Lecture on chapter 3 Cellular structure (mostly on eukaryotic cells)

Cell Wall

• Function of the Cell Wall

  • Protects the cell from external damage.

  • Maintains the overall shape of the cell.

  • Prevents excessive water uptake and loss.

• Effect on Antibiotics

  • The structure of the bacterial cell wall influences its susceptibility to antibiotics.

  • Overuse of antibiotics reduces their effectiveness; it's crucial to finish prescribed courses.

Differences Between Bacteria and Archaea

• Composition of Cell Walls

  • Bacterial cell walls contain peptidoglycan.

  • Archaeal cell walls do not contain peptidoglycan and exhibit great diversity in composition.

• Membrane Structure

  • Archaeal membranes contain saturated hydrocarbons attached to glycerol at both ends.

Flagella in Prokaryotic Cells

• Functionality of Flagella

  • Present in some prokaryotic cells, potentially having multiple flagella.

  • Used for locomotion, moving the cell through rotary motion (like a propeller).

• Structure of Flagella

  • Composed of a hook, filament, and covered with peptidoglycan.

  • The motor uses hydrogen ions (H+) to generate energy to spin the flagellum.

• Flagella in Archaea

  • Known as archaealum, and may have an S-layer as a protective structure.

  • The motor uses ATP for energy instead of protons.

Eukaryotic Cells Overview

• Characteristics of Eukaryotic Cells

  • Can be unicellular or multicellular.

  • Have a membrane-bound nucleus that contains genetic material.

  • Exhibit compartmentalization through membrane-bound organelles (e.g. mitochondria, endoplasmic reticulum).

  • Contain a cytoskeleton, providing support and maintaining cell shape.

Comparison of Plant and Animal Cells

• Common Structures

  • Both have plasma membranes, nuclei, mitochondria.

  • Eukaryotic characteristics include membrane-bound organelles and cytoskeleton.

• Unique Structures in Plant Cells

  • Cell Wall: A rigid outer layer providing support.

  • Chloroplasts: Organelles for photosynthesis.

  • Central Vacuoles: Large storage spaces for water, nutrients, and waste.

Detailed Structure of the Nucleus in Eukaryotic Cells

• Functions

  • Controls cell activities, stores genetic material (DNA).

• Components

  • Nuclear Envelope: A double phospholipid membrane surrounding the nucleus that regulates material entry and exit.

  • Nucleolus: Region within the nucleus where ribosomal RNA is synthesized.

  • Nuclear Pores: Openings allowing materials to pass in and out of the nucleus.

Ribosomes and Protein Synthesis

• Roles

  • Ribosomes are the protein factories of cells, synthesizing proteins from amino acids.

  • Found in all cell types across three domains: Bacteria, Archaea, and Eukaryotes.

• Types of RNA Involved

  • mRNA: Carries instructions from DNA to ribosomes.

  • tRNA: Assembles the correct amino acids into proteins.

Endomembrane System

• Functionality

  • A system of membranes within eukaryotic cells that compartmentalizes various cell functions (e.g. protein synthesis, lipid production).

  • Differentiates between eukaryotic and prokaryotic cells due to its presence in eukaryotes only.

Endoplasmic Reticulum (ER)

• Types of ER

  • Rough ER: Has ribosomes; involved in protein synthesis and processes proteins for secretion, lysosomes, or plasma membranes.

  • Smooth ER: Lacks ribosomes; involved in lipid synthesis, detoxification, and calcium storage.

• Rough vs Smooth ER Functionality

  • Rough ER is more abundant in cells producing digestive enzymes (e.g. pancreatic cells).

  • Smooth ER is more abundant in cells detoxifying substances (e.g. liver cells).

Cellular Quiz Preparation

• Focus Areas for Study

  • Familiarize with bolded terms and relevant tests or experiments from the lab manual.

  • Pay special attention to the structure and function differences between plant and animal cells.