7.7 Common Ancestry

01Shared features across life

All living things share DNA/RNA as genetic material, the same genetic code, ribosomes, ATP, and core pathways like glycolysis. That universality points to a single common ancestor (LUCA).

Eukaryotes share additional features: membrane-bound organelles, linear chromosomes, introns, cytoskeleton.

02Notebook box

Universal features → common ancestor of all life. Eukaryote-only features → common ancestor of eukaryotes.

Worked example: Why can a human gene work in yeast? → Shared eukaryotic machinery from common ancestry.

Key takeaways

✦Universal code and ribosomes = common ancestry.
✦Glycolysis is ancient.
✦Eukaryotes share organelles and introns.

Watch outProkaryotes lack introns and a nucleus — don't list those as universal.

Quick check

Did it stick?

1.Which is evidence of common ancestry of all life?

2.Glycolysis being in nearly every organism suggests it…

3.A feature shared by eukaryotes but not prokaryotes: