Processes

Mitosis

Process of nuclear division producing genetically identical daughter cells

Prophase chromosomes condense and spindle forms

Prometaphase nuclear envelope breaks down and kinetochores attach

Metaphase chromosomes align at equator

Anaphase sister chromatids separate

Telophase nuclei reform

Cytokinesis divides cytoplasm

DNA Packaging

DNA wraps around histones forming nucleosomes, Nucleosomes coil into chromatin fibres, Chromatin condenses into chromosomes during mitosis

Protein Secretion Pathway

Ribosome synthesises protein on rough ER, Protein folded and modified in ER lumen, Transport vesicles move proteins to Golgi, Golgi modifies and sorts proteins, Secretory vesicles fuse with membrane releasing proteins by exocytosis

Vesicle Transport

Vesicles bud from membranes carrying cargo, Motor proteins move vesicles along microtubules using ATP, Vesicles dock and fuse with target membranes releasing contents

Endocytosis and Exocytosis

Endocytosis imports materials using vesicles, Includes phagocytosis, pinocytosis and receptor-mediated endocytosis, Exocytosis releases materials when vesicles fuse with plasma membrane

Membrane Transport

Simple diffusion moves molecules down concentration gradient without proteins, Facilitated diffusion uses channel or carrier proteins, Active transport uses ATP to move substances against gradient, Osmosis is water diffusion across selectively permeable membrane

Aquaporin Function

Aquaporins are selective water channels, Allow rapid osmosis across membranes, Positive amino acids repel ions so only water passes

Enzyme Catalysis

Substrate binds active site forming enzyme-substrate complex, Induced fit improves binding, Enzymes lower activation energy by orienting substrates, straining bonds and providing favourable microenvironment, Products released and enzyme reused

Enzyme Regulation

Competitive inhibitors bind active site, Non-competitive inhibitors bind allosteric site changing active site shape, Allosteric regulators activate or inhibit enzymes, Feedback inhibition occurs when end product shuts down pathway

Glycolysis

Occurs in cytosol, Glucose converted to 2 pyruvate, 2 ATP net and 2 NADH, Includes energy investment phase using ATP and payoff phase producing ATP by substrate-level phosphorylation

Link Reaction

Pyruvate enters mitochondrial matrix, Pyruvate oxidised releasing CO2, NAD+ reduced to NADH, Acetate joins coenzyme A forming acetyl-CoA

Krebs Cycle

Occurs in mitochondrial matrix, Acetyl-CoA combines with oxaloacetate forming citrate, Redox reactions release CO2 and produce 3 NADH, 1 FADH2 and 1 ATP per turn, Oxaloacetate regenerated

Electron Transport Chain

Occurs on inner mitochondrial membrane, NADH and FADH2 donate electrons to protein complexes, Energy released pumps H+ into intermembrane space, Oxygen accepts electrons forming water

Chemiosmosis

Proton gradient drives H+ through ATP synthase, ATP synthase changes shape as protons flow through, ADP and Pi combine to form ATP

Oxidative Phosphorylation

ATP production powered by ETC and chemiosmosis, Electron transfer creates proton gradient, Chemiosmosis through ATP synthase generates ATP, Oxygen acts as final electron acceptor

Fermentation

Occurs without oxygen, Regenerates NAD+ allowing glycolysis to continue, Lactic acid fermentation forms lactate, Alcohol fermentation forms ethanol and CO2

Beta-Oxidation

Fatty acids broken into 2-carbon acetyl-CoA units in mitochondrial matrix, Acetyl-CoA enters Krebs cycle, NADH and FADH2 generated for ATP production

Photosynthesis Overview

Light-dependent reactions occur in thylakoid membranes producing ATP and NADPH, Water split releasing oxygen, Calvin cycle occurs in stroma fixing CO2 into sugars