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MDCAT Prep · Biology · Quick Reference

Lesson 6 — Genetics Cheat Sheet

Biology
In one line: DNA is transcribed into mRNA in the nucleus, then translated into protein at 80S ribosomes, 3 bases at a time.

Key Ideas

1Central dogma. DNA → (transcription) → mRNA → (translation) → Protein.
2Transcription. In the nucleus by RNA polymerase; template read 3'→5', mRNA made 5'→3'; mRNA uses uracil not thymine.
3Translation. At 80S ribosomes; tRNA carries amino acids; codon = 3 bases = 1 amino acid.
4Mutations. Point = 1 base change. Frameshift = insertion/deletion shifting every codon after it.
5Sickle cell disease. GAG→GTG point mutation swaps Glu→Val in beta-globin; carriers gain malaria resistance.

Codon Quick Reference

Start codon
AUG (methionine)
Stop codons
UAA, UAG, UGA
RNA base replacing thymine
Uracil
Sickle cell mutation
GAG → GTG (Glu → Val)