Unit 6: Topic 7 - Mutations Flashcards
How is the phenotype of an organism determined, and what can cause new phenotypes?
Phenotype is determined by an organism’s genotype, and as a result, a change or disruption in genetic information can cause a new phenotype to be present. The disruption is usually caused by a mutation, one example being cystic fibrosis which is caused by a gene mutation.
How is phenotype and protein production affected when there is an alteration of DNA?
Because a DNA mutation changes genotype, the resulting transcribed genetic information will differ, and as a result, it may change the protein produced or the amount of it, either stopping or increasing production of it. Because proteins are the underlying cause of an organism’s phenotype, mutations cause changes in the phenotype of organisms.
What are and what are the types of point and frame-shift mutations?
Point Mutations (Affecting one/few nucleotides): Silent mutation (Changing of a nucleotide does not affect the amino acid it codes for), Missense mutation (Changing of a nucleotide causes the genetic code to produce a different amino acid), Nonsense mutation (Change in nucleotide causes it to code for a stop codon and terminating the entire chain of amino acids). Frameshift Mutations (Changes the entirety of the nucleotide ordering after the site of mutation): Insertion (Extra base pairs added to DNA), Deletion (nucleotides in a region of DNA are lost), Substitution (Switch one base pair for another).
Why can DNA mutations benefit, disadvantage, or have no effect on protein and phenotype of an organism?
DNA mutations can benefit organisms by producing a phenotype that gives them an evolutionary advantage, while a disadvantage (more often) can negatively affect an organism’s normal function and functionality, causing disease, death, or an unfavorable phenotype. Mutations can also neither benefit nor disadvantage. They are silent mutations and don’t affect the protein being produced.
What causes random DNA mutations and how do they affect genetic variation?
Errors in DNA replication or repair and external factors like radiation, reactive chemicals, or infectious agents. The organisms that live with mutations in their DNA bring genetic variety to their species. They can be beneficial to the organism and, in turn, the species or disadvantageous to the organism.
What can an error in mitosis or meiosis result in?
An error in mitosis/meiosis can result in a change in chromosome number. Usually, new phenotypes and human disorders are caused as a result (remember nondisjunction). One example is a mutation occurring in the kinetochore genes, inhibiting normal behavior and resulting in an unequal amount of chromosomes in the gametes of the organism.
How does natural selection relate to genetic changes?
If a genetic change is to the organism’s benefit in the specific environmental conditions it is in, it will have greater survival and reproduction rate than the other organisms (in its species). When reproduction occurs, the genetic variation will continue in the offspring.
What occurs if viruses infect the same host cell?
Recombinant phages with DNA that underwent reassortment in the host cell. This can cause new viruses or “strains of viruses” such as Covid-19’s strains.
Explain transformation and how it increases variation
A bacteria cell takes up DNA externally. If the DNA is in the form of a plasmid it will be passed onto the offspring (the DNA will be copied).
Explain transduction and how it increases variation
Bacteriophages move chromosomal DNA from two different locations. This is by transferring host cell DNA when being created. This ultimately creates greater genetic variety among viruses and, in turn, spreads their various genetic information to other cells.
Explain conjugation and how it increases variation
DNA is transferred from one bacteria cell to another by the first cell extending a structure (pilus) and transferring a plasmid to the other bacteria cell. The reason why the first cell can extend a pilus and transfer its DNA is due to it having a site for the DNA transfer to occur as well as DNA which codes for proteins of the pilus. This adds further genetic variation to bacteria cells due to the cell-cell transfer of genetic information.
Explain transposition and how it increases variation
Transposable elements (DNA regions that insert themselves or copies of themselves in other regions) will move from the chromosome to the plasmid and, from there, pass onto other bacteria or offspring. Transposition allows specific genes to spread through an entire population, creating greater genetic variation among the population.
