Endoplasmic reticulum/ribosomes By: Russell Sabine And Conner McLeod

Ribosomes What are Ribosomes? Where are they located in a cell? What do they do? How do they do it? 1: Ribosomes are a small organelle that are made of 2 sub-units that are each made of ribosomal RNA and proteins. One of the units is larger than the other and many ribosomes can be found in the cell. They are found in both Eukaryotic and Prokaryotic cells. 2:They are either in the cytosol or attached to the Endoplasmic reticulum. 3: Ribosomes are the protein producing factories of cells. They take amino acids and RNA and covert them into useful proteins. 4: The process starts when mRNA binds to the RNA of the smaller sub-unit of the ribosome. Then the larger unit closes on top of the mRNA, trapping it. Transfer RNA then enters the larger sub-unit and deposits amino acids according to the code on the mRNA. There is a specific start and stop codon on the mRNA. The start one is what causes the first tRNA to bind to the ribosome while the stop releases the

Endoplasmic Reticulum What is it? What are the 2 different kinds? Where is it located? 1: The endoplasmic reticulum is a large organelle of the cell. It is made of a network of tubules, citstamae, and vesicles, with a membrane. It is only found in Eukaryotic cells. Vesicles are small things like proteins that are surround with a membrane. 2: There are 2 kinds of ER. The first is rough ER and the second is smooth. 3: ER is attached to the nucleus and stretches up near the cell membrane. The Golgi complex is found at the membrane end. The rough ER is the part attached to the nucleus while smooth ER is farther away from the nucleus. The ER, both rough and smooth, is one continuation of the nuclear membrane.

Rough Endoplasmic reticulum 1. Why is it called rough? 2. What does it do? 3. Why do ribosomes need ER? 1: Rough ER is called rough because it looks rough under a microscope, due to the ribosomes attached to it. 2: The rough ER helps ribosome's produce secretions. 3: A secretion means that it will be taken out of the cell for use somewhere else. When a ribosome “recognizes” a strand of amino acids destined to be a secretion, it binds to the ER at a ribophorin. Then as the ribosome continues to produce the amino acid chain, the amino acid chain is pushed inside the ER. From hear it is transported to the smooth ER and then out of the ER, to the Golgi aparatus.

Smooth Endoplasmic Reticulum 1. Why is it called smooth? 2. What does it do? 1: Smooth ER is called smooth because it looks smooth under a microscope compared to rough ER. 2: Smooth ER is where the cell produces lipids and steroids. It is also where ions and steroids are stored in the cell and where things are detoxified. The smooth ER also helps with metabolic processes.

More on ER 1. What makes smooth and rough ER so different? 2. Why do ribosome's only attach to rough ER? 1: The main difference between smooth ER and rough ER is the presence or lack of ribosome's. This causes rough ER to deal with proteins while smooth ER deals with non-proteins. 2: Ribosome's don’t only attach to rough ER. That is just where they mainly attach since it is next to the nucleus and thus it is easy for mRNA to get there. Most smooth ER actually has some ribosome's attached to it. This has the strange property of allowing the cell to determine how much percent of the ER it wants to be smooth or rough at any given time based on what it requires.

To sum it up Ribosome's produce proteins. When they produce secretions they attach to the RER. From here the protein is sent to the Golgi. Meanwhile SER produces lipids and steroids. While it does this it has ions and steroids in storage to be released as needed. It also helps digest sugars and detoxify substances that enter the cell.