Chapter 8 Flashcards
(41 cards)
Can transposons cause mutations?
- they can be used to generate mutations by being inserted into cell’s genome
- inactivated the gene in which it inserts
What are Transposons?
- “jumping genes”
- can move from one location to another within DNA of same cell
- considered Horizontal gene transfer
What is a horizontal gene transfer?
The transfer of a gene from one organism to another
Examples of horizontal gene transfer:
- Transformation
- Transduction
- Conjugation
- Transposons
What is vertical gene transfer?
Transfer of genes from parent to offspring
What is an Auxotroph?
Mutant that requires growth factor
What is a Prototroph?
Mutant that doesn’t require growth factor.
What is a Wild Type?
Orriginal, non-mutated
If a gene can only grow if tryptophan is present, than the mutant would be a(n) ________ and would be designated by _____.
Autotroph, Trp-
How do you designate a gene that is sensitive?
s
Str
What is reversion?
When a mutant changes back to its original state
What are spontaneous mutations?
Mutations that occur naturally within a cell
Large populations usually contain mutants
What effect does the environment have on spontaneous mutations?
- the environment selects for cells that are able to grow well in its conditions
- if the mutated cell survives better it will outlive the other wild type cells.
What is a knockout mutation?
Mutation that inactivated gene
Why do base substitutions survive better in aerobic conditions?
They can oxidize nucleobase guanine
Deletion & Addition of nucleotides commonly causes ______.
Frame shift mutation
What is a mutagen?
What are the 2 types?
Agent that induces change.
- Chemical
- Radiation
What 2 types of chemical agents cause base substitutions?
- Nitrous Acid- converts cytosine to uracil
2. Alkylating agent- adds alky to nucleobases
What chemical agent causes frame shift mutation?
Enthidium bromide- inserts between base pairs
What are 2 types of Radiation mutagens?
- Ultraviolet irradiation
2. X-Rays
Why is ultraviolet irradiation considered a mutagen?
- Forms covalent bonds between thymines
- distorts the molecule
- mutation results from SOS repair mechanism
Why are X-Rays considered mutagens?
-causes double strand to break & produce lethal deletions
If a gene can only grow if Tryptophan is present, than the wild type would be a(n) ________, and be designated by _____.
Prototroph, Trp+
Because it can synthesize tryptophan on its own
What is proofreading?
- DNA Polymerase repairs errors in DNA to prevent mutations
- VERY efficient but not flawless
