Microbiology 25 Lecture Notes Review

A comprehensive set of practice questions covering microbiology basics including chemistry, cell structure, bacterial pathogenesis, and virology.

What are the charge, mass, and location of a proton?

Positive charge; about $1$ atomic mass unit; located in the nucleus.

What is the atomic number of an atom?

The number of protons in an atom.

What is the half-life of carbon-14?

Approximately $5,700$ years.

How is carbon-14 dating utilized in archaeology?

It is used for estimating the age of organic material generally less than about $75,000$ years old.

What does the octet rule state regarding atomic stability?

An atom is stable when its first shell contains $2$ electrons or its outermost shell contains $8$ electrons.

Which type of chemical bond is categorized as the strongest?

Covalent bonds are strongest, while ionic bonds are intermediate and hydrogen bonds are weakest.

Why does ice float on liquid water?

Water expands below $4$ degrees Celsius, making solid ice less dense than liquid water.

How does the hydrogen ion concentration change between each unit on the pH scale?

It changes tenfold; for example, $pH\,4$ is $100$ times more acidic than $pH\,6$.

Which buffer system maintains human blood pH between $7.35-7.4$?

The carbonic acid-bicarbonate buffer system.

Which two functional groups are present in every amino acid?

An amino group and a carboxyl group.

Which of the four major biological macromolecules is not considered a true polymer?

Lipids.

What are the component monosaccharides of sucrose, lactose, and maltose?

Sucrose is made of glucose and fructose; lactose is made of galactose and glucose; maltose is made of glucose and glucose.

What are the specific functions of cellulose and chitin?

Cellulose is a structural polysaccharide in plant cell walls, and chitin is found in fungal cell walls and arthropod exoskeletons.

How do saturated and unsaturated fats differ in their chemical structure?

Saturated fats are filled with hydrogen and usually solid, while unsaturated fats contain double bonds and are often liquid.

What defines the primary and secondary structures of a protein?

Primary structure is the amino acid sequence; secondary structure is local folding produced mainly by hydrogen bonds.

What are the three components of a nucleotide?

A five-carbon sugar, a phosphate group, and a nitrogenous base.

What are the primary differences between prokaryotic and eukaryotic cells?

Prokaryotes are smaller and lack a nucleus and membrane-bound organelles, while eukaryotes are larger and contain them.

What do the bacterial shape terms coccus, bacillus, and spirillum describe?

Coccus is round, bacillus is rod-shaped, and spirillum is a rigid spiral.

What is the main structural material of the bacterial cell wall?

Peptidoglycan.

What color do Gram-positive and Gram-negative bacteria appear after staining?

Gram-positive appear purple or blue; Gram-negative appear pink or red.

What is LPS and where is it found?

Lipopolysaccharide is found in the Gram-negative outer membrane; its lipid A portion acts as endotoxin.

How do beta-lactam antibiotics like penicillin function?

They prevent peptidoglycan cell-wall synthesis, allowing osmotic pressure to lyse the cell.

Which bacterial genera are known for producing endospores?

Bacillus and Clostridium.

What does the endosymbiosis theory propose about mitochondria and chloroplasts?

It proposes they evolved from bacteria engulfed by an ancestral host cell.

What is the underlying cause of Tay-Sachs disease at the cellular level?

A missing lysosomal enzyme prevents proper lipid breakdown, causing lipid accumulation and neuronal damage.

What enzyme do peroxisomes use to neutralize hydrogen peroxide?

Catalase, which converts hydrogen peroxide into water and oxygen ($2H_2O_2 \rightarrow 2H_2O + O_2$).

What happens to a cell placed in a hypotonic solution?

Water enters the cell; it swells and may burst.

What is a virus composed of?

DNA or RNA enclosed in a protein capsid; some also possess an envelope.

What is the difference between a positive-sense and a negative-sense single-stranded RNA virus?

Positive-sense RNA acts directly as mRNA; negative-sense RNA must be copied into positive-sense RNA by RNA-dependent RNA polymerase.

What is the role of reverse transcriptase in Retroviridae?

It converts RNA into DNA that integrates into the host chromosome as a provirus.

What are the five stages of viral replication?

Attachment, penetration, synthesis, maturation (assembly), and release.

What is the difference between the lytic and lysogenic viral cycles?

The lytic cycle involves immediate replication and host cell death; the lysogenic cycle involves the viral genome remaining latent or integrated as a prophage.

According to the lecture, what percentage of cancers are associated with viral infection?

About $15$ percent.

Which viruses are specifically linked to liver cancer and cervical cancer?

Hepatitis B and C are linked to liver cancer; Human papillomavirus (HPV) is linked to cervical cancer.

What is a prion and what type of diseases does it cause?

An infectious misfolded protein that causes transmissible spongiform encephalopathies like Mad Cow disease and Creutzfeldt-Jakob disease.