📖 Notes
LESSON 05 OF 17
Every High-Yield Cell Topic
Every High-Yield Cell Topic
Mitochondria, ribosomes, the fluid mosaic model, osmosis, and the lysosomal storage diseases that show up again and again in past papers.
High-Yield Overview
Four Topics That Repeat Every Year
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Mitochondria
Double membrane, cristae inside, own DNA, and the site of the Krebs cycle + oxidative phosphorylation.
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Ribosomes
80S in eukaryotes (40S+60S) vs 70S in prokaryotes (30S+50S) — protein synthesis machinery.
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Lysosomal Diseases
Tay-Sachs (hexosaminidase A deficiency) and Gaucher (glucocerebrosidase deficiency) — classic recall pairs.
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Osmosis
Hypotonic swells/bursts a cell (lysis); hypertonic shrinks it (plasmolysis in plant cells).
Mitochondria & Ribosomes
- Mitochondria: double membrane, inner folds called cristae, site of the Krebs cycle + oxidative phosphorylation, has its own DNA
- Ribosomes: 80S in eukaryotes (40S + 60S subunits), 70S in prokaryotes (30S + 50S subunits) — the site of protein synthesis
Lysosomal Storage Diseases
- Tay-Sachs disease: hexosaminidase A deficiency
- Gaucher disease: glucocerebrosidase deficiency
Fluid Mosaic Model
- Phospholipid bilayer forms the membrane's core structure
- Integral and peripheral proteins are embedded within/on the membrane
- Glycoproteins on the surface handle cell recognition
Osmosis
Osmosis Outcomes
REFERENCEHypotonic solution → cell swells → may burst (lysis) Hypertonic solution → cell shrinks (plasmolysis in plants)
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Exam tip
Lysosomal storage diseases are a favourite MDCAT past-paper topic precisely because they connect an organelle (lysosome) to a named disease and its missing enzyme — expect a direct recall question.