Chapter 4 questions

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Tunxis Summer 2012

Which of the following is not found in all bacterial cells?

a. cell membrane
b. a nucleoid
c. ribosomes
d. actin cytoskeleton

d. actin cytoskeleton

Pili are tubular shafts in _____ bacteria that serve as a means of _____.

a. gram-positive, genetic exchange
b. gram-positive, attachment
c. gram-negative, genetic exchange
d. gram-negative, protection

c. gram-negative, genetic exchange

An example of a glycocalyx is

a. a capsule
b. a pilus
c. an outer membrane
d. a cell wall

a. a capsule

Which of the following is a primary bacterial cell wall function?

a. transport
b. motility
c. support
d. adhesion

c. support

-shape, support for osmotic pressure changes,

Which of the following is present in both gram-positive and gram negative cell walls?

a. an outer membrane
b. peptidoglycan
c. teichoic acid
d. lipopolysaccharides

b. peptidoglycan

Bacterial endospores usually function in

a. reproduction
b. survival
c. protein synthesis
d. storage

b. survival

T/F
One major difference in the envelope structure between gram+ and gram- bacteria is the presence or absence of the cytoplasmic membrane.

False.
Gram+: two layers = a thick peptidoglycan cell wall + cytoplasmic membrane
Gram-: three layers = an outer membrane (LPS), a thin cell wall (peptidoglycan) and a cytoplasmic membrane

T/F
A research microbiologist looking at evolutionary relatedness between two bacterial species is more likely to use Bergey's Manual of Determinative Bacteriology than Bergey's Manual of Systematic Bacteriology.

False.
Determinative = phenotypic characteristcs
Systematic = prokaryotic relatedness/evolution

T/F
Nanobes may or may not actually be bacteria.

True.

T/F
Both bacteria and archaea are prokaryotes.

True.

T/F
A collection of bacteria that share an overall similar pattern of traits is called a species.

True.

Compare cell envelopes of gram+/- bacteria

Gram+: two layers = a thick peptidoglycan cell wall + cytoplasmic membrane
Gram-: three layers = an outer membrane (LPS), a thin cell wall (peptidoglycan) and a cytoplasmic membrane

What function does peptidoglycan serve?

It gives strong/flexible support to the cell -- it also gives support for osmotic pressure changes to prevent lysis

Give a simple description of peptidoglycan.

A macromolecule composed of repeating, long glycan (sugar) chains cross-liked by short peptide (protein) fragments

What happens to a cell that has its peptidoglycan disrupted or removed?

No protection from lysis

What functions does the LPS layer serve.

- polysaccharide chains extending off its surface function as antigens and receptors
- outer membrane serves as a partial chemical sieve by allowing only relatively small molecules to penetrate (porin proteins)
- protection: the pepditoglycan layer is protected by the LPS layer so most antibiotics don't work

Draw and label 3 bacterial shapes

Coccus, rod/bacillus, Spirillium/spirochete

What is the prefix used for bacteria arranged in chains? in groups?

· Prefix diplo- cell arranged in pairs
· Prefix staphylo- cells arranged in clusters
· Prefix strepto- refers to bacteria arrange in chains

How are spirochetes and spirilla different?

Spirillum = slightly curled or spiral-shaped cylinder twisted twice or more along its axis
Spirochete = more flexible form that resembles a spring; smaller & thinner

What is a coccobacillus? a vibrio?

Coccobacillus is a rod that is short and plumb
Vibrio is a rod that is gently curved

What is pleomorphism?

Cells of a single species that vary in shape and size...due to individual variations in cell wall structure caused by nutritional or slight genetic differences

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