Download Mutations

Topic:
Mutations
Notes
Name: ___________________________ Date:____________
Objective: SWBAT understand gene and chromosomal mutations.
Questions/Main
Ideas:
What are
mutations?
Mutations are changes in the DNA that affect genetic information.
- 2 types of mutations: Gene mutations and chromosomal mutations.
What are gene
mutations?
Gene Mutations
- DNA fails to copy accurately, leading to mistakes
- A nucleotide is deleted, inserted or substituted for the wrong one.
- When a gene mutation occurs, it can affect what protein is made.
What causes
mutations to
occur?
Possible causes:
- External influences, such as exposure to nuclear radiation, UV
radiation, or other carcinogens.
- There are checkpoints in the cell cycle that allow proteins to check for
errors (proofread). If these proteins don’t work, mistakes get missed.
What are
examples of Gene
mutations?
Types of Gene Mutations:
- Point mutations- affect only one nucleotide.
- Example: substitution
AGCACCTAGGTC
AGCACGTAGGTC
G (Guanine)
substitutes
C (Cytosine)
Normal Sentence →THE BIG FAT CAT ATE THE WET RAT
After substitution → THE BIZ FAT CAT ATE THE WET RAT
- Frameshift mutations- shift the entire frame (sequence of nucleotides).
Examples: deletion, insertion
AGCACCTAGGTC
AGACCTAGGTC
This deletion
changed the
sequence.
Normal Sentence→ THE BIG FAT CAT ATE THE WET RAT
After deletion→
THB IGF ATC ATA TET HEW ETR AT
Normal Sentence→ THE BIG FAT CAT ATE THE WET RAT
After insertion→
THE BIG ZFA TCA TAT ETH EWE TRA T
Frameshift mutations have more of an effect than point mutations on the
resulting amino acid chain. Why?
What are
examples of
Chromosomal
mutations?
Chromosomal Mutations- involve changes in whole chromosomes
- Can occur in Mitosis (from cell to cell) or Meiosis (from parent to
offspring)
- Can involve rearranging chromosome structure or changes in the
number of chromosomes.
- Can be harmful (genetic disorder or death), neutral, or beneficial
(make stronger plants)
Types of Chromosomal Mutations
1. Deletion = one or more genes are lost
2. Duplication = a segment of the chromosome is repeated
3. Inversion = chromosome segment breaks free
= attaches in reverse order
4.
Translocation = lost segment or entire chromosome attaches to a
different chromosome.
Altered genes may be passed on to every cell that develops from it, causing
an altered phenotype.
Summary: