mutations Flashcards
(22 cards)
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.
too few sex chromosomes
This is the case where only one sex chromosome is inherited. this can be caused by the y chromosome not having sufficient genes to support life leaving the x chromosome
some features of turner syndrome (having only the x chromosome)
–Short stature.
–Broad chest.
–Poor breast development.
–Increased weight/obesity.
too many sex chromosomes
individuals inherit more than two sex chromosomes. It results from non-disjunction of the sex chromosomes.
Klinefelter syndrome
where a male inherits two X chromosomes in addition to his Y chromosome. A Y-carrying sperm could fertilise an egg carrying two X chromosomes giving rise to Klinefelter. Possible characteristics include lanky youthful build and facial appearance.
allele
alternative form of a gene
homozygous
(GG) same alleles or genes for a particular gene
heterozygous
(Gg) different alleles or genes
