OCR A-Level Biology Genetics Summary

Mutation
Change in the sequence of bases in DNA
:
.




Substitution
Swapping of bases to form
·

a new nucleotide
:

.




Deletion/insertion Frameshift
·
:
mutation

for
Degenerative Several different codons code the some amino acid
·
:




Effects of mutations No effect , damaging beneficial
:

,
-




Silent No notable effect
· :




Nonsense Creates stop codon - shortened protein
·

a
:




Missense Creation of the incorrect amino acid
· :




Amorph :

loss of protein function
Reduced protein function
Hypomorph
:




Increased protein function
Hypermorph
:




Mutagens Chemical physical or biological agent that causes mutation
:

,




Ionizing radiation
·



physical
:




Chemical
Deaminating agents
·
:




Biological Alkylating agents base analogs
·


viruses
:


, ,




Chromosome mutation Occur in meiosis
:


Normally
·
Deletion Section of :

the chromosome breaks off and is lost in the cel

·
Duplication :

Sections of the chromosome duplicate
·

Translocation :

Sections bream off and join a
non-homologous Chromosome
·
Inversion Section breaus off reverses and the chromosome
rejoins
:



, ,