diff --git a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md
index 970602e..7adfab8 100644
--- a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
+++ b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
@@ -1,27 +1,49 @@
-# Unit 2 Biology
-- Tissues
-- Organs,
-- Systems of living things
+# Unit 2: Biology
 
-## Celular Biology
-A person contains roughly 100 billion cells
-- there are roughly to different types of cell s found in mammals
-- cells are roughly 20 $`\um`$ (micrometer, $`10^{-6}`$ m), around 250 cells / cm
+## Cellular Biology
+A person contains roughly 100 trillion cells
+- Cells are roughly 20 `μm` (micrometre, 10<sup>-6</sup> m), around 250 cells / cm
 
 ## Cell Theory
 1. All living things are composed of cells 
-2. cells are the basic units of living organisms
-3. all cells came from pre-existing cells
+2. Cells are the basic units of living organisms
+3. All cells came from pre-existing cells
 
-## Types Of Cells
-`Prokaryotic cell`: Meaning before/lacking
+## Eukaryotic versus Prokaryotic Cells
+`Prokaryotic cell`: Meaning before/lacking nucleus
 
-`Eukaryotic cell`: Has organelles, meaning true, complete.
+`Eukaryotic cell`: Means complete nucleus
 
-|Part Of Cell|Prokaryotic|Eukaryotic|
+|Factors|Prokaryotic|Eukaryotic|
 |:-----------|:----------|:---------|
-|DNA|In nucleoid region|Usually in membrane, bound nucleus|
+|DNA|In nucleoid region|Usually in membrane-bound nucleus|
 |Size|Usually smaller|Usually larger|
-|Organelles|No membrane, bound organelles|Membrane, bound organelle, the bigger, the more complex|
-|Organization|Usually singler celled|Often multicellular|
-|Metabolism|May not need oxygen|Usually needs oxygen to exist|
\ No newline at end of file
+|Organelles|Not membrane-bound, smaller|Membrane-bound, more complex|
+|Organization|Usually singlecelled|Often form multicellular organisms|
+|Metabolism|May not need oxygen|Usually need oxygen|
+
+## Cellular Organelles
+
+### Cell Membrane
+ - Controls what substances enter/leave the cell selectively via various receptors/osmosis
+    - Allows nutrients to enter
+    - Allows waste products to leave
+ - Surrounds and holds other organelles in cell
+ - Interact with outside chemicals (e.g., hormones) 
+
+### Nucleus
+ - 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)
+    - 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)
+ - Produce "large" and "small" units of complete ribosomes, which either remain free or mix with endoplasmic reticulum, forming rough endoplasmic reticulum (RER)
+ - Is *not* surrounded by a membrane, literally is just same as rest of nucleus but denser
+