Topic 13: Carbohydrate Catabolism

bacterial colony

In lab, presence of an exoenzyme is determined by looking for a change in the substrate outside of a(n) ________.

fermentative bacterium

Determination of oxidative or ________ can be done by using OF medium.

Catabolism

chemical reactions that release energy from the decomposition of complex organic molecules

Carboyhydrates can be classified based on size

monosaccharides, oligosaccharides, and polysaccharides

Monosaccharides

simple sugars containing three to seven carbon atoms

Oligosaccharides

composed of two to about twenty monosaccharide molecules

Polysaccharides

consist of eight or more monosaccharide molecules

Fermentative catabolism

do not require oxygen but may occur in its presence

OF medium

nutrient semisolid agar deep containing a high concentration of carbohydrate and a low concentration of peptone

two tubes used

one open to air and one closed to keep air out

contains bromthymol blue

turns yellow in presence of acids (indicates catabolism); turns dark blue in presence of alkaline conditions (indicates fermentation)

acids are produced as intermediates in respiration and indicator will turn yellow in the top of the open test tube

oxidative organism

What is catabolism?

chemical reactions that release energy from the decomposition of complex organic molecules

Why does most bacteria catabolize carbohydrates?

for carbon and energy

What are carbohydrates?

organic molecules that contain carbon, hydrogeb, and oxygen in the ratio (CH2O)n

How are carbohydrates classified by?

size

What are monosaccharides?

simple sugars containing 3 - 7 carbon atoms

What are oligosaccharides?

composed of 2 - 20 monosaccharide molecules

What are the most common oligosacchardies?

disaccharides

What are polysaccharides?

consist of 8+ monosaccharide molecules

Exoenzymes are mainly ___ enzymes that leave the cell and break down, by the addition of water, large substrates into smaller compoents, which can then be transported into the cell.

hydrolytic

What exoenzyme hydrolyzes starch into smaller carbohydrates?

amylase

What can be release by hydrolysis?

glucose

How is presence of exoenzyme determined in lab setting?

looking for a change in the substrate outside of a bacterial colony

Can glucose directly enter a cell?

yes

Glucose can be catabolized by endoenymes oxidatively producing ___ and ___.

carbon dioxide and water

What does oxidative catabolism require?

O2

What is difference between oxidative catabolism and fermentative catabolism?

oxidative requires O2 and fermentative does not require O2

Can fermentative catabolism occur in the presence of O2?

yes

What are the end products of fermentation?

organic acids and sometimes gases

In lab, what can be used to determine if bacterium is oxidative or fermentative?

OF medium

What is OF medium?

nutrient semisolid agar deep containing a high concentration of carbohydrate and a low concentration of peptone

Why is peptone present in OF medium?

supports growth of bacteria that doesn't use carbohydrate