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Chapter 5

BIOL359 Chapter Notes - Chapter 5: Silent Mutation, Genetic Drift, Deoxyribose


Department
Biology
Course Code
BIOL359
Professor
Jonathan Witt
Chapter
5

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Mutation = ultimate source of all genetic variation, allows forces like Natural selection and
genetic drift to act on.
- Without mutation, NO evolution
Meiosis = creates genetic variation, SHIFTS EXISTING alleles
Mutation = CREATES NEW ALLELES
DNA consists of:
- 4 carbon sugar called deoxyribose, phosphate group, distinctive nitrogen-containing
base.
- AT CG pairing,
oCytosine and Thyminen are PYRIMIDINES (just hexagon)
oAdenine guanine are PURINES – bigger structure (hexagon+pentagon)
- Complementary base pairing.
Different types of mutations
- Point mutation
oAlters a single point in the base sequence of a gene
oTwo types, transitions and transversions
oTRANSITIONS MORE COMMON
oCan be SYNONYMOUS (do not change amino acid) or NON-SYNONYMOUS
(amino acid replacement)
oMany are SYNONYMOUS (silent) because of genetic code redundancy.
Transition = substitution of a PURINE with a PURINE or a PYRIMIDINE with a PYRIMIDINE
Tranversion = substitution of a PURINE with a PYRIMIDINE, vice versa, more likely to change
shape of a molecule, error corrections more likely to detect conformational change.
Indels = insertion or deletion of one or more nucleotides in DNA sequence, causes
FRAMESHIFTS.
- Jumping gene = inserts chunk of sequence into middle of protein
- Insertion = inserts a base
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