II. Components of Eukaryotic cells D. The Endomembrane System

1. Plasma Membrane

All cells

Encloses cell contents (selectively permeable, not cell wall)

Regulates what and how much passes through membrane

2. Nuclear Envelope

Encloses DNA, instructions for a protein (mRNA) leave through nuclear pores

To Ribosome which form

Primary polypeptide

3. Endoplasmic Reticulum (ER)

ER continuous with nuclear envelope

Smooth ER, no ribosomes

Rough ER, surface has ribosomes

(lumen-internal space)

Rough ER Functions

Proteins folded and modified

Secrete glycoproteins (proteins bonded carbohydrates)

Distributes transport vesicles

Cell membrane factory

Smooth ER Functions

Synthesizes lipids

metabolzies polysaccrides (breaks down glycogen)

Detozifies drugs and poisonsstores calcium ions Ca^2+

4. Golgi Apparatus

Structure

Stacks of membranous sacs (cisternae)

Not continuous with ER

Cis face

Receiving side from ER

Trans face

Shipping side

Functions of Golgi Apparatus

Modifies ER products

Sorts and packages

Mafactures some macromolecules

Shipping product using transport vesicles

5. Lysosomes

Sacs of hydrolytic enzymes “cell stomach”

Primary lysosomes

Buds off golgi- no food yet

Food enters in vacuole-> fuses with lysosome -> forms

Secondary lysosome

Breaks down complex macromolecules

6. Vacuoles

Maintenance compartments

Structure

Membrane bound containers forom er and golgi apparatus

Functions

Food vacoules, store food,

Contractile vacoles- pump water out

Central vacoules- in plant cells hold water