Mutations (18.3) Flashcards
Define: Mutation
A permanent change in the genetic material of an organism
How do mutations spread throughout the body?
All mutations are inheritable; they are copied during DNA replication and passed on to daughter cells
Which mutations are passed on to future generations?
Only mutations that affect the genetic information in the gametes of an organism are passed on to the organism’s offspring (germ line mutations)
Define: Gametes
The reproductive cells
What are somatic cell mutations?
Mutations that occur in the body cells
What are germ line mutations?
Mutations that occur in reproductive cells
What are germ line mutations?
Mutations that occur in reproductive cells
Define: Point Mutations
Genetic mutations that occur when one or a few nucleotides are changed in a DNA sequence
What is the one type of point mutation?
Substitution mutation
What is a substitution mutation?
When a nucleotide in a DNA sequence is replaced by a different nucleotide
What is a frameshift mutation?
Genetic mutations that occur when a nucleotide is either added or deleted from a DNA sequence, resulting in a shift of the “reading frame” of the genetic code
What are the two types of frameshift mutations?
- Insertions
- Deletions
What is an insertion mutation?
An extra base is slipped in
What is a deletion mutation?
A base is removed/missing
What are the three types of substitution mutations?
- Missense mutation: results in an altered protein (e.g. sickle cell anemia)
- Silent mutation: has no effect on a cell’s metabolism
- Nonsense mutation: renders gene unable to code for a functional polypeptide
What type of protein does a missense mutation result in?
Slightly altered but still functional protein (e.g. sickle cell anemia)
What type of protein does a silent mutation result in?
Has no effect on the protein made
What type of protein does a nonsense mutation result in?
Renders gene unable to code for a functional polypeptide
What are the two ways mutations are caused?
Mutations may be spontaneous (DNA polymerase incorrectly pairing nucleotides) or induced by a mutagen
What are the two types of mutagens
Chemical, physical and infectious mutagens
How does a physical mutagen cause mutations
By forcibly breaking a nucleotide sequence causing random changes
What are some examples of physical mutagens?
- X-ray
- UV radiation
How does a chemical mutagen cause mutations?
- Enters cell’s nucleus and causes permanent change in genetic material by chemically reacting with DNA (nitrates)
- Most are carcinogenic (cancer-causing)
What are some examples of chemical mutagens?
- Cigarette smoke
- Benzoyl peroxide
Most chemical mutagens are _____________.
Carcinogenic
What are infectious mutagens?
Bacterial or viral pathogens
What are some examples of infectious mutagens?
- HPV virus
- Helicobacter pylori (bacteria spread through contaminated food)
