Chapter 9: Mutations Flashcards
What is a mutation?
A change in gene or chromosome
Where can errors occur which produce a mutation in a gene or chromosome?
DNA replication, cell division or damage from mutagens
How can errors in DNA replication cause a mutation?
Spontaneous mutations can occur during the non-dividing synthesis phase of a celll cycle when unwound DNA is vulnerable.
What are the two errors in DNA replication that cause a mutation called?
Point and Frameshift
How does a mutation occur from the point in DNA replication?
A point mutation is an error just affecting a single nucleotide. A substitution mutation is a point mutation
What is a substitution mutation?
Where one nucleotide is replaced by another. This can have big effects or non-effects depending on the codon and polypeptide
How can point mutations be avoided?
Before replication, DNA is proofread and any mistakes corrected, if they are not corrected they will continue to replicate in the following cells
How does mutation occur from frameshift?
The deletion or addition of one or more nucleotides. These can be referred to as indel. refer to pg 175 figure 9.1.3
What is an indel?
A collective term for mutations caused by insertion or deletion and the effect is a frameshift mutation
What are the causes of mutations from mutagen damage?
Physical, UV radiation, ionising radiation, heat and chemical
How does mutation occur from cell division (non-disjunction)
It occurs during meiosis l where chromosomes fail to separate causing the daughter cells to have abnormal amounts of chromosomes. Or it can occur during meiosis ll which results in (2n + 1 and 2n - 1)
What is trisomy?
A cell with 3 chromosomes (3n)
What is monosomy?
A cell with 1 chromosome (1n)
What type of aneuploidy is Down syndrome?
trisomy 21 ( needs more work on this dot point) page 184
