BIO 304 · Human Anatomy & Physiology
Cell Structure & Organelles
The Cell · Module 2
A reference for the Cell Structure video. The plasma membrane defines the cell; the nucleus runs the program; organelles in the cytoplasm do the work of life.
How to use this sheet Toggle the toolbar above. Notes prints the full reference for review. Study prints as a fill-in-the-blank worksheet , print it, then write each definition while you watch the video or read your book. Quiz me is on-screen typing practice; type the term, click Reveal to check yourself.
- Identify the components of the plasma membrane and describe what each contributes.
- Name the major cytoplasmic organelles and the job each one performs.
- Trace a protein from its gene in the nucleus to its release outside the cell, naming every organelle it passes through.
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Plasma Membrane & Nucleus
Membrane
- Phospholipid bilayertwo layers of phospholipids; hydrophilic heads out, hydrophobic tails in
- Integral proteinsspan the membrane; channels, carriers, receptors
- Peripheral proteinsattach to one side; signaling and structure
- Cholesterolfluidity buffer; keeps membrane stable across temperatures
- Glycoproteins / glycolipidssugar tags on the outer surface; cell-cell ID
Nucleus
- Nuclear envelopedouble membrane with pores; separates DNA from cytoplasm
- Nuclear poresgate mRNA, ribosomal subunits in and out
- ChromatinDNA + histone proteins; decondensed working state
- Nucleolusdark spot inside nucleus; builds ribosomal subunits
Cytoplasmic Organelles
Synthesis & processing
- Ribosomesprotein factories; free or bound to RER
- Rough ER (RER)studded with ribosomes; makes membrane and secreted proteins
- Smooth ER (SER)lipid & steroid synthesis; calcium storage in muscle
- Golgi apparatusmodifies, sorts, packages proteins for delivery
Energy & recycling
- Mitochondriondouble-membrane ATP factory; cristae for surface area
- Lysosomeacidic digestive vesicle; recycles cell components
- Peroxisomebreaks down fatty acids and detoxifies (esp. in liver)
Structure & motion
- Microfilamentsactin; cell shape, movement, division
- Microtubulestubulin; tracks for transport, spindle in division
- Intermediate filamentstension-bearing scaffolding (keratin, lamins)
- Centriolesorganize spindle during mitosis
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