2. What Are Mutations?
What Are Mutations?
• Changes in the
nucleotide sequence of
DNA
• May occur in somatic
cells (aren’t passed to
offspring)
• May occur in gametes
(eggs & sperm) and be
passed to offspring
3. Are Mutations Helpful or
Harmful?
• Mutations happen
regularly
• Almost all mutations are
neutral
• Chemicals & UV
radiation cause
mutations
• Many mutations are
repaired by enzymes
4. Are Mutations Helpful or
Harmful?
• Some type of skin
cancers and leukemia
result from somatic
mutations
• Some mutations may
improve an organism’s
survival (beneficial)
13. Nondisjunction
• Failure of chromosomes to separate
during meiosis
• Causes gamete to have too many or
too few chromosomes
• Disorders:
– Down Syndrome – three 21st
chromosomes
– Turner Syndrome – single X chromosome
– Klinefelter’s Syndrome – XXY chromosomes
17. Gene Mutations
• Change in the
nucleotide sequence
of a gene
• May only involve a
single nucleotide
• May be due to copying
errors, chemicals,
viruses, etc.
18. Types of Gene Mutations
• Include:
– Point Mutations
– Substitutions
– Insertions
– Deletions
– Frameshift
19. Point Mutation
• Change of a single
nucleotide
• Includes the
deletion, insertion, or
substitution of ONE
nucleotide in a gene
20. Point Mutation
• Sickle Cell
disease is the
result of one
nucleotide
substitution
• Occurs in the
hemoglobin gene
21. Frameshift Mutation
• Inserting or deleting
one or more nucleotides
• Changes the “reading
frame” like changing a
sentence
• Proteins built
incorrectly
