A Tour of the Cell Protein Export Pathway Biology 1 Fall 2013 Standard 2 (Chapter 3) A Tour of the Cell Protein Export Pathway Biology 1 Fall 2013

Standard 2- Proficiency Goal: Distinguishes the role of different organelles in a eukaryotic or prokaryotic cell and is able to relate them to the overall function of the cell. Compare and contrast plant and animal cells. Describes the steps of the protein export pathway. Recognizes how different substances move across the membrane.

Standard 2 Advanced Goal: Given a real-life scenario, the student can determine why the organism/cell is not functioning in the way it is supposed to, and establish how it will affect the cell/organism. Use the organelle functions discussed in class to explain the formation of a protein in a eukaryotic cell, beginning with the instructions contained in DNA.

What are proteins and why are they important? Protein- long chains of amino acids with unique shapes that are important for many different jobs in the cell. Important jobs: Enzymes- speed up chemical reactions Antibodies- fight diseases Keratin/collagen/actin- provide body structure in skin, muscles, nails, hair, bone Hemoglobin- transports oxygen through blood

Protein Export Pathway Now let’s discuss where they are made and how they travel through and out of the cell……

Protein Export Pathway 1. First, in order for proteins to be made,the cell will need to provide the instructions for how they are made. Those instructions are made from the DNA in the nucleus. 1st

Protein Export Pathway 2. Second, those instructions are sent to tiny little organelles called ribosomes, where the proteins are made according to the instructions sent from the nucleus. (Side note: We will actually devote a good length of time second semester discussing exactly how proteins are made!) 2nd (It’s pointing to a tiny little ribosome!)

Protein Export Pathway 3. Third, after the protein is made, it is transported through the endoplasmic reticulum. 3rd (It’s pointing to the entire ER.)

Protein Export Pathway 4. Fourth, after traveling through the ER, the Golgi Apparatus receives the protein. Here the Golgi sorts, modifies, and packages the protein and then puts the protein into vesicles. 4th Vesicle

Protein Export Pathway 5. Now that the protein is in a vesicle, the vesicle serves as a transport compartment that ships the protein out of the cell. It does this through a process called exocytosis. 5A. Vesicle with protein in it ready to go through exocytosis. 5B. Vesicle fusing with cell membrane and letting the protein out of the cell.

Quick Check Where do the instructions come from to make proteins? What organelle makes the protein? How does the protein get to the Golgi? What does the Golgi do with the protein? How does the protein get out of the cell?