The 4 phases of mitosis in order — never get them backwards
Prophase, Metaphase, Anaphase, Telophase. Every cell division follows this sequence. "PMAT" — remember it like a doormat you wipe your feet on.
P
Prophase — chromatin condenses into chromosomes
M
Metaphase — chromosomes line up at the middle
A
Anaphase — chromosomes are pulled Apart to poles
T
Telophase — two new nuclei form, cell begins to divide
🧬 Cell Biology
"Mighty Mitochondria Make Energy"
Mitochondria Function
Mitochondria — the powerhouse of the cell
Mitochondria produce ATP through cellular respiration. They have their own DNA, their own ribosomes, and a double membrane — inner and outer.
🧬 Cell Biology
Plant cells have a WALL, CHL, and VAC
Plant vs Animal Cells
Three things plant cells have that animal cells don't
Cell Wall, Chloroplasts, and large central Vacuole. Animal cells have none of these. Everything else (nucleus, mitochondria, ER, Golgi) — both have.
🧬 Cell Biology
"Go Pack and Ship"
Golgi Apparatus Function
The Golgi apparatus — the cell's postal service
Golgi receives proteins from the ER, packages them, modifies them, and ships them to their destination. Cis face receives, trans face ships out.
🧬 Cell Biology
ATP = Energy Currency
ATP Function
ATP is the universal energy currency of all cells
Adenosine Triphosphate stores energy in its phosphate bonds. When broken (ATP → ADP + Pi), energy is released for cellular work. 36-38 ATP per glucose in aerobic respiration.
Smooth vs Rough ER
Smooth ER = lipids & detox. Rough ER = proteins (has ribosomes).
Smooth vs Rough ER
Two types of endoplasmic reticulum — never mix them up again
Rough ER: studded with ribosomes → makes proteins for export. Smooth ER: no ribosomes → makes lipids, steroids, and detoxifies drugs. Picture the rough one as bumpy with ribosomes, smooth as a clean highway.
Lysosomes
Lysosomes are the cell's stomach — digest waste, old organelles, and invaders
Lysosomes
The cell's cleanup crew — full of digestive enzymes
Lysosomes contain hydrolytic enzymes that break down proteins, lipids, carbohydrates, and nucleic acids. They digest worn-out organelles (autophagy), foreign invaders, and cellular debris. Low pH inside (~4.8) activates the enzymes.
Osmosis
Osmosis: water moves from LOW solute (HIGH water) to HIGH solute (LOW water)
Osmosis
Water always moves toward where there is MORE dissolved stuff
Imagine salt pulling water toward it. Hypertonic solution: more solute outside → cell shrinks (crenation in animals, plasmolysis in plants). Hypotonic: less solute outside → cell swells. Isotonic: equal → no net movement.
The complete cell cycle in order — from growth to division
Interphase (G1, S, G2): cell grows and DNA replicates. Prophase: chromosomes condense. Metaphase: chromosomes line up at the middle. Anaphase: chromosomes pulled Apart to opposite poles. Telophase: two nuclei form. Then cytokinesis splits the cell.
I
Interphase — growth and DNA replication
P
Prophase — chromosomes condense
M
Metaphase — line up in Middle
A
Anaphase — pulled Apart
T
Telophase — two nuclei form
Active vs Passive Transport
Active transport moves AGAINST the gradient — needs ATP. Passive = no energy needed.
Active vs Passive Transport
The key difference: does the cell have to spend energy?
Passive transport (diffusion, osmosis, facilitated diffusion): moves with the concentration gradient — downhill, no energy needed. Active transport (sodium-potassium pump, endocytosis): moves against the gradient — uphill, costs ATP. Think: active = effort = energy.
Nucleus and Gene Expression
Nucleus = control center. DNA → RNA here. Protein made at ribosomes.
Nucleus and Gene Expression
The nucleus runs the show — but proteins are made outside it
DNA stays in the nucleus. It's transcribed to mRNA, which exits through nuclear pores to ribosomes. Ribosomes translate mRNA into protein. Free ribosomes: proteins for inside the cell. Ribosomes on rough ER: proteins for export or membranes.
Prokaryote vs Eukaryote
Prokaryote vs Eukaryote: No nucleus vs Has nucleus. Bacteria are prokaryotes. Animals, plants, fungi are eukaryotes.
Prokaryote vs Eukaryote
The most fundamental division in all of biology
Prokaryotes: no membrane-bound nucleus, no membrane-bound organelles, smaller (1-10 µm), circular DNA. Bacteria and Archaea. Eukaryotes: true nucleus, membrane-bound organelles, larger (10-100 µm), linear DNA on chromosomes. All animals, plants, fungi, protists.