Lecture 4: Microbial Cell Structure and Function

General Information

• Date: Wednesday, September 11th
• Lecture Number: 4
• Chapter: 4
• Attendance Code: 8858
• Word of the Day: Eukaryote (spelling matters)

Important Reminders

• Homework

  • Extra credit: Finished
  • Assignment 1: Submit ASAP if not already done
  • Assignment 2: Due Friday by 5:00 PM
  • Late submissions: Inform via Canvas to adjust grades

• Upcoming Schedule

  • Finish Chapter 4 today
  • Chapter 5 next week
  • Chapter 6 & 7 shortly after
  • Review session and exam available on the following Wednesday
  • Download LockDown Browser for exams

Chapter 3 Review Highlights

• Importance: Fundamental for biology understanding
• Study Tips
  • Discuss concepts with a study group
  • Use posted study guides on Canvas
• Study Group Formation: Encouraged for better grasp of material

Key Concepts in Chapter 4

• Prokaryote vs. Eukaryote
  • Prokaryotes: Simple cells, no organelles, circular chromosomes
  • Eukaryotes: Complex cells, organelles, paired chromosomes
• Cell Shapes
  • Bacillus (rod-shaped), Coccus (spherical), Spiral

Gram Staining

• Purpose: Classify bacteria into gram-positive (purple) and gram-negative (pink)
• Mechanism: Crystal violet and iodine mordant
• Differences
  • Gram-positive: Easier to kill, no outer membrane
  • Gram-negative: More resistant, outer membrane

Bacterial Cell Walls

• Peptidoglycan: Major component, provides structure
• Gram-positive: Thick peptidoglycan layer, teichoic acids
• Gram-negative: Thin peptidoglycan, outer membrane with LPS

Other Structures

• Glycocalyx: Sticky material, either a capsule or slime layer
• Flagella: Tail-like structures for movement
• Fimbriae and Pili
  • Fimbriae: Attachment
  • Pili: DNA transfer, twitching motility

Movement Across Membranes

• Simple Diffusion: High to low concentration
• Facilitated Diffusion: Requires transporter proteins, no energy
• Active Transport: Requires energy (ATP)
• Osmosis: Water movement, balance concentration
  • Isotonic: No net movement
  • Hypotonic: Water moves in, cell may burst
  • Hypertonic: Water moves out, cell shrinks

Inclusions and Organelles

• Inclusions: Storage and waste
• Organelles
  • Nucleus: DNA
  • ER: Transport
  • Golgi Complex: Protein modification
  • Mitochondria: ATP production
  • Chloroplasts: Photosynthesis

Key Takeaways

• Model of Origin: Evidence suggests chloroplast and mitochondria were originally bacteria
• Endospores: Resistant cells, important in harsh environments

Final Remarks

• Encourage questions and discussion
• Use resources on Canvas for additional study materials