IBDP Biology 2025 SL&HL: D1.3 Mutations and gene editing Study Notes

Consequences of mutations (if any)

Consequences of base substitutions (if any)

Single-nucleotide polymorphism (SNP) do not always change an amino acid in the polypeptide

Some substitutions do not change any amino acid
“Silent mutation”

Some substitutions do change one amino acid
“Missense mutation”

Some substitutions do change the amino acids
“Nonsense mutation”

The three reading frames of mRNA

Some insertions do change the amino acids
“frameshift mutation”

Some insertions do change the amino acid(s)
“frameshift mutation” and “non-frameshift mutation”

Some insertions do change amino acids
“frameshift mutation”

“Somatic” refers to the body
“Germline” refers to gametes

All cancers = uncontrolled cell division due to gene mutation
Cancer cells continuously divide by mitosis
Tumour = mass of cancerous cells
Tumour keeps getting bigger
Cancerous cells induce development of new blood vessels around tumour
To get oxygen and nutrients transported in blood
– Healthy cells/tissues around tumour get less oxygen and nutrients
Some organs may malfunction…. fail
Metastasis = cancerous cells break away from malignant tumour

– Carried to other parts of body by bloodstream
Creation of new, secondary tumours
If not treated, cancer may cause death

Begnin tumours do NOT spread