The Endomembrane System Do Now 1130 Week 1440

The Endomembrane System Do Now: 11/30 (Week 14/40) OBJECTIVES: 1. Describe the structure and functions of organelles involved with protein production in cells, including rough ER, smooth ER, ribosomes, the Golgi apparatus, and vesicles. 2. Identify which organelles are found in eukaryotic cells but not prokaryotes. TASK: Six classmates raced one another on the playground during recess. Use a matrix (grid) to find out who came in first, second, third, fourth, fifth, and sixth. 1. Alice crossed the finished line immediately after Austin. 2. Aaron finished right between Allen and Abby. 3. Adam won the race. 4. Aaron came in right after the boy who finished second. 5. Austin saw four people finish before him. 6. Allen did not finish fourth.

General Cell Terminology • Everything between the nucleus and the cell membrane is called CYTOPLASM. • CYTOPLASM is: – All of the organelles like mitochondria, etc. – The CYTOSOL, which is the aqueous solution everything else floats around in

I. The Nucleus The nucleus is a small sphere that holds all of a cell’s DNA.

The nucleus is surrounded by a lipid membrane called the nuclear envelope, which is very similar to the cell membrane. It has openings called nuclear pores that allow things in and out of the nucleus.

Most of the inside of a nucleus is made up of chromatin, which is a mix of DNA and certain proteins.

The nucleolus is a small dark part inside a nucleus where ribosomes are made.

II. The Endomembrane system • The endomembrane system is a series of folded lipid membranes where protein production takes place. It includes: – The nuclear envelope – The rough and smooth endoplasmic reticulum – The Golgi bodies – vesicles • PROKARYOTES have NO INTERNAL MEMBRANES. Protein production occurs in the cytoplasm

The Endoplasmic Reticulum • Structure: The endoplasmic reticulum is a large series of folded membranes attached to the outside of the nucleus. • Function: Nucleic acids and proteins travel through the tubes and folds during the process of protein production.

Two Parts of the ER • The first part has RIBOSOMES attached to it, and is therefore called the ROUGH endoplasmic reticulum • The second part has no ribosomes and is called the SMOOTH ER. • The function of the smooth ER is to produce new lipids for vesicles and membranes.

About those SUPER IMPORTANT ribosomes… • Very important function: RIBOSOMES MAKE PROTEINS! Structure: Two pieces of RNA stuck together

More on Ribosomes in the Future… • We’ll learn more about how ribosomes make proteins when we study molecular genetics. The ribosome basics: – Made of r. RNA; – thousands per cell. – Use the information in m. RNA to build a polypeptide from amino acids. – Found in all cell types.

Do Now 12/1: Protein Production OBJECTIVES: 1. Describe the structure & function of the Golgi apparatus, lysosomes, chloroplasts & mitochondria. TASK: 1. HW Check: 4. 7 -4. 10 2. Put the following steps in the order in which they occur: I. Ribosomes attached to the ER build proteins from amino acids II. DNA in the nucleus stores genetic information III. New polypeptides are packaged into vesicles IV. An m. RNA copy of DNA instructions travels to the ER

Rough then Smooth • The rough ER is where polypeptides are built. • The smooth ER has several functions – Most importantly: • Lipid synthesis (for membranes) • Home to many enzymes.

Golgi • Structure: folded membranes • Function: Proteins are finished – folded into correct conformations & quarternary structures – Modified chemically • Addition of chemical groups (e. g. heme in hemoglobin, etc. ) • Modified amino acids – label proteins so they get delivered to the right places. • What might they be labeled with?

Smooth Endoplasmic Reticulum Protein Production Transport Vesicle Outgoing Transport Vesicles Amino Acids Rough Endoplasmic Reticulum Golgi Apparatus m. RNA Ribosome Transport Vesicles Nucleus (DNA)