Chap#3|Endoplasmic reticulum|RER and SER|FSc biology part 1|New Edition Book скачать в хорошем качестве

Chap#3|Endoplasmic reticulum|RER and SER|FSc biology part 1|New Edition Book

Here’s Chapter 3 | Endoplasmic Reticulum & Rough (RER) vs Smooth (SER) — FSc Biology Part 1 (New Edition Book) explained in a clear, exam-friendly way 👇 ⸻ 📌 Endoplasmic Reticulum (ER) — Definition • ER is a network of membranous channels and sacs throughout the cytoplasm of eukaryotic cells. • It is continuous with the nuclear envelope and often extends toward the cell membrane. • ER separates internal channels from the cytoplasm, allowing transport and synthesis processes inside these tubules/cisternae.  ⸻ 📌 Types of Endoplasmic Reticulum ER has two main types, based on whether ribosomes are present on its surface: 1. Rough Endoplasmic Reticulum (RER) 2. Smooth Endoplasmic Reticulum (SER) ⸻ 🟩 1. Rough Endoplasmic Reticulum (RER) 🔹 Structure • Studded with ribosomes on its cytoplasmic surface — gives a “rough” appearance. • Made of flattened sacs (cisternae). • Continuous with the outer nuclear membrane.  🔹 Functions ✔ Protein synthesis — ribosomes on RER make proteins. ✔ Protein modification and folding — proteins may be processed inside the RER lumen. ✔ Transport — newly made proteins are moved via vesicles to the Golgi apparatus. ✔ Membrane synthesis — adds proteins and some lipids to cellular membranes.  🔹 Where found? Cells that make many proteins e.g., pancreatic cells, liver cells, plasma cells.  ⸻ 🟦 2. Smooth Endoplasmic Reticulum (SER) 🔹 Structure • No ribosomes — “smooth” appearance. • Formed mainly of tubules and vesicles rather than flattened sacs.  🔹 Functions ✔ Lipid synthesis — makes phospholipids, cholesterol & steroids. ✔ Carbohydrate metabolism — helps in sugar breakdown and conversion. ✔ Detoxification — especially in liver cells (detoxifies drugs & poisons). ✔ Calcium storage — e.g., sarcoplasmic reticulum in muscle cells stores & releases Ca²⁺.  🔹 Where found? Abundant in cells making steroids (e.g., adrenal cortex), liver cells, muscle cells.  ⸻ 📊 RER vs SER — Quick Comparison Feature RER SER Ribosomes Present (rough) Absent (smooth) Main function Protein synthesis & processing Lipid synthesis & metabolism Structure Flattened sacs Tubules & vesicles Role in cell Makes proteins for secretion and membranes Makes lipids, detoxifies, Ca²⁺ storage ⸻ 🧠 Remember for FSc Exams • RER = Rough = Ribosomes = Proteins • SER = Smooth = No Ribosomes = Synthesis of Lipids & Detox • ER is part of the endomembrane system involved in synthesis & transport of materials within the cell.