Cell organelles

Page 1: Introduction

• The Cell Organelles

  • Lecturer: Dr. Albertina Shatri

  • Institution: UNAM

  • Contact: #067

Page 2: Lecture Objectives

• By the end of the lecture:

  • Identify different eukaryotic cell organelles and their functions.

  • Understand the difference between membranous and non-membranous organelles.

  • Understand protein synthesis and organelles involved in protein synthesis.

Page 3: Eukaryotic Model Cellular Anatomy

• Key Cellular Organelles:

  • Centriole

  • Lysosome

  • Mitochondrion

  • Vacuole

  • Nuclear envelope

  • Nucleolus

  • Chromatin

  • Nuclear pore

  • Nucleus

  • Plasma membrane

  • Cytoplasm

  • Smooth endoplasmic reticulum

  • Rough endoplasmic reticulum

  • Ribosomes

  • Golgi complex

  • Microfilaments

  • Microtubules

Page 4: Eukaryotic Membranous Organelles

1. Cell Nucleus

   • Contains:

     • Genetic material (DNA)

   • Functions:

     • Stores and processes genetic information

     • DNA and RNA synthesis

     • Control protein synthesis

Page 5: Nuclear Envelope

• Structure:

  • Double membrane surrounding the nucleus

  • Fluid content: Nucleoplasm, which consists of ions, RNA and DNA nucleotides, proteins, and small amounts of RNA & DNA

  • Components of Nuclear Structure:

    • Nucleus

    • Nucleolus

    • Nuclear pores

    • Chromatin

Page 6: Nuclear Pores & Nucleolus

2. Nuclear Pores

   • Cover about 10% of the nucleus' surface

   • Permits the movement of ions and small molecules

   • Too small for proteins and DNA passage

   • Allows communication between nucleus and cytosol

3. Nucleolus

   • Involved in ribosome production.

Page 7: Chromatin Composition

4. Chromatin

   • Composed of DNA, RNA, and proteins

   • Functions:

     • Scattered throughout the nucleus

     • Condenses to form chromosomes during cell division

     • Copies (sister chromatids) formed during S-phase of the cell cycle

Page 8: Chromatin Functions

• Functions of Chromatin:

  • Packages DNA to fit in the cell

  • Reinforces DNA for mitosis

  • Prevents DNA damage

  • Controls gene expression and DNA replication

Page 9: DNA and RNA Bases

• Base Pairing:

  • Three pyrimidine bases: thymine, cytosine, and uracil

  • Two purine bases: adenine and guanine

• Structural Differences of DNA and RNA:

  • RNA contains ribose sugar, DNA contains deoxyribose sugar

  • RNA has uracil instead of thymine

Page 10: Ribosomes

2. Ribosomes

   • Consists of rRNA and proteins

   • Types:

     • Free (scattered)

     • Fixed (attached to ER)

   • Function: Carry out protein synthesis

Page 11: Endoplasmic Reticulum (ER)

3. Endoplasmic Reticulum

   • Network of membranous channels extending through cytoplasm

   • Attached to nucleus via membranes

   • Types of ER:

     • Rough ER (with ribosomes; aids in protein packaging)

     • Smooth ER (without ribosomes; synthesizes lipids)

Page 12: Golgi Apparatus

4. Golgi Apparatus

   • Consists of five to six stacks of membrane discs

   • Major Functions:

     1. Separates proteins according to destination

     2. Post-translational modifications (glycoprotein formation)

     3. Packages materials into vesicles for export

Page 13: Protein Synthesis Overview

• Organelles Involved in Protein Synthesis:

  1. Nucleus

     • Regulates protein synthesis

  2. Ribosomes

     • Synthesizes proteins

  3. Rough ER

     • Packages synthesized proteins

  4. Golgi Apparatus

     • Stores and reassembles proteins

Page 14: Process of Protein Synthesis

• Stages of Protein Synthesis:

  • DNA transcription occurs in the nucleus

  • RNA polymerase transcribes DNA into mRNA

  • DNA translation occurs in cytoplasm

  • mRNA binds with ribosome and tRNA delivers amino acids

Page 15: Importance of Protein Synthesis

• Why is Protein Synthesis Important?

  • Proteins form structure and control chemical reactions in organisms

  • Examples of proteins: walls of arteries, ligaments, hair, nails, muscles, bones, and antibodies

  • Protein Structures:

    • Primary

    • Secondary

    • Tertiary

    • Quaternary

Page 16: Endoplasmic System Summary

• Pathways:

  1. Golgi vesicle containing proteins to be secreted becomes a secretory vesicle

  2. Secretory vesicles release proteins by exocytosis

  3. Golgi vesicle containing digestive enzymes becomes a lysosome which fuses with ingested substances

Page 17: Cytoplasm

5. Cytoplasm

   • Jelly-like fluid that fills a cell

   • Composed of mostly water and salts

   • Function: Provides shape to the cell

   • Cytosol: part of cytoplasm without organelles

Page 18: Mitochondria

6. Mitochondria

   • Double membrane with inner folds called cristae

   • Known as the