D1.3 Gene Editing and Mutations

Normal RBC v.s. Sickle RBC base substitution example

Normal RBC: CTC (DNA) —> GAG (mRNA) —> Glu (AA) —> a globular protein structure

Sickle RBC: CAC (DNA) —> GUG (mRNA) —> Val (AA) —> a fibrous protein structure

USE MNEMONIC

Describe frameshift mutations (insertions and deletions)

The triplets sequence changes, so the reading frame shifts, usually resulting in non-functioning proteins

State 2 Causes of Mutations

1. Mutagens

2. Error in DNA replication or repair

State examples of mutagens

Chemical mutagens

1. Mustard Gas

2. Nitrous Acid

3. Dioxin

Radiation mutagens

1. X ray

2. UV

3. Radioactive isotopes

Outline how gene mutation is random

• Can occur randomly anywhere on the genome

• Some bases are more prone to mutations

• Have no deliberate mechanisms for mutations

Distinguish somatic VS germ cells

Somatic Cells:

• All cells but germ cells

• Cause disease like cnacer

• Not passed on to offspring

Germ cells:

• Cells that give rise to gamates (egg and sperm)

• Lead to mutations in gamates too

• Passed on to offspring but has various effects

somatic cells are all cell but germ cells, germ cells are cells that give rise to gametes

mutation causes diseases during a lifetime in somatic cells, while fo rgerm cells it leads to mutation in the gametes

Describe overall imapct of mutation in species

• Leads to genetic variation

• Mostly harmful or neutral

• Beneficial ones: help survive and evolve in natural selection

Conserved sequences

Identical or similar DNA sequences across a species or group of species

Highly conserved sequences

Similar DNA sequences over long periods of evolution

3 hypotheses for highly conserved sequences

1. (Null hypothesis) it happened randomly

2. the gene’s proteins are fundamental to life that variations and mutations do not survive

3. There was a low mutation rate (low rate of transcription, translation, replication)