Unit 14: Mutation and DNA Repair Flashcards
(39 cards)
What is a mutation?
A change in the DNA sequence that gives a different protein or no protein.
What are germ-line mutations?
Mutations that occur in germ-line cells, giving rise to sperm and egg, are called germ-line mutations.
Can germ-line cells be passed generation to the next?
Yes, germ-line mutations can be passed from one generation to the next.
What are somatic mutations?
Cells not in the germ line are somatic cells, thus, mutations in such cells are called somatic mutations.
Can somatic cells be passed generation to the next?
No, somatic cells divide by mitosis and only direct descendants of the original mutated cell will carry the mutation.
What is the fitness of a mutation?
The fitness of a mutation describes its value to the survival and reproductive success of the organism.
What are lethal mutations?
Many mutations are lethal and cause embryos to be non-viable.
What are harmful mutations?
Non-lethal, but lower survival and reproduction.
What are silent mutations?
Neutral, no effect on phenotype.
What are beneficial mutations?
Useful, usually in a new environment.
What are the four types of mutations?
- Bases changed (substitution).
- Bases removed (deletion).
- Bases added (insertion)
- Bases inverted (inversion)
What are the four effects of mutations?
- Silent mutation
- Missense mutation
- Nonsense mutation
- Frameshift mutation
What is a silent mutaiton?
A base-pair change that does not alter the resulting amino acid due to the redundancy of the genetic code.
What is a missense mutation?
A base-pair change that results in an amino acid change in the protein.
What is a nonsense mutation?
A base-pair change that creates a stop codon in place of a codon specifying an amino acid.
What is a frameshift mutation?
An insertion or deletion that causes the reading frame to shift.
__ _____ ______ is the result of a single base substitution.
Sickle Cell Anemia is the result of a single base substitution.
________ _______ may cause the _____ disorder
Different mutations may cause the same disorder.
What causes a mutation?
Can occur spontaneously or can be induced by a mutagen.
What is a mutagen?
A mutagen is an agent that causes a mutation.
What are spontaneous mutations?
Bases that are found in uncommon forms that base pair with a non-complementary base.
If a spontaneous mutation occurs during replication…
a mutation will persist in one copy of the DNA.
What is DNA symmetry and how may it lead to spontaneous mutations?
DNA symmetry means the sequence is very repetitive or mirror-like.
(Ex. AAAAAA, GCGCGC, TACTACTAC).
This makes it hard for enzymes (like DNA polymerase) to read or copy it accurately during replication.
Mistakes = spontaneous mutations
How do duplicated copies of genes cause misalignment of genes during crossing over?
If a gene is duplicated, it can confuse chromosomes during crossing over. This misalignment may cause unequal swaps, leading to duplications or deletions — a type of spontaneous mutation.
