8.1 Mutations Flashcards
What is a point/gene mutation?
change in DNA base sequence
changes the amino acid sequence
changes primary structure
changes tertiary structure
changes the function
When does a point mutation occur?
during DNA replication in interphase
What increases the chance of mutations?
mutagens
Why are mutations a good thing?
important for an organism to live through natural selection
the population can evolve
What is a chromosome mutation?
a change in the number of chromosomes - extra/less
When does a chromosome mutation occur?
during meiosis in anaphase 1 or 2
What are all the different types of point mutations?
substitution
insertion
deletion
duplication
inversion
transloaction
What is substitution mutation?
only 1 amino acid is changed in the sequence
Why does a substitution reaction have little effect?
degenerate code - can code for the same amino acid so its a silent mutation
What is insertion mutation?
adding an extra base to the sequence
What is a frameshift?
every codon downstream of the mutation will change so potentially every amino acid downstream of the mutation will change
What is deletion mutation?
removal of a base
What is duplication mutation?
the base that came before is copied and inserted
What is inversion mutation?
a group of bases becomes separated from the DNA and rejoin in reverse order
What is translocation mutation?
bases are separated from DNA sequence and one chromosome is inserted in a different chromosome
What 3 types of mutation cause a frameshift?
insertion
deletion
duplication
What are the 2 results from chromosome mutations?
polysomy or polyploidy
What does polysomy mean?
occurs when 1 homo pairs fail to separate in the process of non-disjunction = 22 pairs
there is an extra chromosome
What does polyploidy mean?
all homo pairs have failed to seperate and end up in the gametes so there is more than 2 sets of chromosomes
What does non-disjunction result in?
the gamete has one more or one less chromosome
When does a whole change in a set of chromosomes occur?
when an organism has 3 or more sets of chromosomes rather than 2
What is hybridisation?
the combining of genes of different varieties or species of organism to produce a hybrid
What is triploid?
3 sets of chromosomes
What causes down-syndrome?
a tripsomy 21 gamete
What is monosomy?
1 set of chromosomes
When does production of gametes occur in a female?
when a featusn and continues each month
What type of female gamete is most likely to experience non-disjunction?
older gametes
What are mutagens?
any outside factor that increases the rate of mutation
What are carcinogens?
mutagens that cause cancer
What are examples of physical mutagens?
ionisinf radiation
x-rays
alpha and beta particles
How do physical mutagens work?
breaks the polypeptide chain in DNA
What are examples of biological mutagens?
viruses
benzopyrene in tobacco smoke
How does a virus work as a mutagen?
injects viral material and disrupts DNA bases
