Micro HW 2

catabolism vs anabolism

Catabolism breaks down compounds to release their energy; anabolism uses energy to make compounds.

Why would a cell ferment rather than respire?

There is no oxygen present and it cannot use anaerobic respiration OR it lacks the ability to respire (i.e., no electron transport chain).

Most enzymes function best at

slightly above pH 7 and low salt concentrations.

The sugar component of RNA and DNA nucleotides is synthesized

as ribose and then changed to deoxyribose.

Your brother has a bacterial infection. He tells you he going to the gym where he plans to sit in the sauna for an hour. He thinks that this will cure his infection, because the heat in the sauna will denature the enzymes of the bacteria making him ill. You are a nursing student who is currently studying microbiology. You tell him that

his plan won't work; homeostasis will keep his body temperature constant even in the sauna, so the bacteria (and his normal microbiota and body cells) will not be impacted.

Environmental factors that may affect enzyme activity include

temperature, pH, AND salt.

Which of the following does/ do NOT affect enzyme activity?

Temperature AND humidity

Glycolysis, the Entner-Duodoroff pathway, and the pentose phosphate pathway all produce

pyruvate

Enzymes speed up reactions by

lowering activation energy

An early attempt by Cohn at bacterial classification grouped bacteria according to their

shape

From most general to most specific, which is the correct order?

Kingdom, phylum, class, order, family, genus, species

Which technique(s) is/are used to help identify and classify bacteria?

• Microscopic examination

• Culture characteristics

• Biochemical tests

• Nucleic acid analysis

Very often clinically relevant information may be obtained by examining

a wet mount AND the size and shape of the organism.

Gram-positive encapsulated diplococci found in sputum are likely

Streptococcus pneumoniae

Intracellular Gram-negative diplococci found in a urethral sample from a male is indicative of

Neisseria gonorrhoeae.

Media that change color as a result of the biochemical activity of growing bacteria

usually contain a pH indicator.

If an acid-fast bacterium is detected in a clinical sample, then the organism could be

Mycobacterium leprae

You are a lab technician processing patient samples. You perform a Gram stain on the sample and observe chains of spherical purple cells. From this you can conclude that

the sample contains a streptococcus and additional identification is needed

You are a lab technician processing a patient sample taken from a throat swab. You have performed a Gram stain and observed chains of purple spherical cells. A catalase test is positive. Colonies on blood agar are β-hemolytic. From these results you can conclude that

the sample does NOT contain Streptococcus pyogenes

Nucleic acid techniques have great power as diagnostic tools because they may be

used to differentiate species.

DNA probes have been very useful in

identifying organisms in pure culture.

Why are molecular methods particularly useful for identification of microbes that are difficult to grow?

Since all microbes have DNA, and we can often detect and identify them through even very small amounts of their DNA, molecular methods allow us to identify microbes even when they can't be grown at all.

Sequencing of rRNA is useful for

determining evolutionary relationships AND identification of unknown bacteria.

When DNA probes are used to identify bacterial DNA similarities by hybridization, the probe DNA is heated and the template DNA is treated to separate the two strands. Why would the probe DNA be heated?

The probe may contain parts that are double-stranded. Heating it up breaks the hydrogen bonds holding the strands together, creating single-stranded sequences that hybridize with their complementary targets.

Members of the genus Mycoplasma have no cell wall, making them somewhat unique in the microbial world. How do they prevent osmotic lysis?

Their cytoplasmic membrane is rich in sterols to help provide added strength and rigidity.

Modern approaches to evolutionary taxonomy often involve

comparison of DNA or RNA.

The more closely related two organisms are,

the more similar their nucleic acid sequence

PCR requires all of the following EXCEPT

DNA ligase

During PCR, which primer anneals to DNA with its 3' end toward the center of the sequence to be amplified?

Both the forward primer and the reverse primer.

Which of the following is unlikely to be the recognition site of a restriction endonculease?

GCTTGC
CGAACG