Lecture 18_250 review

Exam 3 Review Topics

• This section covers essential topics that are recommended for review.

Eukaryotes & Viruses

General Pathogenesis, Signs/Symptoms, and Diseases

• Giardia

  • Pathogenesis: Giardiasis caused by Giardia lamblia, a protozoan parasite.

  • Signs/Symptoms: Diarrhea, abdominal pain, bloating, nausea, and weight loss.

  • Disease: It causes intestinal malabsorption and dehydration.

• Candida

  • Pathogenesis: Infection caused by the overgrowth of Candida species, commonly C. albicans.

  • Signs/Symptoms: Oral thrush, vaginal yeast infections, skin infections, and systemic candidiasis in immunocompromised individuals.

  • Disease: Can lead to invasive candidiasis affecting multiple organs.

• Aspergillus

  • Pathogenesis: Caused by Aspergillus species, mostly A. fumigatus.

  • Signs/Symptoms: Respiratory issues including cough, fever, and difficulty breathing; can lead to allergic reactions.

  • Disease: Can cause aspergillosis, which may be invasive, particularly in immunocompromised patients.

• Ascaris

  • Pathogenesis: Infection due to Ascaris lumbricoides, a large intestinal roundworm.

  • Signs/Symptoms: Often asymptomatic; possible abdominal pain, malnutrition, and intestinal blockage.

  • Disease: Ascariasis can lead to complications like pneumonia from larvae migration.

Bacteriophage – Tailed Virus

Replication Steps

• Attachment: Bacteriophage binds to specific receptors on the bacterial surface.

• Penetration: The viral DNA is injected into the host cell.

• Biosynthesis: Host machinery synthesizes viral components.

• Maturation: Assembly of new phage particles occurs.

• Release: Lysis of the host cell releases new phages to infect other bacteria.

Lytic Cycle vs Lysogenic Cycle

• Lytic Cycle

  • Immediate replication and destruction of the host cell upon infection.

  • Produces a large number of virulent phages.

• Lysogenic Cycle

  • Viral DNA integrates into the host genome as a prophage.

  • The phage remains dormant and replicates along with the host cell during cell division, leading to a temperate phage.

Key Definitions

• Virulent Phage: Phages that exclusively reproduce via the lytic cycle and cause cell death.

• Temperate Phage: Phages that can enter both the lytic and lysogenic cycles.

• Prophage: The viral DNA that has integrated into the host genome during the lysogenic cycle.