Mutations Flashcards
What is a mutation
It is a change in the genetic information of a cell (alternation to the sequence of nitrogenous bases)
they are the cause of biodiversity but can also lead to sickness
What are mutations in somatic cells
Somatic cells do not give rise to eggs or sperm so their mutations cannot be passed to an offspring
What are mutations in germ cells
Germ cells become eggs or sperm, so their mutations can be passed to an offspring
What are point mutations
changes in one nucleotide pair
What is the affect of point mutations
it can lead to the production of an abnormal protein (not always)
What are mutations caused by
Spontaneous errors (mistakes in DNA replication)
Mutagens (high energy radition)
What are chromosomal Mutations
they are when a large segment of DNA is moved, inverted, deleted, or duplicated
What are Base Substitutions
they involve the replacement of one nucleotide with another
What are the types of base substitutions
Missense
Nonsense
Silent
What are silent mutations
they have no effect on the amino acid produced by a codon because of redundancy in genetic code
(TTG–>TTA: still encodes Leucine)
What are Missense mutations
They code for a different amino acid which may affect the function of a protein
(AAA–>GAA: codes for Glutamic acid instead of lysine)
usually reduces the function
What is nonsense mutations
an amino acid codon is changed into a stop codon
always leads to nonfunctional protein
What are Insertions/Deletion mutations
insert or delete a nucleotide
What are the affects of insertions/deletions
- alter the reading frame of mRNA so the nucleotides are grouped into different codons (frame shift)
-changes many amino acids downstream of the mutation
-produces a nonfunctional polypeptide
