Module 16: Mutations Flashcards
What are mutations?
Changes in the nucleotide sequence of DNA.
Do mutations always cause disease?
No.
Some mutations have no effect on phenotype.
What are germline mutations?
Mutations that occur in sex cells (sperm or egg) and are transmitted to the offspring.
Are somatic cell mutations inherited between generations?
No.
What are cancer-causing mutations?
Somatic cell mutations that interfere in cell cycle regulation.
What is non-disjunction?
The failure of sister chromatids to separate properly during cell division.
What are the 4 types of large-scale mutations?
- Deletion.
- Duplication.
- Inversion.
- Translocation.
What are large-scale mutations?
Mutations involving the partial rearrangement or even non-disjunction of chromosomes.
Includes multiple genes.
What would a large-scale mutations in a germ cell likely cause?
A miscarriage.
What are small-scale mutations?
Mutations involving only one or a few base pairs.
What are point mutations?
A mutation in a single nucleotide in a DNA sequence.
What are the types of point mutations?
- Substitution.
- Insertion.
- Deletion.
What are silent mutations?
A mutation in the DNA sequence that has no observable effect on the produced protein.
e.g. a substituted nucleotide produces a codon that codes for the same amino acid
What are missense mutations?
A mutation in the DNA sequence that results in a change in amino acid production.
This can have minimal or major effects depending on specific amino acid properties
What mutation occurs when a stop codon is put into place prematurely?
A nonsense mutation.
What mutation occurs when a stop mutation mutates and gets lost?
A sense mutation.
What are agents that increase mutation rates?
Mutagens.
When do deletion and insertion mutations have minimal impact?
When they occur in intron or non-coding nucleotide sequences.
Why do deletion and insertion mutations often have a disastrous effect on encoded proteins?
The codon reading frame is altered if the deletion or insertion does not involve a multiple of 3 nucleotides.
Do mutations occur spontaneously?
Yes.
Do mutations occur spontaneously?
Yes.
However, there is a higher frequency of mutations when mutagens are present.
Are most mutations harmful?
Yes.
What is a potential benefit of mutations?
Genetic variation.
What are the types of mutagens?
- Physical agents. includes UV and ionising radiation
- Chemical agents. includes chemicals that interact with DNA
What types of mutations cause human genetic disorders?
Germline mutations.
What are oncogenes?
Mutated genes involved in cell growth or cell division.
Normal cells are proto-oncogenes.
What are tumour suppressor genes?
Protein products that inhibit cell division.
What are the 3 stages of tumour growth?
- Benign. Starts with single mutation and contained.
- Malignant. Begining to penetrative surrounding tissue.
- Metastatic. Spreading throughout the body.
What is polymorphism?
A DNA variant that is acceptable.
What are translocation mutations?
The changing of segments from one chromosome to a nonhomologous chromosome.
Can be reciprocal or non-reciprocal.
What most commonly causes defects in genes that control cell growth or division?
Environmental factors.
