Microbiology Quiz 1

Taken from quiz questions from quiz 1

If a microscope can magnify 100-times, which of the following microbes could be seen in it? (Choose all that are correct.) Explain why
A. 0.5 µm bacterium

B. 1 µm bacterium

C. 2 µm bacterium

D. 5 µm µm

B, C & D | Minimum visible size = 200 µm ÷ 100 = 2 µm. So only bacteria ≥ 2 µm are visible (2 µm and 5 µm). Smaller ones (0.5, 1 µm) magnify to under 200 µm, so the eye still can't resolve them.

Cells of the following Domains have nuclei (choose all that are correct)?

A. Eukarya

B. Bacteria

C. Archaea

D. Prokarya

A. Eukarya

Based on our present understanding, which statement is probably true? (Choose one.)

A.Bacteria and Archaea diverged from a Eukarya ancestor.

B. Bacteria and Eukarya evolved from an archaeal ancestor.

 C. Bacteria and Eukarya evolved from one line; Archaea had a totally different ancestor.

 D. Bacteria, Archaea, and Eukarya all diverged from a common universal ancestor or community of organisms.

D. Bacteria, Archaea, and Eukarya all diverged from a common universal ancestor or community of organisms.

Which domains contain microbes? (Choose all that are correct.)

Bacteria

Archaea

Eukarya

All of the above

Which of the following contain prokaryotic cells? (Choose one.)

 

Bacteria and fungi

Archaea and fungi

Protozoa and animals

Bacteria and Archaea

Bacteria and Archaea

Ribosomal RNAs can be used to study phylogenetic relationships between organisms. (True or false?) and why?

True:

1. Because it is functionally universal, every cell has it

2. It is functionally critical so it changes very slow. Because the ribosomes job is translation any mutations to rRNA are lethal and is weeded out by selection making it highly conserved

3. It has both conserved and variable regions. This means there are parts of the rRNA molecule that contain parts you can find in all life on earth, alongside parts that are more variable among species. the conserved regions allow you to compare sequences from completely different organisms and the variable regions allow you to tell organisms apart from one another

4. It is not transferred horizontally, meaning it is passed down from parent to offspring matching true ancestry.

You have isolated a new organism that is a small coccus-shaped bacterium that stains purple in a gram stain. Based on this, the most likely identification of the cells is __________. 

Gram Positive bacteria.

After penicillin treatment, growing cells would lyse ...

In hypotonic medium.

A mutant lacking LPS is sensitive to detergents and hydrophobic molecules because ...

LPS (lipopolysaccharide) coats the outer surface of a gram-negative outer membrane, and it’s sugar portion is hydrophilic. Molecules and detergents that are hydrophilic cannot easily pass through a hydrophilic layer (like dissolves like). The LPS layer acts as a chemical shield that repels hydrophobic molecules/detergents. If you remove that shield the membrane can be easilt disrupted.
Two misconceptions: LPS does not block things based on size, it repels things based on its hydrophilic chemistry. LPS and porins are not the same thing, porins are a protein chamber, while LPS itself does not have any pore like structures.

Mycolic acids add a __________ coating to the outside of bacterial cells. (Choose all that are correct.)
Waxy

Phospholipid

Protein

Waxy

How does the cytoplasmic membrane differ between Bacteria and Archaea? (Choose all that are correct.)

The glycerol-lipid linkage

Branching within the lipid portion

Using a bismuth group instead of a phospho group

Archaea use sugars instead of phospholipids

The glycerol-lipid linkage

Branching within the lipid portion

Cytoplasmic membranes are found in members of which of the three domains? 

Bacteria

Archaea

Eukarya

All three

Prokaryotic chromosomes are generally linear. (True or false?)

A: False. Prokaryotic (bacterial/archaeal) chromosomes are generally a single circular loop of DNA. Linear chromosomes are the eukaryotic pattern. (This is also why an incoming piece of transformed DNA needs its own origin of replication — the circular chromosome has one, and stray linear DNA without one won't get copied.)

How is the prokaryotic nucleoid different from the eukaryotic nucleus? (Choose all that are correct.)

