Mutations (Khan Academy) Flashcards
What is a mutagen?
A chemical substance or physical event that can cause genetic mutations.
How are mutagens classified in terms of source?
endogenous
exogenous
What are reactive oxygen species (ROS)?
A type of unstable molecule that contains oxygen and that easily reacts with other molecules in a cell. It’s produced in a cell.
What are the types of DNA damage by ROS?
Double strand break - breaking DNA into segments
Base modification - swapping of nuleic acid
What are intercalators?
A type of exogenous mutagens, molecules which fit themselves between the two strands of DNA and cause deformation.
What are base analogues?
A type of exogenous mutagens, molecules which “impersonate” bases but act differently.
What are the most common types of anneuploidy in humans?
monosomy - missing one copy of a chromosome in a pair
trisomy - having a third copy of a chromosome
What is the cause of aneuploidy?
Nondisjunction of chromosomes - failure of homologous chromosomes to separate during meiosis I or sister chromatids during meiosis II or mitosis.
What are the types of chromosomal rearrangements?
duplication
deletion
inverison
translocation
What takes place during duplication in a chromosome?
A part of a chromosome is copied more than one time.
What happens during deletion in a chromosome?
A part of a chromosome is removed.
What happens during inversion in a chromosome?
A chromosomal region is flipped around so that it points in the opposite direction.
What happens during translocation in chromosomes?
A piece of one chromosome gets attached to another chromosome.
What are the types of chromosomal translocation?
Translocation can be reciprocal or non-reciprocal.
A reciprocal translocation involves two chromosomes swapping segments.
A non-reciprocal translocation means that a chunk of one chromosome moves to another.
What are the ways bacteria can share genes?
transformation
transduction
conjugation
What happens in bacterial transformation?
A bacterium takes in DNA from its environment, often DNA that’s been shed by other bacteria.
What happens in bacterial transduction?
Viruses that infect bacteria move short pieces of chromosomal DNA from one bacterium to another “by accident.”
What happens in bacterial conjugation?
DNA is transferred from one bacterium to another. After the donor cell pulls itself close to the recipient using a structure called a pilus, DNA is transferred between cells. In most cases, this DNA is in the form of a plasmid.
What is a fertility factor in bacteria?
A chunk of DNA that codes for the proteins that make up the sex pilus. It also contains a special site where DNA transfer during conjugation begins.
What are transposable elements?
Chunks of DNA which “jump” from one place to another within a genome, cutting and pasting themselves or inserting copies of themselves in new spots.
What are the two sources of genetic variation in viruses?
recombination - swapping fragments of DNA between viruses
random mutation
