Carbohydrate Metabolism (Ivanov)

Question 1

Caries is the progressive destruction of mineralized tissues of the teeth (enamel, dentin, and cementum) initiated by ______ activity on ______ dietary carbohydrates at the _______.

Answer 1

-Microbial -Fermentable -Tooth surface

Question 2

Why is the molecular structure of carbohydrates important?

Answer 2

Structure determines whether it is fermentable

Question 3

The only nutrients that can be absorbed directly.

Answer 3

-Water -Inorganic salts -Vitamins -Certain lipids

Question 4

______ is the hydrolysis of complex foodstuffs to simpler components.

Answer 4

Digestion

Question 5

______ is the process by which the products of digestion are transported from the lumen of the intestine into the intestinal epithelial cells (and ultimately the circulatory system).

Answer 5

Absorption

Question 6

The pH of saliva is…

Answer 6

Close to neutral pH (6.4 - 7.3)

Question 7

Saliva moistens food. Particularly important are _____ which are glycoproteins which are approximately 60% by weight carbohydrate; very viscous and help disperse the solid into a form that can be more readily digested.

Answer 7

Mucins

Question 8

Saliva contains ______, which initiates the hydrolysis of glycogen and starches by catalyzing the hydrolysis of a-1,4 glycosidic bonds.

Answer 8

Amaylase

Question 9

Why do carbohydrates play a dominant role (compared to other nutrients) in caries formation?

Answer 9

• Readily available (most of energy)
• Simple carbohydrates can be directly absorbed by bacteria in the mouth
• Amaylase helps to release mono- and disaccharides from complex polysaccharides
• Acid is released during carb. fermentation by mouth microbes
• Sucrose is used in the synthesis to exopolysaccharides, a key component of bacterial biofilms

Question 10

Carbohydrate processing enzymes secreted by S. mutans

Answer 10

Question 11

Movement down a concentration gradient; requires neither a membrane “transporter” nor a source of energy (such as ATP or an ion gradient)

Answer 11

Simple Diffusion

Question 12

Movement down a concentration gradient; requires a membrane “transporter”, but not a source of energy (such as ATP or an ion gradient)

Answer 12

Facilitated Transport

Question 13

Movement against a concentration gradient; requires both a membrane “transporter” and a source of energy (such as ATP or an ion gradient)

Answer 13

Active Transport

Question 14

Can carbs be absorbed by simple diffusion?

Answer 14

No

Question 15

Modes of active transport of sugars in S. mutans

Answer 15

Question 16

Breakdown, capture “energy” in various biochemical intermediates or “carriers”

Answer 16

Catabolic Processes

Question 17

Synthesis, expend “energy” in various biochemical intermediates or “carriers” to enable biosynthesis

Answer 17

Anabolic Processes

Question 18

ATP synthesis ______ significant free energy; ATP hydrolysis ______ significant free energy. ATP is the universal short-term storage of chemical energy in biology.

Answer 18

-Requires -Yields

Question 19

Reactions in which there is a net transfer of electrons from one species to another.

Answer 19

Reduction-Oxidation (Redox)

Question 20

The species that gives up electrons

Answer 20

Reductant

Question 21

The species that takes up electrons

Answer 21

Oxidant

Question 22

Pyridine Nucleotides

Answer 22

NAD+/NADH NADP+/NADPH

Question 23

Glycolysis pathway splits glucose into _______.

Answer 23

Two molecules of pyruvate

Question 24

Pyruvate is converted to _______ by ______.

Answer 24

-Acetyl-CoA -Pyruvate dehydrogenase complex

Question 25

In the Citric Acid Cycle the acetyl group of Acetyl-CoA is converted into ____ and the energy is harvested by converting ____ to ______.

Answer 25

-CO2 -NAD+ to NADH

Question 26

The Electron Transfer Chain and the Oxidative Phosphorylation pathways pass electrons from ______ to _____ and use the energy to synthesize ATP.

Answer 26

NADH to oxygen

Question 27

Glycolysis under anaerobic conditions

Answer 27

Pyruvate is converted to lactate which is excreted from cells as lactic acid

Question 28

Phosphoglucoisomerase

Answer 28

-Reversible reaction (means that ΔGo´ is close to 0) -F-6-P is NOT irreversibly “committed” to the glycolytic pathway

Question 29

Phosphofructokinase (PFK)

Answer 29

-Irreversible reaction; catalyzes the “committed” step in the pathway -Important regulatory enzyme; regulated allosterically in the following manner: -Stimulated by AMP and ADP -Inhibited by ATP and Citrate

Question 30

Pyruvate Kinase

Answer 30

-Irreversible reaction (ΔGo´ = -7.5 kcal/mol). Thermodynamically this “pulls” the series of reactions from F-1,6-bisP to pyruvate -Regulates the pathway -Activated by AMP, ADP, F-1,6-bisP -Inhibited by ATP

Question 31

Glucan synthesis by ______ is required for biofilm formation.

Answer 31

Glycosyltransferases

Question 32

Secreted ftf and fruA enzymes may be used by S. mutans to ________ in the biofilm

Answer 32

Store carbohydrates