Help with Compound Macromolecules

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GRE Subject Test: Biochemistry, Cell, and Molecular Biology › Help with Compound Macromolecules

Questions 1 - 1

Glycogen is a polymer of glucose that is held together by __________ bonds. The branch points are held together by __________ bonds.

$\alpha\ \text{1-4}\ .\ .\ .\ \alpha\ \text{1-6}$

$\alpha\ \text{1-6}\ .\ .\ .\ \alpha\ \text{1-4}$

$\beta\ \text{1-4}\ .\ .\ .\ \beta\ \text{1-6}$

$\beta\ \text{1-6}\ .\ .\ .\ \beta\ \text{1-4}$

Explanation

$\alpha\ \text{1-4}$ bonds are on the same plane, while $\alpha\ \text{1-6}$ bonds are not on the same plane; therefore, the $\alpha\ \text{1-6}$ bonds are much more useful for making branch points off of existing glycogen chains.

$\beta$ linkages cannot be easily broken down by eukaryotes and animals. Glycogen must be easily accessible as an energy source, and does not contain any $\beta$ glycosidic linkages.

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