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39 Cards in this Set
- Front
- Back
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Where do somatic mutations occur? |
In non-reproductive cells |
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What's the characteristics of somatic mutation? |
Not inherited, not passed on to offspring. Mutation passed by mitosis in body |
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Where does germ-line mutations occur? |
In reproductive cells |
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Whats the inheritance characteristics of germ-line cells? |
Mutation happens in cells that give rise to gametes. Passed on to half the populations by sexual reproduction, carrying all mutant cells Other half carry none. |
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What are the basic types of gene mutations? |
Base substitution Base insertion Base deletion |
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What's the genetic mutation in fragile-x syndrome? |
CGG sequence is copied to 50-1500 repeats instead of 6-54 in normal range. |
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What happens when there is more insertion repeats than less in genetic mutation? |
Earlier age of onset, More severe More chance of expanding to more repeats. |
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What's the characteristics of fragile-x syndrome? |
Fragile site in the long arm of x chromosome |
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What are the symptoms of fragile-x syndrome? |
Autism, intellectual disability |
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What's the genetic model behind insertion of repeated sequence? |
During replication, one strand slipped and form a hairpin, causing lengthening of that DNA and all the daughter DNAs following this. |
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What's transition and transversion? |
Transition: point mutation with purine to purine or pyrimidine to pyrimidine. Transversion: Purine to pyrimidine or pyrimidine to purine. |
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What are missense, nonsense and silent mutation? |
Missense: A point mutation causes shift from one codon to another. Nonsense: A point mutation that causes a shift to stop codon, translation stop prematurely Silent: A point mutation that doesn't cause any effect on amino acid encoding. |
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What are the names of three types of mutation in terms of change in function? |
Gain-of-function, Loss-of-function and neutral mutation |
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What's a forward, reverse and |
Forward: wild type to mutant phenotype Reverse: mutant to wild type Suppressor: mutation at a different site, causing two mutation genotypes, but restore the wildtype phenotype |
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Give examples of intragenic suppressor mutations? |
A suppressor mutation that acts on the same gene of the first mutation. An original deletion, suppressor insertion. An original insertion, suppressor deletion An original missense(substitution), suppressor substitube another base May restore the original amino acid |
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What's a suppressor mutation? |
A second mutation that covers the effect of a first mutation to reverse/restore the phenotype |
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What's an intergenic mutation? |
Occurs in another gene, different than the first mutation |
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Give and example of intergenic mutation? |
A nonsense mutation result in a premature stop codon. In another tRNA encoding gene, mutation in the anticodon provides the pairing, so translation continued. |
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What's a frameshift mutation? |
A mutation that results in a change in reading frame of a gene |
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What's expanding trinucleotide repeats? |
A mutation in which the number of repeated trinucleotide sequence is increased |
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What's gain-of-function mutation? |
The appearance of a new trait or function or the emergence of an inappropriate trait or function in an inappropriate time |
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What's loss-of-function mutation? |
The complete or partial loss of function. |
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What's a tautomer? |
Interconvertible constitutional isomer. |
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Draw the four bases and their rare tautomeric form. |
~ |
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What's the anomalous base pairing arrangements? Draw |
C(rare)-A (double bond) G(rare)-T (triple bond) |
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What's the nonstandard base pairing/ Wobble structure? Draw. |
~~ |
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What can the consequence of unequal crossing over be? |
One strand: insertion The other strand: deletion |
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What are the examples of a spontaneous chemical changes in genetic mutation? |
Depurination Deamination |
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What's the occurrence of depurination in a mammalian cell? |
Very common, 10,000 times per day per cell. |
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What's the consequence of apurination? |
Each time the apurinated strand is synthesized, a random, mostly likely A, inserted to the complement strand, causing mutation each time. |
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What's the examples of deamination? |
The loss of NH2 group from 5-methylcytosine to thymine or from cytosine to uracil |
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What's an example of a chemically inducted mutation? |
Using base analog, for eg. 5-bromouracil (Bu) interrupts DNA. |
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What is Bu analogous to? What are the pairings? |
To Thymine. Bu pairs with Adenine(top 2), and Guanine through wobble.(bottom 2) |
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What is the possibility of mutation for Bu interaction on the gene? |
Bu can imitate T which interacts A and possibly G wobble. When G wobble pairs, A to G transition mutation happens. |
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What are the examples of the alteration in bases with chemicals? |
Guanine: alkylation, bind to T (bottom 2 pairs) Cytosine: deamination, bind Adenine (top 2) Cytosine: hydroxylation, bind Adenine (top 2) |
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What are the actions of intercalating agents on DNA? |
Insert between base pairs, Result in insertions and deletions of replication |
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What are the examples of intercalating agents? |
Proflavin Acridine orange Ethidium bromide |
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How can uv light disrupt DNA structure? |
By forming pyrimidine dimers of covalent bonds under uv light. DNA is distorted (like a bump), replication blocked |
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How can we determine the carcinogenic effect of a chemical? |
Using the Ames Test. Bacteria requiring His (His-) cultured on two plates, with and without chemicals added Only mutant colonies grow More mutation on chemical plate, more harm it can do to DNA.
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