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DNA and Mutations. Mutation Facts #1-5 Write down five facts about mutations as we go through the...
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Transcript of DNA and Mutations. Mutation Facts #1-5 Write down five facts about mutations as we go through the...
DNA and Mutations
Mutation Facts #1-5 • Write down five facts about mutations as we go
through the following videoclips • Video 1• Video 2 – Repair• Video 3 – Repair• Addition and Deletion Mutations
What is a Mutation? • change in the DNA code• Lead to frameshifts – the message is no longer
correctly passed • Protein Outcomes:• 1. changed – different from the original• 2. no change - silent mutations• 3. incomplete - amino acid is changed to a
"stop" codon
3 Types of Mutations:• 1. Substitution - one
base for another• Sickle-cell Anemia• GAG into GUG• Valine becomes
glutamic acid
• 2. Insertion - extra bases
• Huntington's disease – CAG repeat
• fragile X syndrome – CGG repeat
Fragile X syndrome• triplet CGG is repeated
(CGGCGGCGGCGG, etc.).• repeats as few as 5 or as many
as 50 will not cause harm. Even 100 repeats usually cause no harm.
• longer repeats have a tendency to grow longer from one generation to the next (as many as 4000 repeats).
• 3. Deletion - a section of DNA is lost, or deleted.
• Duchenne Muscular Dystrophy (DMD)
• DMD gene codes for dystrophin (protein)
• protein holds skeletal muscle cells together - missing in DMD
Mutations lead to Genetic Disorders
• One Wrong Letter - Tay Sachs • Finding Cures is Hard - Cystic Fibrosis
Chromosome Disorders • Chromosome: Coiled DNA and proteins
Chromosome Arrangement
• Called a Karyotype• Receive one from
mom, one from dad, they are homologs
Chromosome 21“Trisomy 21’
Down Syndrome
Kleinfelter’s syndrome - XXY• Male• Develop some breast
tissue• Little body hair • typically tall• Infertility results - no
sperm
Turner’s Syndrome – X• No Y means Turner’s
people are female. • no ovaries develop don’t undergo puberty and they are sterile.
• Hormone treatment cures all but the sterility.
• Other symptoms: short stature, webbed skin and low hairline at the neck
Mutations – good or bad?• Discuss with your lab partner.
Reflection
1. DNA codes for proteins. If DNA is mutated, how might this cause a disease? (Connect proteins to disease).
2. How is it possible for two identical twins, with identical DNA sequences, have different traits – for instance one gets cancer and one does not.
What is Epigenetics?
• the study of changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the DNA