Chapter 13: Altering the Genetic Material: Mutation, DNA Repair, and Cancer Flashcards
Define mutation.
13.1
a heritable change in the genetic material
T or F: New mutations are much more likely to be harmful than beneficial to the individual.
13.1
true
What are the two basic types of change that gene mutations can cause?
13.1
1) the base sequence within a gene can be changed
2) one or more base pairs can be added to or removed from a gene
What type of mutation is this?
A wild-type DNA sequence is 5’ -ACACGTTGAT- 3’.
It is converted to 5’ -ACACGTTAAT - 3’.
13.1
point mutation/base substitution; where G is replaced with A
Where must a mutation occur if its is to directly affect an amino acid sequence?
13.1
the coding region of a protein-encoding gene
There are 4 different types of effects that point mutations have on polypeptides. Name each one and briefly describe them.
BONUS: DRAW IT!
13.1
- Silent (causes no change)
- Missense (changes one amino acid in the polypeptide)
- Nonsense (changes a normal codon to a stop codon and shortens the polypeptide)
- Frameshift (produces a different amino acid sequence)
A point mutation affects only a single ____ pair within the DNA.
13.1
base
____ and ________ mutations can cause more dramatic changes to a polypeptide sequence than ________ mutations.
13.1
nonsense and frameshift; missense
T or F: Mutations within noncoding sequences can affect gene expression.
13.1
true
What effects do the following sequences have on mutation?
Promoter, transcriptionl regulatory element, splice sites, translational regulatory element, and intergenic region.
13.1
Promoter: increase or decrease the rate of transcription
Transcriptional RE: alter the regulation of transcription
Splice sites: alter ability of pre-mRNA to be properly spliced
Translational RE: alter the ability of mRNA to be translationally regulated
Intergenic region: not as likely to affect gene expression
Define a germ-line mutation.
13.1
a mutation that occurs in a germ-line cell, which gives rise to gametes; can be passed from parent to offspring
Consider a germ-line mutation that occurs in a sperm which fertilizes a normal egg to produce a zygote. In the individual that results from this zygote ____% of the cells will contain the mutation, and ____ % of the gametes produced by that individual will carry the mutation.
13.1
100; 50
T or F: A somatic mutation is transmitted to the offspring of the individual that carries it.
13.1
false; it is NOT
germ-line mutations ARE passed from parent to offspring
T or F: Germ-line mutations affect the whole organism, while somatic mutations affect a limited area of the body.
13.1
true
Bacterial colonies can be transferred from a master plate to secondary plates in the same configuration using a transferring agent such as a sterile velevet cloth. What is this technique know as?
13.2
replica plating
Which two scientists are responsible for using replica plating to show that mutations are random events?
13.2
Joshua and Esther Lederberg
The results of the replica plating experiment performed by the Lederbergs supported their hypothesis that mutations are random events by demonstrating what?
13.2
The T1 mutation developed in the original population before exposure to bateriophages.
What type of mutation results from abnormalities that naturally occur during biological processes?
13.2
spontaneous mutations
Define induced mutations.
13.2
Mutations that are caused by environmental agents that enter the cell and alter the structure of DNA.
The technique of replica plating allows for the:
13.2
identification of transformed cells
How do the effects of germ-line mutations in a parent progress over the lifetime of an offspring receiving that mutation?
13.2
All of the cells of the individual’s body, but only half of the gametes produced by that individual will carry the mutation.
What are two types of physical mutagens?
13.2
X-rays and UV light
What are the three outcomes that are caused by chemical mutagens?
13.2
1) covalent modification (ex: nitrous acid deaminates bases)
2) base analogues (ex: 5-Bromouracil and 2-Aminopurine)
3) distortion of the DNA double helix (ex: benzo[a]pyrene
Define ioning and nonionizing radiation.
13.2
Ioning: Radiation that is short-wavelength and high energy, and often leads to base deletions and breaks in one or both DNA strands
Nonionizing: Radiation that has a longer wavelength and lower energy, which penetrates the skin and often leads to thymine dimers
