ThatBioTutor's Content Notes (Pure Bio 2025)

1. Cells Learning Outcomes: Identify and state the functions of plant and animal cell organelles State the relationship between cell structure and function (w.r.t. RBC, root hair cell, muscle cell) Compare structures of plant and animal cells Keywords: Organelle, membrane, cellular activities Steroids, detoxification, protein synthesis Small and temporary, large central, cell sap Modifies, sorts and packages Partially permeable, fully permeable Biconcave, surface area to volume ratio, flexible, bell-shaped, long, narrow protrusion If you're our student: Cells Crash Course Clips 1. Identifying structures Component/OrganelleFunction Visible underLightMicroscope? Nucleus  Contains DNA (in the form of chromatin) Controlscellular activities Y Nuclear envelope Separates nucleus from cytoplasm Y Rough EndoplasmicReticulum  Studded with ribosomes Ribosomessynthesise proteins (for transport out of thecell) N Smooth EndoplasmicReticulum  Synthesises fats and steroids **Pro Tip: A class of molecules, including sexhormones Carries outdetoxification: where harmful substances areconverted to harmless ones N Cytoplasm  Place where most cellular activities occur Containsorganelles Y 1. Cells 1

 Site ofanaerobic respiration Vacuole Animals: Severalsmall and temporary vacuoles Store food and water Plants: Have alarge central vacuole Storescell sap (water + dissolved substances such as:sugars, amino acids, mineral salts) Y (plants)N (animals) Golgi body/apparatus• Modifies, Sorts and Packages substances intovesicles for secretion out of cellN Mitochondria  Site of aerobic respiration, where foodsubstances (such as glucose) are broken downto release energy N Chloroplast (plants only)  Site of photosynthesis Y Cell surfacemembrane/plasmamembrane • Partially permeable Controls movement of substances in and outof the cell Y Cell wall (plants only)  Fully permeable Made ofcellulose Gives cell its shape Y Ribosomes • Protein synthesis N Memory Hacks] Golgi Body: When receiving vesicles from ER, says "Majulah SingaPura" Modifies, Sorts and Packages substances into vesicles for secretion out of cell Rough ER Proteins  Meat. When you bite into meat patty, has a rough texture Rough ER synthesises proteins Smooth ER Lipids  Oil. Oil is smooth and slippery. Smooth ER synthesises lipids 2. Linking Structure to Function Cell Structure Red Blood Cell How it is adapted to its function Biconcave, increases surface area to volume ratio, so oxygen can diffuse in/out of it faster Lacks a nucleus hence has more space for more haemoglobin, to transport more oxygen Flexible, so it can squeeze through tiny capillaries Can become bell-shaped in capillaries, further increasing surface area to volume ratio 1. Cells 2

Root Hair Cell Has a long, narrow protrusion (root hair), that increases surface area to volume ratio, for faster absorption of water and mineral salts Have many mitochondria to generate a lot of energy via aerobic respiration As they need to pum