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Page 1: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Mutations

Page 2: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

A Few Words on Mutations

• Mutations can be neutral, positive, damaging or lethal

• Can occur at the single base or chromosomal level

• Naturally occurring mutations are RANDOM– can introduce new traits– most mutations are harmful

Page 3: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Causes of Mutations

• radiation• chemical• high temperature• age

Page 4: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Chromosomal Mutations

• Structural– Change in length or arrangement of nucleotides

on chromosomes

• Nondisjunction– Change in chromosome number– Caused by errors in meiosis

Page 5: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Structural Chromosomal Mutations

• Cause birth defects or cancer• Can be one of the following:– Deletions– Duplications– Inversions– Translocations

Page 6: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Deletion

• When part of a chromosome is deleted, usually due to unequal crossing over.

Page 7: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Cri-Du-Chat Syndrome• 1 in 216,000 births

• 46 chromosomes

• #5 Deletion of lower arm

Symptoms:

Moon-shaped face

Heart disease

Mentally retarded

Malformed larynx

Normal lifespan

Page 8: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Duplication

• When part of a chromosome is duplicated, again usually due to unequal crossing over.

Page 9: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Duplication

• Huntington’s– incidence: 1/10,000

in U.S.–nervous system

degenerates

– late onset–may not show

symptoms until past reproductive age

Page 10: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Inversion

• An inversion is a type of mutation where a sequence of nucleotides in the DNA is reversed, or inverted

Page 11: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Translocation

• Mutuation when a there is a rearrangement of parts between nonhomologous chromosomes

http://en.wikipedia.org/wiki/Chromosomes
Page 12: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Burkitt Lymphoma

Translocation of the Myc gene on chromosome 8

Normal Myc genes control cell growth and division•Translocated Myc genes don’t function properly

•Leads to cancer of the lymph nodes

http://en.wikipedia.org/wiki/Image:Large_facial_Burkitt's_Lymphoma.JPG
Page 13: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Nondisjuction

• Error in meiosis in which chromosomes fail to separate.

• Can happen in Meiosis I or Meiosis II

Page 14: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Changes to Chromosome Number

• Monosomy 2n-1– 45 chromosomes– Turners (XO)

• Trisomy 2n+1– 47 chromosomes– Down syndrome(trisomy 21), Klinefelters (XXY),

Triple X (XXX), Jacobs (XYY)• Polyploidy (Triploid, Tetraploid, etc)

Page 15: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Down Syndrome: Trisomy

Down Syndrome

1 in 1,250 births

47 chromosomesXY or XX

#21 Trisomy Nondisjunction

1 in 31,000 births

46 chromosomesXY=97%

XX=3%

#14/21 Translocation

Page 16: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Down SyndromeShort, broad hands Stubby fingersRough skinImpotency in malesMentally retardedSmall round faceProtruding tongueShort lifespan

http://upload.wikimedia.org/wikipedia/commons/9/9d/Brushfield.jpg
Page 17: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Turners Syndrome1 in 5,000 births

45 chromosomes X only

#23 MonosomyNondisjunction

96-98% do not survive to birthNo menstruationNo breast developmentNarrow hipsBroad shoulders and neck

Page 18: Mutations. A Few Words on Mutations Mutations can be neutral, positive, damaging or lethal Can occur at the single base or chromosomal level Naturally

Klinefelter Syndrome1 in 1,100 births

47 chromosomesXXY only

#23 Trisomy Nondisjunction

Scarce beard

Longer fingers and arms

Sterile

Delicate skin

Low mental ability

Normal lifespan


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