AP Biology Unit 2 - The Cell

Sep 30, 2026

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AP Biology Unit 2 review material focused on core cellular structures and the major mechanisms of membrane transport. Covers organelles including nucleus, rough and smooth ER, Golgi complex, ribosomes, mitochondria, chloroplasts, lysosomes, and vacuoles with their key structural features and functions. Reviews how membrane composition supports transport, then compares simple diffusion, facilitated diffusion, active transport, and vesicle-based processes such as endocytosis and exocytosis, ending with a pathway from rough ER to the Golgi and plasma membrane.

LanguageEnglish

CategoryExam

FormatPDF

Pages21

Reading Time53 min

AccessFree to download

Today’s Plan

Cellular Organelles

Membrane Transport

Endocytosis and Exocytosis

ER to Golgi to Plasma Membrane Pathway

The Cell @apbiopenguins AP Biology students are penguins because they are Dressed for Success! You are now an AP Bio Penguin! Resource Reminders: Daily Review on IG stories 374 page Review Guide on Weebly Recorded FRQ Fridays on YouTube 120+ Quizizz Games on Weebly Review PowerPoints on Weebly Weebly: [www.apbiopenguins.weebly.com](www.apbiopenguins.weebly.com) Today’s Plan Cellular Organelles Membrane Transport Practice Questions Unit 2 Q&A Nucleus Structure: • Double membrane (nuclear envelope) with pores Functions: • Stores genetic information (DNA) • Synthesis of RNA • Ribosome subunit assembly Structure: Rough ER • Membrane studded with ribosomes attached to nuclear envelope Functions: • Site of membrane-bound protein and secreted protein synthesis • Cell compartmentalization • Mechanical support • Role in intracellular transport Smooth ER Structure: • Folded, tubelike structure (cisternae) Functions: • Detoxification • Calcium Storage • Lipid synthesis Cellular Organelles Structure: • Membrane-bound structure composed on flattened sacs (cisternae) Functions: • Folding and chemical modification of synthesized proteins • Packaging protein traffic Golgi Complex Structure: • Composed of rRNA and protein • Large & small subunits • Types: bound or free (cytoplasmic) Functions: • Protein synthesis Ribosomes Mitochondria Structure: • Double membrane (outer: smooth; inner: highly folded) Functions: • Site of oxidative phosphorylation (cristae/inner membrane) • Site of Krebs Cycle (matrix) Cellular Organelles Structure: • Double outer membrane (thylakoid sac stacked: grana and fluid: stroma) Functions: • Site of photosynthesis • Thylakoid: Light Reactions • Stroma: Calvin-Benson Cycle Chloroplast Mitochondria Structure: • Double membrane (outer: smooth; inner: highly folded) Functions: • Site of oxidative phosphorylation (cristae/inner membrane) • Site of Krebs Cycle (matrix) Lysosome Structure: • membrane-enclosed sacs that contain hydrolytic enzymes Functions: • Intracellular digestion (recycle cell organic materials & programmed cell death: apoptosis) Cellular Organelles Structure: • membrane-bound sac Functions: • storage and release of macromolecules and cellular waste products • Central: water retention – turgor pressure • Contractile: osmoregulation (protist) • Food: phagocytosis, fuse with lysosome Vacuole Structure: • Double outer membrane (thylakoid sac stacked: grana and fluid: stroma) Functions: • Site of photosynthesis • Thylakoid: Light Reactions • Stroma: Calvin-Benson Cycle Chloroplast Surface Area: Volume Smaller cells typically have a higher surface area-to-volume ratio and more efficient exchange of materials with the environment. Simple Diffusion • Passive Transport, No NRG • Down concentration gradient • Small, Nonpolar • No transport protein needed • Examples: CO2 , O2 , N2 , steroids • Small amount of H2O leak through membrane Facilitated Diffusion • Passive Transport, No NRG • Down concentration gradient • Small Molecules • Requires transport protein Channel vs. Carrier protein • Example: water, Na+ , K+, Ca+ Active Transport • Requires input of NRG • Against concentration gradient • Requires transport protein (carrier protein) • Example: Na+ , K+, Ca+ , H+ Membrane Transport Plasma Membrane Composed of: • Phospholipids • Membrane Proteins • Glycolipids/Glycoproteins • Cholesterol Simple Diffusion • Passive Transport, No NRG • Down concentration gradient • Small, Nonpolar • No transport protein needed • Examples: CO2 , O2 , N2 , steroids • Small amount of H2O leak through membrane Facilitated Diffusion • Passive Transport, No NRG • Down concentration gradient • Small Molecules • Requires transport protein Channel vs. Carrier protein • Example: water, Na+ , K+, Ca+ Act

FAQs

What is the nucleus responsible for in AP Bio Unit 2?

The nucleus stores genetic information (DNA), synthesizes RNA, and supports ribosome subunit assembly.

How do simple diffusion and facilitated diffusion differ?

Simple diffusion is passive transport down the concentration gradient without a transport protein, while facilitated diffusion also moves down the gradient but requires a transport protein (channel vs carrier).

What do endocytosis and exocytosis accomplish?

Endocytosis imports materials, including phagocytosis (cellular eating) and pinocytosis (cellular drinking), plus receptor-mediated uptake. Exocytosis exports materials.

Sep 30, 2026

Upload by aboduw