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Flashcards in Rhizobium Deck (15):

What do you put in the petrie dish for the first step

2 drops of water and one drop of 70% alcohol


What is the first thing you do with the nodule and why?

Roll it around in one of the drops of water to remove soil


After removing the soil from the nodule what do you do with it why?

Transfer it to the 70% alcohol causing the bacteria of the surface of the nodule to crenate


After putting the nodule in the alcohol what is the next thing you do and why?

Rinse it in the second drop of water to remove alcohol


What is the last thing you do with the nodule

Place it on a slide, and squeeze it with the forceps to release the bacteroids and smear it around


What do you stain the slide with?

Carbol fuchsin


What are the cells shaped like?

Unusually shaped like clubs or the letters "V" or "Y"


What are the 2 purposes?

1. To understand how bacteria are the sole source of fixed nitrogen
2. Identify bacteroids from a root nodule


What is nitrogen fixation?

Provides plants with nitrogen in a form that they can use


What are the two chemicals that gaseous nitrogen (N2) can convert to?

Ammonium (NH4+) & Ammonia (NH3)


How are Rhizobium and certain plants in a symbiotic relationship?

The plant provides nutrients and protection (nodule) for the bacteria and the bacteria provides NH3 to the plant


Why does the Rhizobium bacterium have a unique appearance?

Because it is growing in the nodule so the bacteria has a altered cell wall


What is the only environment nitrogen fixation can occur in and why?

An anaerobic environment because the enzymes involved in converting N2 to NH3 can only function without O2


How does the nodule of the bacteria establish an anaerobic environment?

The plant and the bacteria work together to make a molecule called leghemoglobin


What turns the nodules pink and why?

The leghemoglobin (it turns pink when it binds to O2)