Chocolate Agar Composition and Preparation
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Questions and Answers

What specific temperature and pressure conditions are required for sterilizing Blood Agar?

Blood Agar must be sterilized at 15 lbs pressure and 121°C.

Why is mammalian blood added to the medium at a temperature of 80-85°C?

Mammalian blood is added at this temperature to prevent destruction of the blood cells while ensuring they have been lysed.

What is the primary use of Chocolate Agar in microbiology?

Chocolate Agar is primarily used for the isolation and cultivation of fastidious microorganisms, such as Haemophilus influenzae.

What distinguishes Chocolate Agar from regular Blood Agar?

<p>Chocolate Agar is distinguished by its brown coloration, which results from lysed red blood cells, while regular Blood Agar maintains its red color.</p> Signup and view all the answers

Name two control organisms that are typically tested on Chocolate Agar and their significance.

<p>The control organisms are Haemophilus influenzae and Neisseria gonorrhoeae, indicating good growth on the medium.</p> Signup and view all the answers

What is the main purpose of adding heated mammalian blood to Chocolate Agar?

<p>The main purpose is to provide nutrients and growth factors for fastidious microorganisms.</p> Signup and view all the answers

At what temperature should the mammalian blood be added to Chocolate Agar during preparation?

<p>Mammalian blood should be added at a temperature of 80-85°C.</p> Signup and view all the answers

Why is Chocolate Agar named so if it does not contain chocolate?

<p>It is named for its chocolate-brown coloration resulting from the lysis of red blood cells.</p> Signup and view all the answers

What is one characteristic of the organisms that can be cultivated on Chocolate Agar?

<p>They are typically fastidious microorganisms, such as respiratory bacteria.</p> Signup and view all the answers

What is the initial step in preparing Chocolate Agar before adding blood?

<p>The initial step is to dissolve Blood Agar in boiling distilled water.</p> Signup and view all the answers

Chocolate Agar contains heated mammalian ______, typically at a concentration of 5-10%.

<p>blood</p> Signup and view all the answers

The procedure for making Chocolate Agar includes autoclaving at 15lbs pressure, 121°C for ______ minutes.

<p>15</p> Signup and view all the answers

After adding blood at 80-85°C, the mixture is cooled to ______ °C before pouring into sterile Petri plates.

<p>45-50</p> Signup and view all the answers

Chocolate Agar is used for the isolation and cultivation of fastidious microorganisms, such as ______ influenzae.

<p>Haemophilus</p> Signup and view all the answers

No chocolate is actually contained in the plate; it is named for its ______.

<p>coloration</p> Signup and view all the answers

Flashcards

Chocolate Agar Composition

A blood agar medium with heated mammalian blood (usually sheep or horse), typically 5-10%.

Chocolate Agar Preparation

Dissolve 40g of blood agar in 1000ml distilled water, boil completely, sterilize by autoclaving, and add heated blood.

Blood Heating Temperature

Heat blood to 80-85°C to lyse blood cells.

Chocolate Agar Use

Used to cultivate fastidious microorganisms, like respiratory bacteria (Haemophilus influenzae).

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Chocolate Agar's Name Origin

Named for the color, not containing chocolate.

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What makes Chocolate Agar special?

It's a blood agar with heated mammalian blood, typically 5-10%, which gives the medium its characteristic brown color.

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Why heat the blood?

Heating the blood to 80-85°C lyses (breaks open) the red blood cells, which releases growth factors needed by certain bacteria.

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What are fastidious microorganisms?

Bacteria like Haemophilus influenzae that require special nutrients found in blood agar to grow.

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How to prepare Chocolate Agar?

Dissolve 40g of blood agar in 1000ml water, heat to boiling, sterilize using autoclaving, then add heated blood.

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What is Chocolate Agar used for?

Cultivating fastidious bacteria like Haemophilus influenzae.

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What is Chocolate Agar?

Chocolate agar is a type of blood agar that contains heated mammalian blood, typically 5-10%. It's used to grow picky bacteria like Haemophilus influenzae.

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Why is it called 'Chocolate' Agar?

The name comes from the medium's brown color, not because it contains chocolate. The color comes from the heated blood.

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How is Chocolate Agar made?

It's prepared by dissolving blood agar in water, boiling it, sterilizing it, and then adding heated blood at a specific temperature.

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What is the purpose of heating the blood?

Heating the blood lyses (breaks open) red blood cells, releasing essential growth factors for certain bacteria like Haemophilus influenzae.

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What bacteria grow well on Chocolate Agar?

Chocolate agar supports the growth of fastidious bacteria like Haemophilus influenzae and Neisseria gonorrhoeae.

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Who grows well on Chocolate Agar?

Fastidious organisms like Haemophilus influenzae, requiring special nutrients found in heated blood.

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What's the purpose of heated blood?

Heating the blood lyses (breaks open) red blood cells, releasing growth factors needed by bacteria like Haemophilus influenzae.

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Study Notes

Chocolate Agar Composition

  • Contains heated mammalian blood (typically sheep or horse), usually 5-10%.

Preparation Procedure

  • Dissolve 40g of blood agar in 1000ml distilled water by heating to boiling.
  • Sterilize by autoclaving at 15lbs pressure, 121°C for 15 minutes.
  • Add 5-10% mammalian blood at 80-85°C (blood cells lysed at 56°C).
  • Cool the mixture to 45-50°C and pour into sterile Petri dishes.

Purpose

  • Used to isolate and cultivate a range of fastidious microorganisms, including respiratory bacteria like Haemophilus influenzae.

Naming

  • Named for its brown or "chocolate" color, no actual chocolate is present.

Control Organisms

  • Haemophilus influenzae and Neisseria gonorrhoeae show good growth on chocolate agar.

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Description

This quiz covers the composition and preparation of chocolate agar, a specialized medium used for isolating fastidious microorganisms. Learn about the procedure and purpose behind its use, as well as the control organisms commonly tested on this agar. Enhance your understanding of this critical laboratory process.

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