The Endomembrane SystemA Tour of the Protein Synthesis Pathway

Essential Question(s)

1. Why do eukaryotic cells maintain internal membranes that partition cells into specialized regions?

Prokaryotes vs. Eukaryotes

Prokaryote Eukaryote

Compartmentalization

Cellular Work

Building Proteins

Cells

Proteins

DNA

Organism

Protein Synthesis Overview

Ribosome rER Golgi Vesicles

The Protein Assembly Line

The Endomembrane System

Nucleus

Endomembrane System

Nucleus

Nucleus

Nucleolus

Ribosomes

Types of Ribosomes

Bound Ribosomes Free Ribosomes

Endoplasmic Reticulum

Rough ER

Smooth ER

Synthesizing Secreted Proteins

cytoplasm

cisternalspace

mRNA

ribosomemembrane ofendoplasmic reticulum

polypeptide

signalsequence

ribosome

Golgi Apparatus

Vesicular Transport

vesicleBUDDINGfrom roughER

protein

ribosome

migratingtransportvesicle

FUSIONof vesiclewith Golgiapparatus

Putting it All Together

proteins

transportvesicle

Golgiapparatus

vesicle

smooth ER

rough ERnuclear pore

nucleus

ribosome

cellmembrane protein secreted

cytoplasm

Putting it All Together

Enduring Understandings1. Archaea and bacteria generally lack internal membranes and

organelles and have a cell wall.

2. Membranes and membrane-bound organelles in eukaryotic cells localize – compartmentalize – intracellular metabolic processes and specific enzymatic reactions.

3. Internal membranes facilitate cellular processes by minimizing competing interactions and by increasing surface area where reactions occur.

4. Ribosomes are small , universal structures comprised of two interacting parts; ribosomal RNA and protein. In a sequential manner, these cellular components interact to become the site of protein synthesis where the translation of genetic instructions yields specific polypeptides.

Enduring Understandings5. Rough endoplasmic reticulum – rER – functions to

compartmentalize the cell, serves as mechanical support, provides site-specific protein synthesis with membrane-bound ribosomes and plays a role in intracellular transport.

6. The smooth endoplasmic reticulum – sER – synthesizes lipids.

7. The Golgi complex is a membrane-bound structure that consists of a series of flattened membrane sacs, called cisternae.

8. Functions of the Golgi include synthesis and packaging of materials – small molecules – for transport in vesicles and production of lysosomes

Small Group CFU 1• Take 2 minutes

• Spend the next 2 minutes with your partner clarify your understanding of the topic by asking and answering your questions with your partner. Be sure to identify content that you missed or were confused about, and clarify these points.

• Annotate your notes using symbols to identify the main ideas, underlining or highlighting key terms, or adding supporting details, examples or explanations to figures.

• After three minutes have expired, work with your partner to answer the multiple choice notes-check questions. You may discuss the solutions with only your partner, quietly.

• Answer each of these questions using your notes, and underline the statement or phrase that provides the answer. This will denote the most importance information for your review later on.

• Record any clarifying questions at the bottom of your page

Protein Synthesis Overview

Synthesizing Secreted Proteins

cytoplasm

cisternalspace

mRNA

ribosomemembrane ofendoplasmic reticulum

polypeptide

signalsequence

ribosome

Putting it All Together

proteins

transportvesicle

Golgiapparatus

vesicle

smooth ER

rough ERnuclear pore

nucleus

ribosome

cellmembrane protein secreted

cytoplasm