chapter 18 Flashcards
what is mutation
inherited change in the dna sequence
who can inherit the mutation
cells or organisms
what is the cause of all genetic variation, disease and disorder
mutation
what is a somatic mutation
mutation in somatic tissue
does not produce gametes
what is germline mutation
mutations in cells that produce gametes, can be passed to future generations
what is gene mutation
mutation that affects a single gene
how is a gene mutation observed
through phenotypic affects
what is a chromosome mutation
mutation that affect the number or structure of chromosomes
Can be observed directly
Define base substitution (fig 18.2a)
Alteration of a single nucleotide in the DNA
- thymine can be inserted for a guanine
what is a transition base mutation
purine is replaced by a different purine or a pyramidine is replaced by a different pyrimidine
what is transversion
purine replaced by pyramidine or vice versa
Define insertions and deletions and state what type of mutation these cause
Insertions and deletions: addition or removal of one or more nucleotide pairs
Insertions and deletions can lead to framshift mutations
what is a frameshift mutation
changes in the reading frame of the gene,
what happens to the amino acids after frameshift mutation
usually alter all amino acids encoded by nucleotides after the mutation
what is a frame insertion or deletion
change to a genes reading frame
Define expanding nucleotide repeats
Mutations in which the number of copies of a set or nucleotides increases
what can expanding nucleotide repeats caus
- ALS
Explain how strand slippage can cause the expansion of nucleotide repeats
Misalignment of the sequences or stalling of replication through hairpin formation
Explain how expanding nucleotide repeats correspond to anticipation
Diseases caused by expanding nucleotide repeats become more severe in each generation
what is anticipation
symptoms of a genetic disorder become more severe
what is the diffrence between normal and mutant sequeince
normal: mutant cell dies and is replaced by a normal cell
mutant cell: DNA sequence producers new phenotypes
what are the three effect of a base substitution
- missense mutation
- nonsense mutation
3.silent mutation
what is a missense mutation
base substitution that results in a different amino acid in the protein
what is a nonsense mutation
changes a sense codon( one that specicifes an amino acid) intoa nonsense codon( one that terminates translation)
what is a sense codon
specifies an amino acid
what is nonsense codon
codon that terminates translation
what is a silent mutation
change of the dna within a protein coding portion does not affect the sequence of amino acids that make up the protein
what is a codon
sequence of 3 nucleotides that codes for a specific amino acid
what is forward mutation
alters the wild tupe phenotype
what is reverse mutation
changes a mutant phenotype into wild type
what is neutral mutation
-missense mutation changes the amino acid sequence but not the function
what is loss of function
cause the complete or partial absence of normal protein.
Alters the structure of the protein and it no longer works correctly
what is gain of funciton mutation
causes the cell to produce a protein or gene product whose function is not normally present
what is conditional mutation
mutations expressed only under certain conditions
example: conditional mutations affect the phenotype at elevated temps
what is lethal mutation
mutations that cause premature death
what is suppressor mutation
genetic change that hides or suprpresses the effect of another mutation
where does a suppressor mutation occur
at a site distinct from the site of the original mutation
what is intragenic suppressor
take place in the same gene that contains the mutation being suppressed
what is intergenic suppressor mutation
occurs in a gene other than the one bearing the original mutation it suppresses
what does INTERgenic mutation affect
the way mRNA is translated
Differentiate between spontaneous and induced mutations
Understand how strand slippage causes insertions/ deletions and nucleotide repeat expansion
Understand how unequal crossing causes insertions and deletions
Understand how depurinatin can cause base substittions
Understand how base analogs can cause mispairings during replication
Understand how intercalating agents result in frameshift mutations and know that ethidium bromide is a type of intercalating agent
Name 2 types of radiation and briefly explain the types of mutations they cause
what can transposons do
they can cause gene mutations and chromosome arragements
what are transpososn
jumping genes
what is direct repair
altered bases get repaired directly
Explain how genetic disease associated with defective repair pathways can increase the incidence of cancer
