Science form 4 Mutation
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Transcript of Science form 4 Mutation
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Do you ever see someone who
downs syndromeout
there?
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Why do these happen to them?
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3.4 MUTATION
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Learning outcomesAt the end of the lesson, you are able to
1. State what mutation is
2. State the types of mutation
3. List examples of mutation
4. Identify the causes of mutation
5. State the advantages anddisadvantages of mutation
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Mutation: the spontaneous
change to the structure of genes orchromosomes / genetic information.
Occurs in
Somatic/body cells
(can be passed downthrough mitosis)
Gametes/reproductivecells
(inherited)
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TYPES OF MUTATION
Gene mutation
Change in the
structureofDNA
Chromosome mutation
A change in the
numberand thestructureof
chromosomes.
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Downs syndrome: an extra chromosome in
autosome 21 (47 chromosomes)
Klinefelters syndrome: a male with extra X
chromosome (XXY)
Turners syndrome: a female with one less Xchromosome (XO)
Polyploidy: having one or more chromosomes ina set of chromosome
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Colour blindness: a mutated gene in theXchromosome
Sickle cell anemia: mutation in gene that
produces haemoglobin; inefficient in transportingoxygen in the blood
Albinism:the gene for skin colouris mutated;
unable to produce black pigment (melanin)
Haemophilia: mutation in gene that is importantfor blood-clotting
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Downs syndrome
Additional or EXTRA
chromosome at autosome 21.(47 Chromosomes)
Physical retardation
Thick neckSlanted eyes
Protuding tongue
Reduced resistance to diseases
Need Special Care.
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Klinefelters syndrome
A male with extra X chromosomes
(having XXY)
Infertile
Underdeveloped testes
Narrow shoulder
Some female characteristics
Enlarged breasts
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Turners syndromeA female having one less X
chromosome (XO)Infertile
Short
Mentally retardedHas no ovaries
Small breasts
Folded skin on neck
No menstrual cycle
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Polyploidy
The number of chromosomes is increased by one
or more sets. More common in plants.
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Colour blindness
Mutant gene (recessive gene) on the Xchromosome.
Not able to differentiate colours
especiallygreen and red
More common in
males because male has onlyone X chromosome
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Albinism
The gene for skin colour is mutated
(recessive gene)
Unable to produce melanin (black
pigment)
White hair
Pink eyes and pinkish skin
Skin is sensitive to sunlight
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Sickle-cell anemia
Mutation in gene that produce
haemoglobin
Sickle-cell shaped of red blood cells
Not efficient in transporting oxygen
Facing painful crises such as chest pain,
bone pain,Yellowing of eyes
Inherited from both parents
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Haemophilia
Mutation in chromosome X (for blood
clotting)
Have problem in blood clotting
May bleed continuously or for a longer
period
A woman carrier may inherit thedisease to a son
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Spontaneous changes
during cell division
Exposure to physicalmutagens: UV radiation,
X-rays, radioactiveradiation
Environmental change: thechange of temperature for along period causes genetic
evolution in organism
Exposure to chemicalmutagens: Benzene,
formaldehyde, nicotine,sodium nitrite, pesticides
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Give rise to variationwhich leads todifferences in traits
Better chance of
survival when newspecies are moreresistant to diseases
Advantages
Cause physical
defects/deformities
Causes geneticdiseases
Some chromosome
mutations and genemutation are lethal(fatal)
Causes mental
defects
Disadvantages
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QUIZPlease take a pieceof paper and write
your answersclearly.
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1. State the sex chromosomes for
i) male
ii) female 2. State 1 advantage and 1 disadvantage of
mutations.
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