It is condensed

It is supercoiled

It is circular

It lacks a membrane boundary

It is because it lacks a membrane boundary. It is a defining difference because eukaryotic is enclosed in a nuclear membrane, while prokaryotes do not havw that.

A bacterium with a larger genome would encode __________ genes than one with a small genome, and would likely be able to thrive in __________ diverse environments. (more or less)

More, More

The generation time of a microbe that doubles 6 times in 24 hours is:

4 hours: generation time | g = t/n

Human pathogens are generally considered ...

Psychrophiles

Mesophiles

Thermophiles

Hyperthermophiles

Mesophiles

What is the starting material for PHB granules?

Acetyl-CoA

Which of the following are considered building blocks? (Choose all that are correct.)

Fatty acids

Amino acids

Proteins

Nucleotides

Sugars

Fatty acids, Amino acids, Nucleotides, Sugars

Which of the following are considered fueling products? (Choose all that are correct.)

ATP

NADH

Pyruvate

Pentose-5-Phosphate

Amino acids

ATP, NADH, Pyruvate, Pentose-5-Phosphate

What is the Delta Gº’ of the reaction: ADP + Pi > ATP?

 

+31 kJ/mol

The process in which pyruvate is reduced into compounds such as ethanol and lactate is known as:
Also give an explanation of how it works

Fermentation | Fermentation reduces pyruvate to ethanol or lactate in order to regenerate NAD⁺, letting glycolysis (and its ATP production) continue without oxygen. Little ATP, anaerobic, waste products.

What sources of energy can be used by an organism? (Choose all that are correct.)

Organic chemicals

Inorganic chemicals

Light

Radiation

Organic chemicals, Inorganic chemicals, Light

Which of the following can be used as terminal electron acceptors for anaerobic respirations? (Choose all that are correct.)

Sº

NO₃^-

O₂

Fe3+

Fumarate

Sº NO₃^- Fe3+, Fumarate

Which of the following are properties of 16S rRNA that make it useful for microbial classification? (Choose all that apply.)

 

Occurs in all organisms

Functions as part of the ribosome in all cell

Has variable and conserved regions

Interacts with the Shine Dalgarno sequence

Mutations occur at a steady rate

Occurs in all organisms

Functions as part of the ribosome in all cells

Has variable and conserved regions

Mutations occur at a steady rate

What is the evolutionary distance between these sequences:

Microbe X:     AGGUACGUUACCTAT  

Microbe Y:     UGGUACGGUUCCTAT

Also what is the formula?

20, distance = number of differing positions/total positions * 100. There are 15 positions 3 differences here so 3/15 times 100 = 20

Which of the following will improve your ability to see microbes in the microscope. (Choose all that are correct.)

Use a microscope with any magnification possibilities

Stain the cells

Use very dilute samples, with less than 1000 microbes/mL

Microbes are only in human feces, so only use that as a source

Stain the cells

Lipopolysaccharide (LPS) is located on

 

The outer leaflet of the outer membrane

Prokaryotic cell membranes contain many kinds of proteins (about 70% of the mass of the membrane). What are some of the functions of these proteins?

Transport

Environmental sensing proteins

ATPase

Electron transport chain

What keeps the DNA in a prokaryotic cell nucleoid in an organized and condensed form? (Choose all that are correct.)

 

Cations and DNA binding proteins

Which of these is not found in any prokaryotic cell?

Plasmids that are stably inherited

Storage granules containing DNA

Circular DNA with regulated supercoiling

Membrane-enclosed magnetosomes

Gas vesicles surrounded by protein shells

 

Storage granules containing DNA

Fermentations utilize the electron transport chain. (True or false?)

False: Fermentation does not use the electron transport chain. It regenerates NAD⁺ by reducing pyruvate directly to a waste product (ethanol or lactate). The ETC is used by respiration (aerobic and anaerobic), where electrons are passed to a terminal acceptor — that's the very thing that separates respiration from fermentation.

A cell that uses carbon dioxide as its source of cell carbon is a(n) __________.

An autotroph