY=20%
#18 Trisomy Nondisjunction
Edward’s Trisomy Syndrome
Small headMentally retardedInternal organ abnormalities90% die before 5 months of age
Jacob’s Syndrome1 in 1,800 births
47 chromosomesXYY only
#23 Trisomy Nondisjunction
Jacob’s Syndrome
Normal physicallyNormal mentallyIncrease in testosteroneAcneNormal lifespan
?
Kleinfelter Syndrome1 in 1,100 births
47 chromosomesXXY only
#23 Trisomy Nondisjunction
Kleinfelter SyndromeScarce beardLonger fingers and armsSterileDelicate skinLow mental abilityNormal lifespan
Triple X Syndrome
1 in 2,500 births
47 chromosomesXXX only
#23 TrisomyNondisjunction
Triple X Syndrome
Normally physically Normal mentallyTallFertilenormal lifespan
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