diff --git a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md
index ed3e075..aab106c 100644
--- a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
+++ b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
@@ -50,12 +50,14 @@ A person contains roughly 100 trillion cells
  - Holds deoxyribonucleic acid (DNA) in form of chromatin
     - DNA is a double helix that make genes
         - Genes are a complete set of instructions to make a complete product (typically proteins)
+        - `Genes`: one of the many sets of instructions, in your DNA, found on a **chromosome**, for making a functional product (mostly proteins)
     - Chromatin is DNA wrapped tightly in protein
     - Chromosomes are even more tightly wrapped chromatin used in cell division only
  - Surrounded by a double membrane
  - Substances enter and exit the nucleus via nuclear pores
  - Messenger RNA (mRNA) is encoded from DNA and sent to ribosomes to produce proteins
 
+
 ### Nucleolus
  - Dense region of DNA located in the nucleus
  - This area of DNA is specially for ribosomal DNA (rDNA), or DNA used to make ribosomes
@@ -66,4 +68,17 @@ A person contains roughly 100 trillion cells
 ### Cytoplasm & Cytosol
  - Cytosol is the fluid cells contain
  - All organelles are suspended in cytosol
- - Cytoplasm is the cytosol along with everything in a cell, excluding the nucleus
\ No newline at end of file
+ - Cytoplasm is the cytosol along with everything in a cell, excluding the nucleus
+
+## Rough Endoplasmic reticulum
+The endoplasmic reticulum is a network of tubules and flattened sacs with a "rough" appearance because of the presence of ribosomes on the surface
+
+### Function
+- Protein synthesis
+    - About half of the cell's proteins are made here, by the ribosomes
+- Protein movement
+    - Proteins are transported by vesicles throught the cell to other organelles, like the golgi apparatus
+- Protein "Proof-Reading"
+    - pre-existing proteins are center the rough-ER for modification
+
+