MUTATIONS Mutations can occur in DNA replication Protein Synthesis.
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Transcript of MUTATIONS Mutations can occur in DNA replication Protein Synthesis.
MUTATIONS
Mutations can occur in•DNA replication•Protein Synthesis
Replication Error
• Nondisjunction: chromosomes fail to properly separate during anaphase
Whole chromosome mutations: May be diagnosed by a karyotype. Examples: Down’s syndrome (trisomy), Turner’s syndrome (X0), Klinefelter’s syndrome (XXY)
Mutations can affect a single base, several bases, or an entire chromosome.Example: translocation
Mutations can occur during replication or protein synthesis.
Mistakes could occur in either step
TRANSCRIPTION TRANSLATION
Occurs inside the nucleus when the DNA strands separate
Occurs in the cytoplasm at a ribosome
mRNA is made using the DNA template, then it leaves the nucleus via a nuclear pore
mRNA lined up at ribosome has “codon” (three base sequence) that the tRNA matches with an “anticodon”.
An
erro
r in
bas
e se
quen
ce in
DN
A o
r m
RN
A w
ould
res
ult i
n th
e w
rong
am
ino
acid
.
Frameshift Mutations:reading errors cause insertions or deletions
8
Making ProteinsMaking Proteins
DNADNA: TAC CGA TCG TGA ACT
mRNAmRNA: AUG GCU AGC ACU UGA
ProteinProtein: Met-Ala-Ser-Thr-Stop
TranscriptionTranscription
TranslationTranslation
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Effect of Mutation Effect of Mutation on Proteinon Protein
DNADNA: TAC CGA TCG TGA ACT
mRNAmRNA: AUG GCU AGC ACU UGA
ProteinProtein: Met-Ala-Ser-Thr-Stop
TranscriptionTranscription
TranslationTranslation
C
G
Gly
Point mutation: a single base is incorrect.
Which amino acid would be delivered?
Would every single
base change
result in a different
amino acid?
Internal Mutations: a change in nucleotide sequence
• Occur during replication• Usually fatal to the cell, but vital for increasing genetic variety• Mutagen = agent that causes mutations (UV rays, chemicals, asbestos, cigarette smoke, etc.)
Types of Internal Mutations• Changes in nucleotide sequence• Are usually fatal to the cell, but vital for increasing
genetic variety• Types: