D 1.3 Mutation and gene editing

Gene mutations

Permanent structural changes to DNA sequences.

Base sequence

Order of nucleotides in DNA.

Insertions

Adding extra nucleotides into DNA.

Deletions

Removing nucleotides from DNA.

Substitutions

Replacing one base with another in DNA.

Same-sense mutations

Codon changes that do not alter amino acids.

Nonsense mutations

Codon changes to stop codons, terminating translation.

Mis-sense mutations

Codon changes resulting in different amino acids.

Sickle cell anemia

Genetic disorder caused by mis-sense mutation.: base substitution mutation in hemoblogin gene. changes flexible red blood cells into rigid, sickle-shaped cells. glutamic acid (GAG) to valine (GTG)

Single nucleotide polymorphisms (SNPs)

Inherited mutations present in 1% or more of population.

Neutral mutations

Mutations with no significant effects on phenotype.

Deleterious mutations

Harmful mutations that can cause death.

Beneficial mutations

Rare mutations that provide advantages.

Frameshift mutations

Altered reading frame due to insertions or deletions.

Codons

Triplet sequences of nucleotides coding for amino acids.

Amino acid sequence

Order of amino acids in a polypeptide.

Mutagens

Agents that increase mutation frequency above background.

Random mutations

Unpredictable changes occurring in any gene.

Somatic Cell Mutations

Mutations in non-gamete body cells.

Consequences of Somatic Mutations

Limited to individual; not inherited.

deamination

cytosine bases are more likely to mutate to uracil

2 types of mutagens

chemical mutagens high energy radiation

effect of high radiation energy

break bonds in strands od dna, allowing nucleotide to be inserted or deleted