BSCI 223 Lecture Notes - Lecture 1: Yeast Extract, Tryptone, Metabolic Pathway
SchoolUniversity of Maryland
DepartmentBiological Sciences Program
Course CodeBSCI 223
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A. Which medium would you consider to be Complex?
Which medium is Defined? Which medium is Rich?
Which medium is minimal? Explain your answers.
Medium #2 is defined (**could add NaCl and H2O or glucose
and it would still be defined) and minimal because it contains
only biochemical ingredients whereas 1 has the exception of
yeast extract. It contains polyurethane, a known nutrient for
ETPUM. It contains the minimal necessity for the bacteria’s
growth and only the aerobic ETPUM grew.
Medium #1 is complex (inclusion of 2 extracts- yeast and
tryptone) because the components include yeast extract and
carbon energy sources. It is also rich because it allows
growth for both the aerobic and anaerobic ETPUM. Possible
to be minimal and defined because it doesn’t grow in just
any condition- anaerobic did not grow.
B. Given that polyurethane is a huge polymer (MW
>>100,000 Daltons), why is it important that the
polyurethanase is a secreted enzyme? IF we assume
that the polyurethane is the source of energy for the
organism, how can material (carbon atoms) from it find
its way into the central metabolic pathways of this
microbe? What is the entry point ? What happens after
its entry into the metabolic pathway?
Polyurethanase is a secreted enzyme by the microbe in
order to break down polyurethane. Since the polymer is an
important source of energy for the organism, it needs to be
broken down in order for ETPUM’s growth. Metabolism is
controlled by enzymes. Carbon from the material enters
through the membrane, where proton motive force (PMF)
takes place by active transport with membrane proteins as
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