mutations Flashcards
what is a mutation
change in the DNA base sequence. it happens when DNA is duplicated, and is a spontaneous and permanent change that can cause illness, allergic reactions or even death. can be beneficial or harmful.
what factors will cause mutation
- Harmful radiation- UV; X-Rays; Gamma Rays.
- Carcinogens – chemicals that can cause cancer; e.g. formaldehyde; dioxin; mustard gas; sulfur dioxide, etc…
*these factors may not directly cause mutations, but can increase a risk of mutations
substitution
when a nitrogenous base (nucleic acid is swapped with another).
deletion
when a nitrogenous base is removed from the original sequence.
insertion
when a nitrogenous base is added to the original sequence.
explain gene mutations
only one amino acid will be affected but it will change which protein/amino acid is formed. protein will not be useful anymore - problem and can be fatal. it will change the placement as ribosome reads 3 bases at a time. all the rest of the amino acids or codons will be affected.
deletion
the loss of a chromosome
duplication
section of a chromosome occurs twice.
inversion
a section of a chromosome breaks off and joins back in but in the wrong order.
translocation
a part of a chromosome breaks off and joins to another chromosome.
what is karyotyping used to determine
–Gender of organism
–Presence of disease/condition
–Species type.
karyotyping
classification of chromosomes in an organism according to structure/appearance (the picture of all the chromosomes)
non-disjunction
This is the case when chromosomes do not separate correctly during cell division
too many autosomes
Sometimes people are born with 45 autosomes because the mother could’ve had a mutation and produced a zygote with 47 chromosomes
down syndrome
During meiosis, in the reduction division the two homologous chromosomes (21) do not separate.
