Carbohydrates

*energy storage *cell structure *cell communication

3 functions of polysaccharides

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?

Cholesterol is the precursor for many important molecules such as sex hormones.

Glycogen

Example of animal polysaccaride?

Cellulose

Example of plant polysaccaride?

Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them?

For carbon skeletons of equal length, saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols do.

* Cellulose molecules are polymers of beta-glucose, whereas amylose molecules are polymers of alpha-glucose *In Cellulose, every other glucose molecule is turned "upside down" and every other glycosidic linkage is above the plain of the glucose molecules; in amylose all the glucose molecules are "right-side up" and all of the glycosidic linkages are below the plain of the glucose molecules *A single cellulose molecule can form hydrogen bonds with other cellulose molecules; an amylose molecule cannot form hydrogen bonds with other amylose molecules

Humans possess enzymes such as amylase, which can catalyze the breakdown of starches such as amylose. In contrast, animals do not possess enzymes that can catalyze the breakdown of cellulose. Thus, any cellulose that Humans consume passes through the digestive tract as fiber. The inability of humans to break down and digest cellulose is the result of cellulose's chemical structure. How does the structure of a cellulose molecule differ from that of a starch molecule such as amylose?

Glycosidic linkage

Maltose is a disaccharide that consists of two molecules of glucose. A covalent bond links carbon number 1 of the first glucose molecule to an oxygen atom, which is then linked to carbon number 4 of the second molecule of glucose by a covalent bond. This pair of covalent bonds, which links the two molecules of glucose by way of an oxygen atom, is referred to as a...

Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)?

Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar.

Glycogen is highly branched molecule, whereas amylose consists of an un-branched chain of glucose molecules

Plants use starch molecules such as amylose to store glucose molecules that are synthesized by photosynthesis. Animals store glucose (that is ultimately obtained from the consumption of plants) in more complex molecules such as glycogen. How does the structure of a glycogen molecule differ from the structure of an amylose molecule?

Amylase is an enzyme that breaks down starch. Why cannot the same enzyme break down cellulose?

The monosaccharide monomers in cellulose are bonded together differently than those in starch.

Glycosidic linkages

The reaction between multiple molecules of alpha glucose form 1-4 ______?

glycosidic linkages

The subunits (monomers) in cellulose are linked together by __________.

False

True or false? Starch molecules such as amylose are synthesized by hydrolysis reactions.

True

True or false? Sucrose (table sugar) is a disaccharide that consists of a molecule of glucose linked to a molecule of fructose. The covalent bond that links these two molecules is essentially identical to the covalent bond that links two molecules of glucose in maltose. The only difference is the identity (number) of the carbon atoms that are linked.

True

True or false? Sucrose is made naturally by plants such as sugar cane and sugar beets.

True

True or false? α-glucose is a common monosaccharide that is the primary energy source for cellular respiration, as well as the building block for polysaccharides such as starch and glycogen

True

True or false? β-glucose is a common monosaccharide that is the building block of cellulose

Spiral

When multiple Alpha glucose bond, the shape is more _____?

Linear

When multiple beta glucose bond, the glycosidic linkages tend to be more _____?

The hydroxyl group on carbon number one is oriented below the plane of the molecule

Which statement (or statements) accurately describes the structure of a α-glucose molecule?

The hydroxyl group that is bonded to carbon number one is oriented above the plain of the molecule

Which statement (or statements) accurately describes the structure of a β-glucose molecule?

f a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __________.

a charged or polar end and an uncharged or nonpolar end

Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least?

cellulose (in the lettuce)

Carbohydrates are used in our bodies mainly for __________.

energy storage and release

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________.

ester linkages

A polysaccharide that is used for storing energy in human muscle and liver cells is __________.

glycogen

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the a form. Which of the following could amylase break down?

glycogen, starch, and amylopectin

The fatty acid tails of a phospholipid are __________ because they __________.

hydrophobic ... have no charges to which water molecules can adhere

The sex hormones estradiol and testosterone belong to which class of molecules?

lipids

The lipids that form the main structural component of cell membranes are __________

phospholipids

The polysaccharide that you are most likely to have eaten recently is __________.

starch

Carbohydrates can function in which of the following ways?

structural support and energy storage

The overall three-dimensional shape of a single polypeptide is called its __________

tertiary structure