03. Introduction to Microbiology

Question 1

Types of Microorganisms

Answer 1

Microorganisms or microbes: a diverse group of single-celled and multicellular organisms, most of which cannot be seen with the naked eye. Viruses, bacteria, fungi.

Pathogenic microorganisms: microorganisms that cause disease in humans

Question 2

Structure of Viruses

Answer 2

Simplest in terms of structure.

Contain a single type of nucleic acid – either DNA or RNA (it’s genome), surrounded by a capsid or protein coat

Host-cell specific and will only invade specific cells.

Obligate intracellular parasites: cannot replicate outside of host cell, therefore they are dependent on their host cell

Question 3

Classification of Viruses

Answer 3

Characteristics used for viral classification:

Genetic material

• Type - DNA vs. RNA
• Strandedness - single vs. double

Capsid

• Size and shape
• Enveloped vs. Non-enveloped

Method of replication

• Replicate in nucleus of cell vs. replicate in the cytoplasm of cell

Question 4

Structure of Bacteria

Answer 4

Bacteria are Prokaryotic organisms: single-celled with a plasma membrane and cell wall

Question 5

Classification of Bacteria

Answer 5

Gram Stain

• Gram positive versus gram negative

Shape & Arrangement

• Spherical, rod, corkscrew
• Clusters, pairs, chains

Question 6

Diagnostic Microbiology (4)

Answer 6

Microscopy

• Light
• Fluorescence
• Electron

Culture

• Bacterial & Fungal
• Viral

Diagnostic Immunology (use antigen-antibody reaction. EIA)

Molecular Diagnostics (detect sequence of DNA or RNA. PCR)

Question 7

2 types of culture medium

Answer 7

fluid (broth)

solid (agar): single microbe can form visible colonies

Question 8

Advantages of PCR

Answer 8

Can be utilized to detect any type of microbe: virus, bacteria, fungi, protozoa

Can be utilized on various types of clinical samples: blood, urine, respiratory secretions, CSF