PLASMA MEMBRANE

• Often called phospholipid bilayer
• Comprises: Proteins, Cholesterol, Carbohydrates.
• Separates cell from external environment; controls the flow of material into and out of it.

CYTOSOL

• Aqueous solution that bathes organelles and contains a variety of molecules
• Portion of cytoplasm not contained within organelles
• Free ribosomes

ENDOMEMBRANE SYSTEM

• Select group of membranous organelles that regulate protein trafficking and metabolism

NUCLEUS

• Nuclear envelope with pores (double-membrane)
• Site of DNA replication and RNA synthesis (transcription)
• Contains: chromatin, nucleolus (rRNA and ribosomal proteins)

ENDOPLASMIC RETICULUM

• Continuous with nuclear envelope
• Cisternae enclose a space called the ER lumen
• Rough ER: with bound ribosomes; site of protein synthesis, processing and secretion
• Smooth ER: no ribosomes; lipid synthesis, carbohydrate metabolism, detoxification

TRANSPORT VESICLE

• Keeps secretory proteins separate from proteins synthesized in the cytosol

GOLGI APPARATUS

• cis side faces the nucleus, trans side where cargo exits
• Modifies, stores and secretes molecules that it receives from the ER
• Synthesizes its own macromolecules

LYSOSOME

• Vesicle that contains hydrolytic enzymes; digests endosomal cargo

ENDOSOME

• Forms when cell engulfs nutrients or other particles via endocytosis

RIBOSOMES

• Two subunits: one large and one small
• Synthesize proteins via translation
• Can be bound to rough ER or free (suspended in cytosol)

MITOCHONDRION

• Double-membrane bound: inner membrane invaginates to form cristae
• Space within cristae: matrix (contains free ribosomes)
• Space between inner and outer membranes: intermembrane space
• Synthesizes ATP via citric acid cycle and oxidative phosphorylation (couples oxidation of nutrients with ADP phosphorylation)

PEROXISOME

• Single-membrane bound vesicle
• Produce hydrogen peroxide from detoxification of substances (i.e. alcohol)

CYTOSKELETON

• Microfilaments, intermediate filaments and microtubules
• Anchors organelles and provides structural framework

CENTROSOME

• Where microtubules nucleate
• Contains two small structure called centrioles
• Functions in cell division

DOUBLE MEMBRANE BOUND ORGANELLES

• Nucleus
• Mitochondria

CLINICAL CORRELATIONS

• Rough ER Network and Pancreatic beta cells
  – Specialize in synthesizing and secreting the peptide hormone insulin; large rough ER network proportional to their secretory activity
• Smooth ER and Hepatic cells
  – Drugs and/or alcohol can induce the proliferation of smooth ER, which accelerates detoxification
• Lysosomes and Tay-Sachs disease
  – Lysosomal storage disease that presents when lysosomes are missing a lipid-digesting enzyme (or its active form)
  – Lipids accumulate in cells because lysosomes cannot digest them; impair brain function