Chapter 9: Mutations Flashcards
What is an intraspecific variation?
Differences between characteristics or phenotypes of individuals of same species
What are mutations?
A change in a gene or chromosome relative to the original; may also refer to the process of generating change
What is a mutagen?
Any agent capable of inducing mutation
When can mutations occur?
They may arise spontaneously during the DNA replication part of the cell cycle, or during cell division
What can impact the rate at which mutations occur?
It can be increased by physical or chemical mutagens
What are spontaneous mutations?
Mutations occurring in the absence of exposure to mutagens
When can spontaneous mutations occur?
During the non-dividing S (synthesis) phase of the cell cycle, when the DNA is unwound for replication and is exposed and vulnerable to damage (refer to figure 9.1.2 pg 174 for example)
What is a point mutation?
A mutation that affects a single base-pair position within a gene
What are single nucleotide polymorphism (SNP)
A nucleotide difference that occurs at one given position in the gene
What is a substitution mutation?
A mutation in which a single nucleotide is swapped for another
What are indels?
A collective term for mutations caused by insertions and/or deletions
What is a frameshift mutation?
A mutation that dislocates the translational reading frame (refer to figure 9.1.3 pg 175 for diagram of frameshift)
What are some examples of physical mutagens?
Ionizing radiation, UV radiation, and heat
What is ionizing radiation?
Radiation that is strong enough to break chemical bonds in molecules, and removes tightly bound electrons from the orbits of individual atoms, causing atoms to become charged or ionized
How does UV radiation cause mutations?
It can affect the chemical structure of nitrogen bases, fusing adjacent thymine or cytosine bases in the DNA sequence
How do X-rays cause mutations?
They cause the deletion of adenine and guanine bases, creating gaps in the double helix. These aberrations disrupt complementary bases pairing during DNA replication
What are double-strand breaks?
A mutation involving breaks in both of the sugar-phosphate backbones at the same nucleotide pair, resulting in the complete breakage of a chromosome
What is apoptosis?
A programmed series of events lead to natural cell death when the internal contents of the cell are dismantled by various enzymes
What are some chemical mutagens?
Refer to table 9.1.2 pg 175
What is aneuploidy?
A genome variant having unconventional chromosome number due to loss or addition to one of or a small number of chromosomes
What is non-disjunction?
The failure of homologous partner chromosomes in meiotic cell division or sister chromatids in mitotic division to separate to opposite poles
What is trisomy?
When somatic cells contain three copies of a particular chromosome
What is monosomy?
When somatic cells contain only one copy of a particular chromosome pair
How does non-disjunction lead to aneuploidy?
If the homologous partner does not separate to opposite poles, there will then be an unconventional number of chromosomes in a genome (refer to figure 9.2.3 pg 179 for more info)
What causes down syndrome?
An extra chromosome 21 in each cell (trisomy 21) (refer to figure 9.2.3 pg 179 for colour stain of a female with down syndrome)
What does somatic mean?
A body cell that will not pass its genes onto nect generation
What is mitosis?
A type of nuclear division that produces daughter cells with the same chromosomal content as the parent cells; the basis for growth and repair in multicellular individuals, and for asexual reproduction in many eukaryotic species (refer to figure 9.3.1 pg 185 for diagram of mutations in mitosis)
What is a germ-line?
The cell line in eukaryotic organsims from which sex cells are produced
What does congenital mean?
Present at birth; may or may not be inherited congenitally
What impacts the variations in characteristics (phenotype) of individual species?
It is determined by the unque paired combinations of alleles in its coding genes (genotype) pg 193
