3.8.1 DNA Mutations (C20) Flashcards
Mutations are
changes to the base sequence of DNA
Mutations occur through errors during..
DNA replication
mutation rate can be increased by
mutagenic agents
Types of mutations that can occur include:
- substitution
- deletion/addition
- duplication
- inversion
- translocation
substitution mutation is when…
one or more bases are swapped for another
Effect of substitution mutations can be..
- no effect (silent - if same AA coded for)
2. change triplet code - different AA coded for
deletion mutations is when
a one or more bases are removed
Effect of a deletion mutation…
frameshift to the left - changes the entire triplet code from that point on - changes amino acid sequence
Addition mutations are when
one or more bases are added
Effect of an addition mutation…
frame shift to the right - changes the triplet code from that point on - changes the amino acid sequence
An inversion mutation is when..
a sequence of bases is reversed
A duplication mutation is when…
one or more bases are duplicated/repeated
A translocation mutation is when..
a sequence of bases is moved from one location to another (could be in the same chromosome or different)
What is significant about the order of the bases in DNA?
determine the order of the amino acids in the protein
chains of amino acids make
polypeptides
A change in the amino acid sequence of a protein means…
it may not fold properly, altering its tertiary structure - rendering it non-functional.
genetic mutations can cause certain disorders e.g.
cystic fibrosis, cancers
Why do not all mutations affect the order of the amino acids?
degenerative nature of genetic code - some AA coded for by more than 1 triplet code
examples of mutagenic agents include
UV radiation, ionising radiation, chemicals, some viruses
mutations that occur in cells post fertilisation are called..
acquired mutations
Name 2 genes that control cell division
proto-oncogenes and tumour suppressor genes
Mutations in genes that control cell division can lead to …
uncontrolled cell growth - tumour formation
Define a tumour..
a mass of abnormal cells that divides out of control
Cancer is…
a tumour that invades and destroys surrounding tissue and made spread to other parts of the body
Why is the genetic code described as being universal?
The triplet codes code for the same amino acids in all organisms
