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

  1. 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

  2. Nucleolus

    • Involved in ribosome production.

Page 7: Chromatin Composition

  1. 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

  1. Ribosomes

    • Consists of rRNA and proteins

    • Types:

      • Free (scattered)

      • Fixed (attached to ER)

    • Function: Carry out protein synthesis

Page 11: Endoplasmic Reticulum (ER)

  1. 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

  1. 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

  1. 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

  1. Mitochondria

    • Double membrane with inner folds called cristae

    • Known as the