Chapter 15 - Gene Mutations Flashcards
What term refers to a heritable change in the genetic material?
Mutation
What is the positive side of Allelic variations provided by mutations?
They are the foundation for evolutionary change and necessary for a species to adapt to changes in the environment
What is the negative side of Allelic variations provided by mutations?
New mutations are more likely to be harmful that beneficial and are often the cause of diseases
What is a point mutation?
A change in a single base pair
What is the change of a pyrimidine (C, T) to another pyrimidine or a purine (A, G) to another purine called?
Transition
What is the change of a pyrimidine (C, T) to a purine (A, G) or vice versa called?
Transversion
Which is more common? A Transversion or a Transition?
A Transition
What else can mutations involve?
Deletion or Addition
What type of mutation is a base substitution that does not alter the amino acid sequence of the polypeptide? (AGT to AGC = both code for serine)
Silent Mutation
What type of mutation is a base substitution in which an amino acid change does occur? (GAG to GTG = Glutamic Acid to Valine)
Missense Mutation
What type of mutation is Sickle-Cell Anemia?
Missense Mutation
What type of mutation is a base substitutions that change a normal codon to a stop codon?
Nonsense Mutation
What type of mutation involves the addition or deletion of a number of nucleotides that is not divisible by three?
Frameshift Mutation
Where can mutations change levels of gene expression?
In the Core Promoter
What type of mutation increases expression?
Up mutations
What type of mutation decreases expression?
Down mutations
What is the possible effect of a mutation on the Promoter?
It may increase or decrease the rate of transcription
What is the possible effect of a mutation on the Regulatory Element/Operator Site?
It may disrupt the ability of the gene to be properly regulated
What is the possible effect of a mutation on the 5’-UTR/3’-UTR?
It may alter the ability of mRNA to be translated; may alter mRNA stability
What is the possible effect of a mutation on the Splice Recognition Sequence?
It may alter the ability of pre-mRNA to be properly spliced
What is the relatively prevalent genotype called in a natural population?
The wild-type genotype
What type of mutation changes a wild-type genotype into some new variation?
A Forward Mutation
What type of mutation changes a mutant allele back to the wild-type genotype?
A Reverse Mutation (reversion)
What type of mutation decreases the chance of survival?
Deleterious Mutations
What is the most extreme Deleterious Mutation?
Lethal Mutations
What type of mutation enhances the survival or reproductive success of an organism?
Beneficial Mutations
What can affect the whether a given mutation is deleterious or beneficial?
The environment
What is it called when mutations affect the phenotype only under a defined set of conditions? (Ex. Temperature-Sensitive mutation)
Conditional Mutations
What is a second-site mutation that can counteract the effects of a first mutation?
Suppressor Mutation or Suppressors
What is a second mutant site within the same gene as the first mutation?
Intragenic Supressor
What is a second mutant site in a different gene from the first mutation?
Intergenic Suppressor
What are the two types of Animal Cell classifications?
Germ-line cells and Somatic Cells
What type of cells that give rise to gametes such as eggs and sperm?
Germ-line Cells
What type of cells are all other cells?
Somatic Cells
What type of mutations occur directly in a sperm or egg cell, or in one of their precursor cells?
Germ-line Mutations
What type of mutations occur directly in a body cell, or one of its precursor cells?
Somatic Mutations
What type of mutations result form abnormalities in cellular/biological processes?
Spontaneous Mutations
What type of mutations are caused by environmental agents?
Induced Mutations
What are the agents known to alter DNA structure?
Mutagens
What is the abnormal crossing over that may cause deletions, duplications, translocations, and inversions called?
Aberrant Recombination (Spontaneous)
What is the abnormal chromosomal segregation that may cause aneuploidy or polyploidy?
Aberrant Segregation (Spontaneous)
What is a mistake by DNA polymerase that may cause a point mutation?
Errors in DNA Replication (Spontaneous)
What are elements that can insert themselves into the sequence of a gene?
Transposable Elements (Spontaneous)
What is the linkage between purines (Adenine and Guanine) and deoxyribose that can spontaneously break? If not repaired, this can lead to mutation.
Depurination (Spontaneous)
What is it called when Cytosine and 5-methylcytosine can spontaneously deaminate to create uracil or thymine?
Deamination (Spontaneous)
What is a spontaneous change in base structure that can cause mutations if they occur immediately prior to DNA replication?
Tautomeric Shifts (Spontaneous)
What are the products of normal metabolic processes, such as reactive oxygen species, it may be chemically reactive agents that can alter the structure of DNA?
Toxic Metabolic Products (Spontaneous)
What are chemical substances that may cause changes in the structure of DNA?
Chemical Agents (Induced)
What are physical phenomena such as UV light and X-rays that can damage the DNA?
Physical Agents (Induced)
What is the likelihood that a gene will be altered by a new mutation?
Mutation Rate
What is the range of a mutation rate
10^(-5) to 10^(-6) per generation
What are the three types of spontaneous mutations that can arise by three types of chemical changes?
- Depurination
- Deamination
- Tautomeric Shift
What is the term for a covalent bond between deoxyribose and a purine base that undergoes a spontaneous reaction with water that releases the base from the sugar?
Apurinic Site
What type of bases tend to create hot spots for mutation in Deamination?
Methylated Cytosine Bases
What is the common, stable form of thymine and guanine?
The Keto form
What is the form that thymine and guanine can interconvert into at a low rate?
The Enol form
What is the common, stable form of adenine and cytosine?
The Amino form
When must a mutation occur for a tautomeric shift to be the cause?
Prior to DNA replication
What is an unusual form of mutation that causes several human genetic diseases called?
Trinucleotide Repeat Expansion (TNRE)
