Unit 2, part 8 Flashcards
What is a genetic mutation?
A permanent change in the DNA sequence that can be passed on to descendants.
What is the difference between somatic and germline mutations?
Germline mutations occur in gametes and can be passed to offspring; somatic mutations occur in non-germ cells and are not passed to offspring.
How are gene mutations categorized?
By types of gene mutations and their effects, including base substitutions, insertions, and deletions.
What are the types of base substitutions?
- Silent * Missense * Nonsense * Read-through
What is a frameshift mutation?
An insertion or deletion that alters the reading frame of a gene.
What are the potential effects of mutations?
- Detrimental * Neutral * Beneficial
What is a germline mutation?
A mutation in gametes that results in the entire organism carrying the mutation.
What is a somatic mutation?
A mutation in non-germ cells that is passed to daughter cells through mitosis.
What are the phenotypic effects of forward mutations?
Changes from wildtype (WT) to mutant (new novel mutation).
What is a reverse mutation?
Changes a mutant phenotype back to the wild-type phenotype.
What is a missense mutation?
Changes a sense codon into a different sense codon, resulting in the incorporation of a different amino acid in the protein.
What is a nonsense mutation?
Changes a sense codon into a nonsense (stop) codon, causing premature termination of translation.
What is a silent mutation?
Changes a sense codon into a synonymous codon, leaving the amino acid sequence of the protein unchanged.
What is a loss-of-function mutation?
Causes a complete or partial loss of function of the protein.
What is a gain-of-function mutation?
Produces a new trait or causes a trait to be exhibited in new places.
What are the causes of spontaneous mutations?
Naturally occurring mutations that happen during replication due to wobble or strand slippage.
What are mutagens?
Anything in the environment that increases the mutation rate.
What is the role of DNA repair mechanisms?
To correct potential mutations through detection, excision, polymerization, and ligation.
What is a neutral mutation?
Changes the amino acid sequence of a protein without altering its ability to function.
True or False: Somatic mutations can be passed to offspring.
False
Fill in the blank: A _______ mutation causes premature death.
lethal
What are the three main types of DNA repair mechanisms?
Direct repair, Base-excision repair, Nucleotide-excision repair
These mechanisms are critical for maintaining genomic integrity.
What is the difference between somatic cell mutations and germ line mutations?
Germ-line mutations impact the organism’s progeny and somatic mutations impact the organism itself, but are not passed on to progeny
Germ-line mutations can lead to hereditary diseases, while somatic mutations typically affect only the individual.
True or False: DNA repair pathways have a lot of redundancy because they are so important.
True
Loss of function and gain of function mutations are generally ______.
recessive
True or False: Defects in DNA repair systems do not cause disease.
False
What are the main types of chromosomal mutations?
- Rearrangements
- Aneuploidy
- Polyploidy
These mutations can significantly impact genetic stability and organismal development.
What are the types of rearrangements in chromosomal mutations?
- Duplications
- Deletions
- Inversions
- Translocations
What is aneuploidy?
Change in the number of individual chromosomes
This condition can lead to various genetic disorders, including Down syndrome (Trisomy 21).
What is polyploidy?
Change in the number of complete sets of chromosomes
Common in plants but rare in animals.
What are the types of duplications in chromosomal mutations?
- Tandem
- Displaced
- Reverse
What are the types of deletions in chromosomal mutations?
- Interstitial
- Terminal
Terminal deletions can result in the loss of centromeres, leading to chromosomal loss during meiosis.
What is an inversion in chromosomal mutations?
A chromosomal segment is inverted (turn 180°)
Inversions can affect gene expression without losing any genes.
What is a translocation in chromosomal mutations?
Movement of chromosomal segments between non-homologous chromosomes or within the same chromosome
What is a reciprocal translocation?
A two-way exchange of segments between non-homologous chromosomes
What is a non-reciprocal translocation?
A one-way exchange of segment(s) between chromosomes
What is the ‘Philadelphia chromosome’?
A gene called ‘BCR-abl’ formed on chromosome 22 due to a translocation, often found in chronic myelogenous leukemia
What is a Robertsonian translocation?
Short arm of a chromosome is exchanged with the long arm of another chromosome, resulting in one large chromosome and one small fragment
True or False: Sex chromosome aneuploidies are often lethal.
False
What is the primary cause of aneuploidy?
Non-disjunction: failure of homologous chromosomes or sister chromatids to separate normally during mitosis or meiosis
What is autopolyploidy?
Nondisjunction of entire sets of chromosomes from the same species
This can be advantageous in agriculture.
What is allopolyploidy?
Polyploidy where sets of chromosomes come from different, but typically related, species
What can result in sterility?
Seedless plants
Seedless plants often cannot reproduce naturally.
What is allopolyploidy?
Sets of chromosomes come from different, but typically related, species
Allopolyploidy is primarily used in plant cultivation.
What percentage of flowering species are affected by allopolyploidy?
40%
This indicates a significant role in the evolution of flowering plants.
What percentage of grasses are affected by allopolyploidy?
80%
Allopolyploidy is particularly common in grass species.
What is a rare event in allopolyploidy?
Hybridization between species
This involves gametes fusing and nondisjunction in mitosis.
In allopolyploidy, what must happen for a full set of homologous chromosomes to be produced?
Gametes must fuse, then have nondisjunction in mitosis
This allows for the reproduction of asexually derived plants.
What is an example of an allopolyploid plant?
Wheat
Wheat is an allohexaploid with 42 chromosomes from 3 distinct species.
How many chromosomes does wheat have?
42 chromosomes
It is derived from 3 distinct species, each with a diploid set of 14 chromosomes.
True or False: Allopolyploidy is primarily a tool for animal cultivation.
False
Allopolyploidy is primarily a tool for plant cultivation.
